perceived gc phenomenon

[tryonziess]

i have 8 completed gc modules with servo and 0.1 resistors. i am checking each from the output of my cd player to a single speaker. each single module has fine absolutely silent characteristics. however, when i parallel or bridge two or more modules they sound terrible. i am adjusting the power with the variac so no over- heating issues are occurring. has anyone else experienced this:

[gootee]

tryonziess,

I think you will need to provide some more details. A schematic of your amps might be helpful. A schematic showing how you are interconnecting them might be helpful, also.

Are you familiar with Application Note AN-1192, from national.com?

From your very-limited original description, about the only good guess I can come up with is that you are somehow activating the chips' built-in protection circuitry, which is known to make them sound terrible.

- Tom Gootee

http://www.fullnet.com/~tomg/index.html

-

[BWRX]

If all of the gc modules are the same, a differential input signal will be needed to make a bridged amp from two modules. It could be possible that one input was grounded and the other was fed the audio signal.

For parallel operation some resistors in series with each amp's output will be needed. Maybe they were not used and the DC servos were fighting for control of the output offset?

[tryonziess]

the output resistors are .1 ohm 0.1 tolerance. when in the bridge mode i was driving with the drv134 line driver. i have never used these package amps before or any others for that matter. i just noticed when what seemed like perfectly satisfactory items were used together they did not combine with the same quality sound.

[gootee]

Originally posted by tryonziess
the output resistors are .1 ohm 0.1 tolerance. when in the bridge mode i was driving with the drv134 line driver. i have never used these package amps before or any others for that matter. i just noticed when what seemed like perfectly satisfactory items were used together they did not combine with the same quality sound.

I think you should assume that they CAN work extremely well together and focus on looking for something wrong with your implementation of that part of the setup. But, as I have already mentioned, most of us would probably need much-more-detailed information (and maybe even some sort of responses to our questions and requests) to be able to hope to be effective in trying to help you.