ISO REGEN launch thread! (product web page up; photos, etc.)

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The Singxer SU-1 was not designed to accept 7V DC power input onto its main board.  There is one small chip on the SU-1 downstream side circuitry (with the various outputs like I2S, coax, etc.) that is wired directly to the +5V output of the internal LPS, so if you feed in external +7V that chip will at minimum be running over spec.  I would not recommend doing this.  There is a reason why the SU-1 internal LPS outputs +5V instead of the +3.3V needed by most of the chips.

 

Separately, the upstream section of SU-1 (including XMOS chip) is entirely USB bus powered, so feeding +5V into an ISO REGEN driving a SU-1 USB port *MAY* be problematic.  With +5V feed, the ISO REGEN VBus output voltage is essentially unregulated (+5V is too low to fulfill the minimum dropout requirement of the LDO regulator for VBus).  Whether this can even work will depend on whether the VBus delivered by ISO REGEN falls below +4.5V at any time, as that is supposed to be the minimum VBus required by the SU-1 at its USB port.  Even if it can work, the SU-1 will still be receiving unregulated VBus voltage from ISO REGEN in this scenario, though not sure how big of an issue this may be.

 

I have not tried intentionally lowering the VBus voltage entering the SU-1 USB port to see at what voltage the circuit stops working.  It is possible the voltage regulator in there may still work being fed a bit less than +4.5V, but I won't know unless I try, and right now I'm not inclined to try...

 

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18 minutes ago, thyname said:

Let me rephrase my question:

 

Can somebody confirm the power supply voltage requirement for each device:

 

1 - microRendu: 6-9 Volts DC

2 - ISO Regen: 6-9 Volts DC

3 - Singxer SU-1 external power supply: 5 Volts only??

 

Thanks.

All correct.  Don't run anything higher than 5V DC into the SU-1.  There is one chip inside directly powered by the 5V feed, so the 7V setting of an UpTone LPS-1 is a no-no for SU-1.

 

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3 hours ago, thyname said:

Hmmm... For now I have microRendu and SU-1 (ordered the DC conversion kit already), as well as LPS-1 currently powering the microRendu. Ordered the ISO Regen, but that does not arrive until June (did not get into the first launch batch).

 

I was hoping I could use existing LPS-1 for both SU-1 and uRendu via Y cable, but it looks like this would not work, as I need to set the LPS-1 at 5v, and uRendu needs at least 6 (range is 6-9). Which means that I may need to buy the second LPS-1 now, or just go back to powering uRendu with its iFi iPower. Or maybe I buy a (cheaper) sBooster. Don't know....

Another option is to insert an additional discrete regulator between the DC input jack and the SU-1 board +5V input.  This regulator will then accept 7V DC from the LPS-1 and generate 5V to feed the SU-1.  With good soldering skills, a 3-pin discrete regulator plus an input capacitor should not be too hard to add to the SU-1.

 

LPS-1 @7V ==> additional linear regulator @5V out ==> SU-1 board

 

If you want this regulator to have very low noise spec, the Belleson or Sparko Labs discrete regulators can be considered.  It would then make sense to also replace the LD1086 LDO regulator on the SU-1 board, otherwise you can end up with an ultra-low noise regulator feeding a higher noise regulator downstream.

 

Come to think of it, the above sounds a bit over the top to me, but I guess far more extreme measures have been done for the sake of achieving better sound...

 

 

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8 minutes ago, ElviaCaprice said:

Question:  If the ISO Regen GI is disabled, do I still need to feed the 5V vbus to the USB input of the ISO Regen?

John S. already answered earlier in this thread.  The ISO REGEN needs 5V Vbus to power the upstream side of the isolator chip inside.  Without this 5V Vbus the data connection between upstream and downstream side will be broken, so 5V Vbus must run from the upstream device into the ISO REGEN.  This is true regardless of the position of the GI switch.

