A novel way to massively improve the SQ of computer audio streaming

[auricgoldfinger]

9 minutes ago, austinpop said:

Resolution

 

This was an artifact of the lowered noise floor of this PSU. PGGB dovetails into this beautifully. Because PGGB reveals so much more low-level nuance in the music, the deployment of a PSU that lowers the noise floor allows that nuance to come through. I was hearing details and cues I hadn't previously. This was particularly evident in my PGGBed version of Solti's Mahler 8th, where I could hear individual instruments even during full-throated orchestral passages. 

 

 

Excellent post, Rajiv!  I'm curious...if you were at a live performance of Solti's Mahler 8th, would you be able to hear individual instruments during full-throated passages, or is that a function of listening to PGGBed files through your headphones?

[ray-dude]

9 minutes ago, austinpop said:

The net impact of all these areas of improvement was that I just could not get enough of the DC4 ARC6 while it was here at chez austinpop! Every listening session has gone deep into the night, and has taken a remarkable amount of willpower to end. Suffice it to say, I'm a bit sleep-deprived and very depressed to be packing this thing up and sending it on to Roy and Ray for the remainder of its grand tour.

 

Great write up Rajiv!

 

Having had prototype components strewn all over my living room and dining room for 6 months, stepping backwards to my DC3 was a very very difficult thing to do.  Can't wait to hear the pre production units and some of that ARC6 magic again!

 

For DC4 owners, be prepared for an absolutely stunning lift to whatever impact DC4 has in your chain.  Pretty remarkable, esp. with a device that scales like the Chord DAVE.

[austinpop]

12 minutes ago, auricgoldfinger said:

 

Excellent post, Rajiv!  I'm curious...if you were at a live performance of Solti's Mahler 8th, would you be able to hear individual instruments during full-throated passages, or is that a function of listening to PGGBed files through your headphones?

 

Thanks for calling out my sloppy phrasing, Brian! You're correct, that's not what I was trying to convey. Here is my edited sentence:

 

...where I could hear instrument groups as a collection of individual instruments, rather than a homogeneous whole, even during full-throated orchestral passages. 

[austinpop]

33 minutes ago, ray-dude said:

 

Great write up Rajiv!

 

Having had prototype components strewn all over my living room and dining room for 6 months, stepping backwards to my DC3 was a very very difficult thing to do.  Can't wait to hear the pre production units and some of that ARC6 magic again!

 

For DC4 owners, be prepared for an absolutely stunning lift to whatever impact DC4 has in your chain.  Pretty remarkable, esp. with a device that scales like the Chord DAVE.

 

Kudos to you guys for all your experiments! I'm only hearing the end result, whereas you guys put in the work to suss out different alternatives. The end result is quite stunning.

[BOBO]

Has anyone managed to get their hand on the LTSC version from the Taiko Audio server ?

or does anyone have access to one of their devices to share it with us ?

[Vivling2021]

On 1/29/2021 at 2:05 AM, guiltyboxswapper said:

Needs to be either the -onload or -plus versions to utilise onload, but you can compile and run the onload driver (without full blown onload) and still reap some benefits.  Certainly sounded better than out of the box driver (one included in kernel).

I am using euphony and thinking about buying a solarflare 8522 onload. How to install such a driver to enable unload(ultra low latency) under euphony?  would this "kernal bypass" function hurt or benefit sound quality? Thanks!

[guiltyboxswapper]

1 hour ago, Vivling2021 said:

I am using euphony and thinking about buying a solarflare 8522 onload. How to install such a driver to enable unload(ultra low latency) under euphony?  would this "kernal bypass" function hurt or benefit sound quality? Thanks!

Contact Euphony team, they'll work with you to enable Onload (they have the packages ready to go).  

[Vivling2021]

37 minutes ago, guiltyboxswapper said:

Contact Euphony team, they'll work with you to enable Onload (they have the packages ready to go).  

Message:

We tried compiling Onload drivers for our system several months ago but it didn't work. Not sure if and when we will try again.

Regards,
Željko

 

Just contacted, unfortunatly no.  I wonder how much of an improvement of "Onload" would provide anyway. maybe it could even hurt sound quality by taking up too much CPU resources?   maybe I will just get a 2522

[Gavin1977]

Onload is apparently worthwhile, I haven’t tried to though - happy with 8522 as stock in Windows.  You can load onload in audiolinux and Gentoo player.

[Vivling2021]

I think euphony has some SQ advantage over audiolinux and I am used to it.  So won’t change the system to accommodate onload for now. 
 

I ordered the 2522 on eBay for a good price.  It is a 25g card so maybe it has a better clock than 8522?     
 

The seller did a quick test, does anyone know that this is a 2522 basic or 2522 onload?   the screenshot shows the latency is less than 1ms. 

[seeteeyou]

Yours seemed to be showing "Installed keys 0" so that should be the cheaper model without Onload at all.

 

The ones with Onload would display "Installed keys Plus" as shown below

 

https://www.aliexpress.com/item/1005001708504396.html

 

Even open box ones would cost $550 a piece

 

https://www.ebay.com/itm/194115170400

 

In other words, you'll get what you're paying for IMHO.

[Vivling2021]

39 minutes ago, seeteeyou said:

Yours seemed to be showing "Installed keys 0" so that should be the cheaper model without Onload at all.

 

The ones with Onload would display "Installed keys Plus" as shown below

 

https://www.aliexpress.com/item/1005001708504396.html

 

Even open box ones would cost $550 a piece

 

https://www.ebay.com/itm/194115170400

 

In other words, you'll get what you're paying for IMHO.

I got it for 180 dollars. so it must be the basic version. The latency seems be less than 1ms, very low already, so i am happy. will do some reviews when I received it.

[Chopin75]

On 7/13/2021 at 12:24 PM, auricgoldfinger said:

 

Excellent post, Rajiv!  I'm curious...if you were at a live performance of Solti's Mahler 8th, would you be able to hear individual instruments during full-throated passages, or is that a function of listening to PGGBed files through your headphones?

For Mahler 8 I think you really need surround

Sound 5.1 to do that. Almost always have congestion with stereo 2 speakers or headphones. Try a SACD or surround music files and u will.see what mean. Good thing Euphony can do 5.1. Surround! 

[romaz]

On 7/13/2021 at 9:12 AM, austinpop said:

There is a whole story around how the ARC6 came to be, which will be told some day...

 

It's been awhile since I've posted on this thread.  I like to post when I feel I have something meaningful to contribute.  Hopefully, some of you will find this to be meaningful.  If you have no interest in the Chord DAVE or in power supplies in general, then feel free to ignore this long post.  It is the storyline of how the ARC6 DC4 for DAVE came to be.

 

In November of 2017, while in he U.K. visiting Rob Watts, he was kind enough to share with me the necessary specifications for building an external PSU for DAVE.  In exchange, he had expressed a desire to hear this PSU during his planned visit to my home in March of 2018.  While still in the U.K., I initially approached Paul Hynes with this PSU project.  He expressed interest in it and was confident DAVE could be improved with a better power supply as he had built outboard PSUs for a Berkeley DAC and TotalDAC and those customers were apparently quite pleased.  But because Paul said he was busy and given his history of delays, as I was eager to make sure this PSU was ready in time for Rob's visit in early March, I reached out to Sean Jacobs.  It was a pleasure interacting with Sean and I had the further privilege of picking up this PSU personally from Sean at his home in West Yorkshire, a 2 hour and 20 minute train ride form London.   

 

 

The above is a photo of Sean preparing to explant the stock SMPS from my DAVE.  This photo was taken on January 29, 2018, just weeks before Rob's visit to my home.  To add to the drama, to our knowledge, no one had ever attempted to design a custom PSU for DAVE before and so other than Rob's recommended specifications (minimum of 2A per rail), there was no precedent.  Until I brought my DAVE to Sean that day, he had never actually personally seen a DAVE before and so he designed this PSU based on photos he had seen on the internet.  DAVE has 3 rails and so it remains a mystery to me how he knew which leads on the Molex connector fed which rail.  What's worse is when I got to Sean's house, while the "surgery" proved to be quite easy, because this PSU was designed for 120V AC and because the U.K. operates at 230V AC, we had no way to test it but Sean was pretty confident that it "should" work. 

 

Fortunately, it did work.  The time and effort it took to pick this up personally from Sean, the expense, and the voiding of my DAVE's warranty -- it was worth it.  First of all, it was a pleasure to interact with Sean.  While in West Yorkshire, we had lunch at a local pub that was at least 500 years old.  Not unusual for for people in the U.K. or people from many other countries, I suppose, but as an American, it was novel and I loved it.  During that conversation, I realized Sean wasn't just a PhD-level robotics engineer, an avid mountain climber, and skilled PSU designer and builder, he was also a genuinely nice human being.   As for the resultant SQ improvement from this DC3 for DAVE, it was splendid, better than I hoped for, and Rob was able to hear it for himself during his visit. 

 

The DC3 for DAVE had been the standard I had been living with until August 3, 2020, when Sean designed and built another "first" for my DAVE, this time, a battery-operated DC4.  I was aware of the standard DC4 but as I already had an SR7 for DAVE on order with Paul Hynes, my desire was for a PSU that would allow me to travel with DAVE to a mountain cabin that we frequently stay at that has no reliable electricity.  At the same time, I was intrigued with the concept of a DAVE powered by low-impedance batteries and what that might sound like.  Here is a photo of the battery-powered DC4 versus the larger DC3 chassis:

 

 

Fortuitously, this lightweight and compact PSU which contained Sean's cascaded DC4 regulators had battery inputs that allowed me to connect 3 separate batteries to power each of DAVE's 3 rails. 

