King of tone v2 volume issue

[DaSt]

Hi

Im building the v2 from that page :

http://tagboardeffects.blogspot.fr/2012/10/analogman-king-of-tone.html?m=1

My main problem is that both volumes act on each other which kinda nullifies the effect. I tried many things to debug it without success like unplugging volume B form the second footswitch. In that case when on channel B  no sound at all as expected but when on channel A the volume B still effects the volume..

Also my switch 1 diodes do not at all effect the signal while switch 2 diodes do as expected (using red leds on switch 1)

Any thoughts ?

Thx

[induction]

Sounds like a wiring problem. We need pictures to go any deeper.

[DaSt]

Hi,

I cant take any clear picture of this build as they are too many wires everywhere >.<

Anyway by looking at the vero i believe that behavoir could be expected right ? I mean there are several wire in common with both volume pots. Turning one must change the voltage going though the other i guess ? But i could be dead wrong ^^'

I think i can live with that volume issue. I may tho have two more pressing ones on that build :

- Very loud pop when engaging and disengaging. There already is pulldown so im reviewing the offboard wiring and so on. No luck this far.
- The BA282 I used on switch 1 simply do not modify audibly the signal. I tried some other diodes, which do add distortion but not those. Anyone experienced this on this build ?

THanks

[DaSt]

About the popping i measured 0v on both input and output bypassed and around 2v on output when engaged... no wonder it pops.

There alfeady are pulldowns on the circuit but i still added one between onboard output and not switched ground with no success. With 10m and 470k no change just slightly more and less voltage on output lug respectively. With 56k the volum a pot becomes noisy (sho style) and the volume switch stomp also begins to pop.

For the record the pop never goes away

Any thought ?

[induction]

DaSt wrote

Anyway by looking at the vero i believe that behavoir could be expected right ? I mean there are several wire in common with both volume pots. Turning one must change the voltage going though the other i guess ? But i could be dead wrong ^^'

I think i can live with that volume issue.

You're right. The volume pots are not completely independent. Their wipers are permanently connected via caps, which means that the output signal from the selected pot will see the other volume pot as a path to AC ground. It's wired very similarly to a Les Paul with the pickup selector in the middle, and the interaction between the pots will behave very similarly. When either volume pot is turned all the way down, the other one will go silent as well. Even when neither of them is turned all the way down, they will still influence each other.

If you can live with it, then fine. But if you want the volume pots to be independent, you can do that if you like. An easy way would be to replace Fsw-2 with a 4PDT and switch lug 2 of the pots as well as lug 3. It's also possible to do it with the existing 3PDT by being clever with the wiring. If you're interested let me know and I'll explain how.

- The BA282 I used on switch 1 simply do not modify audibly the signal. I tried some other diodes, which do add distortion but not those. Anyone experienced this on this build ?

Measure the forward voltage of the BA282 and compare it to the forward voltage for the diodes that give distortion. If Vf for the BA282 is much higher than the others, that could explain it. Otherwise, it's possible that one or more of them is damaged, or there is a wiring problem.

[induction]

DaSt wrote

About the popping i measured 0v on both input and output bypassed and around 2v on output when engaged... no wonder it pops.

There alfeady are pulldowns on the circuit but i still added one between onboard output and not switched ground with no success. With 10m and 470k no change just slightly more and less voltage on output lug respectively. With 56k the volum a pot becomes noisy (sho style) and the volume switch stomp also begins to pop.

For the record the pop never goes away

Any thought ?

This definitely indicates a build problem, and pulldowns won't work here. As you say, the output already has a pulldown. Beyond that, the point of pulldown resistors is to remove DC in bypass. You have 0V at the output in bypass, so that's not the problem. The real problem is the 2V on the output when engaged. That should not be happening and can't be cured with a pulldown. The most likely explanation is either shorted output caps or a build mistake. Does it pop in both positions of Fsw2?

[DaSt]

Hi

Yes i thought about the 4pdt but ill be glad to make it work with the current stomp if possible, please :)

Ill meawure the diodes tonite thx

[DaSt]

EDIT : The pop is gone!

