Help needed with a mod to tonestack

[arma61]

Hi diyers

surfing here and there I saw the following schem

http://runoffgroove.com/tonemender.html
and
http://www.muzique.com/lab/atone.htm

I already tested, and liked, this last one

I thought I could link the together like this :


so a sort of "cut&paste"!!of the 2 schem!

circuit already built, and testing, I have following issues :

100k bass - pot I've used a 100kA is working as follow,

0 to 5-7% dirty sound
7 to 80& no sound
80 to 100% bass sound but heavy distorted/farting

tried  100Kb, almost the same

15K treble - pot I've used 22kA it does anything at all

so, taking into account that PCB is correct as per schematic, no solder bridge (at list found till now!!), did I miss anything, did I make something wrong, did I make a mess of it.

Somebody can ask "why you didn't build the tonemender?", I don't like too much MID tones, but I like a lot of bass tone, and the schem. from AMZ seems to be good for me.

Thx for help
Ciao
Armando

[slacker]

The problem is that the bass and treble controls are connected to ground and are directly connected to opamp's inputs and outputs, this means that the controls are messing with the bias of the opamp. R2 and R7 are connected to 4.5volts to correctly bias the opamps, but then R13 and R6 and the tone pots are pulling that voltage down towards ground which is miss biasing the opamp, the lower you turn the tone controls down the worse the problem will be.
To solve the problem connect the bottom of the tone controls to your 4.5volts instead of ground.

[frankclarke]

A coupling cap in the second opamp input (before the 1M) would work with the tonestack grounded.

[arma61]

YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!! YES!!  IT WORKS!! IT'S GREAT, good bass sound tested in this way !!! , flying wires, no shielding...... !!!

Thanks slacker for advice and explanations that helped me greatly!

please be partient with me for the last questions,
- is it right that when both pots are set to 0 there's no sound coming out ?
- what kind of pots you suggest I should use, log or lin, with this kind of circuit

Thanks again,
ciao
Armando

[arma61]

thanks frank, do you mean in this way



do you mean in addition to slacker suggestions?

what value ?

Thx
Armando

[frankclarke]

Yes, exactly right. The shredmaster has the tonestack to 4.5V. The Guvnor 2 has  tonestack to ground/chassis, a 220n after the tonestack, before the Deep opamp. The original Guvnor is different. So either should be OK.
No sound on 0, yes. Log maybe, since they are volume controls, not sure.

[arma61]

thank again frank, I'm going to re-draw the pcb and etch it tomorrow.

just one thing I didn't understand, is your suggestion to be used together with the slacker's one ? or just one of the two ?

Thx
Ciao
Armando

[slacker]

If you do it the way i suggested you don't need the cap. Although adding it won't do any harm.

[arma61]

Again thank you vm for help and suggestions, I've build it this evening, here's a couple of pictures of it, now it's too late, I'll test it tomorrow!

Old style PCB!!


Ready for testing


Ciao
Armando