Could someone have a look at my wiring scheme?

ADawg

So I've been modding my Epiphone SG Special II to have a humbucker-p90-humbucker pickup configuration.

I don't want to drill any more holes, so I've got 2 push/pull pots for PRS style partial coil splitting and turning the p90 on and off. But the main thing I'm unsure of is the way the volume and tone controls will work.

I want the volume control to affect only the humbuckers and the the tone control to affect all 3 pickups.

This is what I've drawn up. Does it look right?

ICBM

Not quite. If you really want the volume control to only affect the humbuckers - ie having no way of turning down the P90, it’s either off or on full - then you need to swap the connections on the volume control, so the 3-way toggle is connected to the middle terminal and the P90 switch, tone control and jack to the end terminal.

ADawg

Oh I see - yeah that makes sense! So, the plan I orginally drew would have had the p90 also being affected by the volume control then, right?

ICBM

ADawg said:

Oh I see - yeah that makes sense! So, the plan I orginally drew would have had the p90 also being affected by the volume control then, right?

Yes, but not really in the right way - just by loading it down to zero, so it would also get progressively more muddy.

The best solution in my opinion is simply to connect the output of the P90 switch to the output of the toggle switch/input of the volume control, and then you will have a master volume and tone with normal pickup switching and switchable P90.

If it matters, I have that exact system on my PRS, although with a mini-humbucker in the middle rather than a P90. It works perfectly and is totally logical to use.

Funkfingers

Proper control over the three pickups really requires more pots and/or switches.

The Epiphone 3HB G400 Custom opts for three volume controls and a master tone. The selector switch offers neck/both/bridge. The centre pickup is then blended via its own volume control. Consequently, it is not possible to have the middle pickup by itself.

The so-called Peter Frampton circuit is, arguably, a more practical alternative.

Neck and bridge pickups via the selector switch, then, the lower volume and tone controls. Centre pickup via the upper volume and tone controls. This way, it is possible to turn down your humbuckers and have just the P90.

I wonder whether the simplest solution might be three on/off switches, like some Eighties shred guitars? One humbucker split per push-pull pot. Job done. 

ADawg

Yeah, I realise its not the most elegant solution, but I'm just experiementing with different setups and configurations right now. I don't want to commit to drilling out new control holes just yet. (plus, I tend to use the tone control more than the volume to be honest)

Although, I was thinking of using a freeway switch down the line, once I've figured out what I like!

Thank you for the advice!

Funkfingers

ADawg said:

I'm just experiementing with different setups and configurations right now.

I figured as much.

Have you routed a P90 cavity yet? The SG body is pretty slim. Deep enough for the cavity but not necessarily leaving much wood for the P90 screws to bite securely. (Obviously, humbucker-sized P90s, suspended through mounting rings, will not face this problem.)

If you intend to use a humbucker-sized P90, consider trying it in the neck/Rhythm position before routing the Epiphone body. 

ADawg

Yup, already routed the cavity and cut out a custom pickguard. I've used a humbucker sized P90 so it fits in nicely. I've played around with P90s in the neck and bridge position as well.

Ive basically been using this as my project guitar for experimenting, I've only really played guitars with 2 humbuckers, so I wanted to try out different configurations. Might even try a triple P90 set up at some point...