True bypassed Maxon AD-900

[Luca1979]

I recently had my AD-900 modded for true bypass, bu now there is a loud "pop" when I switch the pedal on for the first time.
Is there anything I can do to fix it? (other than stomping on the pedal before I start playing).

Thanks

 

[NewarkWilder]

thats pretty common for TB pedals

just stomp on it a few times while you're muted

just out of curiosity, what made you feel the mod was necessary? I actually like the buffer in mine a lot.

 

[Luca1979]

It's because I'm a stupid perfectionist, and I tought that making it true bypass would have restored highs and presence to the sound.
And while that's true, maybe it was better to leave the pedal stock, because the pop noise is disappointing.

 

[NewarkWilder]

hmmm. you've just got me thinking about mine now. i just shot off an email to mike--gonna get the exp pedal mod done for sure, thinking about the TB but if the pop is really that bad i'll probably hold off. You do feel it made a noticeable difference in sound quality though?

also the popping will probably get better as time goes on with it

 

[jamison162]

You need the limiting resistor to bleed off all the stray voltage the caps are building up.

 

[Luca1979]

You need the limiting resistor to bleed off all the stray voltage the caps are building up.

In other words, what does that mean? In concrete, what should I do?

 

[StompBoxBlues]

In other words, what does that mean? In concrete, what should I do?

Look at the recent "Strobostomp" thread here....in there is posted a diagram of how to get rid of the pop with a resistor to ground, but it needs to be on the circuit side (meaning attached to the input of to the delay, NOT in play when bypassed)...

This is the post...read a little before and after (or go to the site it points to...I think Stinkfoots site has this info).

https://www.thegearpage.net/board/index.php?posts/5721950&postcount=110

 

[jamison162]

In other words, what does that mean? In concrete, what should I do?

Take it back to your tech and tell him it makes a popping sound.

 

[Luca1979]

Thanks for the link.
In the diagram, is bridging the two pins of the switch as shown that gets rid of the pop?

Look at the recent "Strobostomp" thread here....in there is posted a diagram of how to get rid of the pop with a resistor to ground, but it needs to be on the circuit side (meaning attached to the input of to the delay, NOT in play when bypassed)...

This is the post...read a little before and after (or go to the site it points to...I think Stinkfoots site has this info).

https://www.thegearpage.net/board/index.php?posts/5721950&postcount=110

 

[StompBoxBlues]

Thanks for the link.
In the diagram, is bridging the two pins of the switch as shown that gets rid of the pop?

Oops...yeah sorry, that is what they said in the following post. But if you look in that thread also SD-1 in particular mentions a pull down to ground.

Since your pedal pops, and is already converted to TB, (look at both drawings and you see, I think this is showing the bad and good way, but I am not 100% on the switch pinouts so don't go by that) I imagine it looks more like the first drawing.

I think you are better off forgetting about the drawing I mentioned, and checking out Stinkfoot (and other) Google for the info, because it isn't hard but basically a large valure resistor to ground on the active side is what you want.

Quoting:

http://www.harmony-central.com/Guitar/Faqs/faq/faq.bypass.txt

Just thought I should add: Some fx circuits may pop when the wiring is
changed to true bypass. That's usually due to an input capacitor which
has no ground reference (now that the input is switched). If that
happens, add a high value (say, 2 megohm) resistor from the input
terminal *of the fx circuit board* to ground. That will keep the cap
at ground potential when the switch is in bypass position.

Or with a photo:
http://www.diystompboxes.com/tbbox/tbbox.jpg



Was this any help?

I think the point was there is something called a "couping capacitor" which is directly attached to the input signal from the guiar, and you want to have one side or the other connected via a 1M or larger resistor to ground (most likely the OTHER side, or far side of the cap).

 

[Angle Loss]

It's because I'm a stupid perfectionist, and I tought that making it true bypass would have restored highs and presence to the sound.
And while that's true, maybe it was better to leave the pedal stock, because the pop noise is disappointing.

Having a buffer helps to preserve highs not take them away. True bypass will suck down more highs than having a buffer. Don't confuse buffered pedals with old MXR/EH style pedals with are neither true bypass nor buffered.

btw, the AD-900 is a great sounding delay. I used one for a long time and it only got bumped off by Echoczar.