Digital to digital....?

I would have sworn I already posted this question. The memory goes first...well, perhaps second. Where would I go to find something to adapt from USB or Fire Wire to digital audio coax or optical. I want to go from my Mac laptop to a digital class D amp.

Tim

Empirical Audio offers these extremely high quality items:

from Empirical Audio

USB Off-Ramp Turbo 2 and USB Freeway 2

These are USB to S/PDIF coaxial converters which allow you to connect your computer

to your high-fidelity audio system and play music stored on your hard-disks. These

converters do not compromise sound quality. In fact, the sound quality is generally

superior to a CD player or even an expensive Transport and outboard DAC. What is

required in order to use these converters is a Digital to Analog Converter or "DAC".

The Converter connects between your computer and your DAC. A USB cable connects

from your computer to the converter and then the converter plugs into your DAC.

Your DAC then generates analog left and right channels to drive your audio system.

The quality of the DAC is critical if you want high-quality playback. Here are some

features in common with the two USB converters that we offer:

* USB to S/PDIF Coaxial converters

* Custom circuit-board designs - not a mod

* All have lower jitter than any stock or even modded Transport

* AES/EBU versions also available

* Standard with a short S/PDIF coaxial cable permanently attached with strain-relief

* Each comes with licensed copy of SRC, the best 24/96 upsampler on the market

* Each comes with an 8 foot USB cable

* All will pass 16/44.1kHz, 24/96kHz, MP3 and iTunes unmodified files

* AC3 support is available using the M-Audio driver

* Works wonderfully with both PC and MAC

Our USB converter products use circuit boards of our own design which are hand

assembled using silver-loaded solder for best sound quality. We use circuit topologies

parts selection and board stackup configurations that result in the lowest noise signals

and the cleanest power of any high-end manufacturer. Even boards designed by large

companies do not use these techniques because they do not lend themselves to

automated assembly or low cost. We consider cost no object. Only performance matters.

We take extreme care in every board design to optimize every aspect, including: power

delivery, signal integrity, speed, electrical noise, isolation, parts selection, ESD and

transmission-line effects. It is this care and design knowledge that enables our designs

to be superior performers.

Our USB converters will outperform even the best Transports you can buy, particularly

with 24/96kHz on a PC or iTunes with a MAC. No other cables required, just a PC with a

USB 1.1 or 2.0 interface and a DAC with a coaxial S/PDIF input. It is recommended that

you dedicate a computer or laptop to the task, particularly when using SRC upsampler.

Thanks Chris, but I'm not a $500 - $1500 cable guy. Let's just say some have the faith, some don't. Do you know of any resources that sell USB/Coax converters of a quality that say...just your average pro recording studio might use? Actually, I would have thought this was a box, not a cable. And actually, it may have been. I never found the "USB Off-Ramp Turbo 2" or the "USB Freeway 2." I found the pricing on basic digital interconnects, knew I was in the wrong place, and backed away sloly with one hand on my wallet.

Tim

Here is a picture of the Empirical Offramp Turbo 2 from T.H.E. Show. The USB Off-Ramp Turbo 2 is $990 plus shipping.

click to enlarge

Here is the link to the unit on the EA site.

Let me think a little about another option for you. If you come across one sooner, let me know.

Pardon my ignorance, but I'm not even sure I understand what it is they're doing here. I just want the zeros and ones that are leaving my Mac via usb or firewire to arrive at an amp via coax. If the amp had a USB port, it would just be a wire. I don't think there is any need to upsample or turbo charge or anything else. Am I missing something?

Tim

If this was that simple I am guessing there wold be many of them available for $10 all over the Internet. Not positive, just my guess. Plus Empirical has created a true audiophile quality solution.

I did find this very sketchy looking device online here. It connects via Toslink for digital audio and 3.5mm for analog audio output. Highly NOT recommended device :-)

Of course you're right. It is, evidently, not something I'm going t be able to pick up at Radio Shack. My signature is not a mis-spelling .

