Upsampling to DSD prior to Decoding with your DAC

[mjs]

I posted something similar in the computer software sub-forum, with not much response, so I thought I'd have go here.

 

Assuming we have a DAC that can decode DSD at a certain bitrate, maybe DSD128 at least, if we are playing back computer files, maybe we can use the software to upsample to DSD before the DAC decodes the digital file, presumably on the basis that the DAC decodes a better result from DSD than from PCM at a lower bitrate. In my case, Audirvana+ can upsample via the Mac Mini to DSD128 which suits my DAC. I have been doing this over the last few days with pretty good results, maybe a bit more air and imaging.

 

Does anyone else have any similar experiences, good, bad or indifferent?

[georgehifi]

Maybe your just experiencing something I've been saying all along for a different reason, that one can't compare PCM (redbook) to DSD on a DSD dac, and have justice done for PCM redbook. 

 

A quote from MoJo Music:

" When a PCM file is played on a DSD or Bit Stream, Delta Sigma  converter, the DAC chip has to convert the PCM to DSD in real time. This is one of the major reasons people claim DSD sounds better than PCM, when in fact, it is just that the chip in most modern single-bit delta sigma DACs do a poor job of decoding PCM."

 

Cheers George

[Guest rmpfyf]

@Keith_W has a few significant posts on this from memory.

[Keith_W]

Thanks for tagging me @rmpfyf. @mjs I have been doing this for more than a year now, using HQPlayer. The downside of doing this is that it is quite CPU intensive. The more you want to upsample, and the more channels you want to convolve, the more powerful CPU you need. Having said that, a Mac Mini should be able to upsample two channels to DSD128 with no problem. HQPlayer's interface is pretty basic, most people run it with third party software (e.g. Roon). 

[mjs]

2 hours ago, georgehifi said:

Maybe your just experiencing something I've been saying all along for a different reason, that one can't compare PCM (redbook) to DSD on a DSD dac, and have justice done for PCM redbook. 

 

A quote from MoJo Music:

" When a PCM file is played on a DSD or Bit Stream, Delta Sigma  converter, the DAC chip has to convert the PCM to DSD in real time. This is one of the major reasons people claim DSD sounds better than PCM, when in fact, it is just that the chip in most modern single-bit delta sigma DACs do a poor job of decoding PCM."

 

Cheers George

George, thanks for your comment, I guess we are sort of talking about the same thing. I'm talking about upsampling the PCM file in software first (in my case using Aurivana+ and the grunt of a Mac Mini) whereas you are referring to the DAC doing the upsampling. I guess most DSD DACs upsample PCM prior to decoding. In my case I have a Luxman DA-250 with a TI PCM1795 chip which 8 x upsamples PCM to 352.8kHz or 384kHz/32bit before decoding. The TI PCM1795 also handles DSD, but I am not sure of the nitty gritty details, I guess 44.1kHz/16bit x 8 = 5.6448MHz or DSD128. Regardless of where the upsampling occurs, is there something that goes missing in the normal PCM decoding process that is maintained in the DSD decoding, ie is the decoding of high bitrate DSD "easier" on the signal than say Redbook PCM?.

13 minutes ago, Keith_W said:

Thanks for tagging me @rmpfyf. @mjs I have been doing this for more than a year now, using HQPlayer. The downside of doing this is that it is quite CPU intensive. The more you want to upsample, and the more channels you want to convolve, the more powerful CPU you need. Having said that, a Mac Mini should be able to upsample two channels to DSD128 with no problem. HQPlayer's interface is pretty basic, most people run it with third party software (e.g. Roon). 

Keith, yes, I don't find any problems using the Mac Mini and Audirvana+ to upsample to DSD128, which is the highest DSD bitrate my DAC can decode.

[frankn]

4 hours ago, georgehifi said:

Maybe your just experiencing something I've been saying all along for a different reason, that one can't compare PCM (redbook) to DSD on a DSD dac, and have justice done for PCM redbook. 

