Build Your Own Clone Message Board

Schematic for the early Brian May Treble Booster. Added a volume control and a trim pot to tune the collector voltage. Most medium gain silicon transistors will do, BC108, 2N3904 etc. I built on perf, very easy little project.

use a trim pot for the 1k resistor - almost works like a gain control, also allows adjustment for single coil vs hummies - 1k doesnt seem like much but in this circuit it makes a difference

Thanks for the tip Dragonfly, I'll try that next time I make one up

Whats the point of the 120K resistor? Seems to me it would lower the pull down's resistance. Less impedance effect?

Also what does the 1nF cap do? The emitter is unity gain and in phase with the input...hmmm...My guess adding or cutting highs?

looks like a neat little project.

may i suggest to add a 4k7 resistor (any value between 3k and 5k6 should work) in front of the 10k bias pot (in series). this would protect to go down to zero resistance between V+ and the collector of Q1.

also, if you don't have a nice, regulated power supply and the pedal hisses, try to add a .01uf cap parallel to the 47uf filter cap (after the R100 resistor)

thanks for posting Kaycee!

I just breadboarded this circuit. Seems pretty quiet, no real need for RF filtering.

I liked it but don't think I will build it. Good clarity and a bit of added girth. 10nF input cap sounded good to my ears. Depending on the amp you might want to raise it a bit.

I added a 2K trimpot in series with the base as Andy suggested. It is very subtle, the gain changes a wee bit.

Hi Chris,

The 1M was an addition by me, added out of habit as pop protection I can't remember whether I added the 1M to my builds or not, but you are right, it should be one or the other - I'm thinking that the 120K which was original may well do the job, but for builds sent out I like to be sure.

I found that adding the 1nf on the breadboard cut out the radio interferance that circuits pick up in my house. I agree that you get a nice clear treble boost from this one.

Actually, thinking more on this. I remember that this was originally on of those amp top type devices that was always on, so the 120k would not have been there to prevent switching pops - I guess it must have some other purpose...

A high pass filter then?