What I want in a DAC

[Doc B.]

Well, we could make it two inches longer. Pulse stretcher?

[glynnw]

OK, I'm not trying to cause trouble by saying what I'd like in the new DAC - but one more thing did just occur to me that is very important for anyone wishing to go directly into amps, as I now do through a Bent TVC.  An output voltage of at least 2 V - preferably more.  The Brick and Ayre are at 2 - the Wavelength Cosecant (which I am hoping yours will be at least the equivalent of) puts out 4.  Pretty cheeky of me to ask for something that makes the Foreplay less necessary, I know, but I am willing to place a deposit whenever you are ready.

[Jim R.]

Dan,

Regarding 24/192 toslink -- I jusst got a 24/192 capable toslink recieverr chip as an upgrade to my AudioGD NFB-2 dac -- that and a new daughterboard with a Wolfson wm-8805 spdif reciver chip so the entire dac now is 24/192 capable except the usb input.  This one will be fed from an Aurality PK-100 music server and will serve tunes either from an attached usb HD, or perhaps over the ethernet connection to files stored on a NAS -- whichever ends up sounding better.

Also, will there be a BNC option in place of the RCA?  If I end up using one of your dacs in my main rig, it will be using a modified mac mini into an Audiophilleo AP2 usb -> spdif converter, which is best used with a direct BNC coupling -- no digital cable required.

If you're interested, I can look into the 24/192 toslink reciver module -- up until a couple weeks ago I thought that the current recievers were only 24/96 capable (though there waere some toshiba recievers that were discontinued some time back that could do 24/192 -- though I believe they were only select parts that tested at the higher rate, not a different design.

Unfortunately, most of the sources -- like the various apple products, are limited to 24/96 on the output side with optical, so that's still a limitation.

My Auraliti should be here any day now, so will soon be giving it a try using a Black Cat Veloce spdif cable.

I still prefer direct usb, but to do that right is somewhat of a large engineering undertaking as the off-the-shelf solutions -- whether async or isosync are still a good deal behind the SOTA usb implementations, which I know is the scale of project that BH probably doesn't want to get involved with, so in that case, I think the spdif is probably the best choice.  Not all usb and not all spdif are equal, and good examples of each can easily outperform average examples of the other.

The direct connect Audiophilleo (especially after cryoing and an external 5v supply for the usb port) is pretty amazing.

Very much looking forward to what will come of all this, especially after my initial taste testing at RMAF.

-- Jim

[GLF]

Doc,

I would like a "standby" mode where the DAC portion can be left on while the analog output is turned off. In my experience tubes seem to warm up a lot quicker than digital. A "standby" mode would help balance tube life and power usage while shortening the time required to warm up.

Andrew

[Yoder]

I would like a "standby" mode where the DAC portion can be left on while the analog output is turned off. In my experience tubes seem to warm up a lot quicker than digital. A "standby" mode would help balance tube life and power usage while shortening the time required to warm up.

Personally, I would prefer an espresso option so I can get tweak while I wait for the warm-up!

[Yoder]

Regarding 24/192 toslink -- I jusst got a 24/192 capable toslink recieverr chip as an upgrade to my AudioGD NFB-2 dac -- that and a new daughterboard with a Wolfson wm-8805 spdif reciver chip so the entire dac now is 24/192 capable except the usb input.  This one will be fed from an Aurality PK-100 music server and will serve tunes either from an attached usb HD, or perhaps over the ethernet connection to files stored on a NAS -- whichever ends up sounding better.

Unfortunately, most of the sources -- like the various apple products, are limited to 24/96 on the output side with optical, so that's still a limitation.


I still prefer direct usb, but to do that right is somewhat of a large engineering undertaking as the off-the-shelf solutions -- whether async or isosync are still a good deal behind the SOTA usb implementations, which I know is the scale of project that BH probably doesn't want to get involved with, so in that case, I think the spdif is probably the best choice.  Not all usb and not all spdif are equal, and good examples of each can easily outperform average examples of the other.

Hey Jim, I am a little confused here. As I understand it TOSLINK is limited physically by its bandwidth to 24/96. That being said I don't see how a 24/192 receiver module could do what it is purported to do based on this limitation. Also, I know that Amarra will only playback in native mode (mostly 16/44.1 in my house), and to be honest I have not seen many 24/96 audio recordings out there, let alone 24/192. Consequently, I am not really sure what the advantage of having a receiver chip that accepts at 192. The only advantage may be in preparing for the future, but given the evolution of ICs then the price will only go down with time.

