How can I make this pedal louder?

[mr_sooty]

I love the original Marshall Bluesbreaker circuit, and have built a few of these for myself and friends. You guys have already helped me successfully tame the high end slightly, for that we changed the values of C8 and C9.

My only gripe now is that the pedal could be a little louder. Currently with the volume control at 12 o'clock, there's actually a slight loss of volume when the pedal is engaged. I would like to change that to a slight boost in volume. Doesn't have to be much, just a little more than it currently has.

Any ideas?
Schematic:
www.generalguitargadgets.com/pdf/ggg_mbb_sc2.pdf
Wiring diagram:
www.generalguitargadgets.com/pdf/ggg_mbb_lo.pdf

[JohnH]

hey sooty - Presumably 12oclock is not max volume? or is it? If not, and if you are happy with the max volume available, then you could change the log volume pot to a linear one, and volume will rise quicker as you turn up. Or, you could add a resistor to the grounded leg of the volume pot, which will raise the volume at half turn (but not max volume), but also it will then not go to zero volume.

If you actually need more maximum volume, then I think another active stage is needed, maybe using a JFET. It may be possible to crank up the existing circuit, but not without changing the tone

John

[mr_sooty]

Hmm, I guess I would prefer max volume to be a little louder, but yeah I suppose just changing the pot would at least create the illusion of extra volume, which could help. You're right, 12 o'clock is not max volume, just half way, but I find that most of the time I have to have the pedal pretty much cranked. It's not a major drama.

If I added that resistor, what value would you suggest?

Edit: I noticed that the Gain is a linear, I wonder if I swap the gain and volume pots over what effect that will have on the gain control. Might give it a try.

[mr_sooty]

OK, tried the linear pot thing. Didn't really make enough difference, and didn't like the Log pot on the gain so much. I guess I'll leave it all as is, unless anybody has any other ideas.

[JohnH]

sooty - if you swap those pots, the gain might become hard to set, though the overall range from max to min would be the same. So although this is safe to try, I wouldnt recommend it unless it is easily reversed. For adding a resistor to the log volume pot, at mid turn, the pot probably has about 10k to 15k to ground, so another 10k or so should add another 4 to 6db at that setting. It might be a good idea to get a trim pot so you can adjust it, 10k or 50k.

John

[mr_sooty]

Thanks for your help man. I may play around with it some more.