Switch pop

[Jewellworks]

I'm having a brain frt...
Ive been working on this Gibson Amp and I'm wanting to use the 3 way rotary off/on/on (polarity reversal) switch like this:
Off/Mute/On
Mute being; I take the grid feeding the PI to ground, and that way, everything is still ON, just quiet. and when you "UnMute", it doesn't slam the plates w high voltage like taking it out of Standby does.
But i know there will be a pop when I go in and out of Mute, but I'm forgetting how to eliminate that. ...a Cap strapped across something? 2.2uf ish... something??

I should mention the switch is a DP3T. The 2 sets were wired Off / polarity +/ polarity - (with the old 2 prong reversal of the wall voltage, and it took both sets to do it). Ive rewired so the first set of lugs is switching 120v on / still on. The 2nd set is unused and I could easily Mute the amp in the 1st position as a quasi-standby. Just no Pop

Remind me?

 

[tubedude]

The normal fix is shunting it with a high value resistor. Or don't hot switch it, Switch out the cathodes.

 

[Jewellworks]

Something like this?

It's sloppy, but....

 

[Telecastoff1]

I just had a similar ordeal with the vibrato switch button for my Twin Reverb. Very easy fix for my issue was to solder a 4.7k ohm resistor between the vibrato switch terminal and the shielded wire going to it. Worked like a charm. No more popping noise when I hit the Vibrato button.

 

[Jewellworks]

I still don't know if my drawing is correct

 

[Mongo Park]

Bump

 

[printer2]

Why not short the two signals leaving the PI together? You are not shorting to ground, the bias voltage on the output tubes remain the same, should be popless.

 

[Jewellworks]

Why not short the two signals leaving the PI together? You are not shorting to ground, the bias voltage on the output tubes remain the same, should be popless.

my concern was adding noise, as well as the pop. i didnt want to add any shielded wire (long run between the plates to the switch) cz this amp doesnt have any otherwise and it would be obvious, -but both the grid and the PI plates (or, in my case, an interstitial transformer) carry a signal. at least when i take the grid to ground, it doesnt carry one anymore. i suppose the same would be true if i wired between the plates...
im really not sure if it makes a difference, but i ended up just taking the grid to ground. only 1 long run. im not hearing much of a pop, so im not to worried about it anymore.
BUT, id still like to know how to wire it up for pops. i still dont understand the concept or how it works. ive seen caps to absorb the pop, ive seen resistors to draw away excess current, but i dont understand where any of it goes.

 

[dan40]

BUT, id still like to know how to wire it up for pops.

If you were wiring a switch for a bypass capacitor or a voicing cap, you would simply attach a high value resistor across the two lugs of the switch. This allows a tiny trickle of current to reach the capacitor when the switch is off. This keeps the cap charged and prevents a switching pop when you throw the switch to engage the capacitor. For what you are trying to accomplish, I'm not sure where the best spot would be to place a resistor so I'll let one of the smarter fellas answer that.

Are you using a single switch for the 120vac wall voltage and the mute function? I only ask because attaching the "mute" wiring to the same switch as the 120vac may create noise being so close to the AC voltage.

 

[Jewellworks]

If you were wiring a switch for a bypass capacitor or a voicing cap, you would simply attach a high value resistor across the two lugs of the switch. This allows a tiny trickle of current to reach the capacitor when the switch is off. This keeps the cap charged and prevents a switching pop when you throw the switch to engage the capacitor. For what you are trying to accomplish, I'm not sure where the best spot would be to place a resistor so I'll let one of the smarter fellas answer that.

Are you using a single switch for the 120vac wall voltage and the mute function? I only ask because attaching the "mute" wiring to the same switch as the 120vac may create noise being so close to the AC voltage.

yes, the power switch is a double pole, 3 way switch. it was originally set up to reverse the polarity of the 120v wall voltage. since installing a 3 wire power cord, i just jumpered the 2 lugs on pole 1 together for the power, leaving the entire 2nd pole unused. so its Off, then in position 1, its On, but muted, (PI Grid to ground) and in position 2, its still On, but unmuted. a quasi-standby, without slamming any high voltages.
im not really hearing a pop, even though there should be a small amount of grid current, but im not worried about it anymore. now the only weird side effect is that when you go from Mute to Off, it unmutes in the Off position, but there is still voltage in the filter caps, so you hear it "dissolving" as the power dissipates. not a huge concern, but it raised my eyebrows for a sec when i first heard it.

 

[dan40]

If you are not noticing any extra noise or hum from the mute wire being in close contact proximity with the 120vac, then your plan should be solid. If any strange new noises do appear in the future, just remember that this may be a potential culprit.

 

[Jewellworks]

If you are not noticing any extra noise or hum from the mute wire being in close contact proximity with the 120vac, then your plan should be solid. If any strange new noises do appear in the future, just remember that this may be a potential culprit.

i didnt really notice until i put it all back together in the cabinet that i was hearing a constant bzzzzzzzzzzz... it was the mute switch, being right on the 120v power switch. i changed it to a shielded wire, just in case, but -not surprisingly- it didnt help at all. so... drat. my cool feature isnt very cool anymore. so i took it out. its pretty quiet without it, otherwise, it worked great.
i dont suppose there is an easy way to filter out that buzzz... is there? -not without seriously effecting the tone of the amp is my guess.

 

[dan40]

i didnt really notice until i put it all back together in the cabinet that i was hearing a constant bzzzzzzzzzzz... it was the mute switch, being right on the 120v power switch. i changed it to a shielded wire, just in case, but -not surprisingly- it didnt help at all. so... drat. my cool feature isnt very cool anymore. so i took it out. its pretty quiet without it, otherwise, it worked great.
i dont suppose there is an easy way to filter out that buzzz... is there? -not without seriously effecting the tone of the amp is my guess.

I'm not really sure that anything other than putting some distance between them will help. Maybe one of the other members will have a workable solution for the noise.

The Fender 5f1 also had a similar issue with the power switch being built into the volume control. Not sure how they were able to get away with it on so many amps but I have heard of some owners moving the switch to a different location because of noise issues.

 

[dan40]

Not sure if they make it but perhaps you could look for a switch with better internal shielding. If they do make such a thing, it would likely be quite a bit more expensive than a standard Carling.