 

 

This allowed me to feed DAVE's digital (5V) rail with any DC source between 14-18V and DAVE's analog (+/-15V) rails with any DC source between 24-30V.  This new platform allowed for lots of experimentation and it especially caught @ray-dude's interest.  Because batteries are known to be "high-impedance" DC sources compared to AC/DC rectification, @Nenon was initially skeptical that a battery-powered DC4 could sound as good as a standard AC-powered DC4 but as Ray came up with the brilliant idea of combining highly volatile and combustible lithium batteries in parallel to achieve peak instantaneous discharge capabilities of up to 1000A, @Nenon had to eventually concede that this type of battery array could outperform a standard DC4 and so he jumped in.  With @austinpop safely monitoring our progress from his fire-safe home in Austin, here is what we learned:

 

1.  Low output impedance is just as important as low noise with respect to SQ when designing a PSU and is more difficult to achieve.  If low noise is all that mattered, then why not just use batteries for everything?  Try battery powering a DAVE with any ol' cheap battery that you can buy from Amazon such as a PowerAdd that are designed for recharging cell phones and what you'll get are soft, slow, and smeared transients, a flat sound stage, and weak dynamic contrasts.  As you start to lower the output impedance from the power source, music starts to take form and comes to life.  It just becomes more 3D and palpable and low output impedance is what differentiates a DC4, SR7, Farad, or LPS-1.2 from the rest.  It's amazing how few ultra-low output impedance PSUs there are that are being sold for audio.  Chances are that if the manufacturer fails to mention "output impedance" or better yet, fails to state the output impedance of their PSU in their ad, that PSU is probably not a low output impedance PSU.  Despite the long wait times for PSUs from Sean Jacobs and Paul Hynes, there's a reason people have queued up for these devices.

 

With respect to our battery experiments, while we had no way to directly measure the impedance of a battery, we could approximate it with an internal resistance meter like this AideTek that you can purchase on Amazon and so this device was especially useful for making relative comparisons:

 

 

If you connect battery cells in series, voltage output goes up but if you connect them in parallel, peak current discharge capability of that array of batteries goes up while the internal resistance of the array as a whole goes down and so we used the peak discharge capability of a battery array as a surrogate for output impedance.  The problem with this from a practical standpoint is the number of batteries that you would need to combine in parallel becomes quite large.  Here is an array that @ray-dude put together.  Imagine having something like this by your DAVE in your listening room:

 

 

This led @Nenon to design capacitor arrays since adding energy storage capacitance in parallel to the batteries effectively drops output impedance.  @Nenon and @ray-dude experimented with capacitors of various sizes and configurations:

 

 

 

We even contemplated these giant paint-can sized caps that were expressly designed by Mundorf for Emile at Taiko Audio:
 

 

What was initially an experiment about batteries soon became more about capacitors.  With capacitors, it was now possible to achieve output impedances of <1 milliohm.  With the aid of these capacitors and at this ultra low level of output impedance, the standard DC4 which @Nenon was kind enough to make available to us for direct A/B comparisons was now soundly being outperformed by batteries.  

 

2.  Low output impedance is important for analog but our testing with DAVE suggests low output impedance is more important for digital.  I think there are many smart engineers, designers, and manufacturers out there that do not believe output impedance matters for digital because it shows in their designs.  These people believe with digital, it's purely about low noise.  For example, with my Oppo UDP-205, it's interesting to note that in stock form, this device has a transformer-based PSU with low ESR caps for the analog side and a basic SMPS for the digital side.  When I opened up a dCS Network Bridge, I noticed the miniscule transformer inside.  As I opened up an Innuos Zenith SE Mk2 music server, the 400VA transformer used by Sean Jacobs was much more massive in comparison despite the fact that the Innuos Zenith uses a low power Pentium CPU and has no high power requirement.  I don't think it's a coincidence that the Innuos sounded much more dynamic than the dCS Network Bridge in my A/B testing:

 

https://www.head-fi.org/threads/review-comparison-of-5-high-end-digital-music-servers-aurender-n10-cad-cat-server-totaldac-d1-server-auralic-aries-audiophile-vortex-box.787020/page-69#post-13801299 

 

With respect to our experiments with DAVE, applying a lower output impedance power source to the analog rails made a notable difference with respect to dynamics but that difference was much more profound on DAVE's digital rail.  If all we did was apply ultra low output impedance power to DAVE's digital rail, it would be already be a significant win.

 

3.  Batteries are ultimately NOT what is best for digital.  Yes, digital is more susceptible to HF noise and digital also gives off more HF noise and so to isolate it from your other components by powering it with batteries makes sense in theory but in practice, it does not necessarily sound better.  Even using a large array of batteries in parallel with approximately 5 milliohms of impedance, while these batteries can discharge quickly, they do not seem to have the agility that transformer-based power sources are capable of.  Since my DC4 has the ability to connect to any DC source, battery or otherwise, I was able to compare various batteries against an SR4T from Paul Hynes.  According to Paul the SR4 has an output impedance of <3 milliohms from DC to 100kHz but when you combine the impedance of the DC cable and the barrel connector (which are horribly high impedance), then the output impedance of both sources are roughly the same and while the batteries and the SR4T achieve roughly the same dynamic contrasts (which is to say both are excellent), the batteries in comparison sound slow, soft, and smeared around the edges.  The tiny SR4T does far better as an energizing source for DAVE's digital rail than a giant LiFePO4 battery.

 

4.  The ARC6 DC4 - A new king is crowned. 

 

 

The ARC6 that @austinpop had in his possession made it to me on Thursday and I have been able to directly compare it against the latest hybrid DC4 that I currently have (which was also built by @Nenon) which uses an SR4T + cap array to power DAVE's digital rail and 2 giant LiFePO4 batteries + cap array to power DAVE's 2 analog rails.  While I preferred the SR4T over batteries on DAVE's digital rail, I had no high-quality transformer-based supply that could output 24-30V for DAVE's analog rails and so I was forced to use batteries there but I found the characteristic "slower" nature of batteries on the analog rails to be to its advantage as the resultant sound was immersive, liquid, non-fatiguing, and pleasingly musical.  I thought the character of the batteries worked really well on the analog rails and so I was very interested to know just how the ARC6 would compare.  

 

The ARC6 manifests the best of everything we learned through our months of experimentation.  It utilizes Sean's cascaded regulation which is in both the ARC6 but also my unit.  It incorporates 594,000 uF of Mundorf capacitors for DAVE's 3 rails but my unit has this, too. 

 

 

The ARC6 uses @Nenon's preferred Mundorf Silver/Gold DC wiring.  Having done careful A/B comparisons against this more expensive Mundorf wire and Sean's less expensive Neotech OCC copper option (which is what comes stock), I have found myself preferring the Mundorf wire and so the unit I have has the same wire.  The only difference is the ARC6 uses @Nenon's and Sean's best transformer-based answer to a giant battery as an energizing source for the capacitor arrays.  With the giant capacitor array, did the energizing source (transformer vs battery) matter that much and if so, which was better?

 

Because I'm capable of assessing the digital and analog rails separately, that's what I did.  On the digital rail, I already knew a transformer is better than a battery and so no surprise, that's what I found.  What wasn't clear was how much better, if at all, the ARC6 was compared to the SR4T and the answer is it's unquestionably better, A LOT BETTER.  I guess I shouldn't be too surprised since the ARC6 is utilizing a giant 600VA transformer with a newly improved recap board along with a giant choke that much more effectively filters rectification noise without stunting dynamics like the older recap board did with the original DC4.  With the SR4T, I'm connecting this energizing device to the DC4 chassis via a DC cable terminated with a high-impedance 2.5mm x 5.5mm barrel connector.  With the ARC6, current paths are much shorter and devoid of high impedance connectors.  Comparing ARC6 vs DC4, both result in excellent dynamic contrasts in large part due to the capacitor array but the ARC6 is just incredibly good with respect to noise floor and clarity.  The "blackness" of the ARC6 over the SR4T in this instance is just eerily striking.  There's just tons of space.  Even when I compared the ARC6 to a giant LiFePO4 battery, most people would assume the battery would be quieter but in this case, it is not.  Batteries create their own noise and the ARC6 is good proof that a properly designed and implemented transformer-based, AC-to-DC rectified circuit can sound cleaner.

 

Regarding ARC6 vs batteries on DAVE's analog rails, this is where things got interesting for me.  It turns out the ARC6 is sensitive to power cords and more specifically, it is sensitive to bad power cords.  Quite randomly, I picked out the first spare power cord from my cabinet that I could find and it happened to be the stock Transparent 12awg power cord that came with my D'Agostino HD preamp that I never previously used and so as far as I know, this power cord had virtually zero hours on it.  For those that have experience with Transparent cabling, their house sound is "fullness" but what I first heard with the ARC6 on the analog rails compared against the batteries was a "leanness" that sounded anything but musical.  At some point, a brightness developed and that is when I realized this changing sound was possibly due to a power cord that wasn't broken in.  After a swap of power cords, it was a relief to find that a different power cord made all the difference.  With an inexpensive TG SLVR power cord I've had for years, it became clear that the ARC6 is a full-bodied and rich sounding PSU and even more emotive and satisfying than the batteries.  There was tremendous dynamics with a giant expansive sound stage that was bigger than the batteries and with a blackness that was just as eerily good here as it was on the digital rail.  From bass to treble, definition was better on the ARC6.  Micro details were much more easily gleaned with amazing clarity.  There was also the most incredibly natural sounding decay I've heard from my DAVE with the ARC6 that lingers in the air longer and gradually disappears.  With the batteries, it lingers then then more abruptly cuts off.   Yes, the batteries still have their appeal but the overall appeal of the qualities of the ARC6 is greater.  

