AIP Mic Pre Rack

[thinktank2]

I built 8 AIP 312 modules and racked them in a 2u rack. They are powered by a power-one supply and for some reason, and I never had this problem before, all of the channels seem to be distorting. I checked the voltage and am getting +/- 16volts coming out. I seem to remember that there was a way to check and see if the opamps are working. Not that all of the modules would be bad. Anyone know how to test the opamps here? All of the modules are chained together as far as the power. I also tested it against some other mic pre's and the mics don't distort when plugged into those. Thanks for any ideas here.

 

[CJ]

I would eliminate the power supply as a possible cause, since all 8 are running off of it.

 

[CJ]

I would eliminate the power supply as a possible cause, since all 8 are running off of it.

 

[drpat]

It sounds like he's saying that all 8 are having problems.

 

[thinktank2]

Right, there is distortion on all 8 channels. I'm going to go through them again this weekend. I remember checking the opamps on my 550a's a while back. Just trying to remember how I did it.

 

[jrmintz]

Did you test the voltage coming from the power supply under load?

 

[Helsing]

For 8 channels Id suggest a 1 amp supply minimum. I racked a pair of 312s and a pair of 550a with a 1/2 amp supply(marginal) and had some problems. Went away with a larger supply.

You might try powering up a single channel with your existing supply. If it works add a channel to the string, one at a time, and see if there is one module that is causing problems.

Power is most often the culprit. I doubt that your 2520s are bad and I would be wary of messing around with them too much. Fairly easy to destroy and $$$

Helsing

 

[thinktank2]

So I finally took off the power leads to all 8 modules and one of the preamps was the culprit. With the other 7 connected to the supply, the voltages +/- were fine. When the 8th was plugged in, the negative dropped to -2 vdc or so and the positive stayed the same. I'm using a power one supply with +/- 15vdc @1.5amps, so there's enough power for all 8. Any ideas on where to look for a possible problem on the one module? Thanks.

 

[Helsing]

Compare the bad board to a good one and search for any differences. You might have a filter cap installed backwards on your negative rail or some other short to ground. Perhaps you have a negative protection diode hooked up in reverse.

If everything looks good Id next try to swap out the opamp.

Helsing

 

[ToobieSnack]

so how about some "gear porn" or this beauty?
i's love to see your pics/
later
ts