What I want in a DAC

[grufti]

I just found the quote by John Siau of Benchmark Media. It is from March 31, 2012:

 

[xcortes]

I have a Pacific Microsonics Model Two sourced from a DAW loaded with Pyramix Software and a Mykerinos card. The difference between 24 192 and 24 96 is easily detectable when listening to it through a high resolution system.

[Noskipallwd]

Don't want to stray of topic, but we are discussing DACs. Where exactly do the hi-rez files originate? I know little or nothing about recording and mastering, but my guess would be that the only source suitable for conversion to 24/192 resolution would be the masters or copies of them. I have found that alot of the files available at HD Tracks and others are vinyl rips. I have been doing some vinyl ripping of my own, using a borrowed Benchmark ADC. I was told that converting vinyl to anything above redbook was a waste of time, but I found ripping to 24/96 gives me the best results. The editing software I use, to remove pops and clicks and so on seems to do a better job with more data. Back to my original thought, I noticed NAD has released a DAC that is capable of 32 bit / 384 khz resolution. What for? Are they hoping that at some point the recording studios will begin producing hi-rez along with other formats for general consumption? Just wondering if these capabilities available now are worth spending money for.

Cheers,
Shawn

[Jim R.]

All sounds very promising (John), do you folks have any idea yet if this will be a one or two chassis dac?  I know that one of the recent prototypes shown was in 2 chassis, but was that for prototype purposes, or is the final dac looking like it will need to be configured as such?

I've got some good time on my CEntrance DAC Mini now and I'm not really warming up to it as I had thought I would, which is opening the door for the BH dac to be part of my stereomour/Orcas system, but rack space is at a real premium and I'm not sure I could manage a 2-chassis configuration.

Thanks for any info you can share,

Jim

[John Swenson]

How many boxes is really up to Doc and PJ, but the current thinking is that it will be a single box, with an optional external power supply to get it to REALLY sing.

Power supply isolation is one of the critical issues with DACs, but to do this DAC full bore will take so many power transformers and chokes that there is no way to fit it all in one box. So the idea is that the base unit will include the power supplies needed to make it sound very good, and have a second box that will bring it over the top.

You will be able to add the external supply at any time so you can buy the base unit first then add the external supply if and when you wish to.

I hope you don't get the impression the base unit is going to sound bad, far from it, In the lab right now I have it running with a power supply configuration close to what will be in the base unit and it smokes everything else I've ever heard (I'm just slightly biased). Maybe "smoked" was the wrong word to use for a tube based DAC, but I hope you get the idea.

John S.

[Jim R.]

Hi John,

Thanks for the reply and that sounds perfect to me.

I don't know how things have progressed since last RMAF, but I was really impressed with what I heard of the dac at that point -- even more so when I later learned that it was being fed directly from the optical out on the Mac Mini.

Now I'm really looking forward to all of this! :-)

-- Jim

[Yoder]

... my guess would be that the only source suitable for conversion to 24/192 resolution would be the masters or copies of them. I have found that alot of the files available at HD Tracks and others are vinyl rips.

As I understand it they use 24/192 for the master in digital recording now days, though some are probably beginning to push that envelop, and are starting to push 24/96 as the consumer standard. Though Apple's iTunes Plus will present a different story about hi-res mp3's.

You sure about the vinyl rips? Most re-masteriing uses the original master tape (There are some good movies on Netflix under "music" called "Classic Albums." You will see Steely Dan, the Dead, etc. using what looks like 24 track tapes and some 8 track from way back.)

I have been doing some vinyl ripping of my own, using a borrowed Benchmark ADC. I was told that converting vinyl to anything above redbook was a waste of time, but I found ripping to 24/96 gives me the best results.

Somebody does not know what they are talking about. Going above Redbook would only be a waste if your intent was to burn all of your vinyl music to CDs. If you have the hardware and software to handle 24/96, or better yet 24/192, and plan on using computer playback then go for it. 24-bit is far superior to 16-bit.

