PI questions

[imaradiostar]

Also, a thought on your original question. Some claim that the Dr Z Ghia amps and the Hammond reverb amps they're based on have a really great distortion tone because of the fixed bias phase inverter. It makes a certain amount of sense as the bias is less like to shift during an overdrive condition. I've not tried one though so i can't say for sure. I know Hiwatts sound cool cranked up so there may be something to this.

With modern components I'd use a zener to fixed bias a phase inverter very simply (more simply than a hiwatt or hammond ao-35). It could be a quick and easy experiment- perhaps you could even make it switchable so you could compare the two designs.

jamie

[wizard333]

Here's an easy way to calculate the -3dB point:

Guitar Pedals: R-C Filter Calculator

Yeah I use that one all the time, so in this instance, treat the grid resistor as twice it's size as per the discussion in Merlin's book and just use the input coupling cap to get the roll off point?
More simple than I anticipated, cool.

have a really great distortion tone because of the fixed bias phase inverter.

The amps I'm familiar with that have that setup have pre-amps that include a lot of gain so I'm not sure I've ever really tried driving the power section hard. I'll give it a shot and see if there is anything noticeable there. Nothing seems different at normal volume levels though. There is a Fender style clean channel pre-amp on two of them, so at least there is a point of reference for what to expect when it is pushed hard.