Hi,
I am considering this mod to a AB763 Deluxe Reverb circuit.
I understand the need for the second .1uf capacitor to prevent the bias voltage for entering the pot.
Why would they both be .1uf? That would reduce the total capacitance to 50 nanofarads per side. Why would they not be .2uf to keep the same capacitance as before the mod. The original circuit only has one .1 cap between the inverter and the output tubes.
Thanks,
Billy
I am considering this mod to a AB763 Deluxe Reverb circuit.

I understand the need for the second .1uf capacitor to prevent the bias voltage for entering the pot.
Why would they both be .1uf? That would reduce the total capacitance to 50 nanofarads per side. Why would they not be .2uf to keep the same capacitance as before the mod. The original circuit only has one .1 cap between the inverter and the output tubes.
Thanks,
Billy
]Why would they both be .1uf? That would reduce the total capacitance to 50 nanofarads per side.
Why would they not be .2uf to keep the same capacitance as before the mod. The original circuit only has
one .1 cap between the inverter and the output tubes.
This circuit could have problems, since the pot sections not tracking closely will cause distortion
because of imbalance. You can certainly use 0.22uF caps if you want.
This is not really a volume control, since it's within a NFB loop.
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It is not capacitance which matters, but LF rolloff - this depends on resistor values too. If the pot and the extra caps are all that has changed, then the LF rolloff (at max setting) will not have changed much either. The LF rolloff will depend on the pot setting, but this sort of thing is probably common in the guitar world.
Hi DF96,
For sure this will act as a variable RC circuit.
I assume the capacitance is 50 nanofarads when the pots are set for zero ohms. It looks like to me the four cap values should be .22uf. The idea is to not have the circuit change anything when not in use.
This is not a big deal to hook up and test to see the effect. If none of these type circuits work well I will most likely buy a power scaling circuit from London Power.
Cheers,
Billy
For sure this will act as a variable RC circuit.
I assume the capacitance is 50 nanofarads when the pots are set for zero ohms. It looks like to me the four cap values should be .22uf. The idea is to not have the circuit change anything when not in use.
This is not a big deal to hook up and test to see the effect. If none of these type circuits work well I will most likely buy a power scaling circuit from London Power.
Cheers,
Billy
That circuit works fine. Unless you really need the .1 total for bass, i would leave it as is, it equals a .047 as coupling.
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