Empirical adding USB interface to virtually ANY DAC

audioengr · « **on:** 13 Aug 2004, 06:39 pm »

For those that want to make their own music server using their PC or laptop, you can now do so using your favorite high-performance DAC. This can rival or exceed the performance of the very best transports.

Here is how it works:

1) Empirical installs a USB interface in your DAC and replaces one of the existing S/PDIF interfaces, such as Toslink or AES/EBU, with the USB interface (modded with Black Gates etc..).
2) Sheetmetal work mounts the USB connector to the DAC.
3) The added electronics is powered from the PC, so no power-draw or new power-supplies are necessary in the DAC.
4) The user loads the USB driver from the provided CDROM
5) The user plugs-in the provided USB cable
6) The user plays .wav files using thier favorite player, such as Windows Media Player

This particular USB interface is also compatible with DD 5.1 and DTS signals from the PC, allowing movie audio to be decoded if the DAC is a SS processor as well.

Pricing:

This is dependent on the difficulty of the sheet-metal work, but we estimate that most will be in the $300-400 range complete.

shokunin · « **Reply #1 on:** 13 Aug 2004, 06:55 pm »

wow, that's cool. What's the primary benefit, other than not needing good soundcard installed in your PC or laptop? Is jitter nearly eliminated since it's interfaces directly with the spdif on the dac?

dave_c · « **Reply #2 on:** 13 Aug 2004, 06:59 pm »

Steve modded my Monarchy DIP Upsampler in a similar fashion. Not only do I have the option to run my system off of my laptop with a huge library of music, but the sound quality is phenominal. Not to mention that Steve's professionalism and craftsmanship are to notch.

I suggest using Foobar2000 with either kernal streaming or ASIO4All instead of WMP. It bypasses the Windows mixer for a direct output to the DAC instead of being resampled by windows.

Jon L · « **Reply #3 on:** 13 Aug 2004, 08:03 pm »

Is it USB 2.0?

If so, the computer must be equipped with USB 2.0, or will USB 1.0 will work also?

audioengr · « **Reply #4 on:** 13 Aug 2004, 09:21 pm »

Quote

What's the primary benefit, other than not needing good soundcard installed in your PC or laptop? Is jitter nearly eliminated since it's interfaces directly with the spdif on the dac?

1) the SP/DIF interface and cable is eliminated and the USB adapter can usually be direct-coupled to the DAC receiver chip. Much less jitter.

2) The USB can be used with laptops

3) The length of the USB cable should not affect the sound quality

audioengr · « **Reply #5 on:** 13 Aug 2004, 10:31 pm »

Quote

the computer must be equipped with USB 2.0, or will USB 1.0 will work also?

USB 1.1 and USB 2.0 will work. USB 1.0 does not support audio.

Jay S · « **Reply #6 on:** 14 Aug 2004, 12:28 am »

Guys, any view if this will work with music files saved in AAC format (I use iTunes)?

Steve, do you think this would be practical with my Scott Nixon Tube Dac? It only has 1 input (coaxial).

I am jazzed that the length of the USB cable shoudn't matter too much. I'd need about a 15 foot run of USB cable from my desk to my stereo.

witchdoctor · « **Reply #7 on:** 14 Aug 2004, 01:27 am »

Will it work with mp-3 files?
My current set up is :
HTPC> M-audiophile soundcard> digital cable> dac>Pre/Pro

Thanks

audioengr · « **Reply #8 on:** 14 Aug 2004, 02:15 am »

Quote

Steve, do you think this would be practical with my Scott Nixon Tube Dac? It only has 1 input (coaxial).

For a bit more, I could add a switch to select between the coax input and the USB, but I would probably want to mod the DAC and replace the transformer and capacitors at the same time to reduce jitter on the coax input.

viggen · « **Reply #9 on:** 18 Aug 2004, 01:20 am »

I store my movies on an external 2.5" usb 2.0 notebook drive and watch it on my laptop. This media's picture and sound is smoother compared to the media stored in the laptop's internal drive as well as in my external usb 2.0 ata drive.

I think usb connection is a very good connection for audio. But, the media source is important too. From my deduction, storing music inside an external notebook drive and transfering the data via usb to an external dac seems to be the way to go for hifi pc audio.

