Pro Reverb Mod Ideas

[foreverstrung]

As TUTs mention, and I have repeated in other places including here, the low-value loop is not a good choice for a musical instrument amp. Fender used 820R for series and 100R for shunt in most of its amps. Increasing the values by ten opens up the sound while retaining the same gain. That's the fist mod I would do.

Other things are pretty standard reliability improvements: Change the screen-stops to 1k-5W wire-wounds or metal-oxide as long as they are flame-proof; change the 1k5 grid-stops to metal-film for better reliability; add 1R-1W metal-oxide cathode current-sense resistors for safe idle monitoring - add meter pin-tip jacks to make this easy.

The FPM kit on our site updates the used and unused channels into a Fender clean plus any distortion you desire. Use ERK or a relay for channel switching.

If you intend to try any power tube swaps, make sure their heater current does not exceed 900mA, like the stock 6L6s. Many other types have heavier heaters and you might want to add an auxiliary PT just to power the output tubes. If you do this, you will have to hang the grid-stop off pin-5, then mount the 1R-1W between pin-1 and pin-8, grounding pin-1. This allows EL-34 and 6CA7 to work and gives a handy support for the current-sense resistors.

Where can I get this FPM kit? I searched a bit but came up short.
Also, some of these mods, any chance I can find some sketches or schematics of these upgrades? Including the power tubes. Right now there are a an old set of Svetlana tubes installed. There vintage. IDK how strong they are. Probably good, but I've got a nice matching pair of RCA's I'd like to consider if these existing tubes end up coming up short
I can print out and refer to these mods you've noted, but I'd really be grateful to have a drawing to refer to. If possible.
Thx
Dave