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V-Twin pedal modification


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8/22/2000 4:57 PM
Andy de Ronde
V-Twin pedal modification
Hi  
 
Is there anybody out there who can provide me with modification-info  
on how to raise the volume for the blues mode (or how to lower the volume  
for the solo mode)?  
My V-Twin pedal is an older type which does not have the functionality (V2-D version  
as written on the printboard)to do this (newer ones have a slider at the bottom  
of the pedal, so i've heard).  
Would it also be possible to reduce the gain somewhat when using the blues mode  
without having to readjust the gainpot (using the blues and solo modes next to  
eachother)?  
Thanks,any information would be more than welcome.  
 
Andy
 
8/23/2000 1:16 AM
Steve A.

Andy:  
 
    I have not done this so it may not be feasible. But if you look at the IC stage used in the Blues/Solo mode check out the feedback resistor that affects the gain. In Solo mode it is 1M; in Blues mode it is the sum of the 1M and a 100k resistor (~91k without digging out my calculator).  
 
    One of these days I plan to take my V-Twin apart again to see if I can replace both of these resistors... maybe bring the 1M down to 270k and adjust the 100k accordingly so that the sum is ~91k.  
 
Steve Ahola  
 
P.S. You do have one of the newer V-Twins with the switch and trim pot on the bottomó right?
 
8/23/2000 5:58 AM
Andy de Ronde

Hi Steve  
 
No, i don't have a V-Twin with the switch and trimpot at the bottom.  
Anyway, i recently came acros some info which looks right and verifies what you are suggesting.  
Here's what it says:  
 
I got this info right from David Goodman at Mesa Boogie.  
I have incorportated this mod and it works.  
As many of you V-twin owners are aware, the volume boost from blues to lead is unuseable.  
Maybe later versions were fixed, mine was definitely way to loud in lead mode.  
If you open up the vtwin, you can replace 2 1/4 watt resistors to bring the voume down to  
just a small boost over the blues volume by changing resistors R11 and R12.  
R11 is a 1 Meg ohm stock, install a 220k ohm in its place.  
R12 is a 100kohm, install a 120kohm resistor in its place.  
R11 and R12 are located (as viewed from the playing position) just below the gain pot, just above a small 3 lead transistor, about 1-1.5" from the left edge of the PWB.  
The resistors are side by side, kind of straddling the small transistor.  
I performed the mod, it works about right.  
 
I think i'll give this a try.  
 
Regards Andy
 
8/23/2000 9:20 AM
Steve A.

Andy:  
 
    Thanks! I'm glad to hear that it can be done (some of the Mesa boards can be difficult to work on).  
 
Steve Ahola
 
8/23/2000 5:37 PM
Andy de Ronde

Steve  
 
I've modified my V-Twin as mentioned above but i regret to say that,to me, it's not satisfying.  
When i powered it up for the first time again i immediatly noticed the you big time loss of that creamy thick overdrive which i like so much from the V-Twin, it's just not there anymore!  
Before the mod i could set the gain to 50% which was more than enough.  
Not so anymore, for the sound to be somewhat acceptable it's almost set at a 100% that's again too much for the blues mode to be right.  
The volume-balance between solo/blues seems right now but the sound is altered way too much.  
I'll give it a chance for a week or so, but i'm sure i'll change it back to it's original state.  
Just thought you wanted to know.  
Any suggestions maybe?  
 
Andy
 
8/24/2000 2:05 AM
Steve A.

Andy:  
 
    I guess you like the sound and response of the Solo mode; FWIW I thought that it was way over the top...  
 
    In your case the solution might be to keep the 1M resistor but replace the 100k one with something larger (220k? 270k?). That way the Solo mode would be identical to stock, but the Blues mode would have more gain and distortion... You know, raising the volume of the Blues mode rather than cutting the volume of the Solo mode.  
 
--Good luck and thanks again for sharing the mod with us!  
 
Steve Ahola  
 
P.S. You might look for the rack mount version of the VTwin... That way you could set the volume and gain of the Blues and Solo modes independently. As long as they share the same IC stage you will have the problems that you mentioned...
 
8/25/2000 5:11 AM
skott

here is an idea. put it back to stock and sell it on ebay. than bid on one that has the switch. they tend to go for the same price.  
 
i did it.  
 
skott
 

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