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futiboho 14th October 2004 10:58 AM

how to compensate diffrence in amp gains in 3-amp system
I will appreciate your advise on what are the practical steps to do this task. The amps I use have gains of 63 (The END, LC Audio) and 32 (Thel Accusound). I know what to do in principle but am interested on details, e.g.:

1) what signal I have to use at the input of the active XO (from what source, e.g. test CD, white noise...?) so that the three ways should pass identical levels of output and then I can measure the V at the amp outputs, to be made (the volts) equal for each amp via adjusting the XO output trims.

2) Are there alternatives? (I don't have an osciloscope and hope the adjustment could be done with what I have (multimeter, test CD, ears...)

many thanks for your insights!

richie00boy 14th October 2004 11:29 AM

Set the XO aside and just feed each input with a 1 kHz sine wave and measure the output voltage with a volt meter. Adjust each amp level control to get the same reading on the meter.

futiboho 14th October 2004 02:15 PM

Thanks. I was talking about a signal through the XO because my amps do not have volume controls while the XO has trimers at its output. Any idea how to set these trimer pots?

richie00boy 15th October 2004 07:27 AM

With your ears. It would be pointless setting the voltage at the speaker terminals all the same anyway as the different drivers will have different sensitivities and efficiencies.

Upupa Epops 15th October 2004 08:04 AM

Is not good to use different amps for active crossover. By my experiences best results are only with the same amps.

futiboho 15th October 2004 08:36 AM

Upupa, I see your point but disagree. My research has made me believe that you have to combine amps that are particularly good at the respective frequency ranges and this is what I did.

AndrewT 15th October 2004 08:53 AM

I agree, select the amps that best suit the frequency range and accept a bit of resetting to equalise volume due to different gains and sensitivities. In the extreme you might use tubes for the treble, class A solid state for mid & class AB for the bass. Not just differnt makes but a whole different philosophy. The problem might be finding a set of matching (nice sounding) amps to experiment with.

Upupa Epops 15th October 2004 09:06 AM

I'm standing along by my words ;) , but I don't take your opinions - judgement will be only our common listening, which is probably rather notreal :D .

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