Mark III reverb mod?

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timv

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I did some searching and only came up with 2 explanations and they are both different. How is the reverb mod done? Heres the 2 descriptions I found:

There are several mods to boost the reverb in the MK III. The easiest one is to place a 3.3K 1/2 watt resistor in series with the black wire at the effects return jack. This will boost the amount of reverb available. It will not change the tone of it. There is another more extensive mod that boosts the amount and can change the tone of the reverb. You should contact Mike B. at Boogie for that one.

You will have to unsolder the black wire from the efx rtn jack, solder the resistor to where the wire was and then solder the wire to the other side of the resistor. Like this:

[efx rtn jack]--black wire--- stock

[ efx rtn jack ]--3.3K resistor--black wire------- mod



Just as a follow-up to my earlier post- Having recieved no reply from Mesa Boogie (remember I live in Australia and have to rely on their email service) I spent several hours trawling the net and eventually came across a posting in a user group almost a decade old. This included the official Mesa fix for the mark III reverb glitch and it is very simple- a 120K resistor soldered between the red lead of the reverb transformer (5 leads of varying colours come out) and ground (I soldered to the earth lug of the reverb send RCA jack-the one with the black wire soldered to it). Total time- 10 minutes including removing and replacing the chassis. Total cost 15 cents


Are one of these right or both? I may be looking at toadmeister's amp for him and he expressed interest in having the reverb mod done, wants a bit more reverb out of it. I'll probably do the R2 mod also but already know that one.
Thanks for any help. I'll take pictures while I do it to share.
 
Anyone have some insight. Is the black wire the one from the circuit board or from the reverb pot? They attach to the same point. I may just have to call MB and get some help...
 
timv said:
Anyone have some insight. Is the black wire the one from the circuit board or from the reverb pot? They attach to the same point. I may just have to call MB and get some help...

Hey timv, you must put your 3.3K in series with the Blk wire coming from the circuit board (this acts to further buffer the reverb output from the FX loop). This is standard in later stripe models. You might also experiment putting a 250pf cap in paralell with good ole R131 (ala lonestar) this will change the tonal character (of the reverb) somewhat from darker to brighter depending on the value of the cap.
 
Does anyone know if his second method works?

"120K resistor soldered between the red lead of the reverb transformer (5 leads of varying colours come out) and ground (I soldered to the earth lug of the reverb send RCA jack-the one with the black wire soldered to it)."
 
Hi, I did the second mod some years ago. It was very simple but I've lost the file that described how to do it.
In my case the mod was done to get rid of a buzz/ghost note that accompanied the reverb (which I think was a known Mark III issue). It definitely fixed the problem, but I'm not sure if it gave more reverb.
 
So I went ahead and did the first mod. I don't notice much in terms of reverb output, but I definitely noticed that the overall volume is lower. This makes the reverb seem louder in comparison. Is this what is supposed to happen?
 
Sorry to pick up on such an old thread! From the info I can gather out there (only having an early Black/No Stripe myself but looking at pictures and info others have posted) version 2 of the Reverb Mod (actually a 110K resistor 2W) is already applied to Factory Green Stripes. Version 1 of the mod is already done to a Red Stripe and possibly a Blue Stripe from the factory but cannot verify this 100%.

Whether both are applied to the Blue and Green stripes and what effect this has I cannot be sure!

No reverb mod is done to Black or Purple stripes from the factory.

Hope that helps someone out there reading this :)
 
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