Tim

Well, because Empirical referred us to M-Audio for drivers, I figured they might be a good source. Besides, M-Audio is an Avid company, the creators of ProTools, digital video editing, etc. They know their way around digital pretty well. I'm left wondering if I'm looking for something TOO simple. Everything seems to contain a dac, multiple processing functions - basically pro and semi-pro recording tools, interfaces for computer-based digital recording of analog instruments. If you get far enough up the food chain they do have some products with digital pass-through that would allow you to take Firewire in and send coax out but I"d be putting a multi-channel mixing board on my desk to accomplish that!

I'll keep looking. I know there's something out there...

Tim

Don't think M-Audio is up to OSX 10.5 yet, they might have just issue drivers for the Firewire prodsucts, but don't think they are out yet for the USB Audiophile products.

Not up to 10.5 myself. I'm running 10.4.11 on an iBook G4. I found the device. M-Audio does make something, I was just asking the wrong question. Even this simple little device has stuff in there I have no use for, including, evidently a cheap 24/96khz dac and an op amp (there's a headphone out), but it allows digital pass-through from USB to optical. That will get the job done. $79.99 at Guitar Center.

Tim

Cool, glad your found something that'll work!

Well, we'll see. If it makes a big mess of my zeros and ones, I'll send it back.

Tim

I think I understand your question and understand your confusion. On the video side of things it is kind of like when our customers want to convert their component video output to HDMI by using a mechanical adapter. Unfortunately it requires a fairly sophisticated active circuit to do it. I think that is what you are looking at here. I understand your desire for such a device. It would make many existing and used DAC's that were designed to handle an SPDIF signal able to handle a USB input. There are many more knowledgable than me but to my knowledge it can't be done without using the approach that has been presented to you. Good luck in your quest and if you find that I am incorrect please let us know.

I did find a simple interface that, among other things, offers pass through of digital from USB to optical. I suspect what's going on in that little box is a bit more complicated than what you would have with a wire with different plugs at each end (definitely not a possibility in USB>Optical. But it's probably not all that complicated either.

Tim

Let us know how that M-Audio unit works out. I was late to see this thread, and also have had no experience with This particular form of audio conversion. I've never thought of it before. Let me just make SURE that I am understanding you correctly. If I am reading the original question right, you want to use your mac (or any) laptop as the music transport, output the digital audio to a USB port on that laptop, and have that output translated to either an optical or 'RCA style' SPDIF input on an amplifier at the other end. ......No DAC added -if possible-, Correct?

(BTW, The memory doesn't really "go", it just slows w-a-y down....)

I don't know about the 'no DAC added' part..... Here is what I found on my first attempt - I cut out the most interesting one (to me): http://www.hagtech.com/hagusb.html

Here is google returned on what so far is my best search on this: http://www.google.com/search?client=safari&rls=en-us&q=USB+to+SPDIF+converter&ie=UTF-8&oe=UTF-8

*Time warp occurs here* It would seem at this point, that you do have to have a DAC in there to change the connections on the ends successfully (or satisfactorily) , but I will continue to look at this some more. I feel like I should know this one..... something about the specific format of SPDIF digital transmission is the hang I think...... I know that my A/D/A box does the conversion from firewire to just about anything else digital. But you don't want to spend that much...... You wouldn't need a mixing desk to use that part of its functionality however. You MAY have hit on it, at the most cost effective price point, with the M-Audio thingy, assuming it does the bit rates you want and that you prefer toslink. The other output appears to be analog audio only, if I am looking at the right unit.

markr

Yes, I think you've got it. No, I don't need a DAC in the signal path, as I'm on my way to a digital class D amp and a dac would defeat the purpose. I started looking for firewire. Everything was too complicated. The little M-Audio device looks like it will do the trick. Let's just hope the pass-through to optical is as simple as possible and a solid 75 ohms.

