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What should I expect deleting my toggle switch and adding a second volume pot?

Gremson

Gremson

Mar 22, 2012
535
576
North-Leftern USA
www.commonlycourteous.com
#1
I've got my old Epi ET-280 that I quite adore and want to make it the most it can be.
With the toggle switch now, I favor the neck pickup. Middle position sounds kinda thin, and the bridge pickup soloed is really only good for the one solo I ever really play in the band I'm in. I'm considering deleting the switch, moving the tone knob to its place, and putting a second volume pot in place of the current tone pots position. I think fading in a bit of the bridge pickup with the neck full on would give me a thicker sound. But that's all just how I imagine it in my head. I'm curious on opinions on how my tone would change if I made this mod. Would the pickups wired like this be hum canceling all the time? Are there any phase issues or something else I should account for? I figure I'd just follow a typical jazz bass wiring schematic to complete this endeavor. What do you guys think?

Here's the beaut in question.
received_10156422246031528.jpeg
 
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#7
Gremson said:
It's all 500k audio taper right now and the sweep and control is alright. I accidentally rewired it with 250k pots thinking off of standard six string wiring (single coils=250k) but it had 500k originally and sounds best that way.
Click to expand...

One thing to note is that if you go to a Jazz Bass-style two-volume wiring scheme, even if you use 500k volume pots, you will likely find that your tone goes back to how it sounded with the 250k volume pot. (Boring tech explanation: this is because as the two volume pots will always be connected to the output, their loads will be combined in parallel -- creating a 250k load to ground, which is what you would have experienced with the single 250k volume pot.) If you like the tone with a 500k volume pot, I'd recommend tracking down two audio taper 1M pots for the volumes (500k for tone is still fine).

EDIT ignore this bit, I forgot that you are keeping the tone control (Of course, you'll also lose the tone control, which will make the tone a bit brighter. The tonal change that comes from replacing a volume control with a larger value is subtly different, but you may never notice honestly.)
 
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#8
Rad. Thanks guys. I hadn't considered wiring in series, but that does sound like a fun thing to try.
I assume I wouldn't have any need or want to switch to 1meg pots like solderfumes suggested if I went the series route?
I think I might give it a try. I've got a few weeks off from gigging in october, so I should have some time to mess around. This'll be fun!
 
#9
One of my basses used to have the standard J set-up- two PUPS, two volumes and a tone and output.

Removed a volume pot, installed a toggle- pups to toggle, toggle to volume, volume to tone, output.

Simple. Also took time to shield the control cavity too- made a WORLD of difference when playing clubs with lots of neon signs and in studio, as the noise floor dropped considerably as well!
 
#10
One thing to consider:
Most of those standard size (not mini) toggles live in a 1/2 inch diameter hole. Most potentiometers need a 3/8 (or a bit smaller) hole. To change from a switch to a pot in that location, you will probably need a new pickguard, which....you may have to make yourself.
 
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#11
micguy said:
One thing to consider:
Most of those standard size (not mini) toggles live in a 1/2 inch diameter hole. Most potentiometers need a 3/8 (or a bit smaller) hole. To change from a switch to a pot in that location, you will probably need a new pickguard, which....you may have to make yourself.
Click to expand...

That’s an excellent point. I’ll confirm the size before I order any parts. I want to avoid having to cut a new pickguard.
 
#12
Gremson said:
That’s an excellent point. I’ll confirm the size before I order any parts. I want to avoid having to cut a new pickguard.
Click to expand...

If you try series wiring and stick to a single volume, then yeah I think sticking to 500k is the right way to go. Those are humbuckers in the bass right? I could imagine the series mode being a bit wooly if so; if you find you’re using that mode most and would like it to be a tad brighter, then it *might* be worth considering trying a (single) 1M volume pot anyway — but I suggest you cross that bridge when you come to it.

As for the size discrepancy between a switch hole and a pot hole, I think you can probably just solve that with the right washer.
 
#13
Those don't look like humbuckers in the bass. (one row of poles)
As far as the hole size, you can ream out the hole to 3/8" for a pot if the switch hole is smaller.

I had the local luthier ream my Mexican p/g out for 3/8" holes.
Using a reamer is the right way to do it.
j0lr4fudldawy2ccoijl.jpg

Try putting a pot in the switch hole first.
If it is 1/2", the 3/8" pot should fit in there just fine.


edited: removed 1/2" (mistake)
 
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#14
Killed_by_Death said:
Those don't look like humbuckers in the bass. (one row of poles)
As far as the hole size, you can ream out the hole to 3/8" for a pot & the 1/2" switch will still fit back in there.

Try it yourself before you ream, put the 1/2" switch into the 3/8" pot hole & see if it won't cover the hole.

I had the local luthier ream my Mexican p/g out for 3/8" holes.
Using a reamer is the right way to do it.

View attachment 3149022
Click to expand...

Ah yes, a little Googling confirms that the pickups are in fact single-coil, so then yes I’d definitely suggest starting with 500k for the volume if you want to do the series wiring and stick to a one-volume setup.

As for the size of the holes, if we are still talking about going to a 2-volume setup (ie replacing the toggle with a second volume), then we’re talking about putting a 3/8” pot shaft into a 1/2” switch hole, and that should be fine (not trying to offend anyone here, but will clarify that 3/8” is smaller than 1/2” just in case that’s the source of our confusion).
 
#16
Killed_by_Death said:
Series wiring doesn't mean you can only have one volume. Check the link in post #6.
However, wiring a 3-way toggle pickup selector in series is probably impossible.

The switch hole might actually be the same size, difficult to tell.
Click to expand...

Hm... I haven't ever seen that wiring scheme before. I think I see what it's doing, seems interesting. It isn't what's normally considered as standard series wiring (there is some extra stuff in the signal path), but looks like some people like the results.

There's another option if you go with fixed series wiring, which is the "spin-a-split" mod. This amounts to giving one of the coils its own *tone* pot. When the tone pot is full on, you essentially get the full series mode wiring (well, almost), but when you turn the tone pot *down* then you get the highs from one pickup alone -- supposedly anyway, I've never tried this. This would mean eliminating the switch and having three pots: one volume, one for the "blend", and one for the master tone.

Invalid Link Removed

(Imagine that your two pickups are the two halves of a humbucker in this wiring diagram.)
 
#18
Another good option is to use a four-way rotary switch wired to select series, parallel, neck only, bridge only. Doesn’t give variable blend but does give quick access to a broad range of useful settings. The series setting may be more to your liking than the parallel setting you have now.

Otto
 

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