# How to true bypass Electro-harmonix pedal?



## devnulljp (Mar 18, 2008)

I have this old Electro Harmonix pedal (an Octave Multiplexer RI: EH-5900; anyone know what year these were?) I'd like to mod for true bypass.
I was thinking about replacing the switch with a DPDT or a 3PDT--Anyone point me to instructions where the wires should go for true bypass?

The switch that's in there has 6 lugs but is only wired up along one side -- is that a DPDT or just a weird SPDT (or something else)?


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## NB-SK (Jul 28, 2007)

I was trying to find the schematic I normally use to draw it up for you, but I seem to have misplaced it. In any case, there is more than one correct way to wire a single 3pdt switch.

I've never done that particular mod since I build my pedals with 3pdt switches only, but, apparently, you'll need to cut the trace at one spot in the circuit in order to create a full bypass if you are moving from a 6 prong switch to a 9 prong one. Seems logical enough to me.

http://www.singlecoil.com/docs/russian_muff.pdf

That's not how I wire my switches, but, like I said, there is more than one way to do it.


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## Wheeman (Dec 4, 2007)

Where's Mark Hammer when you need him?

That switch looks like a DPDT and you might be able to get away with just using that one. You can use a DMM to check for continuity between the poles to make sure it is a DPDT. Put one probe on the middle lug and tap the ones in front and in behind. It looks like a Carling switch so it most likely is a DPDT.

And for wiring that switch, R.G. Keen has done a nice wiring diagram.


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## Guest (Jun 8, 2008)

I'm not going to even try to attempt to tell you how to do that without knowing: a) what pedal that is (holy grail?); and b) seeing the other side of that.

There's something up. That's a DPDT switch, but they're only using one side of it. So there's something happening on that board. Like NB-SK said: you're probably going to need to work on the board to make it happen. It looks like the switch is just toggling between a clean signal coming off the board and an effected signal coming off th board.

And yea: Mark will know.


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## Archer (Aug 29, 2006)

Going to quote David Grissom:


"I don't really care if a pedal is true bypass....as long as I like the way my amp sounds"

Interesting how people are going to all the trouble to get true bypass this and that when the 'classic' tones they are often going for were done with no true bypass pedals and cables that would be (by modern standards) crap.


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## devnulljp (Mar 18, 2008)

Archer said:


> Going to quote David Grissom:
> "I don't really care if a pedal is true bypass....as long as I like the way my amp sounds"


Me too. The reason I'd like to mod it is because I don't like the way it sounds (when it's off). When it's on it's pretty good though... 


Archer said:


> Interesting how people are going to all the trouble to get true bypass this and that when the 'classic' tones they are often going for were done with no true bypass pedals and cables that would be (by modern standards) crap.


I'm not going for classic tones. I don't like it loading down the signal.


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## devnulljp (Mar 18, 2008)

iaresee said:


> I'm not going to even try to attempt to tell you how to do that without knowing: a) what pedal that is (holy grail?)


It's an older Octave Multiplexer reissue


iaresee said:


> and b) seeing the other side of that.


I'll see if I can get a pic of the other side of the board.


iaresee said:


> There's something up. That's a DPDT switch, but they're only using one side of it. So there's something happening on that board. Like NB-SK said: you're probably going to need to work on the board to make it happen. It looks like the switch is just toggling between a clean signal coming off the board and an effected signal coming off th board.


That's what I thought - it _looks_ like a DPDT but they're only using one side of it. I was hoping it might be possible to jumper it and get it to bypass.
Thanks


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## Archer (Aug 29, 2006)

devnulljp said:


> Me too. The reason I'd like to mod it is because I don't like the way it sounds (when it's off). When it's on it's pretty good though...
> I'm not going for classic tones. I don't like it loading down the signal.


Radial makes a nice looper pedal....cheap too. If you dont come up with a solution via modding this pedal you can still get a true bypass with that pedal.


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## devnulljp (Mar 18, 2008)

Archer said:


> Radial makes a nice looper pedal....cheap too. If you dont come up with a solution via modding this pedal you can still get a true bypass with that pedal.


Good idea - I have a couple of TBloops. Will probably just go with that if this turns out to be too complicated.


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## Stratin2traynor (Sep 27, 2006)

I use one of the inexpensive Radial loop pedals with my Magic stomp. They work great.


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## Solid_Gold_Soundlabs (Sep 20, 2006)

Thats a pretty simple mod! the switch is a carling dpdt, so you do not need a new switch for a TB mod. If you want to add an led i would go with a blue 3pdt switch. While you're at it, i would replace the dc jack with a more modern 2.1mm dc jack.

Cheers!
Greg


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## devnulljp (Mar 18, 2008)

Solid_Gold_Soundlabs said:


> Thats a pretty simple mod! the switch is a carling dpdt, so you do not need a new switch for a TB mod. If you want to add an led i would go with a blue 3pdt switch. While you're at it, i would replace the dc jack with a more modern 2.1mm dc jack.
> 
> Cheers!
> Greg


Good news. Any pointers where the wires should go?


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## Ripper (Jul 1, 2006)

try this http://www.muzique.com/lab/truebypass.htm


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