I noticed NAD has released a DAC that is capable of 32 bit / 384 khz resolution. What for? Are they hoping that at some point the recording studios will begin producing hi-rez along with other formats for general consumption? Just wondering if these capabilities available now are worth spending money for.

It is just a numbers game. I have not heard any advantage in up sampling beyond the native rate. That being said, I have not even seen any 32 bit audio for sale. Regarding the purchasing of such, it is NEVER cheaper to buy new technologies. Personally, I don't thing going beyond 24/96 would make much difference to my aged/tired ear drums, and so I am perfectly content with 24/94.

[earwaxxer]

Interesting discussion.... What I might add to the mix is that, IMO and experience, there are potentially other factors that influence the sound at various sampling rates/resolutions. What I have found is that my laptop upsampled redbook (24/96) using Sox and minimum phase settings (0%) sounds the best, better than the usual default linear phase (50%). This is a curious result because my Transporter upsamples redbook in realtime with Sox as well, but passes high res. without upsampling. I have tried various phase settings from linear to minimum. All of them sound better than native redbook, minimum phase is the most 'vinyl like' IMO. This may have to do with filter effects on ring/pre-ring.

So, in this case, redbook that is upsampled before hand appears to sounds superior to redbook that is passed to the DAC as 16/44.1 and upsampled by the DAC. This is not a small effect. It is very clearly different. Everytime I get to doubting myself and switch back to native redbooks rips I come to the same conclusion. I wish it was not true, because I could have my entire 1000 CD collection on my laptop in native rips. Now I have to settle for 250 (large upsampled) albums or so. I would quantify the differences I hear in the area of 'ease and liquidity'. A 'naturalness'. Musical and believable with an added lack of fatigue and irritation. Very clear and obvious.

This effect has also narrowed the gap as far as my system is concerned, if there even is one, between native HD tracks 24/96 downloads and my upsampled redbook. I have not found that high res. downloads sound any better than a good redbook recordings massaged with Sox.

Now the question that is raised in my mind, is what role the various 'decoding' (filtering) processes have on sound quality, irrespective of resolution. Sorry if I'm making things more complicated! The plot thickens!

[earwaxxer]

Interesting new article on the subject...

http://www.enjoythemusic.com/magazine/manufacture/0512/

[Yoder]

Interesting discussion....

Interesting indeed...

I run my audio through Amarra that uses only the native rate, and fixed point. The difference between Amarra and iTunes is profound. (They have a little button one can use to make comparisons.) Use the Amarra parametric equalizer and the difference is even more dramatic. I feed my streaming digital audio from my mini into a 24-bit tube DAC and so really can't provide any feedback as far as 16 vs 24 bit in the DAC goes, but when I play 24/48 or 24/44 files through the system the difference it is like night or day when compared to Redbook specs. The key, for me, seems to be in the bit-depth. I have an external up sampler/clock that allows me to flip from 44.1 to 96 on the fly, and I can sit in front of the speakers and flip 24/44 files between 44.1 and 96 all day long and do not notice any difference. I am going to order a couple of SACDs today (24/96 and 24/192) and will try the same thing. My guess is that there will be a noticeable difference when I downsample a 96 or 192 file to 44. When upsampling the sample rate all that is happening is that a bunch of zeros are being tacked on, and my guess is that that is why I do not hear any difference.

There are some transports/DACs that advertise as having various capabilites using high-end DSPs, and adaptive time filtering "that applies polynomial curve-fitting interpolation that allows for greater data buffering and re-clocking" so as to remove "almost" all digital jitter. For me this creates a conundrum. Namely, all things being equal should I per sue higher bit-rates that that will sound great when played through excellent gear at the native rate, or is it worth per suing high-end DSPs/hardware and the improved algorithms that come with them (firmware that is actually altering the input audio in various ways)?

