GUSTARD DAC-R26 Balanced Decoder R2R+1Bit Dual Native Decoding Music Bridge

[GP123]

Let me translate the last sentence. “In direct DSD mode, send DSD to the independent 1 bit D/A converter, without converting from DSD to PCM.”

What this means is we are correct in assuming that R26 will convert to PCM if direct DSD is off. This also explains why volume control works.

 

[Chodi]

Here is a test R26 owners can perform to verify if they hear the same noise difference as I do.
(I hope Jussi does not mind I share his test file with you)

The test goes as follows:
1. Download the following file (containing an inaudible 1k sine at -120dB):
https://www.signalyst.eu/tmp/sine1k_-120dB-2.wav
2. Let Roon or HQPlayer upsample it to DSD and stream it to R26
3. On R26 toggle Direct DSD = ON and OFF in the menu and listen if you hear a difference in the noise level (best using headphones)

Can anyone here reproduce my findings, do you also hear increase in noise when DSD Direct = ON ? ( in other words using the dedicated DSD DAC)

Sounds to me like the R26 is actually happy with DOP in HQP for flac files. My Denefrips dac will play flac without issue as converted DSD in HQP either in direct DSD on or off. Sounds like perhaps the R26 is only happy doing DSD in DOP for flac files when the DSD is set to off. I don't have the R26 to try but that is what this sounds like to me. If that is the case it would be a design issue between Denafrips and Gustard handling things bit differently. If you get a good clean sound ( no noise) with it off then it is just doing DOP for DSD using HQP which is just fine. It would still probably work set ON with a real DSD file (I am not well versed in streaming so I cannot comment on that). Just my impressions from your description. Now if you get noise with DSD Direct ON and OFF then that is a different matter and certainly a problem.

 

[camrector]

Let me translate the last sentence. “In direct DSD mode, send DSD to the independent 1 bit D/A converter, without converting from DSD to PCM.”

What this means is we are correct in assuming that R26 will convert to PCM if direct DSD is off. This also explains why volume control works.

Volume control doesn’t work because
1-bit DSD64 at 2.8MHz (64 = 2^6) has only 6 bits of dynamic range (~36dB).

We have that picture too and it doesn’t say what you are “translating”

 

[Odezra]

I think the facts we have are:

- dsd direct introduces more noise when upsampling than when using pcm upsampling (nos on)
- there are no cracks or pops in pcm mode
- different people prefer either dsd or pcm upsampling so you need to try which you prefer


Subjectively - I have been testing for the day and still prefer upsampling to 512 dsd regardless of whether dsd direct is set to on or off and this is across both Roon and hqplayer upsampling (and I prefer this over native upsampling). I prefer this over pcm upsampling to 768. Technically this should be odd - as the the flac file is being upsampled to dsd then converted back to pcm (when dsd direct is off). I haven’t tried dop (my sdm pack is set to none in hq player right now). Will see if that changes anything.

 

[camrector]

Sounds to me like the R26 is actually happy with DOP in HQP for flac files. My Denefrips dac will play flac without issue as converted DSD in HQP either in direct DSD on or off. Sounds like perhaps the R26 is only happy doing DSD in DOP for flac files when the DSD is set to off. I don't have the R26 to try but that is what this sounds like to me. If that is the case it would be a design issue between Denafrips and Gustard handling things bit differently. If you get a good clean sound ( no noise) with it off then it is just doing DOP for DSD using HQP which is just fine. It would still probably work set ON with a real DSD file (I am not well versed in streaming so I cannot comment on that). Just my impressions from your description. Now if you get noise with DSD Direct ON and OFF then that is a different matter and certainly a problem.

Lol this is what lead me down this rabbit hole
In Roon I have the setting DSD direct.
DSD via DOP is an option but I don’t use that.
On my R26 I have DSD direct off. Volume is always at fixed.
Sounds amazing. No pops or noise.
Turning DSD direct to On I hear graininess and louder hiss from the music background.
That points to a higher noise floor and bad SINAD. We have the measurement to prove that with DSD direct on SINAD is at 68db and with it off is 92db.

@labeelen who had the issue originallly, also confirmed that the noise he heard went away when he turned DSD direct off.
Unless Gustard says that DsD Direct off converts to pcm, the other explanation is that bypassing this interpolation filter with DSD direct on (which also happens when PCM NOS is on) results in noise.
It is also the reason the volume control doesn’t work because of the way digital volume control works.
I mean PCM NOS stands for NON OVERSAMPLING.

 

[Nada]

lead me down this rabbit hole

Thanks for the deep dive. I blame Sony for this whole DSD debacle

What I dont get is why buy an expensive multibit R2R DAC and then play one bit DSD on it? For those that like the DSD sound wouldn't it be better and cheaper just to buy a one bit noise shaping DAC?

 

[camrector]

DSD DACs oversample so that they can use better and gentler noise shaping filters. Single-bit converters rely on dither and noise-shaping even more. Without noise shaping, SACD/DSD at 64fs (2.8224MHz) would only have 6-bits, or 36dB, of dynamic range, about the same as a not-very-good telephone connection. This is why volume doesn’t work when you bypass the oversampling.

