Delta Sigma DACs

Cheeg, The product of Delta Sigma converter is square wave with modulated duty cycle (Pulse Width Modulation).  The only processing necessary to convert it to analog is to filter (average) it.  DSD (and SACD) is the same product od Delta Sigma converter.

Can a Delta-Sigma DAC translate both DSD and PCM streams to analog?

Yes it can do both, it’s needed for DSD, but if PCM is your priorty (that’s Redbook 16/44, 24/96, or DXD), then your better off for best sound quality with a "well implemented" R2R Multibit dac, discrete or chip, as they do PCM bit perfect, while Delta Sigma is a facsimile it.

MoJo Music.
"When a PCM file is played on a native DSD Delta Sigma single-bit converter, the single-bit 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 Delta Sigma single-bit DACs do a poor job of decoding PCM."

Cheers George

No DAC is perfect. All modern Delta Sigma DACs are actually bit perfect in operation however the noise floor (or resolution) on the very best is about 21 bits. So nothing does 24 bit even remotely perfectly so far. Most good quality delta sigma will be close to bit perfect at 16 bits. However be wary of R-2R DACs as many are only 18 bit or often less (16 bit). For example, the Schiit DACs perform truncation to 24 bit digital data - these are grossly NOT bit perfect because of this throwing away of the least significant bits of data - worse still the truncation operation introduces high amouts of added quantization noise distortion. Definitely about as far from bit perfect as you can get in a modern DAC.

The other factor in many DACs is the final brick wall filter - this causes the final analog result to be slightly different depending on the filter design.

A good DAC and it’s ADC equivalent can be looped more than 10 times with no audible differences.

A bit perfect DAC and its ADC could in theory be looped infinitely and the sound would be identical - so far none exists.


DSD or PCM are just different formats. Mathematically they can be an equally accurate representation of the original musical analog waveform. It is just mathematics - 16 or 24 bit at low sample rate or DSD 1 bit representation at very high frequency. DSD has inherently a huge amount of high frequency noise which must be removed and contains no added audible benefit. Since PCM is what all studios use it is undoubtedly the closest and best distribution format to remain faithful to the product coming from the studios and the mastering process. 

Let's not start this delta sigma vs. R2R chip. You are not going to win.

Jwm, nobody is trying to win anything (that would be juvenile).  Sound quality is a matter of DAC quality and not the architecture.  When you listen to SACD or DSD you're listening to the output of the Delta Sigma converter.

DSD has inherently a huge amount of high frequency noise which must be removed and contains no added audible benefit. Since PCM is what all studios use it is undoubtedly the closest and best distribution format to remain faithful to the product coming from the studios and the mastering process.

That’s why I prefer to listen to PCM, through a well implemented R2R Multibit dacs.
If I had and download DSD then I would have to go to a Delta Sigma dac and take a hit on the PCM, but then there are some very expensive discrete R2R multibit dacs that can convert native dsd, one day maybe the price of these will become affordable.
One of them is here, https://forum.audiogon.com/discussions/denafrips-dac-owner-impressions-feedback-general-discussion-q...

Cheers George

AFAIK, studios use PCM not because of sound quality but because there is no equipment to do mixing on DSD.  Still a lot of people enjoy SACD and DSD in spite it went thru DSD => PCM => DSD transition.

Thanks everyone, that pretty much confirms what I thought.  Now here's the rub: I have a Cambridge CXU that I bought to play my CDs, and to play any SACDs and HDCDs I might want to add to my collection.    It has an onboard DAC with 5 Wolfson WM8740 chips, which use the Delta-Sigma decoding scheme.  I use it only for 2 channel audio, and have it connected to the line inputs of my preamp.  It plays Redbook CDs fine, presumably through the Wolfson DAC (the user manual is hopelessly incomplete).  I had wondered how that worked, but georgehifi's response addresses it, and makes sense to me.

So, you would think that it would be a cinch for it decode SACD's, right?  WRONG!  I recently got my first hybrid SACD, and when I put it in the CXU... nothing.  No sound.  After several email exchanges with their tech folks, they said that I could only play it if I set the "SACD output format" to PCM.  That does give me sound, but I can't figure out if I'm listening to the Redbook version or the DSD version on the hybrid disk.  Why on earth would they require me to use the PCM setting to play a SACD disc through a Delta-Sigma DAC?  Am I missing something here?

Again, SACD is a product of Delta Sigma converter and in order to convert it to analog you need filtering and not another Delta Sigma DAC. I’m afraid you’re stuck with Redbook layer. Your Cambridge CXU can output digital only as S/Pdif and this format won’t work for SACD.

I’m afraid you’re stuck with Redbook layer. Your Cambridge CXU can output digital only as S/Pdif and this format won’t work for SACD.

I don't think that's correct; where did you read that?  The Cambridge site says it plays, among other things, SACD and HDCD formats: https://www.cambridgeaudio.com/usa/en/products/cx/cxu

If it was only capable of S/Pdif, how could it play SACD disks? 

@shadorne 
Then why do R2R DACs sound better than Delta Sigma?

Then why do R2R DACs sound better than Delta Sigma?

In fairness, better or worse sounding is somewhat subjective and at the discretion of the ear of the listener.

