Further Adventures with DC Power for Chord DAVE (and Blu Mk II)

[DAVE JS2]

I reported my surprise at the magnitude of the performance step up when I converted the DAVE to DC power using two Uptone JS2s in a previous post.

 

In summary for new readers I’m on a mission to get good quality, low noise DC power to the DAVE and latterly Blu Mk II. These Chord devices both frustrate and impress me. Its frustrating as its so sensitive to RF noise, but impressive because the new levels of performance that are attained with each improvement surprise me every time. Chord have me conditioned now such that every time I make a power / signal quality improvement, the DAVE (and now Blu Mk II) deliver better results, so I guess I will keep going until that relationship breaksdown.

 

I have more progress that I thought worth sharing on both DAVE, and the Blu Mk II MScalar. The caveats - this is all ‘verboten’ by Chord and done at your own risk - continue to apply.

MScalar FPGA Noise

An issue with Chord’s 1M tap MScaler filter devices is FPGA noise leaking through the dual BNC connection and introducing noise into the D to A conversion process. I think its worth discussing this as its relevant to some of the decisions I made.

 

I’d been on the ‘self ferrite-ing’ journey, adding Wurth cores until I couldn’t hear further improvement as per Rob Watts recommendation. I haven’t tried Wave Storms.

 

The ferrites approach actually bothered me, because of course as well as filtering out the noise over their frequency range, the ferrites also filter out the frequency components of the signal waveform within that same range, taking it further away from the technical ideal of a ‘square wave’. But it was a net sound quality win, so I was happy.

 

But I did want to try optical isolation on those lines, so I ordered Audiowise’s OPTO DX and have had great results:

 

I initially connected them using the ferrited BNC cables on the input to the transmitter OPTO DX unit, and the sound was improved; less edgy / harsh, lower noise floor, better detail - classic ‘less RF noise’. So I then took OFF the ferrites from the same BNC cable and the sound improved further, I imagine due to better signal waveform as there is no filtering.

 

I’d seen it reported that OPTO DX’s responded to good quality DC power and can confirm this, I used a few supplies of increasing quality, each of which improved things. I have ended up with an Uptone ultraCap 1.2 per OPTO DX unit, which itself was a definite step up from one ultraCap powering both OPTO DXs.

 

I also increased the quality of the BNC cables used, from really cheap no-name, through Van Damme (which I’d used with the ferrites), to Oyaide 510, again being rewarded at each stage.

Blu Mk II DC Conversion

Having learned the value of curiosity over the past year, since I had some newly freed-up ferrite cores courtesy of the OPTO DX I tried them on the mains input to the Blu Mk II (now connected to DAVE via OPTO DX). I already had a couple on there from overbuying ferrites for the BNC and had noticed an improvement back then.

 

The further ferrites made further improvements, again the classic lower RF noise traits.

 

So given that the FPGA noise leaking through the dual BNCs connection should now be sorted by the OPTO DX’s, I felt there must be another, power-supply related, noise mechanism at work inside the Blu Mk II.

 

When I initially prepared to DC convert the DAVE I had naturally peeked inside the Blu (curiosity!), so I knew it was the same stock SMPS as in the DAVE in the same casework corridor as in the DAVE (but mounted upside down, for reasons unknown to me).

 

If anyone is interested I’ll happily explain / illustrate what I did, but in brief its the same as doing the DAVE with an upside down SMPS, except that the Blu's CD mechanism covers the Molex power connector into the PCB. I wasn’t brave enough to remove that, so I just extracted the wires and their crimped ramp tagged ends from the connector on the end of the SMPS, and connected to those. I did a similar thing with the DAVE before I had the good fortune to receive a neater solution for that as a gift, and found there was no sound quality improvement from the neater solution (although it really is lovely and neat, thank you!) so I was happy to leave the Blu Mk II in that state.

 

By now I’m sure you have guessed the result - yet more improvement in the ‘lower RF noise’ vein.

ultraCap Quality DC into DAVE

I’ve been happily enjoying the music from my system, and also really enjoyed @ray-dude's latest pieces on his experiences with the Sean Jacobs DC-4.

