Monday, January 7, 2013

Resurrecting a Peavey Ultra 60, Part 2

Reverb Repairs

The Peavey Ultra 60 amplifier didn't include a reverb pan, or the connector cable, so I needed to reverse-engineer the reverb connector and replace the reverb tank. Pretty easy to figure out the connector with the schematic and a digital VOM in hand.

Based on my poking about, here's a drawing of the Ultra 60 reverb connector pinout:

Peavey Ultra reverb pinout

Viewed from the top, front of the chassis, left-to-right. The pins are:

1) Return GND
2) Return signal (from the reverb output)
3) NC
4) Send GND
5) Signal to reverb input

A 5-pin female MOLEX connector works great here. The center pin is unused. It slides right on the the pins. I've fitted the connector with two RCA jacks, and use a pair of pre-made audio cables, short ones.

Here's the connector in situ, with the cables that run to the reverb tank:

The pan type is "EB" ("FB" type works also), i.e., a tank with a somewhat higher input impedance than a standard Fender-type reverb. The 9EB2C1B is an example. 

I used one of the larger EB pans as a replacement. It's 16 3/4 in. long. I had a large and a small reverb tank, tested them both and thought the larger was superior. The pan is screwed to the top of the head case--there is just enough clearance so the pan doesn't touch the power transformer. The recess in the case top is also just wide enough that the pan stays clear of the large vent on top.

Having a working reverb is nice, but it's not pure kandy. It suffers a little in comparison with other reverbs I've heard (and own). The Ultra's reverb is somewhat darker, and "plinkier" than I personally prefer. It does work fine with the gain channels as well as the clean, so that's a plus; no feedback issues. It certainly sounds very good, but it doesn't have that "bright" reverb sound, so it's not the amp for surf music. I'm certainly spoiled by my Ampeg Gemini II :-). At least the larger reverb tank is considerably less "plinky" than the small one. Unfortunately, I don't have a clue as to how it sounds with the stock tank...

EDIT: I might need to rethink the "not for surf music" comment, after getting the "Crunch" channel working (see the footswitch conversion entry). Man or Astroman was playing in my car for two days. I got home I turned Crunch on, with the reverb up to max and the bass way down.  With that channel, the reverb has a nice bright sound--really...not the equal of the Ampeg Gemini II, but not bad at all...

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