Hi, New here... I got a cool front end bass reduction mod...

[caphead]

Hi everybody, as the title indicates I'm new here although I've lurked around here for a while as this forum is an excellent resource for all things Boogie, especially for the Mark series amps. Anyways, I came up with a mod recently that I'd like to share with you all. This mod is designed for any Boogie with a single tone stack (passive EQ) that uses LDRs for channel switching. See here for schematic:

What this mod does is automatically reduce the amount of bass coming from the tone stack in the Lead Channel mode only. This mod addresses the problem that anyone with a Mark II/III knows all too well in that in order to have a tight lead sound, you must greatly reduce the bass at the cost of fullness on the rhythm/clean channel; what the added LDR and trim pot (or set value resistor) does is shunt across the .1 bass cap and .047 mid cap limiting how high the bass control can go in the Lead channel. On the Rhythm channel, the LDR is off and the trim pot has no effect on the function of the bass control. The primary benefit of this mod is that one could set the tone stack for a full sounding clean tone, then click on the Lead channel and adjust the internal trim pot to where the overdrive's bass content sounds comfortable to you.

Sorry, trying to get used to this board's format, how does one post pictures? Here's the link again: https://www.dropbox.com/s/kwy2qerlwh1l5ul/Mesa_Mark_Bass_Reduction_mod.jpg

 

[HelpingFriendly]

That actually sounds worth while. I am interested in how to do it

 

[caphead]

I was giving some thought on how to cater this mod to the Mark III as I don't believe there would be too many people willing to mod anything on their MarkIIC's never mind an actual IIC+, lol! Would this mod make sense to you if it were to be active when the treble shift is pulled? The idea on how to do this would be to add another LDR on top of the LDR for the treble shift. On the earlier (non green pre MarkIII) PCB's it wouldn't be too much of an issue to just solder the switching side of the new LDR anywhere onto the traces, but the MarkIII's board is solder masked which means either you would have to scrape off a little bit of the coating on those traces and drill very small holes or you could just piggy-back the new LDR onto the LDR for the treble shift soldering it's switching side (or the LED part of the LDR) where the treble shift LDR connects to the board. I will draw up a picture on how these added parts can be attached onto the board asap....