 

If you own a DAVE with it's stock PSU, it's hard to accurately convey just how big a step change the ARC6 brings.  It really is transformational and all credit goes to @Nenon and Sean Jacobs.  At the very least, imo, you owe it to yourself to get a DC3 because swapping out DAVE's PSU is among the highest value things you can do to your DAVE and it's easy to do.  I'm sure when Paul Hynes' SR7 for DAVE finally comes out, it will transform your DAVE if you are in line for one.  But with regards to the ARC6, coming from a baseline of a DC3 and then DC4, which are both excellent in their own rights, it's amazing how the ARC6 is just ridiculously better.  

[str-1]

11 hours ago, romaz said:

 

It's been awhile since I've posted on this thread.  I like to post when I feel I have something meaningful to contribute.  Hopefully, some of you will find this to be meaningful.  If you have no interest in the Chord DAVE or in power supplies in general, then feel free to ignore this long post.  It is the storyline of how the ARC6 DC4 for DAVE came to be.

 

In November of 2017, while in he U.K. visiting Rob Watts, he was kind enough to share with me the necessary specifications for building an external PSU for DAVE.  In exchange, he had expressed a desire to hear this PSU during his planned visit to my home in March of 2018.  While still in the U.K., I initially approached Paul Hynes with this PSU project.  He expressed interest in it and was confident DAVE could be improved with a better power supply as he had built outboard PSUs for a Berkeley DAC and TotalDAC and those customers were apparently quite pleased.  But because Paul said he was busy and given his history of delays, as I was eager to make sure this PSU was ready in time for Rob's visit in early March, I reached out to Sean Jacobs.  It was a pleasure interacting with Sean and I had the further privilege of picking up this PSU personally from Sean at his home in West Yorkshire, a 2 hour and 20 minute train ride form London.   

 

 

The above is a photo of Sean preparing to explant the stock SMPS from my DAVE.  This photo was taken on January 29, 2018, just weeks before Rob's visit to my home.  To add to the drama, to our knowledge, no one had ever attempted to design a custom PSU for DAVE before and so other than Rob's recommended specifications (minimum of 2A per rail), there was no precedent.  Until I brought my DAVE to Sean that day, he had never actually personally seen a DAVE before and so he designed this PSU based on photos he had seen on the internet.  DAVE has 3 rails and so it remains a mystery to me how he knew which leads on the Molex connector fed which rail.  What's worse is when I got to Sean's house, while the "surgery" proved to be quite easy, because this PSU was designed for 120V AC and because the U.K. operates at 230V AC, we had no way to test it but Sean was pretty confident that it "should" work. 

 

Fortunately, it did work.  The time and effort it took to pick this up personally from Sean, the expense, and the voiding of my DAVE's warranty -- it was worth it.  First of all, it was a pleasure to interact with Sean.  While in West Yorkshire, we had lunch at a local pub that was at least 500 years old.  Not unusual for for people in the U.K. or people from many other countries, I suppose, but as an American, it was novel and I loved it.  During that conversation, I realized Sean wasn't just a PhD-level robotics engineer, an avid mountain climber, and skilled PSU designer and builder, he was also a genuinely nice human being.   As for the resultant SQ improvement from this DC3 for DAVE, it was splendid, better than I hoped for, and Rob was able to hear it for himself during his visit. 

 

The DC3 for DAVE had been the standard I had been living with until August 3, 2020, when Sean designed and built another "first" for my DAVE, this time, a battery-operated DC4.  I was aware of the standard DC4 but as I already had an SR7 for DAVE on order with Paul Hynes, my desire was for a PSU that would allow me to travel with DAVE to a mountain cabin that we frequently stay at that has no reliable electricity.  At the same time, I was intrigued with the concept of a DAVE powered by low-impedance batteries and what that might sound like.  Here is a photo of the battery-powered DC4 versus the larger DC3 chassis:

 

 

Fortuitously, this lightweight and compact PSU which contained Sean's cascaded DC4 regulators had battery inputs that allowed me to connect 3 separate batteries to power each of DAVE's 3 rails. 

 

 

This allowed me to feed DAVE's digital (5V) rail with any DC source between 14-18V and DAVE's analog (+/-15V) rails with any DC source between 24-30V.  This new platform allowed for lots of experimentation and it especially caught @ray-dude's interest.  Because batteries are known to be "high-impedance" DC sources compared to AC/DC rectification, @Nenon was initially skeptical that a battery-powered DC4 could sound as good as a standard AC-powered DC4 but as Ray came up with the brilliant idea of combining highly volatile and combustible lithium batteries in parallel to achieve peak instantaneous discharge capabilities of up to 1000A, @Nenon had to eventually concede that this type of battery array could outperform a standard DC4 and so he jumped in.  With @austinpop safely monitoring our progress from his fire-safe home in Austin, here is what we learned:

 

1.  Low output impedance is just as important as low noise with respect to SQ when designing a PSU and is more difficult to achieve.  If low noise is all that mattered, then why not just use batteries for everything?  Try battery powering a DAVE with any ol' cheap battery that you can buy from Amazon such as a PowerAdd that are designed for recharging cell phones and what you'll get are soft, slow, and smeared transients, a flat sound stage, and weak dynamic contrasts.  As you start to lower the output impedance from the power source, music starts to take form and comes to life.  It just becomes more 3D and palpable and low output impedance is what differentiates a DC4, SR7, Farad, or LPS-1.2 from the rest.  It's amazing how few ultra-low output impedance PSUs there are that are being sold for audio.  Chances are that if the manufacturer fails to mention "output impedance" or better yet, fails to state the output impedance of their PSU in their ad, that PSU is probably not a low output impedance PSU.  Despite the long wait times for PSUs from Sean Jacobs and Paul Hynes, there's a reason people have queued up for these devices.

 

With respect to our battery experiments, while we had no way to directly measure the impedance of a battery, we could approximate it with an internal resistance meter like this AideTek that you can purchase on Amazon and so this device was especially useful for making relative comparisons:

 

 

If you connect battery cells in series, voltage output goes up but if you connect them in parallel, peak current discharge capability of that array of batteries goes up while the internal resistance of the array as a whole goes down and so we used the peak discharge capability of a battery array as a surrogate for output impedance.  The problem with this from a practical standpoint is the number of batteries that you would need to combine in parallel becomes quite large.  Here is an array that @ray-dude put together.  Imagine having something like this by your DAVE in your listening room:

 

 

This led @Nenon to design capacitor arrays since adding energy storage capacitance in parallel to the batteries effectively drops output impedance.  @Nenon and @ray-dude experimented with capacitors of various sizes and configurations:

 

 

 

We even contemplated these giant paint-can sized caps that were expressly designed by Mundorf for Emile at Taiko Audio:
 

 

What was initially an experiment about batteries soon became more about capacitors.  With capacitors, it was now possible to achieve output impedances of <1 milliohm.  With the aid of these capacitors and at this ultra low level of output impedance, the standard DC4 which @Nenon was kind enough to make available to us for direct A/B comparisons was now soundly being outperformed by batteries.  

 

2.  Low output impedance is important for analog but our testing with DAVE suggests low output impedance is more important for digital.  I think there are many smart engineers, designers, and manufacturers out there that do not believe output impedance matters for digital because it shows in their designs.  These people believe with digital, it's purely about low noise.  For example, with my Oppo UDP-205, it's interesting to note that in stock form, this device has a transformer-based PSU with low ESR caps for the analog side and a basic SMPS for the digital side.  When I opened up a dCS Network Bridge, I noticed the miniscule transformer inside.  As I opened up an Innuos Zenith SE Mk2 music server, the 400VA transformer used by Sean Jacobs was much more massive in comparison despite the fact that the Innuos Zenith uses a low power Pentium CPU and has no high power requirement.  I don't think it's a coincidence that the Innuos sounded much more dynamic than the dCS Network Bridge in my A/B testing:

 

https://www.head-fi.org/threads/review-comparison-of-5-high-end-digital-music-servers-aurender-n10-cad-cat-server-totaldac-d1-server-auralic-aries-audiophile-vortex-box.787020/page-69#post-13801299 

 

With respect to our experiments with DAVE, applying a lower output impedance power source to the analog rails made a notable difference with respect to dynamics but that difference was much more profound on DAVE's digital rail.  If all we did was apply ultra low output impedance power to DAVE's digital rail, it would be already be a significant win.

