Fender Re-Issue Reverb Hacks

This article explains how to tweak the Fender Re-Issue Reverb units to sound more like the old vintage units.

Warning: Tube equipment contains very high voltages, often several hundred to over one-thousand volts! Do not attempt anything described here unless you have training and experience working on tube electronics. Also, doing what is suggested here WILL VOID YOUR WARRANTY. I suggest only modifying equipment which is out of warranty.

Ok, now that the warnings are out of the way, lets proceed.

First, we'll talk about tubes. The original Reverb used a 6K6GT as the driver tube. This tube is long out of production, but is similar and pin-compatible with the 6V6GT which is what Fender puts in the re-issue. The 6V6 is a more powerful tube, and expects a lower transformer impedance than the 6K6. Luckily Fender used a transformer which is essentially identical to the original (13K primary). So the first thing you want is a new old-stock 6K6GT. These tubes are luckily not an audiophile or common guitar amp tube. Changing this tube will lower the amount of drive to the reverb spring, widening the range of the "dwell" control. The drive will be a little smoother, softer without the tendency to plink so much.

The other two tubes are usually a Sovtek 12AX7WA and a Chinese 12AT7. Both are OK tubes, but you can improve these by changing them. I'd start with the 12AX7. Ideally, you would want to get a genuine NOS 7025. These are rare and expensive though. I've found that the 5751, especially GE are excellent in this application and many others. The 5751 is a shock-resistant military dual triode. They are usually completely free from microphonics. They have a gain of 70 vs. 100 for the 12AX7, and for military use are rated only for 280 volts. They sound very smooth and clean. Some can be noisy, but most are pretty good. The 5751 are readily available as well.

The Chinese 12AT7 isn't too bad a tube. But, again nothing beats good old USA (or English, German, Dutch) stuff. The ultimate 12AT7 are Mullard gold pins. The GE's sound good, and the Phillips ECG work well in this application too.

The other tweak requires opening the unit, and removing the tone control PCB. Behind the volume control pot is small 250pf ceramic capacitor. Change this to 390pf, I've tried as high as 470pf. Changing this cap will definitely change the character of tone. I suggest starting with a 390pf film or silver mica cap. See how you like it. To my ear, the sound becomes a bit richer and fuller. Be careful soldering in a new cap. They didn't leave a lot of room, and you don't want to short it to the pot supports.

While you have it taken apart, you might want to check the reverb pan. I've seen a number of these where the springs have come unhooked, or improperly hooked in transport. That's why you should always, always, lock the spring down when you move the unit. You also may want to try a 3-spring pan instead of the stock 2-spring. The 3-spring isn't the vintage sound, but it will make the fullest, lushest, most church-like reverb sound. I put one in my Deluxe Reverb amp, and I really like it.