Being able to install an usb 2.0 output on a transport would also be a good option if that is possible. Either way, I do believe data transfer integrity, as discussed here, will be far better than spdif.

srclose · « **Reply #10 on:** 18 Aug 2004, 03:48 am »

What is the difference between using the motherboard SPDIF output to the DAC rather than the USB out to the DAC, assuming the use of something like Foobar? Is there a greater reduction in jitter with USB compared to a MB SPDIF? Or are these alternative ways of accomplishing essentially the same thing? I know using a MB SPDIF out was much better than my transport.

audioengr · « **Reply #11 on:** 18 Aug 2004, 08:10 pm »

Quote from: srclose

What is the difference between using the motherboard SPDIF output to the DAC rather than the USB out to the DAC, assuming the use of something like Foobar? Is there a greater reduction in jitter with USB compared to a MB SPDIF? Or are these alternative ways of accomplishing essentially the same thing? I know using a MB SPDIF out was much better than my transport.

The difference is that the S/PDIF from the computer has to convert to a 75 ohm interface and drive a cable. When you put the USB into the DAC, it eliminates one or both S/PDIF interfaces and the cable. The CODEC interface is direct to the receiver chip in the DAC.

Yes, there is a greater reduction in jitter. The 75 ohm interface and the cable both add jitter. You can also run a fairly long USB cable without any sound degradation at all. The only issue is maintaining signal integrity to keep the USB protocol running properly. Long S/PDIF cables will have a detrimental effect (dispersion) on sound quality.

witchdoctor · « **Reply #12 on:** 19 Aug 2004, 12:51 am »

Steve,
Does it make a difference if you connect the USB port with a cable or via a wireless usb network adapter?

zybar · « **Reply #13 on:** 19 Aug 2004, 01:00 am »

Steve,

What is the longest the USB cable can be?

George

audioengr · « **Reply #14 on:** 19 Aug 2004, 02:01 am »

Quote from: witchdoctor

Steve,
Does it make a difference if you connect the USB port with a cable or via a wireless usb network adapter?

Yes, the difference is that the wireless adapter must "share" cycles on the wireless network. If you only have on agent on the network, then it will probably work great. However, if there is more than one agent, you may experience drop-outs, since the interface is not guaranteed exclusive bandwidth for a contiguous audio stream. Buffering of data may also be handled differently than a direct USB wired interface. Drop-outs are the main concern, but the clock on the wireless receiver may also have more jitter, resulting in a more jittery audio stream. I dont want to discourage you from trying it though. May be just as good as a wired interface in your case.

audioengr · « **Reply #15 on:** 19 Aug 2004, 08:41 pm »

Quote from: zybar

Steve,

What is the longest the USB cable can be?

George

This are quotes from the Intel USB website FAQ:

"The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent."

"Using cables or short-haul fiber, you can get ranges upwards of a kilometer, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.
Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge."

Using a single cable, the max is 5 meters, but you can put a USB hub in the middle and get another 10 meters easily.

JoshK · « **Reply #16 on:** 19 Aug 2004, 08:52 pm »

I think this is a super cool step! I think eventually many big audio companies will start following suit. I have been brainstorming some ideas on how to implement a top notch music server and this is a great idea.

sunshinedawg · « **Reply #17 on:** 19 Aug 2004, 09:21 pm »

Steve,

I have an M-Audio Sonica, it's the predecessor to the Transit USB. I am interested in getting a Monarchy DIP upsampler and having you do a similiar mod as you did for dave_c.

Would it possible to do this but put a switch in so you could turn the upsampling on and off? How much more complicated would this be? The other alternative would be to just use a Monarchy DIP, with no upsampling, that would be easy right? Thanks

Sean

Hantra · « **Reply #18 on:** 19 Aug 2004, 09:37 pm »

Quote from: viggen

I think usb connection is a very good connection for audio. But, the media source is important too. From my deduction, storing music inside an external notebook drive and transfering the data via usb to an external dac seems to be the way to go for hifi pc audio.
...

So are you saying hook the external drive to the USB of the host PC, and then come back out USB to the DAC?

Just making sure I understand.

viggen · « **Reply #19 on:** 19 Aug 2004, 11:27 pm »

Hantra,

That is what I think is a better way to get audio from your pc. I have not done that yet tho. I base my theory based on observations that my audio and video are better from my usb notebook drive than either my internal notebook drive and my usb ata drive. The output device thus far is only my laptop. The real test is after I get the laptop hooked up to an external dac via usb.