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

[sajunky]

DSD is 1bit. There is no such thing as “6bit DSD” lol.
The intermediate format, is 6bit PCM. It is an internal conversion that is at a high sample rate and noise shaped. That isn’t PCM and it isn’t DSD. There’s a continuum of intermediate formats that can work.

Look at the signal path I posted.
If DSD direct is “off” DSD is converted to PCM and sent to the R2R ladder.
If it is “on” it is sent to to the 1bit DSD DAC

How you can be so sure? In the picture below is not PCM. This method is used for decoding DSD for over 30 years. Both in ChipDACs and discrete implementations.

For all others, advice. If you turn Direct DSD ON, make sure to resample it at least to DSD256. Otherwise there is a lot of noise coming out of bitstream decoder. I know this noise from the past.

Multibit DSD decoding became popular, as it doesn't require upsampling. It is still a native DSD decoder and use a separate set of unary resistors (not a main R2R ladder). In this mode (Direct DSD OFF), Gustard is not different to other brands like Denafrips, Audio GD.

 

[Tshaff]

So I am a total noob to all this audio stuff and it confuses me a lot. If I want to plug this into my Ampandsound Red October and use just my windows laptop as a source, what exactly do I need? Do I just need to install roon and ill be able to either connect from the laptop wirelessly over wifi or use an Ethernet cable if I'd like? Want to buy it but don't know exactly how it works and am hesitant. Don't want it if I need a bunch of extra special stuff that I don't understand.
Thanks!

 

[camrector]

How you can be so sure? In the picture below is not PCM. This method is used for decoding DSD for over 30 years. Both in ChipDACs and discrete implementations.

For all others, advice. If you turn Direct DSD ON, make sure to resample it at least to DSD256. Otherwise there is a lot of noise coming out of bitstream decoder. I know this noise from the past.

Multibit DSD decoding became popular, it it doesn't require upsampling. It is still a native DSD decoder and use a separate set of unary resistors (not a main R2R ladder). In this aspect, Gustard is not different to other brands like Denafrips, Audio GD.

The moment you add more bits, you have a high sampling rate PCM system, not the original (consumer) DSD format which was the bit stream of sigma delta 1-bit converters.

Gustard does not do this 6bit conversion with the R26. They should have but they don’t. I had a one bit DAC. There is no conversion inside of a delta sigma modulator.

 

[mgsu]

So I am a total noob to all this audio stuff and it confuses me a lot. If I want to plug this into my Ampandsound Red October and use just my windows laptop as a source, what exactly do I need? Do I just need to install roon and ill be able to either connect from the laptop wirelessly over wifi or use an Ethernet cable if I'd like? Want to buy it but don't know exactly how it works and am hesitant. Don't want it if I need a bunch of extra special stuff that I don't understand.
Thanks!

So I am a total noob to all this audio stuff and it confuses me a lot. If I want to plug this into my Ampandsound Red October and use just my windows laptop as a source, what exactly do I need? Do I just need to install roon and ill be able to either connect from the laptop wirelessly over wifi or use an Ethernet cable if I'd like? Want to buy it but don't know exactly how it works and am hesitant. Don't want it if I need a bunch of extra special stuff that I don't understand.
Thanks!

You have to options
1.Streaming via ethernet:
Connect the Gustard over ethernet to a switch and stream from your Laptop via Roon over the ethernet to Gustard (Gustard will appear as Roon Endpoint in Roon)
2. Direct USB connection:
connect via USB from your laptop to Gustard

 

[camrector]

How you can be so sure? In the picture below is not PCM. This method is used for decoding DSD for over 30 years. Both in ChipDACs and discrete implementations.

For all others, advice. If you turn Direct DSD ON, make sure to resample it at least to DSD256. Otherwise there is a lot of noise coming out of bitstream decoder. I know this noise from the past.

Multibit DSD decoding became popular, as it doesn't require upsampling. It is still a native DSD decoder and use a separate set of unary resistors (not a main R2R ladder). In this mode (Direct DSD OFF), Gustard is not different to other brands like Denafrips, Audio GD.

This article can help you understand.

https://www.aes.org/e-lib/browse.cfm?elib=9903

“In contrast, multi-bit sigma-delta converters, which output linear PCM code, are in principle infinitely perfectible. (Here, multi-bit refers to at least two bits in the converter.)”

 

[sajunky]

The moment you add more bits, you have a high sampling rate PCM system, not the original (consumer) DSD format which was the bit stream of sigma delta 1-bit converters.

I have one last comment, important. Please do not confuse members of community that Gustard does conversion to PCM for decoding DSD. What you see from layout of the ladder, there are two sections: one R2R for decoding PCM and the other is a set of unary resistors for decoding multibit DSD. The later consist of a hardware implementation of FIR-32/FIR-64 DSP. It is a native DSD decoding (without conversion to the PCM as you wrongly claimed).

Clearly Gustard offer two native DSD decoding methods: one is an obsolete 1-bit or BITSTREAM (with a Direct DSD option ON) and the other one is a multibit DSD as most of modern devices do.

If you have a different opinion, we need a proof. Without a proof, discussion is over.

