Reverb Humming Session 400

[Frank De Vincenzo]

Sonny boy was in town this passed weekend and likes to play the steel when he comes home. He says "what's up with the reverb on this amp dad?" Hmmm, haven't heard that before.
When turning the reverb knob from off to full on this 1977 Session 400 it begins to hum and the more you turn the knob the louder the hum gets. What's happening and is there an easy fix for this? I'm sure you Peavey guys and gals have heard this before.
Thanks in advance cool cats!

[Jack Stoner]

First thought is the often problem "Molex" connector that connects the two reverb pan cables to the amp chassis.

"Reseat" the connector (unplug then plug back in). This may fix it. More drastic is to spray both the male and female contacts with "contact" spray cleaner. If that doesn't fix it the female connectors may need reforming (making them smaller).

[Frank De Vincenzo]

Thank you very much Jack. I will let you know the results.

[Mike Marsh]

Maybe it forgot the words....

[Frank De Vincenzo]

Ugh. There's one in every crowd.
Bahahaha

[Ken Fox]

The original Session 400 and LTD 400 amps had RCA male to male cables. Often times they get reversed where connected under the amp chassis. Reverb will work but more hum when connected wrong. The tank should also be installed with the connectors on the reverb pan facing the speaker. A good cleaning of the connection points should be done as well.

[George Macdonald]

I know this thread is a few months old but I thought my recent experience might be worth mentioning. I have had two different Nashville 112s over the years. The first one didn't hum when the reverb was turned on, but I replaced the original reverb pan with MOD brand pan and it really improved the sound of the reverb, and the MOD pan has the same part number as the Accutronics pan. Now, I recently bought back the second Nash.112 from the guy I sold it to about 4 years ago. He never turned the amp on during that time, but the reverb always had a bad hum. It got worse as you turned it up. I would always use a reverb pedal with the amp. This morning I replace the reverb pan with another MOD brand pan and the hum is gone. You only have to turn the reverb up to about 2 1/2 to get a really nice sounding reverb. I bought the pan from Amplfied Parts for $21.00 plus shipping. It's easy to change. This idea originally came from Tommy White. The part number is: MOD 9EB2C1B.

[Frank De Vincenzo]

I sold this amp some time ago. The issue with the reverb was crusted connections. After a thorough cleaning it was great once more.
It was much to big and heavy for me these days. I went with a pair of Bose S1pro speakers. Times they are a changin’