Build Your Own Clone Message Board

Hey folks. I built a 27V boost for my buddy and he loves it, but he had a couple of requests:

Bypass the Treble cut / boost option altogether

Make the volume knob unity + boost only (as opposed to being able to lower the volume)

Since the treble control is both a boost and a cut, I'm guessing we can't just bypass it with a link but a static resistor might do the job? Any thoughts on the proper value? I considered a trimpot, but that seems undesirable given the board layout.

For the volume knob being an increase only, I'm completely lost here. Anyone have any ideas as to best accomplish this?

These seem like simple changes, I just don't quite have the knowledge to get there. Any advice would be greatly appreciated.

The only technical approach I can think of for this (and I'm not 100% sure it would work, so I'd want to test it or get confirmation from someone else) is to put a resistor in parallel with the pot to change the amount of resistance at the fully CCW position to a value that matches whatever unity volume is. But there's your bigger problem: I would have to imagine that unity volume is going to vary depending on the guitar, what comes before it in the chain, etc.

I'll be interested to hear what others say on this one.

_________________
Scott

My band, Austin Hollow

Personally, I would take it back (because this booster rules) and build him a microamp. But that's me...

Bypass the tone control: looks like just removing the tone pot altogether will turn IC1b into a unity gain buffer. Try that. If it doesn't work (I don't see why it wouldn't) remove the tone pot, remove R8. Install a jumper on the pcb from tone pot pad 1 to the side of R8 that connects to R9 (you might also have to lift IC1 pin 7 so that it is not in the socket - not sure).

Unity gain volume: I would stick a large value trim pot or regular pot in between volume pot lug 1 and its PCB pad. Turn the volume all the way down and adjust the trim pot for unity gain. Measure the resistance of the trim pot at unity and install a somewhat equal value resistor.

_________________
MasterDelayer/Reverbrador/Ampaholic/TopJacker

Morgan pretty much said it all. You could completely bypass the tone control by using a 1k resistor to jump the input of R7 to the output of R9. You'd want to ground the input of IC1b by connecting the output of R7 to ground.

Morgan's suggestion to put a limiting resistance between lug 1 and ground of the volume pot is probably the easiest way to make full turn CCW unity gain. This is a passive volume control. You could however turn IC1b into an active volume control, but you'd have to swap some (probably all) off the components involved for different values. If you disconnected lug 1 of the tone control from the PCB and tied it to lug 2, you'd have a secondary gain control. You'd follow the R1/R2 formula so that a gain of 1 would be full turn CW. You'd have to play with the values to figure out what the gain is for unity, but it would be less than 1.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com