Combined blower (vol/tone bypass) and kill switch

[blake375]

Hi folks

My very first post and it's a cry for help! Probably quite a simple one though.

I'm building a single-pickup (p90) guitar with one tone control and one volume control. To squeeze an extra bit of versatility out of it, I wanted to add a three-way toggle that would give me:
1) Normal (the one pickup with volume and tone working as you'd expect)
2) Volume and tone bypassed, pickup goes straight to jack (commonly called 'blower' mod)
3) No signal to jack (commonly called kill switch)

I'm not particularly interested in staccato kill switch effects, the main purpose of having the kill position is so I can mute the guitar's output without having to roll the volume all the way off. That way I can keep the volume and tone settings where I want them for a particular sound and easily switch between that, or the full-on direct sound of the pickup, or no sound at all.

For obvious reasons I don't want the kill function to be in the center position, but other than that the order is not important.

The internet is full of separate 'kill switch' and 'blower switch' diagrams, what I can't find (and I've really tried!) is something that does both, and I'm not technically able enough to work it out for myself. Can anyone help? 

[newey]

blake375-

Hello and Welcome to G-Nutz2!

You will need a DPDT On-On-On switch. Here's one way to do this. Note that the two red lines between the lower left and upper right switch lugs are not wires, these are just meant to show how the switch is connected internally. You should, however, check the switch that you buy to be sure it operates in this fashion in the center position.

Also note that the pickup is not shorted to itself when in the "kill" position. This could be a bit noisier than if it were shorted to itself when "off". But you'd need a 4-pole switch to do that (well, you'd only need a third pole, but 3-pole toggle switches with an On-On-On configuration either do not exist or are rarer than hen's teeth).

Also note that I haven't shown the complete wiring, but the V and T pots and jack will be wired just as with any guitar with a single V and T set-up. Diagrams for this abound. I have also omitted the string/bridge ground.




As drawn, when the toggle switch is pointed towards the top of the diagram (meaning the lower lugs on both poles are connected to the center lugs, as the toggle operates opposite of the internal connections), the P90's hot connection connects to the V and T pots. When the switch is centered, you get your "blower" position. With the switch "down" (upper lugs connected to center lugs), the pickup is off

[sumgai]

Jul 29, 2022 13:44:39 GMT -5 newey said:

... but the V and T pots and jack will be wired just as with any guitar with a single V and T set-up.

I think you want to show everything here. When you do, you'll see that the V&T pots are still going to affect the output signal when in the alleged 'blower' position. That'll be true because your implication of "normal wiring" means that the wiper of the Vol pot will also be going to the output jack, without surcease.

But don't worry, it can be done, as least I think so.... Start by bringing the Vol wiper back to the lower left terminal of the DPDT switch.  Then realize that the Vol pot will have to be 'wired backwards', or else it will still affect the output level when in blower mode.  That means that my previous sentence is now null and void - you need to bring back the newly-designated outgoing terminal of the pot, not the wiper.  Said wiper is now the pot's incoming signal point. This should work out OK, but we do have to accept that the Tone and Vol pots will interact differently than the usual expectation.  It's not ideal, but it gets the job done with the components at hand.

Jul 29, 2022 13:44:39 GMT -5 newey said:

... note that the pickup is not shorted to itself when in the "kill" position. This could be a bit noisier than if it were shorted to itself when "off".

In order to reduce or kill as much extraneous noise as possible, we don't short the pickup, we short the output. That's easy - simply ground the upper-left terminal, et Voila!

EDIT:  I realized, afterwards, that I've forgotten an important point - we do short a pickup in a multi-pickup setup, and that is meant to squelch any noise that might get through due to the antenna effects of the pup.  But here, we have only the one pickup, so it makes better sense to do the job properly (which we can't do in a two- or three-pickup axe) and short the output.  Sorry for any confusion I may have caused.
[/edit]

HTH




sumgai

[newey]

OK, here's a more complete diagram, V2.0, with the corrections/additions suggested by sumgai. Hopefully this is correct but let's do a double check first(since I screwed it up once already.)

Note that the string ground is still omitted.

[MattB]

Jul 29, 2022 17:09:15 GMT -5 newey said:

OK, here's a more complete diagram, V2.0, with the corrections/additions suggested by sumgai. Hopefully this is correct but let's do a double check first(since I screwed it up once already.)

Note that the string ground is still omitted.

In the middle position the tone pot is still connected via the volume pot.

I think a better solution is to use a 4PDT centre-on toggle. It's a more expensive part, but it gets the job done without compromises.

I think this should work:

[MattB]

The above diagram completely bypasses the volume and tone pots in the blower position. That means the pickup sounds brighter and slightly louder than it does with both pots at 10.

With a 4PDT centre-on it's also possible to wire it up so that in the blower position the pots are still loading the pickup but the wipers are disconnected- that means you get the "both pots at 10" sound instead of the "straight to jack" sound.

[Yogi B]

Jul 30, 2022 1:08:41 GMT -5 MattB said:

I think a better solution is to use a 4PDT centre-on toggle. It's a more expensive part, but it gets the job done without compromises.

