I think I'm not the only fan of Vox amps around here, so this may be useful to someone. I've figured out a way to dramatically surf-ify the reverb in the current line up of Vox AC amps (at least the AC15C and AC30C.
So, first, I replaced the stock reverb pan, a short, three spring, cavernous washy 8EB3C1B with a long, two spring, medium decay pan 4EB2C1B. This makes a substantial difference to the quality of the reverb, but there still isn't enough quantity.
Next, I tried increasing the reverb gain by putting a guitar boost pedal between the pan and the reverb return. As luck would have it, this gave the amp drip so long as I kept the gain under 10dB. Any more becomes a squeal fest.
With this information, I asked a buddy who's an electrical engineer to review the schematic and look for possible gain inside the circuit. Yesterday he gave me the recipe - change C37 from 330pF to 100pF and change R52 from 100k to 330k. Why these values? Well, I'm not an EE so I have no idea!
Also, as an added bonus, the Surfy Drip works with the Vox reverb circuit! The taper isn't as good as with Fender style circuits, but it works.
Video of the final result here: DEMO VIDEO
Also, check the video description for links to the in process testing videos.
here are C37 and R52 on the circuit board:
here is how the surfy drip is connected to the reverb circuit. I put the jack for the pedal through one of the plastic grilles so no drilling of metal or wood.
here you can see the RCA splitter where the surfy drip jack attaches at the reverb return. Also, note the full length reverb pan (4EB2C1B) fits just fine inside the head.
Last edited: Jul 31, 2020 23:24:46