 

3.  Batteries are ultimately NOT what is best for digital.  Yes, digital is more susceptible to HF noise and digital also gives off more HF noise and so to isolate it from your other components by powering it with batteries makes sense in theory but in practice, it does not necessarily sound better.  Even using a large array of batteries in parallel with approximately 5 milliohms of impedance, while these batteries can discharge quickly, they do not seem to have the agility that transformer-based power sources are capable of.  Since my DC4 has the ability to connect to any DC source, battery or otherwise, I was able to compare various batteries against an SR4T from Paul Hynes.  According to Paul the SR4 has an output impedance of <3 milliohms from DC to 100kHz but when you combine the impedance of the DC cable and the barrel connector (which are horribly high impedance), then the output impedance of both sources are roughly the same and while the batteries and the SR4T achieve roughly the same dynamic contrasts (which is to say both are excellent), the batteries in comparison sound slow, soft, and smeared around the edges.  The tiny SR4T does far better as an energizing source for DAVE's digital rail than a giant LiFePO4 battery.

 

4.  The ARC6 DC4 - A new king is crowned. 

 

 

The ARC6 that @austinpop had in his possession made it to me on Thursday and I have been able to directly compare it against the latest hybrid DC4 that I currently have (which was also built by @Nenon) which uses an SR4T + cap array to power DAVE's digital rail and 2 giant LiFePO4 batteries + cap array to power DAVE's 2 analog rails.  While I preferred the SR4T over batteries on DAVE's digital rail, I had no high-quality transformer-based supply that could output 24-30V for DAVE's analog rails and so I was forced to use batteries there but I found the characteristic "slower" nature of batteries on the analog rails to be to its advantage as the resultant sound was immersive, liquid, non-fatiguing, and pleasingly musical.  I thought the character of the batteries worked really well on the analog rails and so I was very interested to know just how the ARC6 would compare.  

 

The ARC6 manifests the best of everything we learned through our months of experimentation.  It utilizes Sean's cascaded regulation which is in both the ARC6 but also my unit.  It incorporates 594,000 uF of Mundorf capacitors for DAVE's 3 rails but my unit has this, too. 

 

 

The ARC6 uses @Nenon's preferred Mundorf Silver/Gold DC wiring.  Having done careful A/B comparisons against this more expensive Mundorf wire and Sean's less expensive Neotech OCC copper option (which is what comes stock), I have found myself preferring the Mundorf wire and so the unit I have has the same wire.  The only difference is the ARC6 uses @Nenon's and Sean's best transformer-based answer to a giant battery as an energizing source for the capacitor arrays.  With the giant capacitor array, did the energizing source (transformer vs battery) matter that much and if so, which was better?

 

Because I'm capable of assessing the digital and analog rails separately, that's what I did.  On the digital rail, I already knew a transformer is better than a battery and so no surprise, that's what I found.  What wasn't clear was how much better, if at all, the ARC6 was compared to the SR4T and the answer is it's unquestionably better, A LOT BETTER.  I guess I shouldn't be too surprised since the ARC6 is utilizing a giant 600VA transformer with a newly improved recap board along with a giant choke that much more effectively filters rectification noise without stunting dynamics like the older recap board did with the original DC4.  With the SR4T, I'm connecting this energizing device to the DC4 chassis via a DC cable terminated with a high-impedance 2.5mm x 5.5mm barrel connector.  With the ARC6, current paths are much shorter and devoid of high impedance connectors.  Comparing ARC6 vs DC4, both result in excellent dynamic contrasts in large part due to the capacitor array but the ARC6 is just incredibly good with respect to noise floor and clarity.  The "blackness" of the ARC6 over the SR4T in this instance is just eerily striking.  There's just tons of space.  Even when I compared the ARC6 to a giant LiFePO4 battery, most people would assume the battery would be quieter but in this case, it is not.  Batteries create their own noise and the ARC6 is good proof that a properly designed and implemented transformer-based, AC-to-DC rectified circuit can sound cleaner.

 

Regarding ARC6 vs batteries on DAVE's analog rails, this is where things got interesting for me.  It turns out the ARC6 is sensitive to power cords and more specifically, it is sensitive to bad power cords.  Quite randomly, I picked out the first spare power cord from my cabinet that I could find and it happened to be the stock Transparent 12awg power cord that came with my D'Agostino HD preamp that I never previously used and so as far as I know, this power cord had virtually zero hours on it.  For those that have experience with Transparent cabling, their house sound is "fullness" but what I first heard with the ARC6 on the analog rails compared against the batteries was a "leanness" that sounded anything but musical.  At some point, a brightness developed and that is when I realized this changing sound was possibly due to a power cord that wasn't broken in.  After a swap of power cords, it was a relief to find that a different power cord made all the difference.  With an inexpensive TG SLVR power cord I've had for years, it became clear that the ARC6 is a full-bodied and rich sounding PSU and even more emotive and satisfying than the batteries.  There was tremendous dynamics with a giant expansive sound stage that was bigger than the batteries and with a blackness that was just as eerily good here as it was on the digital rail.  From bass to treble, definition was better on the ARC6.  Micro details were much more easily gleaned with amazing clarity.  There was also the most incredibly natural sounding decay I've heard from my DAVE with the ARC6 that lingers in the air longer and gradually disappears.  With the batteries, it lingers then then more abruptly cuts off.   Yes, the batteries still have their appeal but the overall appeal of the qualities of the ARC6 is greater.  

 

If you own a DAVE with it's stock PSU, it's hard to accurately convey just how big a step change the ARC6 brings.  It really is transformational and all credit goes to @Nenon and Sean Jacobs.  At the very least, imo, you owe it to yourself to get a DC3 because swapping out DAVE's PSU is among the highest value things you can do to your DAVE and it's easy to do.  I'm sure when Paul Hynes' SR7 for DAVE finally comes out, it will transform your DAVE if you are in line for one.  But with regards to the ARC6, coming from a baseline of a DC3 and then DC4, which are both excellent in their own rights, it's amazing how the ARC6 is just ridiculously better.  

Great to see you back on this thread, Roy.  Another great post!

 

I’ve had a DC4 powering my DAVE with great results since the beginning of the year, and I have already been in touch with Sean about likely upgrade options to an ARC6.  While he can’t yet confirm, with more testing still to do, he was optimistic there would be an upgrade path.  So I will be keeping a close watch for further updates.

 

If I can have my DC4 upgraded to an ARC6, I would need to decide by then whether I would also want the internal wiring upgraded from Neotech to Mundorf.  Can you say a little about the differences you heard between these two options?

 

Can I also ask you, and ask others who have been testing prototype options, if you have a view on what type of power cable is likely to work best with the ARC6?  Most of the cables I have are filtered Shunyata cables (Alpha and Delta), with one cheapish older generation unfiltered Shunyata Venom cable.  Is filtering in the Shunyata style likely to restrict the ARC6?

[Glossator]

16 hours ago, romaz said:

 

It's been awhile since I've posted on this thread.  I like to post when I feel I have something meaningful to contribute.  Hopefully, some of you will find this to be meaningful.  If you have no interest in the Chord DAVE or in power supplies in general, then feel free to ignore this long post.  It is the storyline of how the ARC6 DC4 for DAVE came to be.

 

In November of 2017, while in he U.K. visiting Rob Watts, he was kind enough to share with me the necessary specifications for building an external PSU for DAVE.  In exchange, he had expressed a desire to hear this PSU during his planned visit to my home in March of 2018.  While still in the U.K., I initially approached Paul Hynes with this PSU project.  He expressed interest in it and was confident DAVE could be improved with a better power supply as he had built outboard PSUs for a Berkeley DAC and TotalDAC and those customers were apparently quite pleased.  But because Paul said he was busy and given his history of delays, as I was eager to make sure this PSU was ready in time for Rob's visit in early March, I reached out to Sean Jacobs.  It was a pleasure interacting with Sean and I had the further privilege of picking up this PSU personally from Sean at his home in West Yorkshire, a 2 hour and 20 minute train ride form London.   

 

 

The above is a photo of Sean preparing to explant the stock SMPS from my DAVE.  This photo was taken on January 29, 2018, just weeks before Rob's visit to my home.  To add to the drama, to our knowledge, no one had ever attempted to design a custom PSU for DAVE before and so other than Rob's recommended specifications (minimum of 2A per rail), there was no precedent.  Until I brought my DAVE to Sean that day, he had never actually personally seen a DAVE before and so he designed this PSU based on photos he had seen on the internet.  DAVE has 3 rails and so it remains a mystery to me how he knew which leads on the Molex connector fed which rail.  What's worse is when I got to Sean's house, while the "surgery" proved to be quite easy, because this PSU was designed for 120V AC and because the U.K. operates at 230V AC, we had no way to test it but Sean was pretty confident that it "should" work. 

 

Fortunately, it did work.  The time and effort it took to pick this up personally from Sean, the expense, and the voiding of my DAVE's warranty -- it was worth it.  First of all, it was a pleasure to interact with Sean.  While in West Yorkshire, we had lunch at a local pub that was at least 500 years old.  Not unusual for for people in the U.K. or people from many other countries, I suppose, but as an American, it was novel and I loved it.  During that conversation, I realized Sean wasn't just a PhD-level robotics engineer, an avid mountain climber, and skilled PSU designer and builder, he was also a genuinely nice human being.   As for the resultant SQ improvement from this DC3 for DAVE, it was splendid, better than I hoped for, and Rob was able to hear it for himself during his visit. 

