[boead]

My dilemma is that my PC is about 25 feet from the stereo. I can either run a long RCA cables (which I already made with Belden wire that sound ok) OR I have to run long digital connections. Either Optical or Coaxial RCA.
I’m not even sure is you can get or make a 25-30 foot coaxial cable or optical TOSLINK.
Is there an inherent limit to how long a digital wire can be? I mean a point which degraded sound quality becomes significant?
I found that the longest a USB cable is sold is about 16 feet. Why? Can a USB cable for an audio device be longer then 16 feet?

Is it best to use an external DAC for a Computer close to the computer and use a long RCA to the preamp
OR
Is it best to use a long digital cable from the computer to the DAC at the rack with short IC’s to the preamp?

 

[granodemostasa]

options:
1. use the digital out from a usb audio card (like M-Audio transit),
2. Use long, expensive RCA out from dac, so microdac>long RCA
3. long firewire to dac
4. wireless, like squeezebox, airport express and use either a short digital or short RCA.

i like 4 the best..

 

[boead]

Quote:

Originally Posted by granodemostasa options: 1. use the digital out from a usb audio card (like M-Audio transit), 2. Use long, expensive RCA out from dac, so microdac>long RCA 3. long firewire to dac 4. wireless, like squeezebox, airport express and use either a short digital or short RCA. i like 4 the best..

Will the SqueezeBox act like a Windows sound device? I want it for more then just music.

I’ve heard some negative comments about USB DAC’s being less musical (or Audiophile quality) then they should be when compared to similar DAC that use coaxial.

Any truth to that?

Any opinion on the Scott Nixon DAC+USB or the original DAC+

 

[granodemostasa]

depends. USB dacs convert the signal to spdif before they send it to the dac, so they should sound the same regardless of the signal.. it's just a bad dac. issues relating to usb could be that it is often times unstable and has issues with not so powerful computers.
the scott nixon dacs, on the other hand, are not like that, they convert directly from usb to the dac and are said to be more jitter resistant than conventional dacs.

 

[YngwieJMalmsteen]

This place will make you any length toslink you want. I have 2 of them and wouldn't mind another.

sysconcept.ca

 

[Thaddy]

Also, Blue Jeans Cables can make you a Digital Coax cable to any length, in the case you want to have your DAC closer to your amp.

Also, it looks like a 25 foot analog RCA cable from them would cost $50, using the Belden 1505F conductor.

 

[boead]

Quote:

Originally Posted by Thaddy Also, Blue Jeans Cables can make you a Digital Coax cable to any length, in the case you want to have your DAC closer to your amp. Also, it looks like a 25 foot analog RCA cable from them would cost $50, using the Belden 1505F conductor.

How do you think long optical or coaxial length will affect quality?

 

[Thaddy]

I'm not sure, but using some logic, I tend to see longer runs of analog cables available when compared to digital cable. Sort of how most Toslink cables are < 12 feet in length. So, taking that into consideration, I'd imagine it would be better to have the DAC closer to your computer and run some long RCA cables to the amp/receiver.

edit: As for quality, I have no clue. Wouldn't be hard to test though, given you have multiple inputs on your amp.

 

[darkless]

Since signals sent via optical cables aren't affected by interference and don't degrade (jitter issues from poor optical converters aside) I'd recommend that you grabbed a toslink cable of a suitable length. You can get 25 ft toslink cable for less than $25 shipped here.

(I just clicked one of the first links after googling "toslink 25 ft")

 

[boead]

As I understand it USB, Firewire, AES/EBU(?) transfer digital data much like a hard drive, in packets or groups and this digital signal needs to be converted into SPDIF so it can be clocked and feed into a DAC.

This leads me to believe that it something like jitter as a component that degrades data is a non issue and that in all reality, the data fro the computer to the device that converts to SPDIF is irreverent to Audiophile integrity. I assume this is why devices like a squeezebox can transfer data via RJ45 or wireless and still be HiFi!

Doesn’t sending a digital SPDIF signal through a LONG wire degrade sound where something like jitter is a issue? Do you not think its significant enough?

Since USB needs to carry some voltage to communicate with the hardware chips that are talking to each other, long runs can be problematic. Someone told me they use a 18 foot USB with a Scott Nixon TubeDAC+ with NO apparent problems.

It leads me to believe it would be better to deliver a USB signal to an all-in-one device (like a USB DAC) then it would be to send out a 75ohm signal over lets say 25 or 50 feet of wire to a traditional DAC.

Am I on the right track?

 

[Don Quichotte]

I have an Apogee Mini-Dac w. USB. The USB cable I use with no problems is actually made of two pieces, one about 14 feet long and the other about 5 feet long. I compared it with the shorter (~ 2-3 feet), thicker and better looking cable that came with the Apogee and found the Apogee cable to sound slightly better (more precise, more dynamic, with better detail). I don't know why: is it because of the supposedly better shielding or what?

Apogee recommends a maximum USB cable length of 15 feet and advices against using an USB hub, but the reason they invoke is related to the stability of the connection and not to the sound quality.

 

[boead]

Quote:

Originally Posted by Don Quichotte I have an Apogee Mini-Dac w. USB. The USB cable I use with no problems is actually made of two pieces, one about 14 feet long and the other about 5 feet long. I compared it with the shorter (~ 2-3 feet), thicker and better looking cable that came with the Apogee and found the Apogee cable to sound slightly better (more precise, more dynamic, with better detail). I don't know why: is it because of the supposedly better shielding or what? Apogee recommends a maximum USB cable length of 15 feet and advices against using an USB hub, but the reason they invoke is related to the stability of the connection and not to the sound quality.

I ordered this USB Active Extension in a 16 foot length. http://www.usbcable.com/cat24.htm

I also ordered a 15 foot USB cable AND a 10 foot extension (non-buffered).

I’ll try these configurations.

PC > 15’ USB cable > 16’ active extension > USB DAC > 3’ RCA (MIT S3) > Preamp

PC > 15’ USB cable > 10’ extension > USB DAC > 3’ RCA (MIT S3) > Preamp

PC > 15’ USB cable > USB DAC > 12’ RCA (MIT S3) > Preamp

PC > 2’ USB cable > USB DAC > 35’ RCA (DIY Belden wire) > Preamp

And we’ll see how it sounds with my M-Audio USB DAC. If it’s ok I’d like to try the Scott Nixon USB DAC+ or another USB DAC like the one from Red Wine Audio.

 

[Don Quichotte]

Great! Post your findings!
Quote:

Originally Posted by boead If it’s ok I’d like to try the Scott Nixon USB DAC+ or another USB DAC like the one from Red Wine Audio.

OK by me!

 

[boead]

http://www.redwineaudio.com/USB_Select.html

This unit WITHOUT an analog output stage is $399 which means all this is for the purpose of converting the USB to SPDIF.

He eliminates the USB power, converts to 12V so it can work on battery which is mounted inside.
( he says… this removes the noisy USB port's power supply out of the equation (which is derived from the computer's switch-mode power supply), as well as the length of USB cable that it would have to travel between the computer and DAC…)

He also replace the SPDIF output resistor with Caddock MK-132 precision metal film resistor, direct wiring of the SPDIF output signal to a high-bandwidth 75-ohm BNC digital output jack which I’m not thrilled with! And he adds dampening material to the crystal oscillator which sets the clock for SPDIF, this is from M-Audio.

Lastly he increases the power supply rail capacitance with the use of Black Gate capacitor, and replaces the USB CODEC chip’s critical voltage line decoupling capacitors with Black Gate NX-Hi-Q caps

All this so far just for USB to SPDIF conversion, obviously the most important thing.


If you want an analog output too, he adds this for $100; He completely bypasses of the opamp in the stock analog output stage. The L and R output signals are now directly from the internal DAC's output stage and sent to the RCA output jacks via Black Gate NX-Hi-Q coupling caps.
So the only other thing he’s using from the M-Audio board is the Audiophile 2496 converter.

He also includes a battery charger that plugs into the back. The charger has a ‘charged’ indicator light. Batteries are replicable and said to last 6 to 8 hours.
For an extra $50 he has a slightly larger enclosure and batters with longer life span up to 24 hours.

Not a bad package for $499 and many seem to like it.


Something to consider with the Scott Nixon. With the upgraded power supply its $575 and then you need a power cord! That’s another $125 to $200 easy! So realistically the SN is $700++ and what about a nice NOS tube, that’s another $50.

 

[JahJahBinks]

they sell cables up to 975 feet.

Time to befriend with your neighbor.