That said, and based on the relatively few delta-sigma and multibit DACs I’ve heard, I prefer multibit as it is more authentic and not as digital sounding to my ears.

Cheeg, Yes, it can play SACD but it cannot output it other than analog.

R2R's don't sound better than delta sigma's. Maybe the MSB, but I never had that in house. I have not found an R2R yet that can beat my delta sigma.

Can a Delta-Sigma DAC translate both DSD and PCM streams to analog?

The answer is definitely YES.

I would view with appropriate suspicion the views of those who assert that modern delta sigma chips are inherently inferior, even as applied to PCM. First, IMO you must completely discount the views of a manufacturer (like Mojo Music) who markets a unit using a different kind of chip.

Delta sigma chips have become a target for condemnation because they are ubiquitous. Consider the ESS9038pro Sabre. It’s relatively inexpensive because it is produced in great quantity. It probably has more R&D behind it than any other chip by far. Because it is relatively less expensive its implementation in consumer devices varies from very simple (and cheap) to superb.(and expensive). But they all can tout they use an industry-leading DAC chip.

Bottom line is that some of the best sounding and best reviewed devices use the ESS chip. Many other devices using other chips and technologies are also great sounding and well reviewed. There are those who speak of a sound signature of particular chips. IMO the sound of a modern well designed unit should be of the software and not of the chip. In well designed units that’s what i expect to hear, the particular chip notwithstanding.

The fact that D/A converter is Delta Sigma does not make it DSD capable - ESS9038pro has interface for DSD but Wolfson  WM8740 doesn't.

I’d send another email to Cambridge tech support asking whether the player is actually reading the Redbook layer or is converting the SACD data stream to PCM format.

Judging by the CXU manual, the menus’ appearance is very similar to my Oppo BDP-103. On the Oppo, there are three options - stereo, multi-channel, CD mode. The last option makes it clear that it’s only reading the CD layer of a hybrid disc.

NOTE: Just found a link that might offer a partial explanation - https://techsupport.cambridgeaudio.com/hc/en-us/articles/115002330445-How-can-I-correctly-set-up-the...

I believe the Audio Format section deals only with digital outputs. For DSD output, you need to connect to an outboard processor using HDMI due to copyright restrictions. If you're using analog outputs, then you should be listening to the SACD layer at all times. Still, I'd send an email back to tech support to confirm.

Hi Cheeg, I'm a CXU owner....
The CXU plays the CD or SACD layer on a hybrid SACD (two or multichannel) you have to decide which in the audio set up menu - also make sure you set it to 'PCM' and NOT 'auto' or 'DSD'  - 'auto' seems to cause a delay and DSD is only if you're intending to send DSD out of the player.
The Wolfson DAC's convert the DSD to PCM on board and only play DSD 64 (two or multichannel) your can also play DSD 64 files from USB sticks or by streaming to it.
You can set it to send out DSD from the player via HDMI so if you can find a DAC to hook up that can decode DSD that's another option....
Hope this helps. 

Thanks @angelwars, I appreciate the additional info, especially since I thought this post had died. Since the last post (before yours) I picked up an old Benchmark DAC (version 1), which made a real improvement in the CXU’s sound with both PCM and DSD discs, but still doesn’t sound quite as good as my limited collection of SACD’s. Have you used any external DACs with yours?

Hi Cheeg, no I haven't used an external DAC with the CXU, infact I use it as a DAC for a Virgin Tivo box (HDMI) and my old MacBook (optical) for playing mainly ripped CD's and other files. It does this and plays SACD, DVD Audio and Blu-ray discs pretty darn well. I run it all out analogue bootlaced to a Cambridge CXR120 as I'm a multichannel advocate.
I'm planning on ripping all my discs to files when I can find a simple way of storing and playing it back out, audio and video content.
I'm keen to experience DSD and have some great DSF files ready to go but I'd rather do its right and I'm wary of these hybrid Dac's that claim to to do everything but make the tea. It seems to me that PCM and DSD are different enough to warrant separate DACs....

Oh - how do you hook up the Benchmark to the CXU?
Cheers.

@angelwars  I send the CXU Digital Coaxial Output to the Benchmark Coaxial Input, then use the RCA outputs from the Benchmark to my preamp. 

Shame it doesn't have HDMI then you could try DSD from your SACD's?

That's true -- I don't know why, but the CXU only allows me to send DSD via HDMI, and not by Digital Coax.  If I could take the DSD stream from the HDMI output of the CXU, and convert it to coax, I suppose I could feed that into the Benchmark and see how it sounds (not sure if that's possible; does anyone know?).  It's not a big deal, though, because the CXU's DAC does a nice job on my SACD's, so I can just send the analog output from the CXU to my preamp.  

I think Sony are still twitchy about DSD digital output from SACD and where it goes, I don't think there are many AVR's with HDMI that can handle DSD without converting (my Cambridge CXR doesn't) I think we're both fine letting the CXU do the job. If you get the chance try the CXU with multichannel, honestly it's a game changer! :)

Since there is a fairly well delinated debate going on about Sigma Delta dacs vs R2R Multibit dacs, what do folks here think about the Analog Devices AD1955 dac which is a Multibit Sigma-delta dac?