 

[labeelen]

I think the facts we have are:

- dsd direct introduces more noise when upsampling than when using pcm upsampling (nos on)
- there are no cracks or pops in pcm mode
- different people prefer either dsd or pcm upsampling so you need to try which you prefer


Subjectively - I have been testing for the day and still prefer upsampling to 512 dsd regardless of whether dsd direct is set to on or off and this is across both Roon and hqplayer upsampling (and I prefer this over native upsampling). I prefer this over pcm upsampling to 768. Technically this should be odd - as the the flac file is being upsampled to dsd then converted back to pcm (when dsd direct is off). I haven’t tried dop (my sdm pack is set to none in hq player right now). Will see if that changes anything.

The ‘cracks or pops’ in dsd where solved (for me) with the latest v1.4 firmware

On dsd vs pcm I currently lean more towards upsample (with HQPlayer) to pcm768 (with PCM NOS=OFF in R26 menu) as this gives more detail and spacious sound (to me). DSD on the other hand has more analogue qualities (potentially less fatigueing) but flatter sounding (to me). R26 is however still burning in, so to early for final judgement.

 

[camrector]

Thanks for the deep dive. I blame Sony for this whole DSD debacle

What I dont get is why buy an expensive multibit R2R DAC and then play one bit DSD on it? For those that like the DSD sound wouldn't it be better and cheaper just to buy a one bit noise shaping DAC?

Yeah I hope my ranting doesn’t sound like I’m saying DSD is better or anything like that.
I just want to know everything I can and help out others with this fantastic DAC.
I convert all my DSD to PCM within Roon, because I went down the evil Digital Room Correction path lol. Besides getting this DAC, digital room correction has taken my system to a level I didn’t think possible. I’m shocked at how good it sounds now.

 

[Chodi]

Lol this is what lead me down this rabbit hole
In Roon I have the setting DSD direct.
DSD via DOP is an option but I don’t use that.
On my R26 I have DSD direct off. Volume is always at fixed.
Sounds amazing. No pops or noise.
Turning DSD direct to On I hear graininess and louder hiss from the music background.
That points to a higher noise floor and bad SINAD. We have the measurement to prove that with DSD direct on SINAD is at 68db and with it off is 92db.

@labeelen who had the issue originallly, also confirmed that the noise he heard went away when he turned DSD direct off.
Unless Gustard says that DsD Direct off converts to pcm, the other explanation is that bypassing this interpolation filter with DSD direct on (which also happens when PCM NOS is on) results in noise.
It is also the reason the volume control doesn’t work because of the way digital volume control works.
I mean PCM NOS stands for NON OVERSAMPLING.

Sounds like you do not have experience with HQPlayer (concertainly not every has). I've been using it for several years. There is the option in HQP to set it for DOP. I don't stream but if I did I would think the Roon setting would be pcm and then the HQP setting would be DSD as DOP. The R26 would be set to NOS mode then all the filtering and upsampling would be done by HQP. The volume control in HQP is probably better than the one on the R26 but that is only a guess. You can also disable the volume control in HQP and still use DOP will convert to DSD with the various filter settings in HQP. It is a very versatle piece of software.

 

[camrector]

Sounds like you do not have experience with HQPlayer (concertainly not every has). I've been using it for several years. There is the option in HQP to set it for DOP. I don't stream but if I did I would think the Roon setting would be pcm and then the HQP setting would be DSD as DOP. The R26 would be set to NOS mode then all the filtering and upsampling would be done by HQP. The volume control in HQP is probably better than the one on the R26 but that is only a guess. You can also disable the volume control in HQP and still use DOP will convert to DSD with the various filter settings in HQP. It is a very versatle piece of software.

Yes I’ve never used HQplayer or the R26 volume control.
With Roon I could send DSD as DOP but there is no need for me because DSD can be sent to the R26 native using the LAN input.
I was using pure DSD files with both Direct on/off, and for me it took 2 minutes to hear how much more noise direct “on” had.

 

[labeelen]

Sounds like you do not have experience with HQPlayer (concertainly not every has). I've been using it for several years. There is the option in HQP to set it for DOP. I don't stream but if I did I would think the Roon setting would be pcm and then the HQP setting would be DSD as DOP. The R26 would be set to NOS mode then all the filtering and upsampling would be done by HQP. The volume control in HQP is probably better than the one on the R26 but that is only a guess. You can also disable the volume control in HQP and still use DOP will convert to DSD with the various filter settings in HQP. It is a very versatle piece of software.

I have Roon, HQPlayer and R26. I will try your suggestions later today and will report my findings. Thx

R26 manual does not mention DOP so I’m curious how (and if] it wil be processed and how R26 would interpret it.

 

[Chodi]

I have Roon, HQPlayer and R26. I will try your suggestions later today and will report my findings. Thx

R26 manual does not mention DOP so I’m curious how (and if] it wil be processed and how R26 would interpret it.

Please let us know if this works for you. It may convince me to purchase the R26. I've been on the fence because of your comments and the limitation of Roon as the internal streamer. I am a classical music guy so Roon would not be my first choice. I have heard that Gustard plans to add other sites to their streamer through firmware but I'm a wait and see type of guy.

 

[GP123]

Volume control doesn’t work because
1-bit DSD64 at 2.8MHz (64 = 2^6) has only 6 bits of dynamic range (~36dB).

We have that picture too and it doesn’t say what you are “translating”

I got this reply from Gustard.

 

[Nada]

I got this reply from Gustard.

.... just as predicted