Marshall valvestate 8080 how to get more reverb

[korhipt]

Hi all:

I've just bought a secon hand valvestate 8080.
It sounds "great" but the reverb was very low comparing to my 8280 valvestate.

I changed three resistors in the reverb section and put in the following:
R90 and R91: 1M ohm, R92: 100K Ohm.
This helped get better/more reverb effect.

[Enzo]

Rather than modifying the circuit, did you consider repairing the existing circuit? perhaps you had a weak drive.

[korhipt]

I changed both op amps before and after the reverb tank. It didn't help. I didn't take much time checking the signal i have to say, since i already had these two op amps lying around. tl072 and rc4558. i took a chance But the reverb signal was weak anyhow. Maybe the 5201 didn't switch properly, i don't know, but i'm pleased with the result as it turned out.

[Jecarroll7]

Reverb Problem with Marshall 8200 Valvestate

Hello all, what a great resource. I'm hoping for a bit of help. I am an old radio repair tech by training courtesy of the U.S. Marines which quite literally means I know enough to be dangerious.

I purchased a Marshall Valvestate 8200 head. Replaced a few bad pots and the input jack and all seems to work well except for reverb which is dead. I get nothing moving the knobs.

It uses a reverb pan from Accutronics (Cary IL). With the pan disconnected it reads 33.3 ohms on the input side and 197 ohms on the output side. The electro magnet transformers look identicle. Can anyone confirm the readings?

With no power connected to the reverb PCB, everything seems to check out with the multimeter. Next step is to plug it in a take some scope readings.

Anyone with any ideas that could help point me in the right direction would make it to my christmas card list.

Thanks in advance. - Jim

[beezdyk]

How did you go with an answer?

I have the same issue and wandering whether to change over the tank.

[J M Fahey]

Your resistance readings, on both ends, look reasonable and show that your tank is good. Follow the reverb signal path to see where you lose signal.
For starters,brush lightly the reverb springs with your fingers, żdo you get springy noises out of the speaker?
Unplug RCA male plugs and touch the center pin, żdo you get hum from one of them?.

[Alex R]

Sometimes there is some rubber foam stuff stuck to the tank under the springs. If that degrades it can get the springs a bit gunky and it really limits the sound. Often it will clean off with a brush and some meths/denatured alcohol.