 

The DC3 for DAVE had been the standard I had been living with until August 3, 2020, when Sean designed and built another "first" for my DAVE, this time, a battery-operated DC4.  I was aware of the standard DC4 but as I already had an SR7 for DAVE on order with Paul Hynes, my desire was for a PSU that would allow me to travel with DAVE to a mountain cabin that we frequently stay at that has no reliable electricity.  At the same time, I was intrigued with the concept of a DAVE powered by low-impedance batteries and what that might sound like.  Here is a photo of the battery-powered DC4 versus the larger DC3 chassis:

 

 

Fortuitously, this lightweight and compact PSU which contained Sean's cascaded DC4 regulators had battery inputs that allowed me to connect 3 separate batteries to power each of DAVE's 3 rails. 

 

 

This allowed me to feed DAVE's digital (5V) rail with any DC source between 14-18V and DAVE's analog (+/-15V) rails with any DC source between 24-30V.  This new platform allowed for lots of experimentation and it especially caught @ray-dude's interest.  Because batteries are known to be "high-impedance" DC sources compared to AC/DC rectification, @Nenon was initially skeptical that a battery-powered DC4 could sound as good as a standard AC-powered DC4 but as Ray came up with the brilliant idea of combining highly volatile and combustible lithium batteries in parallel to achieve peak instantaneous discharge capabilities of up to 1000A, @Nenon had to eventually concede that this type of battery array could outperform a standard DC4 and so he jumped in.  With @austinpop safely monitoring our progress from his fire-safe home in Austin, here is what we learned:

 

1.  Low output impedance is just as important as low noise with respect to SQ when designing a PSU and is more difficult to achieve.  If low noise is all that mattered, then why not just use batteries for everything?  Try battery powering a DAVE with any ol' cheap battery that you can buy from Amazon such as a PowerAdd that are designed for recharging cell phones and what you'll get are soft, slow, and smeared transients, a flat sound stage, and weak dynamic contrasts.  As you start to lower the output impedance from the power source, music starts to take form and comes to life.  It just becomes more 3D and palpable and low output impedance is what differentiates a DC4, SR7, Farad, or LPS-1.2 from the rest.  It's amazing how few ultra-low output impedance PSUs there are that are being sold for audio.  Chances are that if the manufacturer fails to mention "output impedance" or better yet, fails to state the output impedance of their PSU in their ad, that PSU is probably not a low output impedance PSU.  Despite the long wait times for PSUs from Sean Jacobs and Paul Hynes, there's a reason people have queued up for these devices.

 

With respect to our battery experiments, while we had no way to directly measure the impedance of a battery, we could approximate it with an internal resistance meter like this AideTek that you can purchase on Amazon and so this device was especially useful for making relative comparisons:

 

 

If you connect battery cells in series, voltage output goes up but if you connect them in parallel, peak current discharge capability of that array of batteries goes up while the internal resistance of the array as a whole goes down and so we used the peak discharge capability of a battery array as a surrogate for output impedance.  The problem with this from a practical standpoint is the number of batteries that you would need to combine in parallel becomes quite large.  Here is an array that @ray-dude put together.  Imagine having something like this by your DAVE in your listening room:

 

 

This led @Nenon to design capacitor arrays since adding energy storage capacitance in parallel to the batteries effectively drops output impedance.  @Nenon and @ray-dude experimented with capacitors of various sizes and configurations:

 

 

 

We even contemplated these giant paint-can sized caps that were expressly designed by Mundorf for Emile at Taiko Audio:
 

 

What was initially an experiment about batteries soon became more about capacitors.  With capacitors, it was now possible to achieve output impedances of <1 milliohm.  With the aid of these capacitors and at this ultra low level of output impedance, the standard DC4 which @Nenon was kind enough to make available to us for direct A/B comparisons was now soundly being outperformed by batteries.  

 

2.  Low output impedance is important for analog but our testing with DAVE suggests low output impedance is more important for digital.  I think there are many smart engineers, designers, and manufacturers out there that do not believe output impedance matters for digital because it shows in their designs.  These people believe with digital, it's purely about low noise.  For example, with my Oppo UDP-205, it's interesting to note that in stock form, this device has a transformer-based PSU with low ESR caps for the analog side and a basic SMPS for the digital side.  When I opened up a dCS Network Bridge, I noticed the miniscule transformer inside.  As I opened up an Innuos Zenith SE Mk2 music server, the 400VA transformer used by Sean Jacobs was much more massive in comparison despite the fact that the Innuos Zenith uses a low power Pentium CPU and has no high power requirement.  I don't think it's a coincidence that the Innuos sounded much more dynamic than the dCS Network Bridge in my A/B testing:

 

https://www.head-fi.org/threads/review-comparison-of-5-high-end-digital-music-servers-aurender-n10-cad-cat-server-totaldac-d1-server-auralic-aries-audiophile-vortex-box.787020/page-69#post-13801299 

 

With respect to our experiments with DAVE, applying a lower output impedance power source to the analog rails made a notable difference with respect to dynamics but that difference was much more profound on DAVE's digital rail.  If all we did was apply ultra low output impedance power to DAVE's digital rail, it would be already be a significant win.

 

3.  Batteries are ultimately NOT what is best for digital.  Yes, digital is more susceptible to HF noise and digital also gives off more HF noise and so to isolate it from your other components by powering it with batteries makes sense in theory but in practice, it does not necessarily sound better.  Even using a large array of batteries in parallel with approximately 5 milliohms of impedance, while these batteries can discharge quickly, they do not seem to have the agility that transformer-based power sources are capable of.  Since my DC4 has the ability to connect to any DC source, battery or otherwise, I was able to compare various batteries against an SR4T from Paul Hynes.  According to Paul the SR4 has an output impedance of <3 milliohms from DC to 100kHz but when you combine the impedance of the DC cable and the barrel connector (which are horribly high impedance), then the output impedance of both sources are roughly the same and while the batteries and the SR4T achieve roughly the same dynamic contrasts (which is to say both are excellent), the batteries in comparison sound slow, soft, and smeared around the edges.  The tiny SR4T does far better as an energizing source for DAVE's digital rail than a giant LiFePO4 battery.

 

4.  The ARC6 DC4 - A new king is crowned. 

 

 

The ARC6 that @austinpop had in his possession made it to me on Thursday and I have been able to directly compare it against the latest hybrid DC4 that I currently have (which was also built by @Nenon) which uses an SR4T + cap array to power DAVE's digital rail and 2 giant LiFePO4 batteries + cap array to power DAVE's 2 analog rails.  While I preferred the SR4T over batteries on DAVE's digital rail, I had no high-quality transformer-based supply that could output 24-30V for DAVE's analog rails and so I was forced to use batteries there but I found the characteristic "slower" nature of batteries on the analog rails to be to its advantage as the resultant sound was immersive, liquid, non-fatiguing, and pleasingly musical.  I thought the character of the batteries worked really well on the analog rails and so I was very interested to know just how the ARC6 would compare.  

 

The ARC6 manifests the best of everything we learned through our months of experimentation.  It utilizes Sean's cascaded regulation which is in both the ARC6 but also my unit.  It incorporates 594,000 uF of Mundorf capacitors for DAVE's 3 rails but my unit has this, too. 

 

 

The ARC6 uses @Nenon's preferred Mundorf Silver/Gold DC wiring.  Having done careful A/B comparisons against this more expensive Mundorf wire and Sean's less expensive Neotech OCC copper option (which is what comes stock), I have found myself preferring the Mundorf wire and so the unit I have has the same wire.  The only difference is the ARC6 uses @Nenon's and Sean's best transformer-based answer to a giant battery as an energizing source for the capacitor arrays.  With the giant capacitor array, did the energizing source (transformer vs battery) matter that much and if so, which was better?

 

Because I'm capable of assessing the digital and analog rails separately, that's what I did.  On the digital rail, I already knew a transformer is better than a battery and so no surprise, that's what I found.  What wasn't clear was how much better, if at all, the ARC6 was compared to the SR4T and the answer is it's unquestionably better, A LOT BETTER.  I guess I shouldn't be too surprised since the ARC6 is utilizing a giant 600VA transformer with a newly improved recap board along with a giant choke that much more effectively filters rectification noise without stunting dynamics like the older recap board did with the original DC4.  With the SR4T, I'm connecting this energizing device to the DC4 chassis via a DC cable terminated with a high-impedance 2.5mm x 5.5mm barrel connector.  With the ARC6, current paths are much shorter and devoid of high impedance connectors.  Comparing ARC6 vs DC4, both result in excellent dynamic contrasts in large part due to the capacitor array but the ARC6 is just incredibly good with respect to noise floor and clarity.  The "blackness" of the ARC6 over the SR4T in this instance is just eerily striking.  There's just tons of space.  Even when I compared the ARC6 to a giant LiFePO4 battery, most people would assume the battery would be quieter but in this case, it is not.  Batteries create their own noise and the ARC6 is good proof that a properly designed and implemented transformer-based, AC-to-DC rectified circuit can sound cleaner.

