please help me figure this out....
i have an amp with 2 sets of inputs - one set goes through a chip which controls volume, bass, treble etc. the other set of inputs has a normal preamp (for microphones). these 2 inputs join at a stereo opamp which then goes to the power amp.
about a year back i replaced the stereo opamp with 2 mono opamps (one inverting, the other non-inverting) so i could bridge both channels of the amp. this has worked fine for ages.
yesterday i took the amp circuit out 'cos i want to use it as a subwoofer amplifier. i connected the inputs to the inputs of the opamps (bypassing bass, treble, volume controls) and the thermal runaway started.
so i hooked the chip back up to the opamps - it was better but thermal runaway was still there.
then i hooked the amp back up exactly how it was - still thermal runaway.
then i took the sub and hooked it up to one channel (not bridged) and it is stable now.
what could i have done wrong??? it was stable (bridged) and now its not. i have got a schematic so i will post it later.
i have an amp with 2 sets of inputs - one set goes through a chip which controls volume, bass, treble etc. the other set of inputs has a normal preamp (for microphones). these 2 inputs join at a stereo opamp which then goes to the power amp.
about a year back i replaced the stereo opamp with 2 mono opamps (one inverting, the other non-inverting) so i could bridge both channels of the amp. this has worked fine for ages.
yesterday i took the amp circuit out 'cos i want to use it as a subwoofer amplifier. i connected the inputs to the inputs of the opamps (bypassing bass, treble, volume controls) and the thermal runaway started.
so i hooked the chip back up to the opamps - it was better but thermal runaway was still there.
then i hooked the amp back up exactly how it was - still thermal runaway.
then i took the sub and hooked it up to one channel (not bridged) and it is stable now.
what could i have done wrong??? it was stable (bridged) and now its not. i have got a schematic so i will post it later.