 

A quote from MoJo Music:

" When a PCM file is played on a DSD or Bit Stream, Delta Sigma  converter, the DAC chip has to convert the PCM to DSD in real time. This is one of the major reasons people claim DSD sounds better than PCM, when in fact, it is just that the chip in most modern single-bit delta sigma DACs do a poor job of decoding PCM."

 

Cheers George

Hi George,

What about the FPGA software DSD DAC's - there is a large body of praise of their conversion & resulting quality playback of CD or higher rate PCM.       

[georgehifi]

1 hour ago, frankn said:

Hi George,

What about the FPGA software DSD DAC's - there is a large body of praise of their conversion & resulting quality playback of CD or higher rate PCM.       

 

Not sure, from what I understand if it reconfigured the PCM into Bitstream (Single-bit) it's not as good as being done with a proper R2R Multibit chip.

 

Maybe that's why were seeing many discrete R2R Multibit dacs coming out now, because the last true Multibit chip was the 24bit Burr Brown PCM1704, it was stopped because of the high cost of manufacturing it, having to finely laser trim the many individual internal microscopic R2R resistors.

 

But now were starting to see hybrids of 4 bits of Multibit together with DSD Bitstream (delta sigma), but from what I gather for PCM (redbook) replay they'er still not as good as real R2R 16bit-24bit Multibit chips of old, or the newer discrete ones now, Total, Denafrips, Holo, Sokeris ect ect.

I listened to Kramer's (Edgar Kramer) Total Dac (Wilson Alexia, passive pre, Gryphone Antillion evo) which is discrete R2R Multibit and it was very good doing pcm Redbook, better than anything I've heard from DSD even though not through the same system. 

 

Cheers George      

Edited May 24, 2017 by georgehifi

[davewantsmoore]

44 minutes ago, georgehifi said:

But now were starting to see hybrids of 4 bits of Multibit together with DSD Bitstream (delta sigma)

 

Hasn't this been common for a long while now ?!

[mjs]

1 hour ago, georgehifi said:

 

Not sure, from what I understand if it reconfigured the PCM into Bitstream (Single-bit) it's not as good as being done with a proper R2R Multibit chip.

     

So, my original issue relates to whether upsampling in the software (in this case as opposed to in the DAC hardware) specifically to DSD and not just upsampled PCM, is better/gives inferior/same/superior results to PCM either through a straight non-unsampling PCM DAC or an upsampling DAC.

[Guest rmpfyf]

2 minutes ago, mjs said:

So, my original issue relates to whether upsampling in the software (in this case as opposed to in the DAC hardware) specifically to DSD and not just upsampled PCM, is better/gives inferior/same/superior results to PCM either through a straight non-unsampling PCM DAC or an upsampling DAC.

 

So far as the content of the data you get, for the same filters etc it doesn't matter where you do your format conversion (from PCM to PDM/DSD) and/or upsampling. 

 

There are potential implications regards jitter, and various strategies to combat these, though this depends on things outside the conversion itself.

 

Software is nice in that allows you an infinite flexibility of sorts in conversion filters, you're not limited to what's in firmware or throughput capacity on either your DAC IC or whatever micro/FPGA/whatever is doing the conversion. 

[georgehifi]

1 hour ago, davewantsmoore said:

 

Hasn't this been common for a long while now ?!

 

Probably around the time of the disappearance "for a decent price" for anyone to buy of the PCM1704's  from places like RS, Element14.Digikey and such.

Now they're up around $130a piece if you can find one http://au.rs-online.com/web/p/audio-dacs/6200290/

 

Where you can get Bitstream Delta Sigma based chip for $10 or even cheaper.

 

Cheers George 

Edited May 24, 2017 by georgehifi

[eltech]

45 minutes ago, mjs said:

So, my original issue relates to whether upsampling in the software (in this case as opposed to in the DAC hardware) specifically to DSD and not just upsampled PCM, is better/gives inferior/same/superior results to PCM either through a straight non-unsampling PCM DAC or an upsampling DAC.

