hi guys,
newbie here. been reading through the forums about Op-amp ugrades and i had my first try a couple of days ago. i used LM4562 as the upgrade.
i have an old 2-way active crossover lying around, when i opened it up i found 10 op-amps:
3 op-amps (2 ba4560, 1 ba4558) in the input section
2 op-amps (2 ba4558) in the filter section
2 op-amps (2 ba4558) in the highpass output section
2 op-amps (2 ba4558) in the lowpass output section
1 op-amp (1 ba4560) in between the powersupply and audio section
been aware of oscillation and dc offset issues, i decided to swap op-amps per section so i can concentrate on a small area should a problem arise.
i swapped out the lowpass section and found 1mv dc offset. i've read anything less than 20mv is acceptable??? then i played music low to high volume, no problem.
then i did the same thing to the highpass section, no problem.
then the one between the power supply and audio section, no problem again.
then the filter section, still no problem.
it is in the input section where the problem starts. since there are two kinds of op-amps, i decided to swap the ba4558 first. no problem there. but when i swap the ba4560, it still plays fine until a particular portion of a particular musical track (michael ruff's I will find you there) causes the entire crossover to 'lock up' and just oscillate.
the rest of the tracks on that cd won't cause the oscillation. i soldered the ba4560 back and the problem goes away.
the two 4560 op-amps are the first two op-amps just after the RCA inputs and they were both configured to have a corner frequency of 21kHz.
all the caps are still stock but i placed 0.1uf ceramics on the +/- pins and + to gnd and - to gnd, nothing helps the 4562.
i would really appreciate any help/suggestions offered
thanks!
newbie here. been reading through the forums about Op-amp ugrades and i had my first try a couple of days ago. i used LM4562 as the upgrade.
i have an old 2-way active crossover lying around, when i opened it up i found 10 op-amps:
3 op-amps (2 ba4560, 1 ba4558) in the input section
2 op-amps (2 ba4558) in the filter section
2 op-amps (2 ba4558) in the highpass output section
2 op-amps (2 ba4558) in the lowpass output section
1 op-amp (1 ba4560) in between the powersupply and audio section
been aware of oscillation and dc offset issues, i decided to swap op-amps per section so i can concentrate on a small area should a problem arise.
i swapped out the lowpass section and found 1mv dc offset. i've read anything less than 20mv is acceptable??? then i played music low to high volume, no problem.
then i did the same thing to the highpass section, no problem.
then the one between the power supply and audio section, no problem again.
then the filter section, still no problem.
it is in the input section where the problem starts. since there are two kinds of op-amps, i decided to swap the ba4558 first. no problem there. but when i swap the ba4560, it still plays fine until a particular portion of a particular musical track (michael ruff's I will find you there) causes the entire crossover to 'lock up' and just oscillate.
the rest of the tracks on that cd won't cause the oscillation. i soldered the ba4560 back and the problem goes away.
the two 4560 op-amps are the first two op-amps just after the RCA inputs and they were both configured to have a corner frequency of 21kHz.
all the caps are still stock but i placed 0.1uf ceramics on the +/- pins and + to gnd and - to gnd, nothing helps the 4562.
i would really appreciate any help/suggestions offered
thanks!
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