Yeah, I don't see this being possible with anything less 'powerful' than either a (true) DP3T or a Mustang style slide switch. So a 4PDT ON/ON/ON is probably going to be the 'smallest' regular toggle switch that you can get away with (and note the order could be switched since a 4PDT ON/ON/ON can be wired to fully emulate a DP3T).

Jul 29, 2022 7:38:31 GMT -5 blake375 said:

For obvious reasons I don't want the kill function to be in the center position, but other than that the order is not important.

I get one reason why you might want this: so you can go directly from regular to blower without a blip of silence. However this is only an advantage assuming that with the kill position at one of the extremes you don't accidentally push the toggle to far when trying to select the middle position (which is quite easy to do) — one can much more confidently select the outer positions by following through with the toggling motion. Relatedly, if the kill position were in the middle it's much less likely to get accidentally knocked into that position by a stray arm. And finally it would make the wiring achiveable with only a DPDT ON/ON/ON, like such:

[newey]

Yogi B has a point about the order of positions. I saw that it was easy to have the kill in the center, but struggled to set it up with the kill at an end position, as maxwell wanted.

So, blake375, for a "true blower", you'll need a bigger/better switch if you want the kill setting at one end. If you're OK with it in the middle, then Yogi's got the goods.

[blake375]

This forum is incredible!!! 

I'm from the UK, so I posted the cry for help at what was, for me, yesterday afternoon. I checked back today to find not only to some solid answers, but a series of really useful and professional-looking diagrams, and a few different options to try out!

Newey, Sumgai, MattB and YogiB, I can't thank you enough!

Now I need to go parts-shopping! It can be a bit tricky sourcing decent parts in the UK, so might take me a while. But I'll be sure to report back once I've tried one of these solutions out.

Thanks again all, much appreciated. 

[reTrEaD]

Jul 30, 2022 1:08:41 GMT -5 MattB said:

I think a better solution is to use a 4PDT centre-on toggle. It's a more expensive part, but it gets the job done without compromises.

I think this should work:

Definitely use a 4PDT on-on-on. Wiring a volume pot "backwards" is a shark sandwich. (That's the PG version of my opinion.)

I didn't proofread your diagram. It seems unlikely you'll find a switch that has internal connections in the center position the way you've shown. This is the most common type:



I haven't had much time to visit GN2 recently but I have noticed your work. I like what I've been seeing.

[MattB]

Jul 30, 2022 7:44:15 GMT -5 blake375 said:

Now I need to go parts-shopping! It can be a bit tricky sourcing decent parts in the UK, so might take me a while.

CPC has 4PDT centre-on toggle switches for a good price:

cpc.farnell.com/multicomp/1m46t1b5m1qe/switch-solder-tag-4pdt-on-on-on/dp/SW04083

There's a £4.99 handling charge for orders under £17.50, but that's still cheaper than anywhere else I know of.

Bitsbox has DPDT centre-on switches, and is generally speaking good value for money:

www.bitsbox.co.uk/index.php?main_page=product_info&cPath=116_127&products_id=3293

[MattB]

Jul 30, 2022 8:20:20 GMT -5 reTrEaD said:

I didn't proofread your diagram. It seems unlikely you'll find a switch that has internal connections in the center position the way you've shown. This is the most common type:

Yes, you're right. I just tested the one I own (which is the same one I linked in the previous post) and it matches the diagram you posted.

Here are corrected diagrams for both versions (I hope):

The second version also removes an unnecessary switch connection.

Jul 30, 2022 8:20:20 GMT -5 reTrEaD said:

I haven't had much time to visit GN2 recently but I have noticed your work. I like what I've been seeing.

[reTrEaD]

Jul 30, 2022 8:58:01 GMT -5 MattB said:

Here are corrected diagrams for both versions (I hope):

They both appear to work as-advertised.

I took the liberty of modifying your first diagram with a fixed resistor (470k) that will load the pickup only in the blower mode. In my estimation this will be in the Goldilocks region. A little brighter than both pots at max clockwise but not as bright as the pickup unloaded. Of course the resistor value could be seasoned to taste.

[sumgai]

As it turns out, I mis-read the OP - I had assumed, incorrectly, that he already had a DPDT on hand.... my bad.

Blake, the later versions shown by MattB, YogiB (not related!), et al, are correct in that you'll need to spend a bit more cash at the outset, but you'll get the desired results with no compromises.

HTH




sumgai

[newey]

Jul 30, 2022 19:35:29 GMT -5 sumgai said:

MattB, YogiB (not related!)

Hmmm . . .How do we know this? Perhaps they're "Twin Brothers of Different Mothers"

[blake375]

Thanks all for the help. I've ordered my components (thanks MattB for the links) and will be working from the last diagram posted in this thread.


I hope this isn't too dumb a question, but is it still possible to have a treble bleed on the volume with this circuit? If yes, would it go across the pot terminals as usual or would it need to be incorporated somewhere else?

In the meantime - back to routing and sanding...