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DIY Stompboxes => Building your own stompbox => Topic started by: yeeshkul on March 04, 2009, 02:11:49 AM

Title: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 02:11:49 AM
Hey guys, i was thinking if i have to add a pulldown resistor to a simple true bypass loop (in/out + send/return). Let's say i have a simple bypass effect in the loop (turned on all the time) - i can't see any difference between this and normal TB switching - a leaky cap can provide DC all the way to the main loop switch. Am i right?
Title: Re: true bypass loop - pulldown?
Post by: cpm on March 04, 2009, 06:42:02 AM
woouldnt be a problem it that pedal has a pulldown resistor
if it doesnt i think its better to mod the padal and not you TB loop
Title: Re: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 06:57:33 AM
I am talking about a simple bypass pedal, not true bypass pedal -> I am having a true bypass loop box with a simple bypass pedal connected to the loop.
Title: Re: true bypass loop - pulldown?
Post by: Andi on March 04, 2009, 10:37:00 AM
What do you mean by "simple bypass pedal"?
Title: Re: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 11:56:08 AM
Sorry, i mean SPDT switched pedal, with no pulldowns, let's say an original Fuzz Face circuit. I have this FF in a simple single true bypass loop box.
Is it a normal routine to add 2 pulldowns on the send/return socket?
Title: Re: true bypass loop - pulldown?
Post by: Andi on March 04, 2009, 02:27:52 PM
Better, I'd say, to ensure the effect itself is properly decoupled.
Title: Re: true bypass loop - pulldown?
Post by: petemoore on March 04, 2009, 02:30:47 PM
  The only thing that'd do is load the signal [parallel 1megs = 500k], with nothing [no caps] to pulldown.
Title: Re: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 02:37:07 PM
Pete i am not sure i explained well what i mean. I will post a picture.
Title: Re: true bypass loop - pulldown?
Post by: MikeH on March 04, 2009, 02:59:57 PM
Pedals with electronic switching like boss, ibanez, and the like, usually have floating (meaning without a pulldown) input caps- which isn't a problem because the input never gets disconnected.  But when it's the first thing in a tb loop, the input ends up hanging open and when you engage the tb loop, the input cap causes a pop.  I fix this by putting a 1m resistor across the send and return jack in tb loops.  Essentially the same as adding one inside the actual pedal but... 1) you don't have to mod a pedal you don't want to and possibly effect any re-sale value, and 2) it will fix the problem for any pedal you decide to put first in the loop, so you don't have to mod ANOTHER pedal if you decide to switch things up.  Which if you're anything like me, you do constantly.
Title: Re: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 03:14:57 PM
(http://www.hoho.cz/osobni/pulldowny.jpg)
Title: Re: true bypass loop - pulldown?
Post by: yeeshkul on March 04, 2009, 03:17:59 PM
yeah Mike, that's exactly what i mean, thanks a lot for confirmation! (I posted - a bit too late anyway :) -  a pic of the Fuzz Face shaped box, but let's say the pedal has no volume pot in the output ...)