Benchmark DAC1 now available with USB

[furball]

Very well written. And thank you for pointing out my misuse of some technical terms.

Well, like you said, it seems there is no hardware that can do what you want to do.

Would a software solution work? Of course then you have to make the software decoder output to 3 S/PDIF output channels. These have to be custom built.

Originally Posted by eweitzman

furball,

PCM refers to how data is encoded/represented: as 16 bit (or 24 bit, etc) periodic samples. The S/PDIF and AES3 transmission standards carry two interleaved channels of PCM and some control info, but their two channel nature is not a limitation of PCM. ADAT carries 8 channels of PCM for example.

Within a playback machine, you might be able to get at the individual data channels after decoding from format XYZ to PCM. Looks like switch-box.com has done that. I read sometime ago that one of the Oppo machines was capable of outputting SACD digital data via the HDMI connection. As it turns out, the DSD data is converted to PCM (24/88 IIRC) and that's what you get. Not DSD, but not reconverted analog either. One of the later HDMI standards (1.3 IIRC) allows protected/DRM data to be passed through the interface with a protection flag.

The legal issues with SACD and DVD-A are different.

Because they are both encrypted digital data on discs, it is illegal to rip the data from the media in the US. But once the data has been converted to PCM signals inside a properly-licensed and manufactured machine, the data can be transported outside to other devices such as our DAC1s. There's a further issue with SACD in that the technology is licensed from Sony who stipulate (via licensing) that the digital DSD data stream NOT be made available outside the box. DVD-A might have similar licensing issues, I don't know about that. I'm pretty sure you can backup or play the decoded "LPCM" hi-rez streams from "enhanced" DVD-V like DualDisc, DAD, and so on. Copying is still verboten because it's copyrighted material, but not because of the encryption sanctions in the DMCA act.

In the case of the Oppo, they must be using one of the DAC chips that accepts DSD data, converts it to PCM, and then converts the PCM to analog. These DAC chips are the basis of the cheap universal players. I think these chips also function as sample rate converters so the PCM version of the DSD data can be grabbed as an output from the DAC chip. That's probably how SACD gets to go down the HDMI pipe in the vanilla Oppo, and also probably what the modifier grabs and sends to the three S/PDIF outputs that he adds to the back of the case.

I was thinking that something like the RME Fireface 400 could output the six PCM channels that could be derived from DTS/DD. It has an ADAT optical port that provides 8 channels of PCM. Again, it comes down to hardware: how would you connect three DAC1s to the ADAT output? Is there a breakout box of some kind that can sit in the middle?

- Eric

[EliasGwinn]

Originally Posted by eweitzman

how would you connect three DAC1s to the ADAT output? Is there a breakout box of some kind that can sit in the middle?

RME TDIF-1

I doubt that the Fireface will convert 5.1 encodes to multi-2-channel PCM's, but I could be wrong. Also, there may be some freeware out there that can do it. If anyone finds anything, let the rest of us know!!

Thanks,
Elias

[joijwall]

Does all this mean DAC1 understands PCM only, or does it know other digital to analog conversions also?
I'm also curious about the different players, both PC based and regular CD-players (at least the ones that plays MP3, I guess a CD is PCM?).
Are all players equally perfect when converting WAV, AIFF, AAC, FLAC etc into PCM? That is, will all send the same PCM-bits? Or do I need to choose player carefully?
/Joachim

[Tarkovsky]

Hi there joijwall, Elias was kind enough to provide us with a guide on the different players out there and how to get bit-perfect playback. You can find it over at the benchmark website but it's also linked to further back in this thread.

[gjwaudio]

Originally Posted by infinitesymphony

Whoa... So, only $3,485 for the ultimate 5.1-channel DAC1 experience.

Well... maybe, but how are you going to change the volume ?

For ULTIMATE quality from such a 3xDAC1 setup, you can't use software to change the levels or you'll be tossing out bits (and some of your "resolution"). How can you implement the analog-domain output control, and have all six channels track together - without introducing another six-ganged volume pot between the DAC1 analog outs and your amplifiers ?

Can you imagine the grief using some Rube-Goldberg-esque arrangement to turn 3 DAC1 knobs in sync ? Sure... a custom Benchmark DAC-Racque to triangulate the controls just right, so the flywheel buffered MasterKnob (actuated by remote controlled step motor) adjusts each sprocket-modified DAC1 volume control via precisely tensioned, non-magnetic carbon fibre chain-link belts.

Laughable indeed... straight out of Charles Rodriguez... but just in case, I'm off to the Patent Office !

Cheers,
Grant

[EliasGwinn]

Originally Posted by joijwall

Does all this mean DAC1 understands PCM only, or does it know other digital to analog conversions also?
I'm also curious about the different players, both PC based and regular CD-players (at least the ones that plays MP3, I guess a CD is PCM?).
Are all players equally perfect when converting WAV, AIFF, AAC, FLAC etc into PCM? That is, will all send the same PCM-bits? Or do I need to choose player carefully?
/Joachim

Here is the link to the "Audio Wiki" on our website.

Main Page - Benchmark

That page is filled with all the information you will need about any player.

There are too many variables to tell you that one player is the best. However, iTunes and Foobar lead the pack.

The DAC1 only works with PCM, which includes MP3's, all varieties of Lossless files, WAV, AIFF, etc. It does not include DSD (SACD). However, Dolby Digital, DTS, and ADAT are all encoded versions of PCM, which can be decoded and converted to the DAC1.

