Same output to two sound cards

[ksariash]

Hey guys. So here's the deal:

I've got two audio devices (USB Speakers + Onboard Audio) and I want to
listen to the same sound output on both.

For example: I'm listening to a song in winamp, it should play on both
my headphones plugged into my laptop, and my usb speakers.

I've been looking for HOURS with no solution. ANY HELP APPRECIATED!
thanks.

 

[Bob I]

The reason is they aren't designed to do that. You may pick one OR the
other. You may solve this with a Y connector.

 

[ksariash]

If you are suggesting I use a Y-splitter, you've probably misunderstood
my problem.

One connects via USB and the other via headphone input jack on my
laptop... there is no way to connect the two together.

 

[ksariash]

WOOT I just found a solution.

It was a little utility named audiorepeater.exe that can be found in
the zip file of the free trial download of a program named virtual
audio cable. You can delete the other files, as this is the only one
you need.

http://software.muzychenko.net/eng/vac.html#download

 

[Bob I]

very good, thanks for posting back your solution.

 

[Chuck]

"They need to be in perfect sync"

Then you will need to use the same audio source and even possibly the same
audio cable lengths.
Even with that, places that are not equidistant from both sound systems may
not be in "perfect sync"
Two identical USB sound cards will not sync the sound, as you have
discovered.

 

[Paul]

"They need to be in perfect sync"

Then you will need to use the same audio source and even possibly the same
audio cable lengths.
Even with that, places that are not equidistant from both sound systems may
not be in "perfect sync"
Two identical USB sound cards will not sync the sound, as you have
discovered.

The time of flight between two sets of speakers, could cause
an echo issue. The listener in the first setup, hears echo coming
from the other room. The 50msec is the time of flight through
air for the sound.

(Listener)

L,R <---- 50msec TOF ----> L,R
Room#1 Room#2
\ /
\ /
\_______ Computer ______/

Adding a delay on the electrical interface on the left hand
sound card, would fix it, so the sound arrived in phase. (Or
closer to being in phase, plus or minus.) The listener doesn't
perceive an echo.

(Listener)

L,R <---- 50msec TOF ----> L,R
Room#1 Room#2
\ /
50ms delay /
\_______ Computer ______/


As soon as the listener walks towards the other room, the compensation
is ruined. The computer would need to know the position of the listener
at all times, to come closer to compensating for listening position.


(Listener - "I hear real bad echo")

L,R <---- 50msec TOF ----> L,R
Room#1 Room#2
\ /
50ms delay /
\_______ Computer ______/

In terms of using a driver, to control multiple PCI sound cards,
something like this might work. But I was unable to find a free
player application with enough flexibility to send the output to
arbitrary cards and jacks. What I wanted to do, was send the left
channel to one sound card, the right channel to the other sound
card, to test the delta latency between the cards. Based on what
I could read, a typical player to drive ASIO, would send all the
output to just one card. The free ASIO implementations use
the Steinberg sample code, and that give away code doesn't handle
pure arbitrary assignment. I won't install this driver, until
I can find a decent free player application to test with.

http://www.asio4all.com/

As for USB, there are some options as to how it delivers sound.
And likely no documentation for individual USB devices, as to
how they happen to do it.

http://www.thewelltemperedcomputer.com/Lib/USB.htm

Paul

 

[Bob I]

Feed both from the SAME card, otherwise they won't be in sync.