Peavey VK100 Head Reverb vs Volume Question

[Cheez_It_Man]

Hello. I bought a VK100 head from a guy on Craigslist. Yesterday I noticed that I could hear a 'reverby' noise anytime the amp was powered on, even when I was not playing through it. The noise stopped when I turned the reverb volume all the way down. A quick look at the tank revealed that one of the springs had broken. No biggie, ordered another one from Amplified Parts.

I removed the tank from the amp, and continued to play. The amp was noticeably louder and sounded better. Is this possible? Would a faulty reverb tank have such an effect on an amp? Maybe I am insane though.

[WRGKMC]

The volume of the amp with reverb turned off shouldn't have changed. Maybe the spring was shorting an electrical contact to ground but you wouldn't hear any change with the reverb knob.

 

Having a full reverb working again, can surely have a pseudo loudness effect on your hearing because it adds three dimensional depth you weren't getting before. I bought a Peavey Studio amp awhile back that was missing the reverb tank. I bought one recently based on my best guess and researching what might work in that amp. I believe I bought a 3 spring tank. The Tank is actually too powerful/sensitive for the reverb circuit. Turning the reverb volume up 1/2 way is like turning reverb all the way up on most any other amp.

 

I suspect the amp came with a budget tank with weak spring coils. They used a stronger preamp circuit to compensate. This has advantages. If the coils are weaker you use a stronger signal to get them to balance and this keeps the mechanical noise like bumping the amp to a minimum. If you use a tank with very strong coils, you may hear the tank too much and it can even wind up causing feedback.

 

This is one reason what its absolutely critical to measure your coils resistances before buying a replacement. Tanks can range from around 8 ohms up to 10,000n ohms depending on the amp circuit being used. Using a low impedance tank in a high impedance circuit may make the tank gain too loud, or worse cause the preamp circuit to overheat and burn out. Hopefully you did buy a match and that's just the normal reverb volume (which is fairly high in most peavey amps)

[onelife]

It is possible that the reverb tank was loading down part of the circuitry - which would be the normal state ofthe amplifier - so removing the tank could result in a bit of a boost.

 

The Fender amplifiers with the pull-out Master Volume control exhibit this phenomena with the boost engaged. Back in the late '70s or early '80s, I used one of the Bright switches in my Twin Reverb to disconnect the Reverb send when I wanted that little bit of boost so that I wasn't constantly pulling out the RCA plug on the back of the amp.

 

On one occasion, I provided the amp for Ben Mink to use. By the time I got to the club he had already set it up and was quite miffed by the intermittent Reverb issues. "I've never seen anything like it" he said "the Reverb shuts off when I turn on the Bright switch."