ruffrecords
Well-known member
I don't normally do active EQ designs but the other day I was playing around with a tube based Baxandall like bass and treble EQ. The Basic schematic is pretty much as per the attached pic I found on the net except the op amp is replace by a tube.
If you simulate this using a voltage source input with zero input impedance all is fine. With the controls centred the response is flat. However, I expect it will in practice be driven by a finite source impedance. So I tried the sim again with the source impedance set to 2500 ohms. Result disaster; there's a 1dB dog leg in the middle of the response. JHowever, if I add a 2500 resistor in series with the op amp output it becomes flat again.
Is this a known property of the Baxandall EQ?
Cheers
Ian
If you simulate this using a voltage source input with zero input impedance all is fine. With the controls centred the response is flat. However, I expect it will in practice be driven by a finite source impedance. So I tried the sim again with the source impedance set to 2500 ohms. Result disaster; there's a 1dB dog leg in the middle of the response. JHowever, if I add a 2500 resistor in series with the op amp output it becomes flat again.
Is this a known property of the Baxandall EQ?
Cheers
Ian