is there a usb to coax out?
May 24, 2004 at 6:45 PM Post #2 of 62
if you can find someone qualified a coax out is easy enough to add to any sound card (or for that matter just about any equipment that converts digital to analog)

They will need to, identify the codec chip and locate the adat output pin then build a small interface board and add the jack

but there is to my knowledge a usb-to-coax adapter and if there is one it is not a good solution usb being more of buss than a true digital output
 
May 24, 2004 at 6:59 PM Post #3 of 62
Hey rick, thanks for the suggestions

the problem is that my 12inch powerbook doesn't have a good soundcard or a pciwhatever slot. it just has two usb 1.1's, a firewire port, an ethernet port, a modem jack, a mic in, and a headphone out

so usb or firewire are the only two external soundcard solutions.

but i want something that uses the usb that i can then plug directly into my DAC

cheers!
 
May 24, 2004 at 7:22 PM Post #4 of 62
maybe a headroom bithead ?

or again ,find a place for the coax jack to be added on the case and have someone track down the adat pin (audio data) on your codec IC ,buffer and r/c filter the interface (the cmos buffer will need to tap the +5V supply) and strap the tiny board (or deadbug layout glued in) to a secure out of the way spot.

no matter the card and what interface is available (usb-firewire) you can still get a digital TTL signal at some point on the chip if you know what you are doing
 
May 24, 2004 at 8:57 PM Post #6 of 62
The Xitel Pro Hi-Fi Link is the only usb > coaxial out that I know of.

It also offers optical and stereo rca jacks. The Xitel stuff doesn't seem too highly regarded on this forum, but I think most people have only complained about the rca outs (its onboard DAC is evidently underpowered, because the unit is powered only by usb, rather than an external wall wart).

Shouldn't matter for you, tho, since you've got your outboard DAC.

Another thing you might have considered (if you still had your Sonica) is an outboard jitter-reduction device, pretty much all of which will convert optical to coax. There's an Audio Alchemy DTI on eBay right now you could 'buy it now' for $100:

http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW
 
May 24, 2004 at 9:10 PM Post #7 of 62
on the whole the USB-To-SPDIF converters suck in the sonics department so if the goal here is to get the best sound (hence the external dac) then a sonic butcher before a good dac makes little sense

some of the USB DACs though can sound very good ,if you power them from an external battery pack and not the usb from the computer

a battery pack with 5 C-cells did it for me when i had my DIY PCM2702 DAC/Headphone amp

a direct ripoff of the Wheatfield DAC I listened to at the HE-01 show and the TI/Burr-Brown data sheets+demo board pdf

sounded good but in the end i had no real use for it so i gave it away
eek.gif
 
May 25, 2004 at 5:37 AM Post #8 of 62
why do you think USB->S/PDIF sucks as a whole? I'm about to experiment a bit with PCM2706 and its I2S and S/PDIF outputs, the chip has Ti's well regarded SpAct PLL, the same as in DIR1703 and I was hoping it will do quite well.. of course I won't even touch the dirty USB power..

I think regulating the USB power rail using some LT1763 low noise LDO to some 4.5V and feed it to PCM2706 and to a TTL->coax S/PDIF logic should do quite well and it's so easy to implement!
 
May 25, 2004 at 10:40 AM Post #9 of 62
Quote:

why do you think USB->S/PDIF sucks as a whole? I'm about to experiment a bit with PCM2706 and its I2S and S/PDIF outputs, the chip has Ti's well regarded SpAct PLL, the same as in DIR1703 and I was hoping it will do quite well.. of course I won't even touch the dirty USB power..


just going by what i have personally heard from the available commercial offerings , maybe it is just the implementation,maybe it inherently just sucks
I don't know

What i can say is-

powering a usb audio interface from the usb connetor is not a good idea and an external dedicated power source (Ac or battery) does make a differnce ,a big difference,so o would concentrate here

I have no experience with the 2706 but only 2702 and the device I built did not have digital outs , an oversight

maybe I need to revisit this and build an all out usb dac to settle the question in my mind once and for all

or maybe get a listen of the wavelength USB DAC which is an interesting design
 
May 25, 2004 at 12:03 PM Post #10 of 62
so i am reading this


http://www.wavelengthaudio.com/Cosecant.html

and I am realising maybe this is the ultimate answer to DACS .

Instead of a usb dac what we have is a sound conventional dac design (close to what I use as my dac which is DIY/modded from a DITB) that has an added benefit of being able to interfeace to a usb port

Some more research is definately in order for the rickmonster.The part about jitter is really interesting and i guess i glossed over that before during my research

I see no reason why i could not add a usb interface and still retain the optical/coax and taking it a step more-add I2S

And then maybe i can , by using the very same dac for ALL things digital decide what really is the best overall digital interface

hmmm.......thrown a a defeatable re-clocking circuit and .....


convergence is coming so i guess i had better get up to speed on this.

dammit , i already had much to do ,now this
wink.gif
 
May 29, 2004 at 4:50 AM Post #13 of 62
rickcr42 ,

when you say that it's better to have a battery power, do you refer to S/PDIF too?
what would you think would be the best configuration to have a USB->coax ?
what difference would there be between the DIY and the commercial stuff (let's say, the Xitel Pro)?
 
May 29, 2004 at 6:23 AM Post #14 of 62
commercial stuff will generaly suck, they are mostly using USB bus' power, if not then some basic noisy regulators.. nothing special by no means.. if you need something right, well you have to build it yourself..
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top