Overdrive / Distortion Circuit... Need Help!

[JasonB]

Hello everyone, you all have been so helpful for a few of my friends with problems in the past so I thought I would ask for some help on this... I have attached a schematic a friend gave to me, but I want to modify it and he was unsure how to do it correctly. I also want to double check it before I build it as I am running out of time to get it finished for a gig I need it for. So if any of you see any errors with it, or anything that needs to be adjusted please let me know!

What I want to add is treble, mid, and bass adjustments before and after the distortion / clipping sections. I have this tone stack calculator http://www.duncanamps.com/tsc/ and it works great but I'm not 100% on where to add the circuits in. I want to add the "Fender" circuit. I would really love some help on placement of those two tone stacks.

And last thing is the MAX1044 chips, I have never had any exp with them. He added them to keep the voltage at the op amps constant. They seem to be correct but the data sheet is confusing for them. So if you know them real well, let me know if they are correct too. Thanks for anyone with any info. I was told this is the best place to ask for help so, I await your help PS - my friend is in the service so that is why I can't ask him for any help right now....

 

[Resqueline]

I see no obvious errors, but it's a complex circuit so I can't warrant it's sound characteristics short of doing a simulation in some program.

The AD's chosen barely manages with a 9V supply so the MAX's are added as voltage doublers to ensure operation with the battery running down. The AD's draws 5mA each and the MAX's can deliver 10mA each, so it should work.

 

[JasonB]

Ok, thanks! Yeah, the AD's were only chosen because I have them laying around here. It was originally planned to use OPA2134's and they work best at 15v. I understand that there is no way to tell what it will sound like. I just want to add treb, mid, and bass adjustments before and after the diode section there before the second half of the first Op Amp, and before the second half of the second Op Amp. Not sure exactly where to stick them...

 

[Resqueline]

Ok.
Tone stacks like that with their high & varying impedance needs to be followed by a buffer amplifier for good results. So one obvious choice would be inserting it at the input of U1a.
But you might want the blend circuit to be unaffected by the first tone stack?
If so you could perhaps get away with a low-impedance stack placed in series with C4.
Then I suggest the U2b tone control to be replaced & configured like U1a with a tone stack in front.