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A/B switch pop

F

flaquito

Guest
Jan 22, 2012
65
2
Central Indiana
#1
I know this isn't really an effect pedal, and I'm not really an effects guy (I'm sorry, don't hate me!), but I figured this would be the right place to post this. I just picked up an A/B/Y switch for the purposes of quickly switching between two basses, through the same amp. I intentionally got a mechanical switch, although it does use a 9v for indicator LEDs, because I don't want to lose my sound if a battery goes out in my switch. When I switch between the two inputs, more often than not I get a ridiculously loud pop. Occasionally it's silent, but not usually. In my searching, I saw various suggestions about pull-down resistors, capacitors, etc., but most discussion about those related to losses in long effects paths. This will be the only pedal between my basses and my amp. Both basses are active electronics, and I don't plan on using the Y switch much, if that matters. So, any suggestions? Can I modify the pedal and make it quieter (I'm quite comfortable with electronics work)? Should I send it back and get a different pedal? Should I turn around and run away with my tail between my legs for daring to post in the effects subforum when I don't actually use effects? :hiding:

Oh, the pedal is this one.
 
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#3
Wow. That does look nice, but a bit steep. Is there anything out there that's similar, but doesn't have stereo, midi control, volume adjustment, and the other features that I won't use?

Thanks for the info, though. It at least gives me a few more keywords to use to search.
 
#4
I have a Korg Pitchblack Plus strobe tuner that has a built in AB switch that is silent. No Y but allows two inputs into tuner. BADASS!!! If you need a new tuner you can kill 2 birds with one stone.
 
#5
Warfender said:
I have a Korg Pitchblack Plus strobe tuner that has a built in AB switch that is silent. No Y but allows two inputs into tuner. BADASS!!! If you need a new tuner you can kill 2 birds with one stone.
Click to expand...

Thanks, I'll keep that in mind, too. I don't really need the Y, anyway.

I guess I'm not too clear on what the point of a buffered switch would be for my scenario. From what I've been able to figure out, the main point of a buffer is to be able to drive long effects chains, long cable runs, etc. without too much signal loss. Does buffering the input or output of the switch eliminate pops? Or is it just that buffered switches have other circuitry or high quality components that eliminate pops? Are pops generally caused by switch bouncing? Grounding issue? Or could it be something putting DC on the line? If that's the case, would a DC filtering capacitor on the output help?

I know there are expensive pedals out there that would solve this problem, but for my use, it's not worth putting that much money into it. I'm looking for a "good-enough" solution, not a perfect solution.

Any additional suggestions are welcome. Thanks!
 
#6
A 1-megohm resistor across each of the A/B box's inputs *should* put an end to the 'pop'...I had to do this years ago with my passive A/B box, I had to play both guitar and organ. Since both your basses are active, there's no issue with potential tone suck.

Any 1-megohm resistor will work: 1/4 watt, 1/8 watt, carbon comp, whatever...Just solder the legs right to the jack terminals between the 'hot' and 'ground' terminals.
 
#7
Crater said:
A 1-megohm resistor across each of the A/B box's inputs *should* put an end to the 'pop'...I had to do this years ago with my passive A/B box, I had to play both guitar and organ. Since both your basses are active, there's no issue with potential tone suck.

Any 1-megohm resistor will work: 1/4 watt, 1/8 watt, carbon comp, whatever...Just solder the legs right to the jack terminals between the 'hot' and 'ground' terminals.
Click to expand...

Thanks!! I was thinking of trying this, but wasn't sure of the ramifications, and whether to go for inputs, output, or both. I've got plenty of 1/4W resistors lying around, so I'll give it a try.
 
#8
After some additional experimenting, I discovered that my switch does not, in fact, pop. It's actually rather quiet. As long as a certain one of my basses is not plugged into it. I was using this to switch between my electric and my new electric upright, but it turns out that my EUB has DC voltage on the output! I've measured it at anywhere from -1.8v to .25v tip-to-shield. When that bass is unplugged, the switch pop goes away.

So, since it isn't an effects pedal issue, I'll take the obvious follow-up question elsewhere (here). Thanks for your advice!
 
#11
flaquito said:
Thanks, I'll keep that in mind, too. I don't really need the Y, anyway.

I guess I'm not too clear on what the point of a buffered switch would be for my scenario. From what I've been able to figure out, the main point of a buffer is to be able to drive long effects chains, long cable runs, etc. without too much signal loss. Does buffering the input or output of the switch eliminate pops? Or is it just that buffered switches have other circuitry or high quality components that eliminate pops? Are pops generally caused by switch bouncing? Grounding issue? Or could it be something putting DC on the line? If that's the case, would a DC filtering capacitor on the output help?

I know there are expensive pedals out there that would solve this problem, but for my use, it's not worth putting that much money into it. I'm looking for a "good-enough" solution, not a perfect solution.

Any additional suggestions are welcome. Thanks!
Click to expand...

The buffered suggestion was probably a result of the known issues of 3pdt mechanical switches (pretty much the standard in the booteek pedal business; also assuming that your A/B/Y is using mechanical switches which appears to be the case on the surface) popping due to charge buildup and sudden release when you stomp on the switch (sorry I don't know the jargon yet). It would appear that that isn't your issue though.

Typically small builders use the 3pdt switches cause they are easier, cheaper and shorten build times. The non engineer solution to that pop is to turn on and off each switch several times after you power your pedalboard up BUT before you turn your amp on. That way you can discharge that buildup.

Lot's of pedals are buffered,...most mass produced pedals (BOSS, DOD, MXR, Maybe EHX) are buffered bypass and don't suffer from the charge buildup issue. If it's a poorly engineered buffer it can tone suck. Some bigger companies are offering TBP pedals now,...but it's really just a lot of marketing hype and bandwagon jumping IMO.
 

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