how can i add a mids control to a tube screamer circuit?

[Ben N]

I'd love to build or get my hands on one of them!

The easiest way would be to buy a couple of behringer EQ pedals and then put the guts of those in a box along with your favourite clipping stage. No-one would ever know, and I won't tell if you won't!

Or Danelectro, the little plastic ones.
This is the mantra of RG: EQ before to determine the character of the clip, & after to shape the overall tone.

[GibsonGM]

Sure, I've been meaning to work on the 'pre' since I read his article on that about 15 yrs ago, but never have    Generally I use an EQ pedal after, having only 1 (decisions).   I'm usually stuck with whatever pot is on the pedal 'before'.  That's a limit.

[snow123]

but the main issue is that the low end is raised by +5db.

welp it turns out i can just lower the bass by adjusting the values of the 2 470k resistors in the active mids control.

[snow123]

YALL I DID THE THING





I FIGURED IT OUT

[snow123]

and for anyone wondering, the main reason i change the input 1uf cap to 2.2uf is 'cause it changes the way the frequencies go down to the low end (idk how to describe it)
here's it with the 2.2uf cap:


and here's with the 1uf cap:




The main reason I changed the 2 470k resistors in the active mids control to 620k and 300k, is 'cause it lowered 10hz to 100hz area to a point that Im happy with.
And I made adjusted some resistor values was so the mids control wouldn't distort when I max it out, and so it would control more of the low mids rather than the high mids, 'cause if it mostly controls the high mids, it just feels like a presence control, which is not what I want.

[snow123]

full schematic:

[m4268588]

"IC 2.1" may be omitted.

[GibsonGM]

How's it SOUND?   Yeah, you only need that "2.1" opamp for the mid to be 'stand-alone'.  What's there can drive it. So it gets simpler for you

[ElectricDruid]

They're right that you don't need the IC2.1 buffer ahead of the tone control. The previous stage can drive it perfectly well.

Since there's not much benefit to having three op-amps in a circuit instead of four (two 8-pin DIPs either way) I'd be inclined to drop the transistor buffer at the output and replace it with the IC2.1 op-amp buffer instead.

[GibsonGM]

Boom, that's an awesome idea Tom.   Will save real estate, and then it's just the 2 IC sockets.  Amazing how a tiny transistor ends up eating space due to caps, R's...

[snow123]

How's it SOUND?   Yeah, you only need that "2.1" opamp for the mid to be 'stand-alone'.  What's there can drive it. So it gets simpler for you

Lol I spent the whole day breadboarding and trying to get it to actually do what I want it to do and make sound like it's actually doing that thing, and I've succeeded in that.

[GibsonGM]

I hope you did! Do you have an audio probe? If so (and you'll need one anyway so make one if you don't)...you can check the output of each section to see what it sounds like! You could even inject signal to each section to hear it 'alone', if you 'break' the connection to previous sections.   

Plenty of 'how to make a probe' available w/a net search.

[snow123]

ok, I'm making a vero layout for this and I'm not gonna replace the in/out buffers but I am omitting IC 2.1, so should I use an lm741 or 1 side of a 4558 for the mids control?

[snow123]

also, from what ive read, the 4558 is just a dual version of the 741, so is there any audible difference between the 2?

[GibsonGM]

Q: why are you going to a vero layout right away?  You can save a step if you just build it on perf board, as a test. Prototype. Same parts you got now.  Same way you forced yourself to think and work on the breadboard, next thing (for me) would be to build it on perf, using my head to line it all up how I want it.  Your way may vary, of course.   

I'd use a 4558 opamp for EACH stage (2 ICs)....hey, just to be in the spirit!  I really don't think there will be an audible difference; but the MOJO is 4558   

No, there is no audible difference from 741, in the audible range.

[snow123]

Q: why are you going to a vero layout right away?  You can save a step if you just build it on perf board, as a test. Prototype. Same parts you got now.  Same way you forced yourself to think and work on the breadboard, next thing (for me) would be to build it on perf, using my head to line it all up how I want it.  Your way may vary, of course.   

i just prefer vero for the most part.

[snow123]

I'd use a 4558 opamp for EACH stage (2 ICs)....hey, just to be in the spirit!  I really don't think there will be an audible difference; but the MOJO is 4558   

ive found the 1458 to get a little more dirty, while the 4558 stays super clean, which is why i used the 1458 for the clipping/tone stages and 4558/741 for the mids control.

[GibsonGM]

That's going to be up to you...yes, I know they are a little more dirty than a TL072...see how they sound with a nearly clean amp 

[snow123]

I just made the vero layout, and is there anything wrong with it?

The main thing Im wondering about is the 10k resistor and 220nf cap that goes after the the 1k resistor and the clipping amp, into the tone stage, but instead of that i put them right after the clipping amp then into the 1k resistor, then that into the tone stage. im just wondering if doing that could cause any issues.

[snow123]

I just made the vero layout, and is there anything wrong with it?

The main thing Im wondering about is the 10k resistor and 220nf cap that goes after the the 1k resistor and the clipping amp, into the tone stage, but instead of that i put them right after the clipping amp then into the 1k resistor, then that into the tone stage. im just wondering if doing that could cause any issues.

and the reason some of the caps are so big is 'cause I was just sizing them proportionate to the actual caps ill be using.