Separate DAC and ADC with Pro Tools on OSX

They are AES/spdif devices. You need some kind of AES or spdif i/o on your computer.

AES and spdif have no separate clock, The clock is recovered from the digital stream itself, at the receiver side, So word clock is not needed.





The ADC is always the clock source, the DAC is always a slave.

Hi Bruce.  First of all, welcome to RGO!  Ross Martin's web site is difficult to figure out, and the photographs are low res so I can't quite make out what some of the switches and inputs/outputs are for.  My understanding is that Ross makes good stuff, you can find some other Ross Martin threads on this site.  I will try to answer your questions, but I personally have never used any RM stuff.  So hopefully others will chime in if I'm off base about anything.

The "Bare Beast", or the updated version called the "Super Beast", is a digital-to-analog convertor.  Yes, it has a USB connector, but that is simply used as another digital input to convert to analog.  In other words, you can have USB, or SPDIF optical, or SPDIF coax (RCA), or AES/EBU connection INTO the box, and you can get an analog out.  The USB connection is NOT used as an interface for input and output to the computer, as you might be thinking.  This is a stand-alone DAC only.

Similarly, the PCM4222 is a stand-alond analog-to-digital convertor only.  An ADC is usually used as the clock source to clock your other devices, and a DAC usually gets it's clock from whatever digital signal is feeding it.

To use these ADC's and DAC's, you need to have them both plugged into another box or card that is the actual computer interface, using one of their digital connections.  There are lots of such devices on the market, you can look at the RME and Lynx websites for some examples.  I've only ever used RME devices, which have really good Mac and PC drivers, but there are lots of others that are less expensive to get you started.  I'm not aware of any interfaces offered by Ross Martin, but I could be missing something on his website.

To answer your points that I've quoted specifically:

1.  Again, the DAC is not an interface in the way you're thinking, though it's USB connection can be used to convert computer output to analog.  It definitely cannot be used to input audio into the computer.

2.  The ADC is actually usually used to supply the clock.  The PCM4222 unit has a wordclock output connection for this purpose.  You may or may not need to use this connection depending on the digital out that you're using, though it never hurts to connect the wordclock output from the ADC into whichever interface you get, at least as far as I am aware.

Also, if you "interface the ADC into the DAC via AES", you will be feeding an analog signal into your ADC and then getting an almost identical analog signal out of the DAC.  This is not something you want, and cannot be used to feed audio into your computer.

3.  Again, you would never use a DAC as a clocking source, you would use the ADC.

I hope some of this helped.  And I hope others chime in if I'm misunderstanding something, an unfortunately not uncommon occurrence.

Oh, the other thing I might mention is that you should consider svart's box that he is developing. It will be a one-rack-unit ADC and DAC, and will probably be ready before Ross Martin builds you a box. You can find some threads on it here. It should be as good or better than Ross's stuff and it will look better, and it will be delivered when svart says it will be delivered. You will still need an interface to use it, same as Ross's stuff.

If you need the built-in preamps, the ULN-2 will probably be great for you. I can't use it because I'm on PC, though Metric Halo is apparently going to appease the PC crowd in the near future. My personal preference is not to use built-in preamps but choose the external preamps that I want. It doesn't hurt to have the built-ins, I just don't want to pay for something I'm not going to use.

There are several really good 2x4 interfaces around, 2x6 if you count the headphone DACs. 2x4 is handy for a small studio.  For example, while mixing you can use one DAC to feed an analog chain and then take the output of the analog chain back into the ADC. And you can use the other DAC for monitoring. All of these interfaces have at least one additional digital I/O, for example to connect svart's box or the RM boxes. And most of them also have an ADAT interface in case you need to expand further.  In your case, since you're on a Mac, you don't really need the ADAT interface because you can use multiple USB devices using device aggregation.

The boxes I've been looking at are the Lynx Hilo, the Prism Lyra 2, the Apogee Symphony 2x6, and the Antelope Pure2. The Pure2 isn't out yet, expected within the next couple of months, and I believe it does not have an ADAT interface.  All of these boxes are in comparable price ranges, more or less, and all are considered by many to be very high quality.  You can find lots of info about them, Google is your friend.

cowboycoalminer this HAS to make your blood boil.

I will say, I'm super stoked for svarts new AD/DA.

I'm on the list!

Go svart!

Maybe he will post something here

Interesting... I emailed RM also, about how the Bare Beast and the pcm4222 interface to the computer, figuring he ought to know how his own gear is designed to work, and this was his response:



Then I sent another email with this question:  "And you confirm the USB port on the Bare Beast is bidirectional, allowing for stereo audio playback and recording, when the pcm4222 is connected to the Bare Beast via AES?"  He responded:

Even if what RM says is true, I can guarantee if I were to do as JK says and pick up a Used $100 USB / FW or Tbolt box at my local Pawn shop with AES / Spidif, I will have drivers into the future! Plus I get a couple of extra Utility I / O !

I have a Focusrite 18i8 that I use with my e-kit. I'm planning on getting a Svart ad/da to use as my 2-mix capture and DAC to monitors via SPDIF to the Focusrite.

Oh - duh...apparently I have the Bare Beast. So, when you connect it via the USB, you have the option of using it as the "Output" in your system. Maybe when you connect the 4222 AD to the Bare Beast you get a full fledged interface connected to the computer? But then, where's the software and routing? I have no idea.