Wah Inductor in a distortion/overdrive pedal?

[The Furious One]

Normally I stay far away from the (won't mention names) site, but I was reading something earlier that directed my attention to his new pedal. It has a wah inductor in the circuit for the midrange tone control. This has me questioning the effect this has on the mid range in a pedal and how I could possibly implement this into any other pedal out there.
I'm curious if this could be the answer to the "sterile mids" problem I seem to have w/ alot pedals I've built or bought. I'm an 80's metal freak and Randy Rhoads was my biggest influence to pick up a guitar in the first place...so it's safe to say that I dig the midrange and this idea has definately grabbed my curiosity.

[rocket]

a mid cut control is very simple with an inductor (and a capacitor) just like a tone control but with the inductor and a capacitor in series rather the only a capacitor.

the centerfrequeny is  1/(2pi*squareroot(LC)).


It would be better to tell us the name of the manufacturer you are refering to. So the forum can be searched and we know what you are talking about.

[amz-fx]

http://www.fulltone.com/GT500.asp

"It has a discrete Inductor-Driven Midrange circuit....never been done in a pedal before."

Has been done...   but the GT500 looks like a nice pedal...

regards, Jack

[petemoore]

  Thanks Mr. Orman !
  I've gotten to really like inductors, even little transformers...
  Wah is not the only type of circuit they can be used to great effect.

[Chris Frailin]

Wow, there's a commercially sold pedal with this feature? I need to see how this works!

[Chris Frailin]

 I can't find any other pedal with this feature (the Fulltone isn't out yet) or any schematics showing how to implement an Inductor as a midrange control. Anyone have a link?

[johngreene]

http://www.fulltone.com/GT500.asp

"It has a discrete Inductor-Driven Midrange circuit....never been done in a pedal before."

Has been done...   but the GT500 looks like a nice pedal...

regards, Jack

Really? where?

Details Jack, inquiring minds want to know. 

--john

[MKB]

Don't know about any pedals, but some of the Ampeg amps use inductors in the mid control circuits.  And you can always simplify an early Mark series Boogie graphic EQ and put it in your pedal, those were really old school with inductors and transistors, no op amps.

[Jay Doyle]

I know nothing of the circuit myself, but if I had to guess this comes from an old manufacturer's hi-fi EQ. But even if it isn't here is one way to do it:

Using the formula rocket mentioned above, figure out the frequency you want with whatever inductor and cap you have (or just build a damn gyrator and cap combo and save a hell of a lot of space, time and frustration finding the right inductor).

Now set up a transistor stage with 10k on the collector and 10k on the source, bias it to 1/2V+ and take the output from the collector. So you have an inverting transistor amplifier stage, with a gain of 1.

Now, attach one outer lug of a 100k pot directly to the collector, the other outer lug to the emitter. Now attach the inductor/cap combo you had to the wiper, and BINGO!, as you rotate the pot towards the emitter the LC network provides an easier path to ground for those frequencies in it's band and boosts them (just as a cap does when it bypasses an emitter), turn the pot towards the collector and instead of boosting, it cuts those signals as it shunts them to ground.

This circuit is mentioned in the Stompbox Cookbook, I think it was an old Tascam EQ from the 70s.

Anyway, this is one way to do it.

Jay Doyle

[Paul Marossy]

I wonder if it's not just the Clapton mid-boost circuit in a pedal. 

[petemoore]

  Transformers do something
  Wah inductors IME do a bit more.
  I got a cheep-0 multi pedal for fixing/scavenging, the inductor went into a Minibooster type pedal. Pretty cool too. Probably has to do with exactly which inductor and where it's put.

[hair force one]

my ibanez renometer eq pedal has 5 inductors in it, guess it makes this heavy brick of gray metal kinda cool... 

[amz-fx]

There is a  Craig Anderton pedal EQ circuit with an inductor...  Gil Ayan's Smooth-n-Slim is an RLC circuit.  The Keeley Nova Wah has two inductors, and though it has "wah" in the name it is actually a variable filter eq.

-Jack

[Harry Palms]

"never been done in a pedal before."

It's definitely been done before.
It's got a lot of potential.

[Chris Frailin]

"never been done in a pedal before."

It's definitely been done before.
It's got a lot of potential.

Oh, but hasn't been done in a commerically sold Distortion pedal, gotcha.

[jonathan perez]

I wonder if it's not just the Clapton mid-boost circuit in a pedal. 

speaking of marossy, why not just intergrate a twin-t circuit with ANY overdrive/distortion, and do the switch combo of one/either/both/none?



sorry, i got distracted...this damn state of the union is getting rediculous...


anyways, i lost train of thought. anyone know what i was getting at?

[Harry Palms]

Oh, but hasn't been done in a commerically sold Distortion pedal, gotcha.

Take a closer look Chris.

[aron]

Here's killer mids!

http://www.diystompboxes.com/amps/pignose150r/distsect150r.jpg

[jonathan perez]

some day, ill buy a pignose amp...

or build...

[ulysses]

mike fullers mojo always cracks me up.

check out the link at the bottom of that gt500 page

http://www.fulltone.com/images/pcb%20pot%20shpeal1.jpg

check this out -> he reacons becasue his pots are surface mounted that it makes them better sounding

yeah dude, those damn jumper wires completly screw with my tone. now im going to have to surface mount everything.

EDIT: hang on a sec, those switchcraft jacks in the gt500 pics are not surface mount. they have the "brittle little jumper wires" on them.. surely this is going to suck his tone down to billy-o.

seriously
ulysses