Reverb knob on Fender amps

Tom Wolverton · Post by **Tom Wolverton** » 2 Jan 2014 9:51 am

Every Fender reverb amp Iâ€™ve ever owned seems to have an overly sensitive reverb dial. The working range for decent reverb seems to fall between 2 and 3 on the dial. Anything above 3 is all surf guitar sounding stuff. Does anyone ever change this pot to a different value, so the working range of the reverb setting is more usable?

Rich Santucci · Post by **Rich Santucci** » 3 Jan 2014 4:37 pm

You're right, they're all about the same, between two and three. The most simple thing to do would be to change the reverb send tube, third tube from left looking at the back of the amp, from a 12AT7 to a 12AU7. You could also change the reverb return tube (4th tube from left looking from the rear) to a 12AT7 or 12AU7.

Ken Metcalf · Post by **Ken Metcalf** » 3 Jan 2014 4:49 pm

Another trick is to take the RCA jack out from the back and run it to the unused channel.
This gives you a 2nd level control plus treble and bass controls for the reverb.
Works pretty good.

Don Griffiths · Post by **Don Griffiths** » 3 Jan 2014 5:01 pm

I've had the same thought about the reverb dial. These sound like some great ideas I will have to experiment with. So the RCA out goes to the non-vibrato channel. I've seen this and heard of doing it but didn't understand what it accomplished until now.

Jon Light · Post by **Jon Light** » 3 Jan 2014 5:14 pm

The following is something I saved 10 years ago from an amp electronics BB. I'd be interested in seeing opinions on it from our resident amp pros.

It is a mod by a guy named Mark Norwine:

The purpose of the following mod is improve the range of the reverb.

Normal BF reverb farts out at or above 3 on the dial.
This will extend the useable range (1-3) from 1-10 on the dial. I call this the Mark Norwine ABS (absolutely better sounding) mod: Replace the 100 K reverb pot with a 250 K Audio taper pot, change the 470K ohm resistor on the wiper to 2.2 M ohms, change the nearby 220 K ohm resistor to ground to 160K.

Tom Wolverton · Post by **Tom Wolverton** » 3 Jan 2014 8:42 pm

That's the mod I was thinking about. Change that pot. Thank you.

Greg Cutshaw · Post by **Greg Cutshaw** » 4 Jan 2014 9:18 am

Fender tube reverbs are great. But if I want a reverb that doesn't surf at higher settings, I now greatly prefer a stand alone reverb box set on hall reverb.

Greg

Jack Hanson · Post by **Jack Hanson** » 4 Jan 2014 12:47 pm

Lest we all forget, Leo Fender first manufactured his 6G15 stand-alone reverb unit intending it as an add-on for use with public address systems. It was only after Dick Dale began playing his Stratocaster through one that it became popular for guitarists. Dick Dale basically pioneered (if not invented) surf guitar. Fender later offered onboard reverb on its blackface combo amps about 1963, and marketed them with surf guitarists in mind. Then, The Beatles happened...

To make a long story short, they're supposed to sound that way.

That's not to say that Fender onboard reverb won't benefit from a little tweaking, however. My tech once modded the 'verb on a silverface DR for me, and it made a huge improvement to an already great-sounding reverb.

Ken Metcalf · Post by **Ken Metcalf** » 4 Jan 2014 3:08 pm

Greg Cutshaw wrote:Fender tube reverbs are great. But if I want a reverb that doesn't surf at higher settings, I now greatly prefer a stand alone reverb box set on hall reverb.

Greg

A stomp box is the simple solution.

Steve Spitz · Post by **Steve Spitz** » 4 Jan 2014 4:05 pm

A stomp box is one idea, but I'd rather not have to use one. I've got some, they work great. I'd rather make my amp reverb more useable, by making the reverb knob less sensitive . My amp tech suggested that mod After I picked up my twin for a bias and tune up. I wish he would have mentioned it earlier. I'd love to have it. I have the long decay three spring pan, and it sounds great, but like the OP states, it's too sensitive, and anything past three is way too wet.

If I had an effects loop, it would be more attractive, as I like sending the signal to the amp first, not thru a pedal. I also don't want another piece of gear. At times, I need to keep it simple.

Bill Leff · Post by **Bill Leff** » 5 Jan 2014 10:55 am

Steve, try the tube change to the 12Au7. Easy fix and and you can always go back. It worked wonders on my Deluxe Reverb.

Tom Wolverton · Post by **Tom Wolverton** » 6 Jan 2014 12:49 pm

Bill, do you mean the reverb send tube?

Originally a 12AT7 ? It does not appear to be a gain stage tube, right? Just a reverb send?

David Gertschen · Post by **David Gertschen** » 8 Jan 2014 10:05 am

There is a gain stage involved in the reverb send circuit. By changing to a different tube, you are just changing the gain factor which may or may not sound better to you. As stated, it is a cheap & easy experiment and will not hurt the amp at all.

12AX7 Gain Factor = 100
12AT7 = 70
12AU7 = 45

You can also do this swap in the V1 & V2 tube chart positions to tame the gain of any input channel.

Tom Wolverton · Post by **Tom Wolverton** » 30 Jan 2014 10:48 am

The 12AU7 switch was nice and easy and got me 90% of what I wanted. Good enough. Thank you all for the suggestions.

Howard Montgomery · Post by **Howard Montgomery** » 30 Jan 2014 10:59 am

"There is a gain stage involved in the reverb send circuit".....I believe he gain stage is 1/2 of the recovery tube (V4), not the send tube (V3). Both halves of the 12AT7 are in parallel on the sending side of the reverb tank. I assume that is the one folks are subbing with a 12AU7.