Tim

A digital class D amp usually refers to how the power supply operates. Most subwoofers are Class D amps and they certainly have to have an analog input. Meridian's active speakers are one of the few devices I know of that can handle a digital input - they have a DAC and power amp section dedicated to each driver. Please be sure that the amp you are considering will actually handle a digital bitstream as an input. We have 5 different class D amplifiers in the store, besides subs, and they all need analog inputs. Again, if there is something I am unaware of, please let me know.

Best wishes

I won't pretend to understand it technically, but it's not an amp I'm considering, it's an amp I own. And I currently come out of a DVD player via digital audio coax, directly into the amp. It also has an optical input. And analogue RCA jacks if you want to come out of a source that has already done the digital to analogue conversion.

Tim

It sounds like you're OK but its' because there is apparently a DAC built into your amp. The digital part of a class D amp refers to how it's power supply works. I know that Classe is working on something that will be similar but basically a DAC/preamp, different from the Benchmark in that it is an active preamp and the inputs will handle everything from vinyl to USB.

Good luck with your project.

It's a Panasonic digital HT receiver (I use it for 2-channel only) and no, there's no DAC in the amp either. Again, I don't pretend to understand what is going on in there. Of what I've read, what I do understand is that it amplifies signals from digital sources in their digital form, without converting them to analog. On the contrary, it contains a 192-kHz/24-bit A/D converter at the front end, to convert the signals from analog sources to digital upon input so they are processed digitally, at up to 192 kHz all the way through the signal chain, until just before the output to speakers (or headphones). It's that last step that I don't quite understand. There is obviously some kind of conversion going on, as putting zeros and ones on the speaker terminals wouldn't be helpful, but as I understand it, it is not a DAC in the conventional sense. I read someone describe it once by saying it's as if the entire amp circuit is a big, high-powered DAC. I didn't understand that either.

This much I do know: The thing was startlingly inexpensive, and it sounds incredible. I don't suppose anyone is going to run out and buy one to replace their McIntosh or Krell, and I can't position it relative to other technologies in terms of subjective terms like "musicality," but the specs are world class, and while my speakers are probably not sophisticated enough to reveal all it has to deliver, when I plug my Senn HD580s in, I can assure you that resolution of detail is NOT a problem. That's why I'm anxious to get the best digital source, my Mac, interfaced into it. I'm currently feeding it from a Toshiba DVD player. I suspect the Mac can do better.

Tim

I have to assume it is being converted to analog somewhere but it is a new one for me. It has to be a DAC but it does sort of sound like the approach that Meridian takes in their digital speakers - it's there but it is being done in some a non-typical way that it isn't readily perceived.

Hey, as long as it sounds good and you're enjoying it, great.

Stumbled on this

http://www.hagtech.com/hagusb.html

Following up on this thread, I am likewise at the point of putting together my Macbook and/or Mini based system and would like to give the DACs on my Yamaha RX-V2700 AVR a shot before investing in an external DAC. Which would everyone choose for cabling between the Mac and the receiver:

USB through the HagUSB converter to digital coax, or

A decent toslink cable with mini toslink on one end and regular on the other (pre-assembled, i.e. not using an adapter).

I know the external USB DAC solution is the best, but for my trying-out purposes, which of the two cables would you choose? I also know that a Pacecar would improve things, but then we're back in $1000 territory and I'd rather consider a USB DAC at that point.

Thanks,

TheOtherTim

Hey Tim - I would try the toslink route in this situation. On the other hand maybe you can demo the HagUSB unit to compare.

Have you found a decent toslink to mini-toslink cable without an adapter? I haven't.

Here's one from Monster. Can't speak for the quality but probably not bad. There may be others out there. I plan on looking around. Thanks for the advice.

http://www.bhphotovideo.com/c/product/239816-REG/Monster_Cable_127005_LightSpeed_100_Tosslink_to.html

Tim