[tictac]

I've got an AKSA 55 power amp with the TLP preamp which I'm using to amplify the output of my computer sound card. With both input cables plugged in I'm getting 60 cycle hum but when I unplug the right side input the noise goes away. However when I unplug the Left channel input the noise is still there. Unplugging either output cable makes thte noise go away too.

Is ther any modification the the TLP that would help with this noise problem or am I looking at some sort of line conditioning to solve this problem?

Thanks from a !st time poster....
TT

[AKSA]

Tictac,

First:  Ensure that there is no hum with input cable REMOVED fromt the TLP, but amp and speakers connected.  This guarantees that there is an earth problem on the input side, from the computer.

If no, the problem is in the grounding of signal earth between TLP and amp.

If yes, the problem is in the grounding of signal earth between TLP and computer.

Usually, if it's 60Hz hum, it indicates magnetic coupling at the mains level.  120Hz is rectified;  at DC, not mains, level.  This implies that it could be picked up either in the layout of wires at the TLP or power amp transformers, or the PC (though this is less likely since PCs use switching supplies).

Hope this helps,

Hugh

[tictac]

Well the problem was upstream of the preamp. I noticed a signal in the peak meter of right channel input of the sound card. Uplugging the right channel sound card input made it go away. The output of my Altec 1692A mixer was plugged into the sound card input. After reading the manual I noticed there are ground lift switches for each channel.

I turned the ground lift for the right channel (really an AC ground) and and the noise is gone. Gotta watch those little details.

thanks again,

TT

[AKSA]

Excellent - a happy ending, the ones I like......

Nice to know it wasn't the preamp or amp!!

Cheers,

Hugh