Many thanks induction. I had to change both tantalum 1u cap i had on output as I had two 1u ceramic caps laying around. Those work just perfectly.

I leave it unboxed for now, waiting for your magic trick to smartly wire the volume pots ;)

[induction]

DaSt wrote

EDIT : The pop is gone!

Many thanks induction. I had to change both tantalum 1u cap i had on output as I had two 1u ceramic caps laying around. Those work just perfectly.

I leave it unboxed for now, waiting for your magic trick to smartly wire the volume pots ;)

Glad you fixed the pop.

The original idea I had for the volume pots didn't work out. Once I drew it up, I realized it would have the same interaction as what you have now. Sorry.

But it is still possible to have non-interacting volume pots with just a 3PDT. The layout you used has both volume pots connected to the output at all times and the inputs (lug 3) to the volume pots are switched. To make them non-interactive, you can do the opposite: tie lug 3 of each volume pot together, and switch the output (lug 2) instead. This will mean that both volume pots are loading the circuit all the time, so it might be a good idea to double the value of those pots (try it and see if it matters).

Here's how to do it:
1. The wire marked FSw2-2 should lead to both volume pots lug 3 (and not to FSw2-2). Lug 2 of each pot should separately go to FSw2-1 and FSw2-3, respectively. FSw2-2 should now lead to the bottom row on the right (where Vol-B 2 is shown on the layout). The wire for Vol-A 2 can be removed and so can the 1u cap that goes from Vol-A 2 to output.

If you can find 250k pots to replace the current volume pots, this should sound the same as you have now, except the volume pots will not be interactive. With 100k pots, you might lose some treble, but you might not. You'd have to try it to be sure.

I also can't guarantee that this switch won't pop, you'll have to test it to be sure.

It's simpler to just use a 4PDT and completely bypass the unused volume pot (that's probably what I'd do), but if 4PDT's are hard to find for you, this way might work.

[DaSt]

Hi,

I think it's wiser to go with a 4PDT indeed. I'll order one and get done with that stompbox in a jiff :)

Thanks again for your help. I have another topic about a Forest Green Compressor if you feel like helping a little more ^^'

2015-12-10 11:08 GMT+01:00 induction [via Guitar FX Layouts] <[hidden email]>:

DaSt wrote

EDIT : The pop is gone!

Many thanks induction. I had to change both tantalum 1u cap i had on output as I had two 1u ceramic caps laying around. Those work just perfectly.

I leave it unboxed for now, waiting for your magic trick to smartly wire the volume pots ;)

Glad you fixed the pop.

The original idea I had for the volume pots didn't work out. Once I drew it up, I realized it would have the same interaction as what you have now. Sorry.

But it is still possible to have non-interacting volume pots with just a 3PDT. The layout you used has both volume pots connected to the output at all times and the inputs (lug 3) to the volume pots are switched. To make them non-interactive, you can do the opposite: tie lug 3 of each volume pot together, and switch the output (lug 2) instead. This will mean that both volume pots are loading the circuit all the time, so it might be a good idea to double the value of those pots (try it and see if it matters).

Here's how to do it:
1. The wire marked FSw2-2 should lead to both volume pots lug 3 (and not to FSw2-2). Lug 2 of each pot should separately go to FSw2-1 and FSw2-3, respectively. FSw2-2 should now lead to the bottom row on the right (where Vol-B 2 is shown on the layout). The wire for Vol-A 2 can be removed and so can the 1u cap that goes from Vol-A 2 to output.

If you can find 250k pots to replace the current volume pots, this should sound the same as you have now, except the volume pots will not be interactive. With 100k pots, you might lose some treble, but you might not. You'd have to try it to be sure.

I also can't guarantee that this switch won't pop, you'll have to test it to be sure.

It's simpler to just use a 4PDT and completely bypass the unused volume pot (that's probably what I'd do), but if 4PDT's are hard to find for you, this way might work.

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