 

I did consider a DC-4 before deciding to convert using JS-2s; the JS-2's significantly lower cost won the day.

 

I had a nagging feeling that the whole process was a little bit of a leap of faith with little hard data, which resurfaced when I read Ray’s new piece saying the DAVE current draw was approx 1A on the +- 15V and approx 2A on the +5V rail.

 

The stock SMPS I had extracted from the DAVE (see photo) had the -15V line rated at 0.5A, and I'd expect there would be a substantial safety margin on that.

 

 

So I decided to measure the actual current (in operation of course), and found them to be pretty low:

 

+15v 0.33A, +5v 0.8A, -15v 0.18A.

 

I found all DAVE's current draws to be basically constant after dipping very slightly below max start up values (my stated figures are the max values I saw) and don't vary with music volume (I use DAVE as pre-amp so cranked it up to check, not a flicker on the current).

 

For completeness I measured Blu currents too: +- 15v currents are similar to DAVE (a bit lower actually), +5v is 2.7A.

Blu’s 5v drops to about 1.5A when no music is playing; I’d imagine due to less / no heavy duty FPGA processing going on.

 

I did a quick experiment using 5v from an Uptone ultraCap 1.2 on the DAVE in place of the DAVE JS-2 rail (this all works fine as ultraCap has a floated ground) and:

A) it worked, so the current is within the 1.1A limit of the ultraCap, which gives me confidence in my current measurements

B) it sounds fantastic! A huge, wonderfully clear / precise, smooth, low noise floor soundstage. Basically I think I'm hearing what @ray-dude reported. And all from improving the quality of supply to the digital electronics only, not the 15V analogue lines.

 

I don’t know how the quality of the DC power of a DC-4 compares to the ultraCap (0.8 microvolts noise?), it would be great to find out the relevant comparative specs of the DC-4. I couldn’t find any when I was considering it (which I admit contributed to me being put off it, but perhaps I didn’t look hard enough for them, or just plain missed them).

 

Regardless, the DAVE current draws are low enough that it would seem you don't need especially beefy LPS's to get the best out of the DAVE, ‘just’ very good quality ones. Which should open up the field of candidates a little (if you are prepared put up with a multi-box solution and some simple wiring tasks).

Where Next?

Great question, glad you asked!

 

I am searching for a suitable way to get similar ‘ultraCap-quality’ DC at +-15V for the DAVE. Yes I’ve asked @Superdad, and no, ultraCap can’t be modded to deliver 15V.  ☹️

 

I am also intrigued at the possible impact of better quality power to the 5V rail of the Blu (2.7A needed) given my experiences with the DAVE and the DC conversion of the Blu helping despite the presence of an OPTO DX. I have an ldovr 3A dual stage regulator on order (also 0.8 microvolts noise quoted) to see if it will sharpen up the JS-2 rail I use for Blu to ultraCap levels.

Thanks for reading! Hope it was of interest.

 

 

@MarkusBarkus @ecwl @asdf1000 @JohnSwenson @skatbelt @kennyb123 @Nenon 

[DAVE JS2]

21 hours ago, ray-dude said:

Ultracap is awesome for being mains isolated.  There is a huge win there.  I have not tried it with DAVE, but I am tempted based on your report (thank you!)

 

The 3A ldovr supply gave me an intriguing result when I tried it to power the 5V line on my DAVE (can't/won't say better or worse, but definitely had its own character).  It would It does give you access to higher voltages as well (although I suspect the characteristics of what makes an optimal supply for 5V will be different that ±15V...the jury is still out for me on that one).

 

Thanks @ray-dude I'd be fascinated to know what you think if you try an ultracap.

 

You have me very intrigued by the ldovr now. I wish he'd hurry up & ship it...

[DAVE JS2]

20 hours ago, skatbelt said:

 

Thx for the update! Farad Super3 super capacitor LPS comes to my mind. Can be ordered in all voltages between 5V and 24V.

 

 

Ah, thanks for that tip @skatbelt I will check them out!

[DAVE JS2]

8 hours ago, kennyb123 said:

The Farad Super3 in 15v brought a very significant improvement to my TT2.  I have no doubt it would do the same for the DAVE.  