Thanks,
Elias

[eweitzman]

Originally Posted by gjwaudio

Well... maybe, but how are you going to change the volume ?
...
Laughable indeed... straight out of Charles Rodriguez... but just in case, I'm off to the Patent Office !

Sorry, Grant, but I beat you to it. 2001 prototype of the two channel version shown below.

I'm considering adapting this to the DAC1PRE. (not)

- Eric

[Wavelength]

Eric,

In most cases the dac chips that have both DSD and PCM inputs do not convert DSD to PCM but actually the reverse. The PCM is converted to a bit stream and outputed as a sigma delta dac. Basically the DSD bypasses the conversion and goes directly to the output.

Many of the original SONY SACD's units had jumpers and other things that when cut or switched the DSD information would come out as SPDIF information and some people had recorded the info into their computer and such. I cannot remember what the deal was but I don't think it was as good of quality as the DSD output was.

Most engineers I talked too that did SACD said the contract the the MONEY was hard to swallow. In general this is what killed the idea. The DVD-A stuff just fell by the wayside because people figured the same thing.

It doesn't really matter at this point. If you are in this forum you all ready realize hard formats will be dead soon and there are more and more hirez download sites poping up all the time.

My DSL line went from 5MBS to 10MBPS last week for no extra charge and I hope too look at some of the new sites and download some 24 bit content.

All my buddies who are musicians are asking about master tapes on line and that's when things will get real interesting. The idea of much more dynamic masters is staggering compared to most of the overlly compressed disks you get now.

Anyway.. have fun back to work,
Gordon

Originally Posted by eweitzman

Within a playback machine, you might be able to get at the individual data channels after decoding from format XYZ to PCM. Looks like switch-box.com has done that. I read sometime ago that one of the Oppo machines was capable of outputting SACD digital data via the HDMI connection. As it turns out, the DSD data is converted to PCM (24/88 IIRC) and that's what you get. Not DSD, but not reconverted analog either. One of the later HDMI standards (1.3 IIRC) allows protected/DRM data to be passed through the interface with a protection flag.

The legal issues with SACD and DVD-A are different.

Because they are both encrypted digital data on discs, it is illegal to rip the data from the media in the US. But once the data has been converted to PCM signals inside a properly-licensed and manufactured machine, the data can be transported outside to other devices such as our DAC1s. There's a further issue with SACD in that the technology is licensed from Sony who stipulate (via licensing) that the digital DSD data stream NOT be made available outside the box. DVD-A might have similar licensing issues, I don't know about that. I'm pretty sure you can backup or play the decoded "LPCM" hi-rez streams from "enhanced" DVD-V like DualDisc, DAD, and so on. Copying is still verboten because it's copyrighted material, but not because of the encryption sanctions in the DMCA act.

In the case of the Oppo, they must be using one of the DAC chips that accepts DSD data, converts it to PCM, and then converts the PCM to analog. These DAC chips are the basis of the cheap universal players. I think these chips also function as sample rate converters so the PCM version of the DSD data can be grabbed as an output from the DAC chip. That's probably how SACD gets to go down the HDMI pipe in the vanilla Oppo, and also probably what the modifier grabs and sends to the three S/PDIF outputs that he adds to the back of the case.

- Eric

[sfogg]

Originally Posted by eweitzman

In the case of the Oppo, they must be using one of the DAC chips that accepts DSD data, converts it to PCM, and then converts the PCM to analog. These DAC chips are the basis of the cheap universal players. I think these chips also function as sample rate converters so the PCM version of the DSD data can be grabbed as an output from the DAC chip. That's probably how SACD gets to go down the HDMI pipe in the vanilla Oppo, and also probably what the modifier grabs and sends to the three S/PDIF outputs that he adds to the back of the case.

Eric,

The DAC(s) in the Oppo are actually PCM only. The all in one chip (audio decoder, post processing, video processing and even HDMI transmitter) converts DSD to PCM for the Oppo's DACs. The 980 does have the ability to output native DSD over its HDMI interface, or converted PCM, but it can never feed DSD to its DACs natively.

Because of the all in one nature of the decoding chips the limitations of audio over HDMI actually apply to its own DACs as well. Audio on HDMI is carried in the VBI of the video. The video bandwidth effects the available audio bandwidth. 480i/p does not have enough bandwidth to carry 6x96/24 so when you have the Oppo set at 480i/p output and play a DVD-A the DACs are fed at 48kHz. If you switch video output to 720p or 1080i/p then the DACs are fed at 96kHz.

Shawn

[sfogg]

Originally Posted by furball

DTS/Dolby Digital signals are encrypted. The encryption is there for copyright protection. Because of the encryption, the DTS/Dolby Digital decoder is both a decoder and a multichannel DAC, you cannot separate out the two. The multichannel digital to analog conversion is done at the decoder level, and the decoder only outputs analog outputs. The decoder will not output PCM style digital output for each of the 5 or 7 channels.

There are many DD/DTS decoders that output PCM to separate DACs within the player/pre-pro or pass the PCM on to additional DSPs for post processing then eventually on the DACs. For example the Oppo DV-980H does this.

There are even pre-pros that will output decoded DD/DTS as PCM over multiple SPDIF connections. Theta Casablanca with the digital outputs card option will do this, pretty much any Meridian from the 565 on will do this too to be able to feed Meridian's DSP speakers.

Shawn