 

Regarding ARC6 vs batteries on DAVE's analog rails, this is where things got interesting for me.  It turns out the ARC6 is sensitive to power cords and more specifically, it is sensitive to bad power cords.  Quite randomly, I picked out the first spare power cord from my cabinet that I could find and it happened to be the stock Transparent 12awg power cord that came with my D'Agostino HD preamp that I never previously used and so as far as I know, this power cord had virtually zero hours on it.  For those that have experience with Transparent cabling, their house sound is "fullness" but what I first heard with the ARC6 on the analog rails compared against the batteries was a "leanness" that sounded anything but musical.  At some point, a brightness developed and that is when I realized this changing sound was possibly due to a power cord that wasn't broken in.  After a swap of power cords, it was a relief to find that a different power cord made all the difference.  With an inexpensive TG SLVR power cord I've had for years, it became clear that the ARC6 is a full-bodied and rich sounding PSU and even more emotive and satisfying than the batteries.  There was tremendous dynamics with a giant expansive sound stage that was bigger than the batteries and with a blackness that was just as eerily good here as it was on the digital rail.  From bass to treble, definition was better on the ARC6.  Micro details were much more easily gleaned with amazing clarity.  There was also the most incredibly natural sounding decay I've heard from my DAVE with the ARC6 that lingers in the air longer and gradually disappears.  With the batteries, it lingers then then more abruptly cuts off.   Yes, the batteries still have their appeal but the overall appeal of the qualities of the ARC6 is greater.  

 

If you own a DAVE with it's stock PSU, it's hard to accurately convey just how big a step change the ARC6 brings.  It really is transformational and all credit goes to @Nenon and Sean Jacobs.  At the very least, imo, you owe it to yourself to get a DC3 because swapping out DAVE's PSU is among the highest value things you can do to your DAVE and it's easy to do.  I'm sure when Paul Hynes' SR7 for DAVE finally comes out, it will transform your DAVE if you are in line for one.  But with regards to the ARC6, coming from a baseline of a DC3 and then DC4, which are both excellent in their own rights, it's amazing how the ARC6 is just ridiculously better.  

Romaz, thank you - really very interesting on lots of fronts!    

 

This may just show fundamental ignorance on my part (in which case apologises!), but it caught my eye that the likes of Danacable drive seem to drive their headphone  cable development by focusing on capacitance and seeking (both through the choice of materials and the weave) to minimise impedance.   This all, of course, all in the analogue domain, but the difference compared to, for example, Utopia with a stock cable is far from small.  I wonder if the same underlying logic is at play ....   Also, from a convenience perspective, I must admit to being rather glad that fixing the capacitance seems to mean that you all have found a solution that does not rely on batteries, let alone ranks of them as per the experiment you, Ray and Nenon tried .....    

[MarcelNL]

On 7/22/2021 at 8:18 PM, Chopin75 said:

For Mahler 8 I think you really need surround

Sound 5.1 to do that. Almost always have congestion with stereo 2 speakers or headphones. Try a SACD or surround music files and u will.see what mean. Good thing Euphony can do 5.1. Surround! 

A year or two ago I had the fortune to hear Mahler 8 (Jaap van Zweden conducting the Rotterdam Philharmonic Orchestra and couple of Choirs), and while you're able to zoom in and zoom out on individual sections there IMO is no way you'll be able to isolate instruments not doing a solo section but for the larger and louder instruments. I can say that I had a blast!

 

 

[Superdad]

23 hours ago, romaz said:

As for the resultant SQ improvement from this DC3 for DAVE, it was splendid, better than I hoped for, and Rob was able to hear it for himself during his visit. 

Hi Roy:

Great to see you posting here again!

Conversion of Chord DAVE for external linear power supplies does seem to be gaining in popularity. A good client of ours (who owns four JS-2s) did so and posted about it at the end of last year:

Here is his set up:

 

23 hours ago, romaz said:

Low output impedance is just as important as low noise with respect to SQ when designing a PSU and is more difficult to achieve.

 

Indeed! It is actually MORE important than low noise for digital circuits. John Swenson has been exposing this for over a decade.

 

23 hours ago, romaz said:

Despite the long wait times for PSUs from Sean Jacobs and Paul Hynes, there's a reason people have queued up for these devices.

 

Well not all fine low-output-impedance power supplies have a long (or infinite in the case of one of the above) wait times...

 

23 hours ago, romaz said:

This led @Nenon to design capacitor arrays since adding energy storage capacitance in parallel to the batteries effectively drops output impedance.  @Nenon and @ray-dude experimented with capacitors of various sizes and configurations:

 

 

 

Here I find it interesting--and perhaps a bit flattering--that Nenon chose to the exact same model of Hammond choke that we have been using in the JS-2 for more than 7 years. It is the hallmark of our piece. Here is a batch on our table today that just had silicone injected into the gaps on one side (doing the other, neat side, tomorrow); this is necessary to keep them mechanically quiet.

 

However, while I can't tell without a schematic, it worry if Nenon is putting large amounts of capacitance post the voltage regulators. That is very bad as it significantly increases output impedance and "slows down" the dynamics of the supply.  

The whole point and beauty of a choke-filtered design (and we discuss this on the JS-2 web page) is to deliver to the regulators a half-sine DC hump--which is devoid of the many high-frequency harmonics of the sawtooth that comes off the rectifying diodes in a traditional transformer>diodes>caps>regulator LPS design. The half-sine of the choke makes the regulators' job much easier as there is then very little harmonic content to filter at the final stage. This allows us to use just a very small amount of capacitance post the regulators--keeping the output impedance low and the supply very "fast."

There are other advantages to a choke-filtered design (power-factor correction and no harmonics kicked back into the wall) but this is not the place to discuss such. 

 

Cheers,

--Alex C.

[Nenon]

2 hours ago, Superdad said:

However, while I can't tell without a schematic, it worry if Nenon is putting large amounts of capacitance post the voltage regulators. That is very bad as it significantly increases output impedance and "slows down" the dynamics of the supply.  

Just to avoid any speculation, there is NO "large amounts of capacitance post the voltage regulators" used here. 

 

2 hours ago, Superdad said:

Here I find it interesting--and perhaps a bit flattering--that Nenon chose to the exact same model of Hammond choke that we have been using in the JS-2 for more than 7 years.

I guess great minds think alike :). To he honest, I never opened or looked inside a JS-2 :). I came across those chokes during the development of the DIY unregulated power supply for the Taiko ATX. Emile from Taiko recommended them to try. 

Those chokes contribute very little to the ARC6 magic, but they do help. I've had everyone who got my prototype power supply listen to it with and without the chokes to confirm (in different systems) if it's worth using them. You lose a little bit of clarity in favor of a bigger stage, but I found this to be beneficial... everything is a tradeoff afterall. In researching why we lose clarity, here is what I discovered. There is 50 feet of very cheap wire in this choke.

 

I did contact Hammond to ask if they can make us a custom order with Neotech 7N or Mundorf silver/gold wire (that would be $9K for 3 chokes). So why exactly those chokes? They do everything just right and are easy to implement. I've tried some much more expensive Lundhals too, but they were more colored. 

 

The Chord DAVE DAC is super transparent, resolving, and tricky. It's tricky because the power supply has such a big influence on the DAVE - it can easily go in different directions. Although, I am quite confident the JS-2 mod listed above will be a big improvement over the stock SMPS. 

 We've spent over 6 months listening to different parts and schematics in some really good systems, including the systems of @romaz, @ray-dude, @austinpop, @Fourlegs, and recently the big Taiko system. As good as the DC4 power supply is, we took that design and tweaked it to what I consider nearly perfection (with careful listening) for the DAVE DAC. 

The good news is - what we did turned out to work amazingly good on other devices too. It was a shocking experience to hear my JCAT XE card with it. 

[Gavin1977]

On 7/26/2021 at 2:47 AM, romaz said:

 

It's been awhile since I've posted on this thread.  I like to post when I feel I have something meaningful to contribute.  Hopefully, some of you will find this to be meaningful.  If you have no interest in the Chord DAVE or in power supplies in general, then feel free to ignore this long post.  It is the storyline of how the ARC6 DC4 for DAVE came to be.

 

In November of 2017, while in he U.K. visiting Rob Watts, he was kind enough to share with me the necessary specifications for building an external PSU for DAVE.  In exchange, he had expressed a desire to hear this PSU during his planned visit to my home in March of 2018.  While still in the U.K., I initially approached Paul Hynes with this PSU project.  He expressed interest in it and was confident DAVE could be improved with a better power supply as he had built outboard PSUs for a Berkeley DAC and TotalDAC and those customers were apparently quite pleased.  But because Paul said he was busy and given his history of delays, as I was eager to make sure this PSU was ready in time for Rob's visit in early March, I reached out to Sean Jacobs.  It was a pleasure interacting with Sean and I had the further privilege of picking up this PSU personally from Sean at his home in West Yorkshire, a 2 hour and 20 minute train ride form London.   

 

 

The above is a photo of Sean preparing to explant the stock SMPS from my DAVE.  This photo was taken on January 29, 2018, just weeks before Rob's visit to my home.  To add to the drama, to our knowledge, no one had ever attempted to design a custom PSU for DAVE before and so other than Rob's recommended specifications (minimum of 2A per rail), there was no precedent.  Until I brought my DAVE to Sean that day, he had never actually personally seen a DAVE before and so he designed this PSU based on photos he had seen on the internet.  DAVE has 3 rails and so it remains a mystery to me how he knew which leads on the Molex connector fed which rail.  What's worse is when I got to Sean's house, while the "surgery" proved to be quite easy, because this PSU was designed for 120V AC and because the U.K. operates at 230V AC, we had no way to test it but Sean was pretty confident that it "should" work. 

