Vox AC15CH reverb pan comparison

[MWaldorf]

Gang, I just did a reverb pan comparison for my AC15CH head,  Stock pan vs. three full length pans - 9EB2C1B, 4EB3C1B, and 4EB2C1B.  Thought some might find it interesting.

https://youtu.be/QP5QsfTOKGM

[MWaldorf]

In case anyone is following this, I tried an additional experiment - I put a clean boost pedal in line with the pan.  It didn't work with the boost before the pan (switch on boost actually made the signal completely dry?!?) but it does work with the boost after the pan.  I'm going to ask an EE friend to look at the circuit and see if this boosting can be replicated within the amp's circuit with any component value changes.

https://youtu.be/6r41HvHzOes

[PRR]

A reverb 'pan' input is a "little loudspeaker" and a VERY heavy load for a guitar pedal.

The pan output is 'a weak guitar' so a g-cord booster may make sense (but there's probably a better way to shave this cat).

http://dealers.korgusa.com/svcfiles/AC15C1_Smanual.pdf

[Williamblake]

Everybody loves a tank comparison. And driver schematics. Thank you. So this Type E design is driven by NJM2147. The only other Type E driver i know are 6BM8 and EF80. I just felt like adding this here because there isn't too much about Type E tanks around.

[MWaldorf]

Thanks guys!  I talked to my EE buddy yesterday and he's reviewing the schematic to see what ways there are to tweak the circuit.  I will continue to report updates here.

[MWaldorf]

My EE friend got back to me with the suggestion to change the values of two compenents at the reverb return op amp - C37 changes from 330pF to 100 pF, and R52 changes from 100k to 330k.  He also told me that in general decreasing the value of C37 will increase the hi frequency gain, and increasing the value of C35 will increase bass frequency gain.  To my ears, adding bass to the reverb would make it muddy so I left that alone.  I tried different values for C37, down to 22pF, but 100pF was the nicest balance of drip without harshness.  There's some ultra high frequency oscillation when the reverb is maxxed, especially when the tremolo is on for some reason, but backing off on the reverb level and a bit of top end cut and it goes away.

Another fun thing I discovered - being a big fan of reverb, I've developed an external mix level adjustment for the Fender 6G15 circuit and vintage Fender -Reverb combos which I call the "Surfy Drip", and, since the Vox pan has the same output impedance as the Fender pan, the pedal works with the Vox, too.  This will make more sense when you watch the video.

video here:
https://youtu.be/qwX6ccQjxOM

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.