3 knob treble boost

[Gus]

A three control treble boost that can use a number of Si NPN transistors.
Volume control wired like a rangemaster
Bias control a 0 to 500k control to adjust bias I would make it an external control
Tone control for mids and highs.
Graph shows the tone control range
Simple sim of a guitar to the left of R7, circuit is R7 to the right




I have built this circuit without the tone control using a TIP 29 transistor.

[Ben N]

Gus, you have been a busy boy!  Those curves look great. I'm not 100% clear on R5 - 100k to 600k?  Is the guitar sim recommended for any place other than first in line after the guitar?

[Gus]

R5 is fixed 100k
R11 is a 500k linear potentiometer wired as a rheostat (wiper and one end)

R5 AND R11 have a range of 100k to 600k(fixed 100k and 0 to 500K)

R5 AND R11 is the bias control

R11 is shown as 70K in the sim for R5 + R11 = 170K total

Sim goes in front of the device the guitar output goes too.

Error on the screen shot I have R5 and R12 as the bias control it should read R5 and R11 100k to 600k

[John Lyons]

One more for the pile of circuits to build Gus. 
Thanks.

[slacker]

I tried this on the breadboard and it sounds very nice, definitely worth trying. Seeing Gus's note about trying medium power transistors I used a BD439, I've used these for boosters before and liked the results.
The bias control is interesting, with it on low resistance it adds a nice bit of gritty distortion to the sound, turning it up cleans up the sound, but it's never completely clean. Near the lowest setting it sounds miss biased and on mine cuts out completely on minimum resistance, don't know if this is to be expected but it would be easy enough to increase R5 a bit to stop it.
The tone control seems quite subtle but useful, might be worth experimenting with different cap values.

Like I said well worth getting the breadboard out for.

[Gus]

Ian

Thanks for the feedback
I find I like a treble boost like this one with the collector at 5VDC and even lower VDC.