Personally, I am very content with going for hi-res audio and playing it at its native sample rate. Correct me if I am wrong, but this is pure, unaltered audio versus audio that has had various algorithms applied to it. Granted, algorithms are used in all digital playback but there seems to be a point where when applying these algorithms we go from decoding the digital signal to actually altering it in various ways from its original form in order to create a "better" sound.

Anyway, 24/48 audio blows me away as it is and I can hardly wait to hear the 24/96 I have on order. I will let you know if I hear any difference when I down sample the sample rate. The two SACDs I am getting are: Pink Floyd-Dark Side of the Moon, and The Band-Cahoots.

[Noskipallwd]

Hello, Yoder and Eric, thanks for the discussion. First off, I should edit the statement about HD Tracks. There seems to be more natively recorded hi-res files available. On many of the early downloads from HD Tracks, and other sites you can hear the vinyl rumble. Very faint, but there nonetheless. It seems there are more recording companies willing to supply Hi-res digital. I made some downloads from Harmonia Mundi and a Norweigan company called 2L,(who also have files available on their website), that sound absolutely fantastic. I am using Pure Vinyl to do my rips from vinyl and I am very happy with the results. I still prefer a pure analog vinyl rig but I think we are making progress.

Cheers,
Shawn

[earwaxxer]

Hey Yoder - Thanks for verifying that I am not the only crazy MF out there obsessing over this stuff!

Its pretty cool that your system gives you that much A/B control to be able to make some comparisons on the fly. I dont have that. I am convinced that shifting the aliasing etc. to higher frequencies with higher sample rates is key. Probably equally as important the filtering algorithms that come into play at the different sample rates. From my systems perspective, I'm not hearing a huge difference with native high res. material. It has more to do with the recording quality. A good example are the 2009 Beatles redbook remasters. Upconverted with Sox they sound as good or better than the native Paul McCartney 'Band on the Run' 24/96 HD Tracks download.

Cheers - Eric

[Yoder]

On many of the early downloads from HD Tracks, and other sites you can hear the vinyl rumble. Very faint, but there nonetheless.

If there is true remastering of older audio going on then they are using reel-to-reel tapes. Only with the original master tape can the sound engineer go in and play with the various tracks on the tape. The movies I referred to above go into a lot of detail about this and they play with eliminating various instruments, enhancing them, etc. This type of work can only be done with the original master tape and not vinyl or with any of the digital codecs (AiFF, WAV,mp3, mv4, etc.) once the tracks have been "compressed" from 24-tracks to stereo. The "rumble" you hear is probably the result of a poor quality master tape. Finding mint perfect master tapes seems to the real challenge today.

Here are a couple of quotes about some HDTracks hi-res audio. "...with our exclusive Rolling Stones release, ABKCO Records undertook a long and painstaking re-mastering process employing state-of-the-art master tape to digital file transfers using the best in Analog to Digital converters to provide HDtracks with the highest quality music files possible."

The engineer for Cat Stevens said:

[Doc B.]

Not all masters are multitrack and thus you can't make that generalization. The term for mixing multitrack session tapes to stereo is mixing, not compressing. A bad master tape will not have lathe rumble. That is an artifact of cutting lacquer or playback on a noisy turntable. A bad master tape can have a lot of other problems - dropouts, rolled off highs, dulled transients, stretched spots and splices, sticky shed, maybe even "rocks", but not lathe or turntable rumble.

[Noskipallwd]

I have a download of Nojima plays Listz that you can hear the stylus hit the record, you can only hear it with volume up above normal listening levels. I have listened to enough vinyl in the last 30 some odd years to recognize that sound, and I am not the only person to notice this on various tracks. Please, don't get me wrong there is nothing wrong with the files quality, the Nojima piece sounds great. I simply, in my own lack of experience,  wonder how this business works. Where exactly is the media originating? Are we paying for files prepared by professionals with studio equipment and backing, or something done half-assed in somebody's basement? (similar to mine)!

Cheers,
Shawn