 

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15 hours ago, JohnSwenson said:

If you feed it 5 volts the internal parts will work fine (they run at less than 5V so their regultors will work fine from 5V). But there is a possible problem, the VBUS coming out of the A jack is 5V, thus there is a very high quality 5V regulator feeding the VBUS pin. All linear regulators require a higher voltage in order to work correctly, thus feeding 5V to a 5V regulator means it is cannot work properly. The result is that the regulator does not improve the quality of the input power and actually drops the voltage slightly.

 

Whether this is important depends on what you are powering the ISO REGEN from and where the VBUS on the downstream port goes. If the ISO REGEN is powered from an LPS-1, the power is already very clean so this issue is not all that big a deal. If it is a lesser power supply, it MAY be an issue. If the DAC you connect to the ISO REGEN uses the VBUS to power its circuitry using 5V may be a significant issue. If the DAC either doesn't use VBUS or just uses it for a handshake, it probably doesn't matter.

 

So the upshot is: don't use 5V unless you have a really compelling reason to do so. If you do use 5V you may be short changing your system, but that depends on what the DAC is doing and what you are getting the 5V from.

 

John S.

For those really wanting to power their ISO REGEN and Singxer SU-1 with a single LPS-1 (via Y DC cable), I wonder if a slightly elevated LPS-1 output voltage can do the trick.

 

The idea here is to feed the ISO REGEN with a DC voltage just high enough to meet the dropout voltage requirement of the TPS7A4700 regulator generating USB VBus for the downstream side.

 

In the scenario of an LPS-1 powering both ISO REGEN and SU-1, the current consumption should be: ISO REGEN downstream side + SU-1 upstream side (just under 100mA measured while streaming DSD512) + SU-1 downstream side (120mA ballpark measured).  These should hopefully add up to well below 0.5A, so something like 5.25V from LPS-1 *MAY* be enough to maintain regulated 5V VBus at the TPS7A4700 output.  I like 5.25V since it is the upper limit of USB VBus and practically anything powered by 5V can take 5.25V, so an LPS-1 output of 5.25V will not suffer reduced device compatibility vs. 5V.  The SU-1 can probably take as high as 5.5V without any part inside running out of spec, though I'd much prefer to stay within 5.25V if it can get the job done.

 

The real question: is it possible to adjust the 5V output setting of an LPS-1 to something like 5.25V?

 

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12 minutes ago, Tunepotato said:

Hello,

John or Alex (Superdad),

I have a question in regards to my forthcoming Iso Regen. I am using an Auralic Vega Dac that doesn't require the 5VBUS to operate. I am planning on powering the Iso with my Vinnie Rossi Mini Pure-DC-4EVR which is a fully isolated Ultracapacitor power supply; currently it is set for 5Vdc output voltage. Vinnie Rossi can upgrade this to a 7Vdc output voltage, but of course this will require that I ship it back to have it upgraded. My question is since my Dac doesn't require the 5VBUS will I be ok with just the current 5Vdc output voltage or will the Iso Regen function better with the 7Vdc upgrade.

Respectfully,

Tunepotato

Not John or Alex, but speaking as a happy owner of an Auralic Vega DAC, I'm pretty sure an ISO REGEN driving a Vega can be powered by 5V DC from your Vinnie Rossi power supply.  The Vega does not utilize USB VBus power at all, so it doesn't care what VBus voltage comes out of the ISO REGEN.

 

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3 minutes ago, Superdad said:

 

Thanks Sam. Can I please forward all my e-mail to you as well?  Answer 100 user questions and earn a free ISO REGEN! 

I can only imagine the amount of email you get for both shipped and unshipped products...

 

Perhaps a FAQ put together with help from the more geeky members would be useful.  There's so much HW out in the field with so much variation it's virtually impossible for anyone to be a know-it-all, except possibly John and yourself...

