[sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..

Tue Jun 18 16:21:49 CEST 2024

I had a similar issue with a hex fuzz, my problem was the transformer has a lot of leakage inductance (magnetic field escaping the core, which used the metal case as a shorted secondary turn and raised hell. 

I tried to shield the transformer with mu-metal, which solved the problem, but got hot as hell. The shorted secondary was now really tightly coupled. 

Best way, move the transformers outside of the case, or put them in a separate steel box inside the case. Alternately you might want to use switching power supplies as someone else suggested. 

You could use a toroidal AC transformer which tend to not leak external fields if you still want linear supplies. They have be expensive and hard to source. 

I'm a big fan of keeping 60Hz (or 50Hz) AC transformers outside of effects.   

Harry Bissell 

-----Original Message-----

From: René <synth at schmitzbits.de>
To: synth-diy <synth-diy at synth-diy.org>
Date: Tuesday, 18 June 2024 9:39 AM EDT
Subject: Re: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..

Actually pot cores have been used by Dunlop in their pre 1990s crybaby. 

https://www.electrosmash.com/crybaby-gcb-95 

Best, 

 René 

  Am 18.06.2024 um 01:36 schrieb BrightBoy via Synth-diy: 
  I know there have been some companies that have offered mu-metal shielding kits for wahs BUT I have no idea if any of them still do these days.   Let Google be your guide.   Cheers,   Jeff     

-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
Sent: Jun 14, 2024 6:26 PM
Cc: <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..   This may be heresy, but replacing the original inductor by a toroidal wound one would prevent picking up external fields. 
There are also ferrite pot cores (that's pot as in shaped like a pot) if you feel experimental. 

paul perry Melbourne Australia  
  On Sat, Jun 15, 2024 at 5:18 AM Tom Wiltshire <tom at electricdruid.net> wrote:  
Yes, exactly! 

Tom 

On 14 Jun 2024, at 19:29, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote: 

  This schematic is a later generation… with input buffering :   <image001.png>    
  De : Tom Wiltshire <tom at electricdruid.net> 
Envoyé : 14 juin 2024 13:52
À : Jean-Pierre Desrochers <jpdesroc at oricom.ca>
Cc : synth-diy at synth-diy.org
Objet : Re: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..     Ok, so it's clear that yours is one of the original old-school Crybabies. Nice. 

 It may not sort out your current issue, but you should really try putting a buffer between the guitar and the wah. At the moment, that input transistor with its low impedance is hanging off your input signal and killing the treble, even when the wah is switched out of circuit (the switch only switches the output). That will affect the whole rest of the pedal chain.  

 On 14 Jun 2024, at 15:54, Jean-Pierre Desrochers via Synth-diy <synth-diy at synth-diy.org> wrote:    

 To answer some questions :  

 ….. With so many power sources, you may be hearing a ground loop.  Never assume that the common return of multiple power sources are all the same potential.  
 There are no ground loops in my pedal board. Unselecting the Wha makes the 60hz hum completely go away.  
 And placing the inductor in a specific way in the Wha metal box almost kill completely the hum.. so no ground loop for sure.  

 ….. I'd start by looking at some of the *other* pedals to see how many could be converted to standard 9V centre-negative, and then reduce the number of transformers to reduce the noise.  
 > 4 of these pedals are powered with there separate AC supplies (9VAC, 9VAC, 7.5VAC & 22VAC).
> The other pedals are powered using 9VDC standard BOSS supplies  

 The 4 x AC powered pedals :  
 2 x LINE6 modelers that could be run using 6VDC supplies (they can run on 4 x 1.5vdc C cells) eliminating two transformers..  
 1 x Blackstar DS2 powered by 16VAC (no possible DC powering):  
 <image001.png>  
 1 x Electro Harmonix Hum Debugger pedal powered by 7.5VAC (no schematic available)  

 The following pictures shows the real actual schematic of my Wha.  
 It’s an Italian Jen Cry Baby with a FASEL branded inductor.  
 The bottom picture shows what I’ve done to ‘place’ the inductor at the ‘sweet spot’ to get the less hum possible. Not bad..
But a shielded inductor could be fine (but expensives..)   

 And again, this is not a ground loop problem..  

 <image004.jpg>  

On Jun 13, 2024, at 4:46 PM, Jean-Pierre Desrochers wrote:
> I have a guitar pedal board that uses 8 pedals.
> The first pedal (receiving the guitar) is a Jim Dunlop Cry Baby Wah-Wah.
> The following pedal is a switchable  overdrive with high gain.
> Then the pedal chain goes on with 6 other pedals to a final tuner that drives a guitar amplifier. Ok.
> 4 of these pedals are powered with there separate AC supplies (9VAC, 9VAC, 7.5VAC & 22VAC).
> The other pedals are powered using 9VDC standard BOSS supplies.
> Here is my problem :
> Since the Wah-Wah is connected at the ‘head’ of the pedal chain and uses an internal 500mH inductor in its circuit
> it acts like the secondary of a transformer picking up 60Hz
> from all the nearby transformers of the board.
> I had to unsolder the inductor from the inside PCB and,
> using short lenghts of wires connected to it … place it in the Wah-Wah housing
> at a ‘specific’ place and angle to get the less 60Hz pickup.
> This is annoying.. 
> Now I can play with a little back ground hum when the Wah-Wah is activated..
> I  was wondering if I could use an active inductor simulator circuit
> In place of the 500mH passive inductor.. (??)
> Feasable ??

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