View Full Version : Hiss on reverb after doing mods!!
it's been said
03-24-2008, 11:55 PM
I have a carvin bel air 2x12 and i did the hasserl mods to it.
now whenever i turn my reverb past 12 o clock i get this way loud hiss and I've noticed that the reverb unit is more noisy overall
are reverb units always noisy and i didnt notice before
i think i might of rehooked the reverb wires wrong but i don't know where to find out for sure
03-25-2008, 04:48 AM
It's impossible to comment on this without seeing a schematic of the amp and mod and knowing how you actually connected the wires.
Maybe you should contact the "inventor" of this mod.
03-25-2008, 10:32 AM
Not sure what the modification is. To answer your question about reverb noise...Yes they are inherently noisy in my experience. Its always fun to get the hiss and hum out of them. It could be the modification you've done has nothing to do with the reverb noise you're hearing now and it came about for other reasons - like a noisy reverb recovery tube for instance.
03-26-2008, 03:06 AM
If you did all of them, you changed the gain structure substantially, bumping it up on the soak channel, and added a variable NFB pot ("attitude") among other niceties. If you have the attitude pot rolled on, the gain is also higher, the amp "looser", and again all this runs through your reverb if it is on. Reverb past 12 is a noisy proposition most times anyway, and these mods increase that noise floor. I like the mods, however, and live with the noise.
You could replace the 2.2M resistor before the reverb input with a 1M pot and a 2M resistor (adding a dwell control) to give more flexibility.
JMHO; I'm sure Rich will be by shortly.
03-26-2008, 10:22 AM
I would agree with slick.. increase the resisitor feeding the reverb tank to something around 1M and see if it reduces some of the noise. You may have a problem with tone loss.. but if youre increasing gain across the board expect the amp to get noisey.
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