 

[Jake2]

If you say 6-bit PCM, It is not. It is 6-bit DSD...
Still DSD. Most of Delta-Sigma chipDACs does the same internally.

Denafrips call it FIR-32 filter. It is DSP implemented in hardware using set of unary resistors (separate ladder from the main PCM R2R ladder). R26 has the same set of resistors.

@sajunky Below is Gustard's product blurb and photo re the R26's DSD capabilities. Does this photo include the 'same set of resistors' you refer?

Camrector has done a lot of great work seeking clarifications from Gustard on a range of matters, including obtaining the R26 DSD/PCM signal flow schematic below and some further email clarifications. Which seem to make it clear that when:

• DSD Direct flag is set to ON the signal is sent to the '1 bit D2A circuit'
• DSD Direct flag is set to OFF, any DSD input signal is 'sent to the ladder'.

Your point about possibly wrong or ambiguous terminology used is reasonable - the language barrier is often an issue with Gustard.

I also appreciate you seem to have a deep technical understanding of DAC technology so I am interested in clarifying what makes you think the R26 takes the same approach as Denafrips with a multibit DSD ladder despite what Gustard have said/provided @camrector ? Is it photos of R26 circuits as below or more general theory?

 

[Jake2]

What you see from layout of the ladder, there are two sections: one R2R for decoding PCM and the other is a set of unary resistors for decoding multibit DSD. The later consist of a hardware implementation of FIR-32/FIR-64 DSP. It is a native DSD decoding (without conversion to the PCM as you wrongly claimed).

It would be really useful - to non-technical types like me - if you could point out exactly which part of the ladder you refer. Are those resistors you refer in this photo or Gustard's DSD 1-bit circuit photo I posted just above?

 

[sajunky]

@Jake2

I edited a photo pointing at a set of resistors dedicated for DSD multibit decoding. The other part you perhaps recognise as a typical R2R ladder.

 

[camrector]

I have one last comment, important. Please do not confuse members of community that Gustard does conversion to PCM for decoding DSD. What you see from layout of the ladder, there are two sections: one R2R for decoding PCM and the other is a set of unary resistors for decoding multibit DSD. The later consist of a hardware implementation of FIR-32/FIR-64 DSP. It is a native DSD decoding (without conversion to the PCM as you wrongly claimed).

Clearly Gustard offer two native DSD decoding methods: one is an obsolete 1-bit or BITSTREAM (with a Direct DSD option ON) and the other one is a multibit DSD as most of modern devices do.

If you have a different opinion, we need a proof. Without a proof, discussion is over.

I have had direct conversation with Gustard about this.
There is NO MULTIBIT CONVERSION WITH DSD. It is either converted to PCM directly (DSD direct off) or it is sent to the 1bit DSD DAC directly.
Look at the signal path I was sent by GUSTARD. Here are the emails too.

 

[Jake2]

@Jake2

I edited a photo pointing at set of resistors dedicated for DSD multibit decoding. The other part you perhaps recognise as a typical R2R ladder.

Thanks for this, appreciate it. Yes I recognize the other part as an R2R ladder

FYI there is a bit of conflicting info here it is not easy to reconcile. See also Gustard email re DSD Direct OFF = convert to PCM.

I guess you would explain this (and the similar reference in the schematic) by saying 'convert to PCM' is a simplification and actually means convert to multibit-DSD, correct?

 

[Jake2]

I have had direct conversation with Gustard about this.
There is NO MULTIBIT CONVERSION WITH DSD. It is either converted to PCM directly (DSD direct off) or it is sent to the 1bit DSD DAC directly.
Look at the signal path I was sent by GUSTARD. Here are the emails too.

Thanks Cam - I was trying to find these email clarifications you'd gotten from Gustard!

 

[camrector]

Thanks for this, appreciate it. Yes I recognize the other part as an R2R ladder

FYI there is a bit of conflicting info here it is not easy to reconcile. See also Gustard email re DSD Direct OFF = convert to PCM.

I guess you would explain this (and the similar reference in the schematic) by saying 'convert to PCM' is a simplification and actually means convert to multibit-DSD, correct?

He might try to say that but that is why I asked Gustard specifically about the interpolation fir filter.

 

[Jake2]

He might try to say that but that is why I asked Gustard specifically about the interpolation fir filter.

Those emails are even clearer than I recalled!

Btw I would say although @sajunky can be a bit blunt at times (much like some Saffa mates of mine!) he is a knowledgeable and well intentioned guy who makes valuable contributions to a number of other threads I'm on. So I'm always interested in his take.

This discussion and a bit if challenge is always healthy if we can try to keep it chilled - maybe @m-i-c-k-e-y could sticky the outcomes (schematics, Gustard emails... anything else) on his OG post.

 

[sajunky]

This discussion and a bit if challenge is always healthy if we can try to keep it chilled - maybe @m-i-c-k-e-y could sticky the outcomes (schematics, Gustard emails... anything else) on his OG post.

I fully support this. When you speak to Gustard, attach this photo and ask them why is the entire section resistors for decoding multibit DSD if not used!

Maybe these Gustard guys refer you the to a developer, they will not spread a nonsense anymore.