The Amarra I bought at RMAF makes a HUGE difference in the audio quality and I am using TOSLINK, USB, and FW. One set-up has the audio leaving the mini at 16/44.1, and is sent to a DIP Combo (wordclock that can upsample to 96). The audio is then fed into a 24/96 tube DAC. I also have Amarra feeding into a FW Duet 24/96. To be honest, I cannot tell any difference in flipping from the native 44.1 to 96 on the DIP since getting Amarra. Before Amarra there was a perceived difference when I used the Audio Midi Setup in Lion or Snow, only then I can hear a difference in feeding my Duet but that is only when Amarra is off. From this end, it all seems to be in the software.

A recent EENews letter had a good article on USB vs. Firewire for audio and just blasted USB. They slammed the bandwidth issue. Yea, there is USB 3 now, but it does not seem to be on many devices. My Duet uses FW and gives me 24/96 audio. I think it sounds far superior to the E-Mu 0404 USB that I have. They say USB 3 will have a theoretical speed of 3Gb/s and that Apple is working on a new FW standard of 5Gb/s. Personally, I think that both will be gone in a few years and replaced with Thunderbolt. For now though, 24/96 seems to be where it is at.

[Jim R.]

Yoder,

Sorry, I keep using toslink and optical interchangeably but what I generally mean is optical.  You can indeed run 24/192 on optical but you have to use ST (a.k.a. - AT&T) adaptors and cabling)  The HiFace Evo, for example delivers 24/192 via optical.  However, even if we limit the discussion to official Toslink, people have run it at 24/176.4, as long as all devices in the chain meet or exceed the manufacturing toleances for the interface chips.

The IEEE can say whatever they want, but I know people running 32-bit 384khz via usb 2.0 with no problems.  There's so much bad press onusb, but it can be done right and my ears tell me it sounds quite fine -- still my favorite dac I've ever owned is usb only, and mostly because the company has so far not been able to get the spdif version sounding as good.

I don't know where you're looking, or not looking, but I have a growing collection of 24/96, 24/176.4 and 24/192 recordings and even on a 16/44.1 dac it is very easy to tell the difference.

Amarra won't upsample?  Not that I use it as upsampling pretty much destroys the integrity of the music, and I'd expect just about any device that upsamples to be a compromise somewhere, somehow.

Does Amarra support integer mode yet?  BTW, even if it does, it won't do so under Lion as Apple did not include a usb driver with integer support in Lion -- you have to go back to SL for that feature, and it is a great one, especially if your dac, like mine is limited to 44/16 and the higher bit rate files have to be downsampled -- different from upsampling in that it is interpolation instead of extrapolation.

Pure Music and Audirvana both support integer mode, and Decibel may now too.

Yes, the software is a big part of it -- especially anything that does away with the iTunes playback engine (Quicktime), which is most of the 3rd party apps.  However, digital audio is so vastly complex and multi-faceted that it's nearly impossible to single out any one aspect as the most important.  Like amplifiers, it's a combination of circuit, components, tubes, execution, and some dumb luck thrown in for good measure.

As for predicting where this business will go, I'll leave that to the psycchics -- they're probably as reliable as anybody else.

Case in point: back in the late 80s when I was a top tier IT guy at a very large company, all the industry rags were predicting the impending death of ethernet -- with the exception that it *may* still have some use in industrial automation systems.  The wave of the future was Novell and IBM token ring networks.  Seen any of those lately?  And where did that ethernet go? Around the globe, and around and around, and around, and everywhere in between.

I thnk all of these are viable interfaces and all of them will be or some time.

And yes, there are 32-bit 384 khz digital files available, though not many, and it's absurd anyway (with the possible exception of dithered digital volume controls.)  Even 24 bits is basically insane and not really fully used -- that's 144 dB dynamic range -- show me a recording that can even come close to that.

Me, I'd be very happy with a 20 bit, 250 khz dac, but no such standard exists, nor will it ever, but to me that seems to make the most sense in terms of reproducing music.

When my Metrum Octave arrives (probably another month yet) I plan o try it with both the audiophilleo AP2 -- at a maximum of 24/176.4, and directly from he mini toslink port on the mini, which will limit everything to 24/96, which means the usb converter only gives me the benefit of 24/176.4 in native mode instead of downsampling to 24/88, and until I try it, I wo't know which is better, but my suspicion is that a glass optical connection with everything above 24/96 downsampled (in integer mode) by a factor of 2 -- meaning that 24/176 will play at 24/88 and 24/192 will play at 24/96.  Not a bad compromise, but to my ears the sampling frequency is much more important than the bit depth once you're beyond 16 bits (or 20 if you have the few files in that forma, whatever it was called -- now owned by microsoft and supported on only a handful of CD players.

