VOX AC30/6 Top Boost w/ Reverb Schematic

[JKowalski]

I'm planning on building a VOX AC30/6 Top Boost with a custom reverb circuit. All the old schematics I could find were incredibly difficult to read so I cleaned one up a bit, double checked questionable values with alternate sources, and drew in a AC30 reverb modification I found into the circuit.

Just wanted to throw it out there on the net for possible use.

If anyone spots any errors, please let me know! For obvious reasons, its highly important to me that I correct it!

[Robert M. Martinelli]

Hi,
here's my 1 cent....

I would reverse the reverb volume pot connections, using the wiper to send the signal to the LTPI and connect the reverb circuit's output at the pot end, the rationale for this being that, if you connect it as shown, when the reverb volume pot is at its minimum, you are grounding the reverb out but the other pot end is 1 Meg from gnd, so you could have some disturbancies entering the LTPI area. Doing it the other way around should minimize the risks for this to occur without losses IMHO ( as you still have the 330 K blending resistor in series with the pot ).

Hope this helps

Best regards

Bob

[JKowalski]

Thanks alot for the tip! I think that might have been just a mistake in drawing. I updated it with the modification and etc.

[Robert M. Martinelli]

Hi again,
I took another look at the schematic, and it looks like the vib/trem modulator tube is of the wrong type, it's indicated as an ECC83, it should be an ECC82.
Though they have the same pinout, their characteristics are quite different ( amplification factor, mutual conductance, plate resistance etc. ) and the ECC83 cannot work as a direct replacement.
Hope this helps
Best regards
Bob

[JKowalski]

I really appreciate you taking the time to look through my schematic.

Thanks for the help. I'll update it again a bit later.