1973 VCF - dc offset
2013-05-01 by goldencardigan
Hi all,
I've just finished building the serge filter and while everything looks and sounds like it is working correctly, I have noticed a bit of dc offset on the lowpass output. With no input signal, the dc voltage swings between +4v through 0v and back to +1v as I turn the cutoff knob.
It appears that the offset would not normally be this high, but I have installed the resonance mode, including using the buffer stages to compesate for the gain loss.
The offset disappears when I turn on the low freq mode.
I'm just not sure if this is normal behavior for the circuit or if I should be chasing a fault. I could of cause add a dc blocking cap to the output, but this would kill the low freq mode.
Has anyone else experienced this?
Cheers
Dean
I've just finished building the serge filter and while everything looks and sounds like it is working correctly, I have noticed a bit of dc offset on the lowpass output. With no input signal, the dc voltage swings between +4v through 0v and back to +1v as I turn the cutoff knob.
It appears that the offset would not normally be this high, but I have installed the resonance mode, including using the buffer stages to compesate for the gain loss.
The offset disappears when I turn on the low freq mode.
I'm just not sure if this is normal behavior for the circuit or if I should be chasing a fault. I could of cause add a dc blocking cap to the output, but this would kill the low freq mode.
Has anyone else experienced this?
Cheers
Dean