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HOLO Audio Spring DAC - R2R DSD512


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Digital Audio Converter (DAC) – Kitsune HiFi

 

From their site:

"The Spring Dac is his newest product and is the first DAC in history to be capable of DSD native on an R2R dac! This spring is capable of DSD512 and actually running on his bespoke discrete ladder dac! this is not your run of the mill dac here, it’s full of unique and well thought out designs and implementations."

 

A few measurements are there too!

 

Spring-1024x576.jpg

146435793342544.jpg

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I'd love to see a thorough review (or six) of this DAC. It's half the price of the T+A DAC 8, and the description on the Kitsune website states that it's "upported currently on MAC and Linux…."

 

--David

Listening Room: Mac mini (Roon Core) > iMac (HQP) > exaSound PlayPoint (as NAA) > exaSound e32 > W4S STP-SE > Benchmark AHB2 > Wilson Sophia Series 2 (Details)

Office: Mac Pro >  AudioQuest DragonFly Red > JBL LSR305

Mobile: iPhone 6S > AudioQuest DragonFly Black > JH Audio JH5

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Some extra info from US distributor KitsuneHifi:

 

"It's truly a unique DAC in that it's the first discrete DAC to be able to process both pcm and native dsd on the same DAC. How is this possible? I thought the same thing, but it does this with discrete resistor networks. There is one DAC module that consists of two separate dedicated discrete resistor network for pcm audio and a dedicated resistor network for dsd native audio. So it has multibit and delta sigma in one DAC module. And it's the first DAC that I'm aware of to ever implement this in one DAC and do it very well!

 

Currently the DAC supports native dsd512 in Linux and Mac and dsd256 with Windows. The drive is being finished for Windows to allow full native dsd512 and should be available 3-4 weeks according to HOLO Audio, designer, Jef Zhu. "

 

Let's wait to get some more info from the designer relative to DSD path, as I think the above has some imperfections.

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Looks like one of the first DSD512 DAC with I2S input!

 

Yes, I2S is nice, but why uses this DAC an AK4137 Sample Rate Converter?

Is PCM converted to DSD or DSD converted to PCM?

This does not make sense at all!

 

Matt

"I want to know why the musicians are on stage, not where". (John Farlowe)

 

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Doesn't the new Lampizator ladder DAC configuration also do both PCM and DSD? Doesn't the totaldac?

In the end, it depends on how good the actual R2R implementation is - just becuase its R2R.

 

Sort of hard for me to believe it can be that great at a fraction of the price of it's ladder DAC competitors. It will be interesting to see what people/reviewers say about it once they hear it.

Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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May I remind you that it has also a NOS mode which bypass any digital oversampling.

 

With diverse and flexible sampling mode conversion mode

1: NOS mode , no digital oversampling, the raw data is directly converted to analog. Because digital oversampling will produce time-domain distortions such as ringing, so NOS avoid these problems. Generally NOS mode other performance indicators have a significant impact, but the Spring is designed to allow top performance while in NOS mode.

2: OS mode , the PCM super-sampled PCM higher frequency, the DSD DSD supersampling to higher frequency, then digital to analog converter.

3: OS PCM mode , enter either PCM or DSD input, all the way to the PCM oversampling analog to digital conversion.

4: OS DSD mode , enter either PCM or DSD input over all sampled DSD approach to digital to analog converter.

 

 

Yes, the AK4137 seems not to work in NOS mode.

 

Matt

"I want to know why the musicians are on stage, not where". (John Farlowe)

 

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This dac does NOT do DSD512. From Jeff Zhu, the designer:

 

 

By now, Spring can't support DSD512. You might see some picture

shows DSD512 but it's not supported by now. I was planned to support that,

but it seems have no music source at all even the test file. Sony has

stopped DSD and turn to DXD now. So DSD256 might be the end of DSD. However,

DSD512 is not so hard. If it is really needed, I can put it into 'May'.

Spring can support DSD512 by upgrading the firmware also, but it must return

to factory. I'm afraid it will bring some troubles for dealing this matter.

 

The oversampling is done by AK4137,

'OS PCM' converts the input stream to PCM no matter it is

PCM or DSD, then send to DAC.

'OS DSD' converts the input stream to DSD no matter is is

PCM or DSD, then send to DAC.

'OS' oversamples the input stream. If it is DSD input, it

oversample to DSD256. If it is PCM input, it oversample to PCM384K or 352.8K

'NOS' does no oversampling. send the input stream directly

to DAC module.

 

About DSD 'native', it is the way the USB transfer the stream. You

know DOP, which is DSD Over PCM. DOP put the DSD into a PCM stream. At the

receiver end, it just unpack the PCM stream and get the DSD back. DOP does

NOT change any bit of DSD stream, just sending it with the package. So it

waste some data rate. At the same data rate, DOP is 1/2 of DSD native, the

other 1/2 is the package. So DOP and DSD native are all bit perfect. The DSD

stream sending to DAC is all the same.

 

So, now you should know, DSD native is just about the way it

transfer the stream. Not describing the way it doing digital to analog

conversion. At the DAC stage, the DSD stream can convert to PCM then do the

final digital to analog covert. Actually, most DAC chips doing this inside

the chip. One point need to be remember, DSD stream can't do volume

attenuation. If this chip can do digital volume control under DSD mode, then

is must converted to PCM already.

 

Let's go back to Spring. If Spring works in 'NOS' mode. There is no

oversampling, no conversion, just the original data doing the final digital

to analog conversion. I will not explain how it does PCM conversion, you

should already know quite well about it. There is a lot of resistor ladder

DAC, they are born to do this. I just explain how Spring can do 'discrete

DSD conversion'. Actually it is like DCS and CHORD. If you looking to DCS

and CHORD's pcb, you will find 'discrete DSD conversion' is also using

switches and precision resistors, like resistor ladder dacs. So, no matter

it is 'discrete DSD conversion' or 'discrete PCM conversion', they all use

the same discrete devices. Just work in different architecture. That makes

possible to combine these two modes in one device.

 

Best Regards

Jeff Zhu

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The AK4137 Sample Rate Converter is limited to DSD256.

 

Matt

 

Hi Tim,

Actually, AK4137 can oversample to DSD512, the data sheet show it's limited to DSD256. But I've tested DSD512, it also works. But that is not writen in data sheet means it's not guarateed by official. So I don't want do that also.

 

 

Best Regards

Jeff Zhu

 

 

 

interesting! :D

 

 

also to those who wonder how his discrete resistor implementation is and how he has achieved such flawless linearity and ultra low THD. :D read this email he wrote me. :D

 

" About the resistor tolerance, his word is partly right, but not accurate. The msb of 16bits value only represent 32768, not 65536, all 16bits is 65535, but the msb is only 32768. There are techniques to reduce this requirement. For example, segment+r2r, using segment into the first few bits, then r2r for the rest of them. Rockna is segment+r2r, TotalDAC is all R2R. And you can see, Rockna's THD spec. is much better than Total. Total uses foil resistor, but they used the simplest architecture. That results an unsatisfied test performance. To my opinion, it's some kind of wasting foil resistors. Soekris also uses segment+r2r. MSB's old model is all r2r, but I don't know about their new models.

 

Anyway, There are ways to improve the performance, the segment+r2r is one way. Trimming is another way. There is an additional r2r ladder in Spring, it compensate the main r2r ladder. It works like trimming, but trimming is to change the resistor value. This additional r2r ladder are digital controled and is to compensate the resistor tolerance. For example, the msb of 16bits should have the value of 32768, but due to tolerance, it represent 32700 in real world. Then that additional r2r ladder will compensate 68 into it. Then it became 32700+68=32768.

 

Actually there are other ways to improve performance, I just told you two stories. There are more stories behind the design. It is really hard. I must count every via holes in layout, every pcb wire has it's impedance and must put attention on it. A via hole can be 50m Ohm, it is 1/20000 of 1K ohm, and you see, it covers 32768 which is the msb of 16bits. Also the switches has self-impedance which is about serval ohm to 30 ohms. If you find this issue. Maybe you will get crazy, it seem an impossible mission. But a good designer will overcome all these problems. It's our value.

 

All the resistor tolerance, switch impedance, line impedance, via hole impedance, finally reflect as linearity. There is a chart shows Spring's linearity, it's excellent. But I suggest you to look at THD performance. A bad linearity must result a bad THD performance. But a good linearity isn't mean to be a good THD performance. THD is dynamic performance, more critical than linearity which is a static performance.

 

If you look at the THD performance, you will find Spring maybe the best among those competitors. I'm applying a patent which contribute a lot of that performance. But I can't tell you how. It's confidential now.

 

 

Best Regards

Jeff Zhu

"

Tim Connor

KitsuneHifi.com / HoloAudio USA

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Does someone know if it's I2s input (HDMI connector) comply with the PS Audio standard?

 

yes, the HDMI i2s is PSaudio standard, I believe Audio-GD uses the same pinout too.

 

Gustard is one of the few that is quite a bit different.

 

But if you get a Singxer SU-1 you can be compatible with anything :D they were smart enough to add dipswitches to set the pinout!

Tim Connor

KitsuneHifi.com / HoloAudio USA

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As I wrote somewhere else (you know where), I prefer waiting for extra info, without jumping to harried conclusions

 

The SRC is not in the audio path when running in NOS mode. NOS mode is direct and indeed bypasses the SRC. This is my preferred listening method without question!!!! The Spring certainly sounds best in NOS. And DSD is a whole level of awesomeness in NOS too. Kind of interesting to know that a discrete resister network is processing the DSD data.

Tim Connor

KitsuneHifi.com / HoloAudio USA

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Sorry for jumping into this thread. I had to since I didn't realize some of these emails made it onto the thread before I was able to update my site. (kitsunehifi)

 

But we will have most of them sold within the week the way things are looking. But i've been asked by one to do a review. I have my personal Level 3 Spring Dac that i'm happy to loan out and have a proper review done. I"m actually quite excited for what may be said about it!