 

Earlier today I posted about an idea of getting an LPS-1 to output 5.25V to power both ISO REGEN and SU-1, and was hoping John or you could weigh in, but then I realized tampering with an LPS-1 would void its warranty.  I guess John's answer to those wanting to do this dual powering is good enough.

 

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8 hours ago, JohnSwenson said:

Changing the voltage on an LPS-1 requires re-writing the firmware in the FPGA, not a trivial task. I think that would be one of the more ambitious reverse engineering tasks. 

 

John S.

Thanks, John!

 

I'll keep my paws off my UpTone gear and work on other things like modding my SU-1 (to use LPS-1).

 

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2 hours ago, Em2016 said:

 

Isn't every asynchronous USB DAC also isochronous ?  

 

In another thread you started, I mentioned that modern USB DACs implement "isochronous transfer mode with asynchronous feedback".  This is on the USB side.  Asynchronous means the USB DAC has the ability to pace the USB sender (e.g. streamer or PC). In USB the data packet rate (8KHz) and data bit rate (480Mbps) are essentially constant, so the USB DAC requests the sender to vary the amount of data carried within the USB data packets.  The USB DAC is essentially the timing master for the USB transfer of digital audio.

 

Once the USB receiver (e.g. XMOS chip) inside a DAC retrieves the data stream, it is sent into a FIFO (first-in first-out) data buffer.  The data is clocked into this buffer with a local USB clock (e.g. oscillator driving XMOS chip), and clocked out of the buffer using one of two audio reference clocks: for example 22.5792MHz for 44.1K/88.2K/176.4K/352.8K sampling rates, and 24.576MHz for 48K/96K/192/384K sampling rates.  The USB clock and the audio reference clocks are completely asychronous (i.e. no fixed timing or phase relationship) relative to each other, since they are all free-running clocks done by individual crystals or oscillators.  The audio stream coming out of the buffer is sent to an oversampler (except for NOS DACs) before finally reaching the digital-to-analog converter for conversion to analog.  This is an over-simplified but I believe technically accurate description.  Some DACs use oversampling capability built into the digital-to-analog converter chip, others use external DSPs to perform the oversampling.  NOS DACs do not oversample the audio before digital-to-analog conversion.

 

 

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11 minutes ago, Em2016 said:

 

Thanks, yes that was useful in that other thread but in this different context I was wondering how a USB reclocker fits in this PC to Async USB chain, where the USB Dac is the MASTER. As in, if the USB Dac controls the overall timing of the sending PC, then what is the reclocker (like in the REGEN) actually doing?

 

But I think it's answered now by you 2 guys above.

In a nutshell, USB reclockers like REGEN and ISO REGEN provide the USB DAC with a USB stream of very high signal integrity, which enables the USB receiver inside the DAC (e.g. XMOS chip) to work less hard to retrieve the digital audio stream and thus generate less electrical noise to contaminate the digital-to-analog section.  Electrical noise coupled to the digital-to-analog converter translates to increased jitter for the conversion which degrades the sound.  A USB reclocker helps minimize noise incoming over the USB cable (e.g. from noisy PC/Mac USB ports) and noise generated within the DAC by the USB receiver circuitry to realize a SQ payoff.

 

Additionally, the ISO REGEN implements galvanic isolation (between its upstream and downstream sides) to break AC leakage loop(s) that are known to impact SQ as well.

 

 

 

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Most DACs in the market today have not achieved total immunity from USB signal quality issues, which is why the reclockers can make audible differences (for the better).  Ideally a DAC should be insensitive to how good or bad the incoming USB signal is, but in practice they are all vulnerable to various degrees.  Designing to achieve this immunity is far from trivial!

 

If inserting a REGEN (or other reclocker) in front of a USB DAC yields no SQ improvement, then it suggests the DAC was very well designed and achieves a high degree of USB noise immunity, making the reclocker redundant & unnecessary.  The vast majority of DACs are not in this category.  Until DAC designers can create better designs to achieve USB noise immunity within the box, the reclockers continue to have a place in digital audio transmission over USB.

