StellarRat
Member
I'm building a spy ear type sound amp. I have an electret microphone connected to an op-amp pre-amp (OPA2134) that feeds an op-amp active filter (300hz - 3000hz bandpass (OPA2134) ) and that feeds a power amp (TPA4861) for the headphones. My question is should filter be the first stage after the mic or where I have it now (after the pre-amp)? I know it can't be last stage because it could never handle the power from the power amp. The circuit is currently fully operational, but I wondering if moving the filter would improve it.
Also, I've seen some circuits of a similar type that actually have a FET as the first pre-amp and that feeds an op-amp instead of just an op-amp as the pre-amp. Is there any particular advantage to that?
Also, I've seen some circuits of a similar type that actually have a FET as the first pre-amp and that feeds an op-amp instead of just an op-amp as the pre-amp. Is there any particular advantage to that?
Last edited: