Clicky noise from 3PDT

[moro]

I'm getting a lot of noise from my 3PDTs. This isn't the electronic pop from LEDs or hanging caps--it's the mechanical click coming through the amp. I don't even have to toggle the switch--just flicking it will cause the click. AFAICT, the click is being transmitted back acoustically through the instrument cable, where it's getting picked up by...the pickups.

Is there any way to minimize / prevent this? I was thinking maybe a rubber washer, but I don't know if that'll make the switch more prone to mechanical failures.

[foxfire]

i had a pedal that i made that popped and, i spent a good 2 hours trying to figure it out. ended up being the in/out wires to the switch wire picking up the mechanical click of the switch. i had them kind of pinched in there so i pulled them free and the click went away. you might want to check your wiring inside the box first?

[tranceracer]

Yea Moro,
I know exactly what you're referring to... which is why I changed from the *clanky* stomp switch to solid state controlled relay using modified tactile plunger.  Works quite well and all I really hear is a very soft *tic* when the relay is engaged.

I saw on SmallBear of a non click stomp switch but not sure if it was 3PDT.

Here's a demo of my single soft touch switch:


Demo of my double soft touch switch:


This is using the 4049 inverter chip.  The only catch to the dual is that in order to get two switches on one chip I had to give up one inverter each so the light is inverse to the relay.  When the light is on the relay is deactivated.   This is fine since my pedals are powered via 9V adapter.

The one down side is it does take up a little more room in the box than a single 3PDT.

-tR

[Mark Hammer]

I can't see a mechanical click being fed acoustically through a cable.

What I CAN see is a switch that has some electronic debouncing issues stemming from mechanical issues, that are manifested in both an electronic source of noise, and an audible acoustical click sound.

(We desparately need some inside pictures of a 3PDT switch here so that folks can see what's inside and what does what.).  The switch is bonehead simple, but there are many ways to both improve upon and detract from, the "sonic purity and dependability" of the resulting signal.

Consider that the stompswitch is merely a couple of see-saws/levers resting on a middle pivot point.  When you step hard enough, the plunger mechanism leans to the opposite side where it is currently, and favours pressing down on that side.  The click you hear is the internal lever/see-saw essentially "giving in" and moving to the other side, where it audibl clicks by one metal contact striking a stationary one.

The movement of the rocker contact (the "lever") is predicated on assumptions about the the height of the fixed contact (which is the other side of the solder lug that you normally don't see because it is on the other side of the housing).  If the soldering takes too long and the resulting heat softens the plastic chassis, I could see that the height or position of that fixed contact might be compromised, such that when the rocker contact moves is bounces against the fixed contact a couple of times in quick succession, rather than making one solid stable contact.

Maybe that's what's going on.

[ItZaLLgOOd]

TranceRacer,  Any chance of you sharing a layout or schematic for your set-up?  It looks very nice.

[gez]

I'm getting a lot of noise from my 3PDTs. This isn't the electronic pop from LEDs or hanging caps--it's the mechanical click coming through the amp. I don't even have to toggle the switch--just flicking it will cause the click. AFAICT, the click is being transmitted back acoustically through the instrument cable, where it's getting picked up by...the pickups.

I agree with Mark, I just don't see how this is possible.  Not from the switch at any rate.  What might be happening is that depressing the switch with your hoof (no offence, just illustrating that these switches take a bit of a battering) causes some vibration of a microphonic cap (or something similar)?  I've never known this, though, so just a guess.

Out of interest, how did you rule out the possibility of electrical popping?

[foxfire]

with my pedal the popping stopped when i removed the switch from the enclosure. that's how i figured it out. with the switch in my hand i could switch it all day without any popping. so i tried tapping the enclosure and it came through the amp. it wasn't till i fiddled with my wires that the noises went away. maybe it was just a coincidence...

[ubersam]

I came across a wah that exhibited that issue. There was no clicking noise when the switch out of the enclosure, but when I tapped the casing I could hear it through the amp. I suspected that the inductor had gone microphonic but I was unable to verify that because the owner did not want to replace the inductor.

[moro]

I'm assuming it's not an electrical pop because like I said, the switch doesn't have to be toggled for me to hear the click. I can just tap it with my hand without depressing it all the way.

[Mark Hammer]

Well then clearly the rocker contacts are not held in place firmly. I suspect what you hear is the rocker contact bouncing up and down in place.

I have made mention before of a dab of grease that is used internally to seat the rocker contacts.  One part of the function of that grease is to assure the rocker contacts don't fall out during assembly.  In other words, the grease acts like a sort of light adhesive to keep the rocker contact seated temporarily.  The other role it has is to damp any vibrational forces that might make the rocker contact vibrate on the spot.

One of the things that I believe happens during use of such switches, is that people apply too much heat during soldering and the heat is conducted via the rocker contact touching the "hidden side" of the solder lug.  That heat causes the grease to soften, liquify, and flow down the rocker contact.

This has two implications.  One is that the reflowed grease forms a barrier to effective contact, and is responsible for the unacceptably high number of switch failures reported by folks.  Another, based on your description, is that the rocker contacts lose their ability to stay seated properly, and may jiggle about inside, creating momentary discontinuities when jostled or struck, resulting in audible clicking and popping.

Can this be remedied or prevented?  I think so.  One trick I have suggested is to always make sure you are soldering the lugs that are NOT in contact with the rocker contacts, so as to leave the grease "thermally insulated" from the heat being applied to the solder lugs.  So, use your meter to see which side the common is NOT currently in contact with, and solder those lugs.  Let the switch cool a bit, step on it to flip to the other set of outside lugs, and now solder them.  Once that has cooled, then you can solder the leads to the common from each set of contacts, using whatever method expedites the making of the solder joint.  For instance, a dab of liquid solder flux, and use of pre-tinned leads is a good idea. You want to be able to get in and out of there fast so that the dab of grease remains thick and viscous...as the creator intended.

Given the volumes that switch manufacturers hope to sell to pedal manufacturers, a failure rate even a tiny fraction of what we experience as builders would spell disaster for those hoping to market their switches.  Clearly, what we experience HAS to be different than what pedal manufacturers experience, and I believe it stems from our one-off practices, which stand in contrast to the mechanized highly efficient and systematic practices of manufacturers.  We have this collective naive view that since a switch is "passive", rather than something like a tranny or IC, that we can do whatever the heck we want with it short of melting it, and everything will still work just fine.  We need to disabuse ourselves of that notion.

[moro]

Well then clearly the rocker contacts are not held in place firmly. I suspect what you hear is the rocker contact bouncing up and down in place.

If this is true, it's pretty depressing because it happens on a good number of my pedals. I'm not great at soldering but I don't think I'm that bad either.

It's kind of hard to describe, but it sounds like the sound is mostly from the switch snapping back into place when I let go. I'll play around with it some more when I get home tonight. I'll also try tapping on the enclosure with my hand.

[Mark Hammer]

Well there IS hope.  I have disassembled many stompswitches, cleaned them up inside, and improved the contact quality, then reassembled them.  If you had some similar damping grease you could probably fix the problem.  Just make sure you are gentle with the tabs when taking the switch apart...and don't lose any parts.

[ayayay!]

Well, not to argue anyone's points, because they're all quite feasible, but couldn't this just be a case of inherent capacitance introduced by the enclosure?  Nearly everything in your signal is suspect in buidling a little capacitance.  R. G. has mentioned the inherent capacitance of breadboards.  Long cable runs (especially cheap cables) definitely can save a small charge.  

[ambulancevoice]

maybe your heating the switch lugs for to long and its causing them to melt and move out of place, leaving the switch slightly faulty, it would explain why its in other pedals aswell

[tranceracer]

TranceRacer,  Any chance of you sharing a layout or schematic for your set-up?  It looks very nice.

The schematic is on geofex.com: "6/14/00 Electronic Switching with the CD4053; an improved Audio Probe"  Scroll down to the 4049 control section at the bottom of the page.

I had to fabricate the tactile stomp switch but any SPST momentary normally open (NO) switch will do.

-tR

[gez]

maybe your heating the switch lugs for to long and its causing them to melt and move out of place, leaving the switch slightly faulty, it would explain why its in other pedals aswell

In a less roundabout way (sorry Mark!  ), that's what Mark just said. 

If this is the case, then the excessive heating when soldering could well be resulting in dodgy output caps too, hence the pop (in conjunction with knackered switches). 

[darron]

i find that i can often get a similar effect by twanging one of the switchcraft jack inputs. if you twang the metal that goes to the tip you can often hear it coming through the amp at the same frequency and decay. it's when i start noticing things like that that i realise what a delicate signal a guitar can produce, and how much care we bother to take with it compared to say a loud keyboard.

[moro]

i had a pedal that i made that popped and, i spent a good 2 hours trying to figure it out. ended up being the in/out wires to the switch wire picking up the mechanical click of the switch. i had them kind of pinched in there so i pulled them free and the click went away. you might want to check your wiring inside the box first?

I did check the wires last night and none were pinched anywhere. (I tend to leave a fair amount of slack with my wiring.) One thing that I didn't have time to do is to take the switch out of the enclosure and see if that makes a difference.

[moro]

The schematic is on geofex.com: "6/14/00 Electronic Switching with the CD4053; an improved Audio Probe"  Scroll down to the 4049 control section at the bottom of the page.

I had to fabricate the tactile stomp switch but any SPST momentary normally open (NO) switch will do.

This is pretty cool. I may try this in my next build. Thanks!

[moro]

i find that i can often get a similar effect by twanging one of the switchcraft jack inputs. if you twang the metal that goes to the tip you can often hear it coming through the amp at the same frequency and decay. it's when i start noticing things like that that i realise what a delicate signal a guitar can produce, and how much care we bother to take with it compared to say a loud keyboard.

I noticed this last night but *only if my guitar is unplugged.* If it's just FX -> amp, I can tap the jacks / plugs with screwdriver and get a very loud clanking sound through the amp. Once I plug the guitar in, though, there's no clank.