 

All I can suggest if that if upsampling to DSD using software sounds preferable to you across all types of music, then its fair to say your DAC, and your ears prefer software upsampling of PCM to DSD.

 

[eltech]

7 minutes ago, georgehifi said:

 

Probably around the time of the disappearance "for a decent price" for anyone to buy of the PCM1704's  from places like RS, Element14.Digikey and such.

 

Cheers George 

Perhaps Dave was talking about the LC7880 from the 1990's?

[georgehifi]

5 minutes ago, eltech said:

Perhaps Dave was talking about the LC7880 from the 1990's?

 

Maybe I was thinking more the Analog Devices hybrids.

 

Cheers George

[eltech]

7 minutes ago, georgehifi said:

 

Maybe I was thinking more the Analog Devices hybrids.

There is a few of this design. Even Burr Brown makes them.

[georgehifi]

34 minutes ago, eltech said:

There is a few of this design. Even Burr Brown makes them.

 

Yes, Burr Brown also.

But from what I've read and tried to understand about these hybrids dacs, giving a couple (I believe it's 5) of bits of Multibit for the Bitstream (Delta Sigma) to ride on, is a half way fix to having all true Multibit only to convert PCM with.

 

Maybe like older Krells "S" models, Class-A plateau biasing, sorta Class-A but not really. 

 

Cheers George

Edited May 24, 2017 by georgehifi

[eltech]

@georgehifi

I think it might have been an engineering exercise. A DAC designed by a committee, but only 1/3rd of the committee liked R2R.

 

[frankn]

2 hours ago, mjs said:

So, my original issue relates to whether upsampling in the software (in this case as opposed to in the DAC hardware) specifically to DSD and not just upsampled PCM, is better/gives inferior/same/superior results to PCM either through a straight non-unsampling PCM DAC or an upsampling DAC.

IMO your "issue" isn't one of better or worse - it is along the lines of which sounds better to you.  For everyone who likes PCM DAC's there are an equal number who like DSD DAC's, and about an equal number on each side of the fence regarding leaving the DAC to do its thing without prior upsampling  or upsample outside of the DAC. 

Given the differences in approaches by manufacturers a lot of the result will come down to what products you are using in your system. 

[firedog]

 A lot of people with DS DACs think they sound better playing DSD, even when it is converted first from PCM. It depends, though on each DAC and how it works. Some, not all,  DACs will take a DSD stream and convert it directly to analog, or to 8 bit DS, and then to analog. 

 

HQ Player is specifically designed for this: In addition to proprietary filters and modulators, part of the rationale behind it is that a powerful computer will do a better job of the upsampling, filtering, and modulating than a much less powerful DAC chip. HQP has a lot of filter/modulator choices that demand quite a powerful PC to run. 

[davewantsmoore]

2 hours ago, georgehifi said:

Probably around the time of the

 

At least a decade in the mainstream from my understanding of DAC architecture.

 

2 hours ago, eltech said:

Perhaps Dave was talking about the LC7880 from the 1990's?

 

Hmm... I can't read Japanese (and can't find an English datasheet) ... but that does look like some sort of hybrid architecture.

 

I was more thinking about the ESS Hyperstream (10 yo)

[georgehifi]

42 minutes ago, davewantsmoore said:

At least a decade in the mainstream from my understanding of DAC architecture.

I was more thinking about the ESS Hyperstream (10 yo)

 

Yes this was around the time of talk about the PCM1704 ceasing production, and only previous large quantity users of this dac like Linn ect were able to still get it for a while longer.

 

 

I vaguely remember there's a very long tech promo/sales video years back of ESS's designer John Mallison, where he introduces the new Sabre 19**** or whatever it is, and says half way through (tedious as it was to listen to) that with this "new" ESS delta sigma based dac they have finally come "close" to getting the "performance" of a Multibit dac doing PCM conversion. And I remember thinking at the time wow! they're still not there.

 

Cheers George 

Edited May 24, 2017 by georgehifi