 

 

 

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Talk about a roller coaster ride in just one morning!

 

My ISO REGEN order arrived this morning (there's definitely an advantage to living in the same state as UpTone - THANKS Alex!!), and was about to tear into the package, when I heard from my wife that she got into a car accident just a quarter mile from home!  A Lyft driver made an unsafe left turn and crashed into my wife's month-old Mercedes C300 (she was going straight with right-of-way), which then hit a pedestrian crossing sign pole.  A total of 4 airbags deployed.  She seems to have sustained only some bruises on the hands (from the airbag) and a scrape on the shoulder (from the seat belt), but I'll need to bring her to be checked out more thoroughly.

 

I guess my planned posting of ISO REGEN listening impressions will have to be postponed.

 

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Thanks, guys, for the well wishes.  My wife was just a bit shook up but is apparently spared of any serious injury.  Thank God for airbags and seat belts.

 

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Just finished setting up my ISO REGEN to drive my modded SU-1 DDC and Holo Audo Spring DAC.  I use two LPS-1 units, one for the ISO REGEN and another for the SU-1.  Source is an AiO Win10 PC running HQPlayer.  Feeder supplies for the LPS-1s are modded Breeze Audio el-cheapo linear supplies.  This is not my usual setup.

 

Will start listening after a few hours of burn-in time.

 

I'm going to a symphony concert tonight (they'll play the Planets by Holst), so my ears should be well calibrated afterwards. ?

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4 minutes ago, R1200CL said:

 

Isn't this quite serious? 

Did the pedestrian survive ?

I'm afraid that sign pole did not survive.  It was almost horizontal after it got hit.

 

I just drove by the spot where the accident occurred, and there were no hints of the accident just a few hours ago, except for that missing pole...

 

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ISO REGEN is not a USB3 hub.  The USB receptacles are USB 2.0, and the Superspeed portion if the hub chip inside is not connected.  John & Alex picked a specific USB3 hub chip to use as USB2 hub for the signal integrity advantage.

 

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56 minutes ago, Superdad said:

 

Gosh Sam, go take care of your traumatized wife.  Or go listen to the ISO REGEN's you received.  You are officially off-duty tonight for answering forum questions!  

My wife seems less traumatized than bummed about her brand new Mercedes being wrecked.  I've never heard so many "I'm fine" from her in one day.

 

About to enjoy the Planets at the concert with my son...

 

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None of the NUCs are fanless, but the fan noise levels differ a lot depending on the exact NUC model.

 

For example, the NUC6i7KYK Skull Canyon is by far the noisiest with a 45W i7-6770HQ mobile Skylake CPU inside.  At the opposite end, my NUC6CAYS (with Celeron J3455 Apollo Lake CPU) has a fan running so quiet that I have to press an ear against the case top to hear it.  Most of the other NUCs, such as NUC5i5MYBE, NUC6i5SYH, or NUC7i5BNH are somewhere in between in terms of fan noise, and are usually audible enough to disqualify them from being in the listening room.

 

I'm preparing to transplant the motherboard of my NUC6i7KYK into an Akasa Galactico fanless case, as the fan noise is intolerable in any room even for non-audio purposes.  I'm hoping this NUC can support HQPlayer upsampling my music library to DSD512 (it's looking encouraging with a few adjustments in place).

 

My NUC6CAYS is being used as NAA for HQPlayer, and its quietness allows it a place next to one of my DACs.

 

Over the past 2 years, I have installed several NUCs into Akasa fanless chassis to use as silent NAS or NAA.  My main music NAS is a D54250WYB NUC board in an Akasa Newton case, along with a couple of Samsung SSDs.  It runs Windows Server 2012 R2 and MinimServer, and sips just 4.3W of AC power when idling.  Absolutely one of the best things I've done for distributing digital audio within my home.