-- Jim

[earwaxxer]

How about Ethernet input? --- Probably really complicated I would assume (very few DAC's use it). With the software end and all that. I use Ethernet with my Squeezebox Transporter. I think its fantastic and it makes sense to me as one of the optimal "bit perfect" low jitter digital platforms. As others have expressed, USB continues to be less than optimum from an audiophile point of view, and it probably will be replaced at some point. I mean, being tethered by a 3ft, $500 USB cable is no pick-nick, when I can use a 25ft $10 Ethernet cable with no effect on sound.

[Yoder]

Hey Jim, regarding the various types of music and the bit rate, I really cannot find a lot of stuff that I like that goes beyond 24/96..if it even hits that. I know the Stones are putting out their entire library with some pretty high specs, but I have not like the Stones since their fiasco at Altamont Speedway. I have searched several stores for downloads and just a few seem to offer at or/above 24/96, and again the selections are very slim.

Lion uses integer up to 24/96, and 32 bit floating. I spent quite awhile talking to an engineer from Amarra, and he said that it will only use the native rate since "software up-sampling does nothing more than tack on a bunch of useless 0's." Also, as I understand it, Amarra has always supported integer mode since that has all that has been available from CoreAudio and Apple for awhile. I use FW with Lion and integer mode is supported (my FW Duet can go up to 24/96 in Lion), and then when I plug in TOSLINK it uses digital streaming. Since most of my current library is comprised of burned CDs and I use Amarra, then TOSLINK is more than adequate for my needs.

I agree that if one has a digital recording that is say 24/96, or 24/192 then there will be a profound difference when compared to 16/44. But, if one if merely playing Redbook CD's then what is the purpose of sending a 24/96 or 24/192 signal to the DAC? It is in those instances of going from 16/44 to say 24/96 on the software side that I cannot perceive any difference.

Personally, I prefer FW over USB, and TOSLINK has been good to me when run into a decent wordclock. Yea, I referred to IEEE but have heard those in the recording say the same thing in regards to FW vs USB. Since Thunderbolt will soon be rolling out with all Intel boards and Sony is now shipping it under a different name, then it is just a matter of time before it begins to dominate. It is already making its way into recording interfaces and storage devices. Please don't get me wrong in thinking that Thunderbolt will someday dominate in the audio market, at least to the extent of comparing me to the IT guy, but if audio, graphics, storage, and general computer power are to continue to evolve and meet the needs of the consumer then a much higher standard than what is available today will be required. 

Regarding the 32/384 files, your comment kind of is where I am coming from regarding the 24/192. As I stated above there are not that many selections available with that format, especially ones that I like, and so it seems that it would be a bit premature to buy into it now since the field is still growing.

The digital audio recording industry still has a lot of growing to do, especially in being convinced that consumers are deserving of better audio quality than that currently provided.

[Jim R.]

I think I see what's going on here -- are you assuming that all 24/192 dacs have to be fed a 24/192 stream?  Sure, there are many 24/192 dacs that internally upsample everything to 24/192, but I'd never choose one like that myself.  Any dac I get needs to support all the common formats natively as I don't care much for upsampling.  Sample rate conversion is what I typically mean to be downsampling -- meanint my 24/192 and 24/176 files get converted down to 24/96, and so on, again assuming the dac is a 24/96 capable one.  I also vastly prefer downsampling in multiples of 2, so the processing overhead is much less (especially in integer mode where it's just a matter of bit shifting for the most part) and no fancy interpolation algorithms have to be used.

When it comes to digital, I'm very much a less is more, Zen kind of guy -- I don't like upsamplers, re-clockers, etc. -- the more you add, the more you take away, IMO.

As far as core audio is concerned, I honestly don't know -- I was always under the impression that it is strictly a floating point internal archicteture, but I'm not an Apple wonk by any means.  From what Rob Robinson at PureMusic told me, in order to do integer mode (assuming your dac supports it, and many do not), he had to completely bypass core audio, disable EQ and dithered volume control, and communicate directly with the usb hardware in port exclusive mode (hog mode).  And the receiver chip on the other side of the equation has to be able to handle the data stream too, which at the present, I haven't looked into and don't fully understand.

Lion of course is another thing entirely, and while they have made some changes/improvements to iTunes, I believe it still is 64-bit floating point and still requires reconfiguration in audiomidi setup in order to switch playback sampling rates -- PM and Amarra, and most other players don't have that limitation.

