How to place a tone stack in a circuit

[Distort_Everything]

Hi everybody, first time poster long time reader.

I was wondering if anybody could help me with something, I've been messing on with the runoffgroove double D and want to add the Fender e series EQ to it, I've tried breadboarding this and it sounds really weird, if I'm 100% honest I'm not sure where the input is on the eq schematic, I'm guessing it's at the top and also guessing that the bottom line is ground?

This feels like the last hurdle on my pedal building journey, the tone stacks admittedly have been the most confusing because every builder seems to put them in different places on the circuits. I understand that before the gain stage and after the gain stage are generally completely different ball games since you're pushing signals into a wall or taking things out afterwards, if anybody could give me any guidance on this would be massively appreciated.

[FSFX]

Tone stacks are very sensitive to the input and output impedance.
You need to check what the requirements are and if necessary scale the component values to suit your circuit.
The simplest rule, like much in audio electronics, is to drive them from a low impedance source and follow them with a high impedance load.

[GibsonGM]

Welcome to the forum, Distort!!  Good question.

I don't know the output impedance of the circuit offhand, but I think perhaps the tone stack should come after the 4.7u cap on the output (?).   That leads me to think, maybe it can't drive the tone stack without too much loss (!), so it could lead to a need to buffer the dist to drive the tone stack....so I would consider moving the switching to the other side of that output buffer, and placing the tone stack at its output (it really isn't needed in bypass anyway!)....so the buffer isn't part of the circuit when switch is in bypass.     So - a little re-working required....stack after output buffer, moving the volume to after the tone stack, the switching...make sense?  Hope so.

Someone's likely to chime in soon with a more elegant solutions for this    

[merlinb]

I'm not sure where the input is on the eq schematic, I'm guessing it's at the top

Guessing won't get you far in electronics

[Distort_Everything]

Welcome to the forum, Distort!!  Good question.

I don't know the output impedance of the circuit offhand, but I think perhaps the tone stack should come after the 4.7u cap on the output (?).   That leads me to think, maybe it can't drive the tone stack without too much loss (!), so it could lead to a need to buffer the dist to drive the tone stack....so I would consider moving the switching to the other side of that output buffer, and placing the tone stack at its output (it really isn't needed in bypass anyway!)....so the buffer isn't part of the circuit when switch is in bypass.     So - a little re-working required....stack after output buffer, moving the volume to after the tone stack, the switching...make sense?  Hope so.

Someone's likely to chime in soon with a more elegant solutions for this

Thanks for this, is the input of this tone stack after the 1u cap at the top? On the others included in the program it says input  and the switch is taken out of the circuit on either side as I only want the high gain side. Found out the hard way now that dealing with CMOS chips is way more difficult than a regular op amp but they sound incredible for drive so it's definitely worth it. Been having a look at active tone stacks as well but still this is the side of the equation I've never dealt with, reason I'm using this one in particular is because I really like the way the Matamp GT120 eq works and its practically identical!

Thanks for all your help, looking forward to see what other people have to say on the matter.

[Distort_Everything]

I'm not sure where the input is on the eq schematic, I'm guessing it's at the top

Guessing won't get you far in electronics

I agree, that's why I came here looking for advice  would definitely explain why it sounded so strange, thanks very much!

[GibsonGM]

Yes, the sine wave symbol is the 'signal generator', of which your guitar is one  

[Dormammu]

I agree, that's why I came here looking for advice  would definitely explain why it sounded so strange, thanks very much!

Well, that sounds weird, because that's not the kind of thing you can use in a box. Don't mess your brain with impedance-schmempedans, because the boxes are stuffed with buffers, like a street dog with flea. Better take a couple of traditional standardized circuits, they'll sound normal.

[ElectricDruid]

Guessing won't get you far in electronics

Merlin's re-draw makes the thing a lot clearer, but honestly who draws a schematic with Ground pointing up at the top?!? That's just daft! Everyone knows ground is at the bottom!^* Frankly, it's no wonder you were confused, Distort.


^*Unless it's a bipolar supply circuit, in which case it would be in the middle with -V below it. There's always a caveat!

[antonis]

but honestly who draws a schematic with Ground pointing up at the top?!?

Probably some down-under fellow..

:cider: :cider: :cider:
(for the usual suspect.. )

[PRR]

You should always go to your roots. Fender 5E5-a.

Schematic: http://www.thevintagesound.com/ffg/schem/pro_5e5-a_schem.gif

Note that a NFB pick-off is "inside" the tone network. This makes many analyses off-base.

And yes, Leo DID put the ground sticking straight up. Somehow it makes more sense from his hand.

The E-type seems to be mostly a curiosity. HBP suggests here that players "perceive the tone controls to shape how much drive the preamp sends to the power section." I'm not sure how that transposes to a pedal.

[Distort_Everything]

You should always go to your roots. Fender 5E5-a.

Schematic: http://www.thevintagesound.com/ffg/schem/pro_5e5-a_schem.gif

Note that a NFB pick-off is "inside" the tone network. This makes many analyses off-base.

And yes, Leo DID put the ground sticking straight up. Somehow it makes more sense from his hand.

The E-type seems to be mostly a curiosity. HBP suggests here that players "perceive the tone controls to shape how much drive the preamp sends to the power section." I'm not sure how that transposes to a pedal.

Really appreciate that man, think just a high pass filter my have to do on this one, just thought it would have been cole to use this sort of control, I'm wondering if it's maybe possible to get the desired effect with gyrators. Just the increase and bass and treble effects the amount of mids in the signal, I always thought it sounded great on the Matamp, will have more of a mess around with the breadboard and have another pop, honestly really appreciate the help from everybody!

[ElectricDruid]

And yes, Leo DID put the ground sticking straight up. Somehow it makes more sense from his hand.

Lol, even I might give Leo Fender a free pass for that!