 

I'm a NOS guy, so this particular Dac is the holy grail for me personally. I'll be comparing it to my NOS11 (audio-gd) and also my dual Soekris Dam1021.

Tim Connor

KitsuneHifi.com / HoloAudio USA

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Sorry for jumping into this thread. I had to since I didn't realize some of these emails made it onto the thread before I was able to update my site. (kitsunehifi)

 

But we will have most of them sold within the week the way things are looking. But i've been asked by one to do a review. I have my personal Level 3 Spring Dac that i'm happy to loan out and have a proper review done. I"m actually quite excited for what may be said about it!

 

I'm a NOS guy, so this particular Dac is the holy grail for me personally. I'll be comparing it to my NOS11 (audio-gd) and also my dual Soekris Dam1021.

 

What would be most interesting is to hear it compared to R2R audiophile favorites like Total DAC and Metrum; or the R2R and DSD playback in Lampizator. Or a current favorite here, the T+A DAC8DSD, which does non-chip 1 bit conversion of DSD.

Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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So way up this page there designer was quoted as saying DSD512 was off because there's no native content and Sony has given up on the standard in favour of DXD, and even then it's still looking sketchy.

 

But what people are doing now is running HQPlayer's upsampling engine and just converting anything to DSD512. Having that feature along with the rest makes this DAC attractive.

 

Is there anyone that could contact the DAC designer and explain that use case, how it's really gaining steam, and try to have it implemented?

 

Sent from my SM-N9200 using Computer Audiophile mobile app

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So way up this page there designer was quoted as saying DSD512 was off because there's no native content and Sony has given up on the standard in favour of DXD, and even then it's still looking sketchy.

 

But what people are doing now is running HQPlayer's upsampling engine and just converting anything to DSD512. Having that feature along with the rest makes this DAC attractive.

 

Is there anyone that could contact the DAC designer and explain that use case, how it's really gaining steam, and try to have it implemented?

 

Sent from my SM-N9200 using Computer Audiophile mobile app

 

I have, He's working on it, but maybe only for his new May dac. Stay tuned.

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So way up this page there designer was quoted as saying DSD512 was off because there's no native content and Sony has given up on the standard in favour of DXD, and even then it's still looking sketchy.

 

But what people are doing now is running HQPlayer's upsampling engine and just converting anything to DSD512. Having that feature along with the rest makes this DAC attractive.

 

Is there anyone that could contact the DAC designer and explain that use case, how it's really gaining steam, and try to have it implemented?

 

Sent from my SM-N9200 using Computer Audiophile mobile app

 

 

I can contact Jeff again. I run KitsuneHiFi.com BTW.

 

Jeff is well aware that many are using HQplayer to upsample to DSD512. What are you saying is looking sketchy and i'll be happy to do my best to clear things up. Jeff has been most helpful in responding to all questions thus far and he is quite passionate about his work.

 

I do know his next dac, "may" will have this feature of upsampling to high rates. But I can keep asking him about getting support for dsd512 upsampling for spring. It just may not happen.

Tim Connor

KitsuneHifi.com / HoloAudio USA

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This dac does NOT do DSD512. From Jeff Zhu, the designer:

 

 

By now, Spring can't support DSD512. You might see some picture shows DSD512 but it's not supported by now. I was planned to support that, but it seems have no music source at all even the test file. Sony has

stopped DSD and turn to DXD now. So DSD256 might be the end of DSD. However, DSD512 is not so hard. If it is really needed, I can put it into 'May'. Spring can support DSD512 by upgrading the firmware also, but it must return

to factory. I'm afraid it will bring some troubles for dealing this matter.

 

Best Regards

Jeff Zhu

 

That's what I was referring to about DSD looking sketchy. I meant Jeff's view of its longevity or whatever.

 

I also didn't know that May wasn't the month of May and that this was just a recently past response, but that actually 'May' is the name of a new DAC he's building. My guess is that May DAC is higher end?

 

Thanks for the 2 responses, guys. I'd be happy to hear DSD 512 was available on a cheaper model from Jeff, though yes, I know the iFi DAC exists for the truely price conscious.

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I'd be happy to hear DSD 512 was available on a cheaper model from Jeff, though yes, I know the iFi DAC exists for the truely price conscious.

 

Me too. It's perhaps worth re-emphasizing that the iFi micro iDSD is based on a Burr-Brown chipset, while the Spring DAC (and presumably the May) is R2R based. An R2R DAC that does DSD is a pretty rare bird, so that really piques my curiosity, especially since it's at an affordable (for me) price point.

 

Any plans to show the Spring and/or the May at RMAF?

 

--David

Listening Room: Mac mini (Roon Core) > iMac (HQP) > exaSound PlayPoint (as NAA) > exaSound e32 > W4S STP-SE > Benchmark AHB2 > Wilson Sophia Series 2 (Details)

Office: Mac Pro >  AudioQuest DragonFly Red > JBL LSR305

Mobile: iPhone 6S > AudioQuest DragonFly Black > JH Audio JH5

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