Using Acoustic Amp to Power Mic for PC Recording

[Cheeky Monkey]

Hi,

My acoustic amp is a Carvin AG100D (3 ch., incl. XLR mic connection on ch. 3). I'm hoping I can use it to power my condenser mic for PC recording, but I'm not entirely sure and I can't seem to find it in my amp documentation.

I just did some experimentation. I connected my mic to the XLR jack and ran a 1/4" cable from the rear panel "stereo line out jack" and into the PC using a 1/8" reducer. I tried recording and am able to hear my voice, but there's a LOT of hum/distortion along with it. Mind you, I did this using a mono cable (don't have a stereo cable at the moment) and I realize the "stereo line out jack" requires a stereo cable. Might this be the problem? Is it possible that the XLR inputs and signal outputs on most amps aren't designed for a nice, quiet signal fit for recording? Further, are there probably impedance issues as well as a ground loop hum thrown in for good measure?

Before I proceed further, I want to make sure I'm doing this the right way to begin with -- and, will my amp serve this purpose at all? I eventually plan to buy a digital recording USB, but for now, to save money, I want to try using the equipment I already have (plus buying a stereo cable if this is all I need).

Thanks in advance for any advice. Much appreciated.

 

[DonF]

Your condensor mic may require a higher phantom power voltage than the AG100D is supplying. What mic are you using? The original AG100D specs say it supplies phantom power at 14 volts, which is rather low. The newer "Series III" model doesn't say what the voltage is, so you'd have to measure it. Alternatively, listen to the mic/amp combination (use a good pair of headphones plugged into the amp) without the computer. Does it sound OK? If so, the voltage is probably adequate.

Since you say you have a stereo line out, I assume you have the Series III. In this case, you should be using a stereo patch cord to connect the amp to the computer. Otherwise, you're shorting one channel's output, which could possibly cause distortion in the other channel.

That brings us to the next point: what kind of sound input device do you have in the computer? If it's a generic SoundBlaster clone, you should be aware that they are often designed to provide a reasonable level of sound output quality, but not necessarily good input quality. Be sure you're connecting the amp to the LINE input, not the MIC input. At any rate, you must face the fact that you will need to get a better input device.

You should also consider getting a dedicated microphone preamp.

HTH.