View Full Version : Audio card and VT card to same amp?

Tom Wood
09-15-2003, 12:21 PM
Hi All,

This is a weird one, but maybe someone is an audio expert. I have both the VT card and a high-end audio card (www.digitalaudio.com) in the same PC. I use them at separate times for separate tasks. However, since the WinXP setting has no effect on audio out of the VT card, I can have both active at the same time. Which is handy when going back and forth.

I have a Presonus HP4 headphone amp that has left and right TRS inputs. I -can- run the left channel of one card into the amp left channel, and the right channel of the other card into the amp right channel. I'm not running audio from both at the same time, I'd just like to be able to leave them both plugged in. The Presonus has a switch that sends either channel to both earphones, so it's like a faked stero effect.

My question is, is there any danger of electrical feedback through the amp from one card to the other that will do any damage to the cards?



09-27-2003, 02:32 PM
There's little danger of anything more severe than a ground loop from plugging in both cards and using your amp's mono switch.

A better way however might be to simply install a passive switch box with both cards as sources and the amp as the destination. You'll need something other than the Circuit City $30 special, since you're dealing with TRS (balanced) signals. Something like the Broadcast Tools SS 8.1 http://www.broadcasttools.com/view_product.asp?productID=38

Or if you're handy with a soldering iron you can build one using two DPDT toggle switches (one each for L and R channels, +/-)

Tom Wood
09-28-2003, 07:29 AM
Thanks Thraddax,

I've been thinking about a simple breakout box.

For anyone still reading, I'm real happy with the HP4. It has connections for four headphones, plus TRS out for speakers, with a mute button. I added a pair of powered speakers and the sound is incredible.

http://www.bayviewproaudio.com/ProductDetail.asp?Products_Action=Find('ProductID' ,'presonushp4')&Products_Position=FIL%3A++Category+LIKE+%27%2AHead phone+Amps%2A%27+AND+Manufacturer+LIKE+%27%2APreSo nus%2A%27ORD%3AABS%3A1KEY%3Apresonushp4PAR%3A

09-28-2003, 05:53 PM
Or, run it through a mixer.

09-29-2003, 11:40 AM
I'll second the recommendation for an external mixer. I have a little Mackie 1202; it works when I'm capturing, when I'm dumping to tape, and the rest of the time to select what I want to listen to on the 'phones (including a little music to edit by). I got it used for $150ish, and it's built like a tank.


Tom Wood
10-20-2003, 08:34 PM
Yeah, a mixer is the way to go. I just won a Mackie 1202 on eBay, and it connects everything together. I don't understand why the RCA connections are the default for recording decks, but the Mackie has them and so does the Sony DSR11, so I guess it's okay.