 

Fortunately, it did work.  The time and effort it took to pick this up personally from Sean, the expense, and the voiding of my DAVE's warranty -- it was worth it.  First of all, it was a pleasure to interact with Sean.  While in West Yorkshire, we had lunch at a local pub that was at least 500 years old.  Not unusual for for people in the U.K. or people from many other countries, I suppose, but as an American, it was novel and I loved it.  During that conversation, I realized Sean wasn't just a PhD-level robotics engineer, an avid mountain climber, and skilled PSU designer and builder, he was also a genuinely nice human being.   As for the resultant SQ improvement from this DC3 for DAVE, it was splendid, better than I hoped for, and Rob was able to hear it for himself during his visit. 

 

The DC3 for DAVE had been the standard I had been living with until August 3, 2020, when Sean designed and built another "first" for my DAVE, this time, a battery-operated DC4.  I was aware of the standard DC4 but as I already had an SR7 for DAVE on order with Paul Hynes, my desire was for a PSU that would allow me to travel with DAVE to a mountain cabin that we frequently stay at that has no reliable electricity.  At the same time, I was intrigued with the concept of a DAVE powered by low-impedance batteries and what that might sound like.  Here is a photo of the battery-powered DC4 versus the larger DC3 chassis:

 

 

Fortuitously, this lightweight and compact PSU which contained Sean's cascaded DC4 regulators had battery inputs that allowed me to connect 3 separate batteries to power each of DAVE's 3 rails. 

 

 

This allowed me to feed DAVE's digital (5V) rail with any DC source between 14-18V and DAVE's analog (+/-15V) rails with any DC source between 24-30V.  This new platform allowed for lots of experimentation and it especially caught @ray-dude's interest.  Because batteries are known to be "high-impedance" DC sources compared to AC/DC rectification, @Nenon was initially skeptical that a battery-powered DC4 could sound as good as a standard AC-powered DC4 but as Ray came up with the brilliant idea of combining highly volatile and combustible lithium batteries in parallel to achieve peak instantaneous discharge capabilities of up to 1000A, @Nenon had to eventually concede that this type of battery array could outperform a standard DC4 and so he jumped in.  With @austinpop safely monitoring our progress from his fire-safe home in Austin, here is what we learned:

 

1.  Low output impedance is just as important as low noise with respect to SQ when designing a PSU and is more difficult to achieve.  If low noise is all that mattered, then why not just use batteries for everything?  Try battery powering a DAVE with any ol' cheap battery that you can buy from Amazon such as a PowerAdd that are designed for recharging cell phones and what you'll get are soft, slow, and smeared transients, a flat sound stage, and weak dynamic contrasts.  As you start to lower the output impedance from the power source, music starts to take form and comes to life.  It just becomes more 3D and palpable and low output impedance is what differentiates a DC4, SR7, Farad, or LPS-1.2 from the rest.  It's amazing how few ultra-low output impedance PSUs there are that are being sold for audio.  Chances are that if the manufacturer fails to mention "output impedance" or better yet, fails to state the output impedance of their PSU in their ad, that PSU is probably not a low output impedance PSU.  Despite the long wait times for PSUs from Sean Jacobs and Paul Hynes, there's a reason people have queued up for these devices.

 

With respect to our battery experiments, while we had no way to directly measure the impedance of a battery, we could approximate it with an internal resistance meter like this AideTek that you can purchase on Amazon and so this device was especially useful for making relative comparisons:

 

 

If you connect battery cells in series, voltage output goes up but if you connect them in parallel, peak current discharge capability of that array of batteries goes up while the internal resistance of the array as a whole goes down and so we used the peak discharge capability of a battery array as a surrogate for output impedance.  The problem with this from a practical standpoint is the number of batteries that you would need to combine in parallel becomes quite large.  Here is an array that @ray-dude put together.  Imagine having something like this by your DAVE in your listening room:

 

 

This led @Nenon to design capacitor arrays since adding energy storage capacitance in parallel to the batteries effectively drops output impedance.  @Nenon and @ray-dude experimented with capacitors of various sizes and configurations:

 

 

 

We even contemplated these giant paint-can sized caps that were expressly designed by Mundorf for Emile at Taiko Audio:
 

 

What was initially an experiment about batteries soon became more about capacitors.  With capacitors, it was now possible to achieve output impedances of <1 milliohm.  With the aid of these capacitors and at this ultra low level of output impedance, the standard DC4 which @Nenon was kind enough to make available to us for direct A/B comparisons was now soundly being outperformed by batteries.  

 

2.  Low output impedance is important for analog but our testing with DAVE suggests low output impedance is more important for digital.  I think there are many smart engineers, designers, and manufacturers out there that do not believe output impedance matters for digital because it shows in their designs.  These people believe with digital, it's purely about low noise.  For example, with my Oppo UDP-205, it's interesting to note that in stock form, this device has a transformer-based PSU with low ESR caps for the analog side and a basic SMPS for the digital side.  When I opened up a dCS Network Bridge, I noticed the miniscule transformer inside.  As I opened up an Innuos Zenith SE Mk2 music server, the 400VA transformer used by Sean Jacobs was much more massive in comparison despite the fact that the Innuos Zenith uses a low power Pentium CPU and has no high power requirement.  I don't think it's a coincidence that the Innuos sounded much more dynamic than the dCS Network Bridge in my A/B testing:

 

https://www.head-fi.org/threads/review-comparison-of-5-high-end-digital-music-servers-aurender-n10-cad-cat-server-totaldac-d1-server-auralic-aries-audiophile-vortex-box.787020/page-69#post-13801299 

 

With respect to our experiments with DAVE, applying a lower output impedance power source to the analog rails made a notable difference with respect to dynamics but that difference was much more profound on DAVE's digital rail.  If all we did was apply ultra low output impedance power to DAVE's digital rail, it would be already be a significant win.

 

3.  Batteries are ultimately NOT what is best for digital.  Yes, digital is more susceptible to HF noise and digital also gives off more HF noise and so to isolate it from your other components by powering it with batteries makes sense in theory but in practice, it does not necessarily sound better.  Even using a large array of batteries in parallel with approximately 5 milliohms of impedance, while these batteries can discharge quickly, they do not seem to have the agility that transformer-based power sources are capable of.  Since my DC4 has the ability to connect to any DC source, battery or otherwise, I was able to compare various batteries against an SR4T from Paul Hynes.  According to Paul the SR4 has an output impedance of <3 milliohms from DC to 100kHz but when you combine the impedance of the DC cable and the barrel connector (which are horribly high impedance), then the output impedance of both sources are roughly the same and while the batteries and the SR4T achieve roughly the same dynamic contrasts (which is to say both are excellent), the batteries in comparison sound slow, soft, and smeared around the edges.  The tiny SR4T does far better as an energizing source for DAVE's digital rail than a giant LiFePO4 battery.

 

4.  The ARC6 DC4 - A new king is crowned. 

 

 

The ARC6 that @austinpop had in his possession made it to me on Thursday and I have been able to directly compare it against the latest hybrid DC4 that I currently have (which was also built by @Nenon) which uses an SR4T + cap array to power DAVE's digital rail and 2 giant LiFePO4 batteries + cap array to power DAVE's 2 analog rails.  While I preferred the SR4T over batteries on DAVE's digital rail, I had no high-quality transformer-based supply that could output 24-30V for DAVE's analog rails and so I was forced to use batteries there but I found the characteristic "slower" nature of batteries on the analog rails to be to its advantage as the resultant sound was immersive, liquid, non-fatiguing, and pleasingly musical.  I thought the character of the batteries worked really well on the analog rails and so I was very interested to know just how the ARC6 would compare.  

 

The ARC6 manifests the best of everything we learned through our months of experimentation.  It utilizes Sean's cascaded regulation which is in both the ARC6 but also my unit.  It incorporates 594,000 uF of Mundorf capacitors for DAVE's 3 rails but my unit has this, too. 

 

 

The ARC6 uses @Nenon's preferred Mundorf Silver/Gold DC wiring.  Having done careful A/B comparisons against this more expensive Mundorf wire and Sean's less expensive Neotech OCC copper option (which is what comes stock), I have found myself preferring the Mundorf wire and so the unit I have has the same wire.  The only difference is the ARC6 uses @Nenon's and Sean's best transformer-based answer to a giant battery as an energizing source for the capacitor arrays.  With the giant capacitor array, did the energizing source (transformer vs battery) matter that much and if so, which was better?

 

Because I'm capable of assessing the digital and analog rails separately, that's what I did.  On the digital rail, I already knew a transformer is better than a battery and so no surprise, that's what I found.  What wasn't clear was how much better, if at all, the ARC6 was compared to the SR4T and the answer is it's unquestionably better, A LOT BETTER.  I guess I shouldn't be too surprised since the ARC6 is utilizing a giant 600VA transformer with a newly improved recap board along with a giant choke that much more effectively filters rectification noise without stunting dynamics like the older recap board did with the original DC4.  With the SR4T, I'm connecting this energizing device to the DC4 chassis via a DC cable terminated with a high-impedance 2.5mm x 5.5mm barrel connector.  With the ARC6, current paths are much shorter and devoid of high impedance connectors.  Comparing ARC6 vs DC4, both result in excellent dynamic contrasts in large part due to the capacitor array but the ARC6 is just incredibly good with respect to noise floor and clarity.  The "blackness" of the ARC6 over the SR4T in this instance is just eerily striking.  There's just tons of space.  Even when I compared the ARC6 to a giant LiFePO4 battery, most people would assume the battery would be quieter but in this case, it is not.  Batteries create their own noise and the ARC6 is good proof that a properly designed and implemented transformer-based, AC-to-DC rectified circuit can sound cleaner.

