So whats the Reverb Mod?

[tictac]

Did I read somewhere about a modification to the input of the Alesis
reverb on a G2R to keep it from overloading?

Does anyone know what this is?

db

[Doug]

In a stock G2r, the useable reverb setting for the send control maxes
out around 3-4. That is because the gain of the reverb driver stage
is set so high (5x) by the stock components. Changing resistor R613
(located on the jack board) from the original 100k (1/4watt 5%) to a
lower value, lowers the gain boost to the reverb and allows the reverb
send control to be turned up higher before it distorts the analog
input stage of the reverb board. A diagram of this resistor location
is included.

Depending on the value of the new resistor (and therefore the gain)
the useable range of the reverb control is extended allowing a finer
adjustment of reverb drive. The resulting gain reduction can be
compensated for by turning the reverb send control higher. The gain
of the driver stage may be set anywhere between 1x and 5x gain and the
reverb will still work fine. The lower the gain, the less chance
there is of damaging the reverb board. I think a gain of 2x is a good
compromise. The engineer I consulted said he would have set the gain
at unity gain (or 1x) if he had designed the circuit. A unity gain
modification was tested on one of my G2r's and my ears told me I would
like slightly more reverb drive, so I recommend a gain of 2x be tried
initially. Installing a resistor value of 43.2k (a 1% resistor value)
for R613 will yield slightly under 2x gain (about 40% of the original
gain.) Should you desire a gain of approximately 3x, change the
resistor to 68k. A resistor value of 82k will give an approximate
gain of 4x and a 22k resistor will give unity gain (1x.) The actual
resistor values may vary slightly according to tolerance. All
resistors are 1/4 watt carbon film types, and either 1%, 2% or 5%
tolerance (no lower value than 22k or greater than 5% tolerance is
recommended.) This modification does not affect the appearance of the
amp in any way, and is easily reversed. With or without the mod, you
should never set the reverb send controls to 10 in my opinion. I
would be interested in hearing from anyone who does have the mod done
(or does it themself) to arrive at the otimum gain setting for the
majority of G2r users.
Perhaps yu could post the results in the group for the benefit of
all. Hope this info helps!

[Ajump...@aol.com]

I am unable to find out how to upload a file to the group, so here is the diagram that goes with the reverb mod explanation...