 

I have two Super3s in 15v as the other is for my HMS. I was planning to sell it given that I no longer use my HMS. But maybe I should hang onto it for when I finally get around to upgrading to DAVE.  All I'd need to add is an LPS-1.2 and a DC cable that would switch the pins to give me -15v.

Thanks @kennyb123,

 

If you are going to get a DAVE and are prepared to accept the potential consequences of opening it up, then I can only recommend the DAVE DC conversion as a 'must-do'.

 

Would love to hear why you no longer use HMS? Do you use HQPlayer?

 

 

[DAVE JS2]

On 2/9/2021 at 5:33 PM, kennyb123 said:

 I'll be posting observations on it in maybe another week or so once it has been given sufficient time to fully settle in.  

 

Looking forward to hearing about it, sounds really interesting!

[DAVE JS2]

5 hours ago, Fourlegs said:

@DAVE JS2 I've been interested to read of your journey. I have been a long time advocate of upgraded power supplies for DACs ever since having an Audio Alchemy Digital Decoding Engine (DDE) DAC many decades ago and realised how much better the sound quality was with an upgraded power supply. Latterly I have used a few different power supplies including Farad, SBooster, Uptone, MCRS, Allo Shanti etc and then got the chance to buy a pre owned Sean Jacobs DC3 conversion for the Dave. I was totally stunned but unfortunately for my wallet Sean announced the DC4 soon after and in a leap of faith I became the owner of the first production DC4 for Dave. I have never ever regretted that decision. After that the only thing I have changed is the dc cables from the DC4 to the Dave where I concluded that they were acting as very efficient RF aerials and taking the RF noise straight to the heart of the Dave where it could wreak maximum havoc. Unlike others who have gone down the exotic materials route for the dc cables I now use heavily shielded dc cables to the Dave and the difference is quite profound.

 

The Dave DC4 was so good that I thought very seriously about converting my Blu MkII but in the end I sold that and bought an Mscaler and added a DC4 to that which from a total outlay point of view was a much more sensible decision. I used to like listening to CDs and from a sound quality standpoint it made sense but now with my Innuos streamer, DC4 Dave and DC4 Mscaler there is no longer any reason to want to play CDs for better sound quality (by way of a confession, like @kennyb123 I am also playing with one of the new Antipodes streamers!).

 

I look forward to your further reports!

 

 

 

Thanks for your message @Fourlegs, thats very cool to have the first ever production unit!

 

Its so interesting to hear just how many people have been down this path before me, I learn so much every time I am on this forum.

 

Fortunately given my paranoia about the sensitivity of DAVE I used shielded cabling in there and the Blu from the get-go, so at least that's one thing I got right first time.

 

I had a different calculation with the Blu Mk II - I haven't played CDs for many years, and felt that it'd be better to swap for a MScalar but was advised that the second hand market for Blu Mk II in the UK is pretty weak now the MScalar is established, and used MScalars seemed to be going for almost new prices in lockdown, so I decided to stick with Blu and convert it in a more cost-effective way. But mainly my wife still wanted to be able to play CDs (which she never does either 🤷‍♂️ ), so that was the end of it...

 

I will obviously have to investigate these Antipodes streamers...!

[DAVE JS2]

On 2/12/2021 at 5:00 PM, LowOrbit said:

I'm not generally known for my patience, this is gonna kill me!

 

If I find a black one in the UK used, I may have to have a word with my dealer (who is great, TBH).

 

 

I'm not the most patient either, but It'll be worth the wait, @LowOrbit! Try and enjoy what you have in the meantime.

[DAVE JS2]

I'm in mourning - on the SAME DAY my OPTO DX premium cables AND second pair of Oyaide BNC cables arrived, and just 2 days before my ldovr 3A regulator arrives, my power amp's left channel decided to fail (the right channel is sounding great, though  🙈).

 

I will get it off for repair on Monday, and will have to exercise patience, like @LowOrbit...

 

I do have a question you all may be able to help me with, though: if I were to use two ultraCaps in 'series' per rail, I believe I could add the potential differences together and get either 14V (7+7) or 16V (7+9) out of them. Neither of these are 15V, but do we think that really matters? If it doesn't matter, would 14 or 16 be better?