 

Regarding ARC6 vs batteries on DAVE's analog rails, this is where things got interesting for me.  It turns out the ARC6 is sensitive to power cords and more specifically, it is sensitive to bad power cords.  Quite randomly, I picked out the first spare power cord from my cabinet that I could find and it happened to be the stock Transparent 12awg power cord that came with my D'Agostino HD preamp that I never previously used and so as far as I know, this power cord had virtually zero hours on it.  For those that have experience with Transparent cabling, their house sound is "fullness" but what I first heard with the ARC6 on the analog rails compared against the batteries was a "leanness" that sounded anything but musical.  At some point, a brightness developed and that is when I realized this changing sound was possibly due to a power cord that wasn't broken in.  After a swap of power cords, it was a relief to find that a different power cord made all the difference.  With an inexpensive TG SLVR power cord I've had for years, it became clear that the ARC6 is a full-bodied and rich sounding PSU and even more emotive and satisfying than the batteries.  There was tremendous dynamics with a giant expansive sound stage that was bigger than the batteries and with a blackness that was just as eerily good here as it was on the digital rail.  From bass to treble, definition was better on the ARC6.  Micro details were much more easily gleaned with amazing clarity.  There was also the most incredibly natural sounding decay I've heard from my DAVE with the ARC6 that lingers in the air longer and gradually disappears.  With the batteries, it lingers then then more abruptly cuts off.   Yes, the batteries still have their appeal but the overall appeal of the qualities of the ARC6 is greater.  

 

If you own a DAVE with it's stock PSU, it's hard to accurately convey just how big a step change the ARC6 brings.  It really is transformational and all credit goes to @Nenon and Sean Jacobs.  At the very least, imo, you owe it to yourself to get a DC3 because swapping out DAVE's PSU is among the highest value things you can do to your DAVE and it's easy to do.  I'm sure when Paul Hynes' SR7 for DAVE finally comes out, it will transform your DAVE if you are in line for one.  But with regards to the ARC6, coming from a baseline of a DC3 and then DC4, which are both excellent in their own rights, it's amazing how the ARC6 is just ridiculously better.  

Those mundorfs are great, but what about ultra caps?  I would have thought they’d be preferable when trying to achieve ultra low impedance.  Also smaller and cheaper.

[Nenon]

9 minutes ago, Gavin1977 said:

Those mundorfs are great, but what about ultra caps?  I would have thought they’d be preferable when trying to achieve ultra low impedance.  Also smaller and cheaper.

Good on paper but not so good sounding when you try them. 

[romaz]

17 hours ago, str-1 said:

If I can have my DC4 upgraded to an ARC6, I would need to decide by then whether I would also want the internal wiring upgraded from Neotech to Mundorf.  Can you say a little about the differences you heard between these two options?

 

Steve, the Neotech single-crystal copper that Sean uses as his standard wire is a very competent wire and if it's all you heard with an ARC6, I'm pretty sure you will be pleased and wonder if you really need anything better.  This is how I felt.  But then @Nenon lent me his Mundorf Silver/Gold (MSG) umbilical and that proved to be an expensive mistake because once I heard it, it was difficult not to go with it.  Performance-wise, it offers a bit better resolution but it was really the tonal qualities of this wire that I like.  Tonally, the sound is more intense and more alive without sounding too forward or fatiguing.  Unlike some silver wire, it does not sound bright or thin and, in fact, it portrays timbres beautifully and accurately (to my ears) but if you're looking for relaxed and laid back, stick with the Neotech.  One word of caution, MSG wire is not cheap and so it is not a high value upgrade.

 

17 hours ago, str-1 said:

Can I also ask you, and ask others who have been testing prototype options, if you have a view on what type of power cable is likely to work best with the ARC6?  Most of the cables I have are filtered Shunyata cables (Alpha and Delta), with one cheapish older generation unfiltered Shunyata Venom cable.  Is filtering in the Shunyata style likely to restrict the ARC6?

 

My suggestion is if you already own these Shunyata cables, go with what you have and see what you think.  I have not experimented with power cords yet for the ARC6 and while I'm confident they'll make a difference, for now, this inexpensive (I paid $200 USD for it years ago), unfiltered TG SLVR power cord (hand built by the late Bob Crump) that I'm using on the ARC6 is very satisfying.  

[Fourlegs]

15 minutes ago, romaz said:

 

Steve, the Neotech single-crystal copper that Sean uses as his standard wire is a very competent wire and if it's all you heard with an ARC6, I'm pretty sure you will be pleased and wonder if you really need anything better.  This is how I felt.  But then @Nenon lent me his Mundorf Silver/Gold (MSG) umbilical and that proved to be an expensive mistake because once I heard it, it was difficult not to go with it.  Performance-wise, it offers a bit better resolution but it was really the tonal qualities of this wire that I like.  Tonally, the sound is more intense and more alive without sounding too forward or fatiguing.  Unlike some silver wire, it does not sound bright or thin and, in fact, it portrays timbres beautifully and accurately (to my ears) but if you're looking for relaxed and laid back, stick with the Neotech.  One word of caution, MSG wire is not cheap and so it is not a high value upgrade.

 

 

My suggestion is if you already own these Shunyata cables, go with what you have and see what you think.  I have not experimented with power cords yet for the ARC6 and while I'm confident they'll make a difference, for now, this inexpensive (I paid $200 USD for it years ago), unfiltered TG SLVR power cord (hand built by the late Bob Crump) that I'm using on the ARC6 is very satisfying.  

 

Thanks for your further thoughts on the DC4 and ARC6 wiring. Both my original DC4 and now the ARC6 TestBed I am using have Neotech internal wiring. This was mainly so that there was an even comparison between the two so that I could properly compare the ARC6 TestBed configuration options on a like for like basis. However now that testing has moved on to the stage where the DC4 has outlived its comparison usefulness I will be converting it to be my ARC6 TestBedTwo and I will use the Mundorf internal wiring for this buld. I will then be able to compare two identical ARC6 side by side, one with Neotech internal wiring and one with Mundorf. I look forward to that and fully anticipate preferring that but with the (considerable) cost consideration to be taken into account.

 

As far as the umbilical goes at the moment I use the heavily shielded Gotham GAC-4/1 11301 UltraPro Star Quad, one cable for the digital and one for the analogue. This on the basis that otherwise one is very efficiently connecting two unshielded RF aerials right into the heart of the Dave circuit boards. However I intend to revisit my choice of umbilical as part of the Mundorf wire ‘bake off’.

[seeteeyou]

On 7/26/2021 at 9:47 AM, romaz said:

According to Paul the SR4 has an output impedance of <3 milliohms from DC to 100kHz but when you combine the impedance of the DC cable and the barrel connector (which are horribly high impedance), then the output impedance of both sources are roughly the same

 

While hardwiring is best, it's just impractical for so many reasons.

 

Besides those Jaeger connectors from Hummel AG, have you ever found anything else that's superior to GX16 or similar ones?

 

Most likely this is one of the best male connectors available in terms of IACS conductivity, though not exactly sure about the impedance

 

https://doublehelixcables.com/product/eidolic-peerless-4-pin-xlr-titanium-shell-ptfe-insulation-rhodium-plated-pure-silver-pin/

 

Paul should have picked Neutrik NC4FD-LX-B for some of his SR7 builds

 

 

While 3-pin Jaeger would appear on others

 

 

 

I've never seen any builds with 4-pin female Jaeger connectors so far, therefore not sure if there were anything from Hummel that would be compatible with those Eidolic Peerless 4-pin XLR at all?

[romaz]

14 hours ago, Glossator said:

This may just show fundamental ignorance on my part (in which case apologises!), but it caught my eye that the likes of Danacable drive seem to drive their headphone  cable development by focusing on capacitance and seeking (both through the choice of materials and the weave) to minimise impedance.   This all, of course, all in the analogue domain, but the difference compared to, for example, Utopia with a stock cable is far from small.  I wonder if the same underlying logic is at play ....   Also, from a convenience perspective, I must admit to being rather glad that fixing the capacitance seems to mean that you all have found a solution that does not rely on batteries, let alone ranks of them as per the experiment you, Ray and Nenon tried .....    

 

The cable capacitance you're talking about is a different story.  As Dana himself is fond of saying, unlike a power supply, a cable is a passive device and its only job is to get out of the way.  A perfect cable that will do no harm will have zero resistance/impedance, capacitance, and inductance but the only cable that would approach this would be a super conductor.  Since super conductors also require super cooling (to zero degrees Kelvin), this impracticality makes all audio cables inherently imperfect and so all cables will add something to the signal, whether it be digital or analog.  

 

Reducing resistance is fairly easy, just use a large enough conductor.  Inductance and capacitance are tougher to deal with and tend to be a zero sum game where construction techniques that decrease one will increase the other.  The trick is to balance them well and it seems this is where cable manufacturers get creative.  Adding capacitance can sometimes add a warmth or softness that is desired and so playing with these parameters could be useful for sound tuning.  

 

With the giant capacitor arrays used in the ARC6, the goal is different.  Used pre-regulator, these giant capacitor arrays serve as energy reservoirs to make sure the regulators are never starved of current.  This would be one way to effectively lower output impedance.