Once my speakers get here, I plan to download a trial of Amarra Mini to see how the playlist/library stuff works and if the program is compatible with VoiceOver, and if it is and I can get away from iTunes, I'd love it, but it will have to be usable with the screen reader, the library will have to be easily manageable, and of course the sound quality will have to be equal to or better than PM, and to my mind that is still not at all a given -- I have way too many friends who have both and still prefer PM in integer mode oover Amarra.  But I'm willing to give it a fair try.

Now, all this aside, and to change the subject somewhat, it seems most people interested in the BH dac are letting the one really most interesting feature of this dac go unnoticed -- that fact that it is a high-res NOS dac.  And I don't mean NOS as in using a New Old Stock dac chip (wh8ile that may in fact be the case), it is referring to the fact that this is a Non-OverSampling dac -- a Kusunoki inspired R/2R conversion ladder, not delta sig or DSD.  There are very, very few hi-res NOS dacs out there and to my ears they are far closer to analog sonics than the delta-sig chips (when done right, that is).

Does anybody get this?  This is big, and what people should be excited about, not just that it's a BH product, that it will have a transformer coupled tube output stage, does 24/192, etc.  I believe you can still count the number of commercially available hi-res NOS dacs on one hand, and for the most part, they are quite expensive.

Anyway, if you (meaning the editorial "you", not anybody in particular) have not grokked this, you should -- this is really the most exciting aspect of this whole project, and certainly what we've come to expect in terms of sonics from BH.

-- Jim

[Tickwomp]

I just completed my "what I want in a DAC" (aside from the fact that it's available:-)

Audio Note DAC 4.1 Limited Edition with new Triple C Output Transformers.  Got about 24 hours on it, and really excited to know that it will get better as it burns in.  From the first track after powering up, it sounds better than my NuForce modded Oppo SE 83. 

Using a Mach2 music server over USB to feed the DAC and then on the VCap'd Extended Foreplay and Paramounts with MQ full nickel and upgraded caps running EML 2a3 to modded Klipsch RF-7s.  Things have never sounded so good.

I'm currently playing with ITAP VNC on my iPad to control the Mac Mini.  Not sure I like that, but at least it's better than messing with a monitor, mouse, and keyboard....

Tickwomp

[Jim R.]

Hi Ken,

Nice setup there!  What are you using for your playback software?  The VNC approach is very slow, as I'm sure you've noticed, but there is supposedly a remote control app for Amarra, though I haven't confirmed or tried that yet (no amarra yet), and the iTunes remote app works fine with PM, and once configured, you can just set things up so that the PM startup script launches at boot time, and then you just use the iTunes remote app on your iPod touch or iPad, or iPhone.  There is no volume control with this setup (and not sure if teh Amarra app does this either), but I run in integer mode and don't use software volume control myself.

-- Jim

[Yoder]

You can use the iTunes remote while running Amarra, and Amarra will allow you to control the volume if you wish. I listened to a talk by one of the guys who founded Amarra (Sonic Studios) last night and he mention both floating point and integer mode and the various algorithms used, but the only thing I was sure of at the end was that Amarra is "bit perfect." He went into quite a bit of detail about the mathematics used, and the overall development of the application.

To get Amarra or any app to run at login with OS X, then goto Preferences->Accounts->(Select User Name)->Login Items and then add (+) your application. When Amarra starts, then iTunes will also start. If you do it manually you must start Amarra first.

[Tickwomp]

Hi Ken,

Nice setup there!  What are you using for your playback software?  The VNC approach is very slow, as I'm sure you've noticed, but there is supposedly a remote control app for Amarra, though I haven't confirmed or tried that yet (no amarra yet), and the iTunes remote app works fine with PM, and once configured, you can just set things up so that the PM startup script launches at boot time, and then you just use the iTunes remote app on your iPod touch or iPad, or iPhone.  There is no volume control with this setup (and not sure if teh Amarra app does this either), but I run in integer mode and don't use software volume control myself.

-- Jim

I bought my Mach2 setup with PureMusic.  My understanding is that the iTunes remote will work with PM too.  But, the remote won't do what the iPad can do regarding searching through almost 2 TB of AIFF files;-)  The Mach2 is configurated for battery use, nice and clean!

[Jim R.]

Ken,

I just got my mini converted to battery power as well, along with a Pi battery buss, but haven't tried that setup yet.  Very soon, I hope.  The Oyen mini-pro 800 FW drive will also get it's power from the battery buss, which is also supposed to make a nice difference.  All to be determined shortly...

-- Jim