New bridge pickup for my SG

[Dave Sloven]

Maybe you wired the toggle switch up wrong?  Sounds like it might be out of phase, I agree.

[yanngiraud]

To give you an idea of what I'm talking about, here's a very rough recording I've made this morning.
First the APH2 neck by Seymour Duncan, then the BKP Old Guards and then both pickups. The volume drop is quite noticeable, right? Problem is: I'm dual about it. On the one hand, I may want to ask the repair guy to solve the soldiering problem and bring the pickups in phase but on the other hand that almost Danelectro-like sound has its charms (reminds me of my Fender Lead II, which has a phase inverter). What do you think (don't focus on the cr@p playing and the barely tuned SG, ok?). 
On the plus side, you can hear how that BKP bridge pickup shines, much much better than the Pearly Gates it replaced (on the other hand, you might see why the Alnico II Pro is my favorite neck pickup ever).
https://soundcloud.com/fleurdumalfrenchband/essai-micros/s-VqtNcSh9rID

[Dave Sloven]

I had this phase issue on a Telecaster that we installed a Seymour Duncan Quarter Pound into.  First we had the neck disconnected so there was no issue.  Then my friend decided to replace the defective wiring and have the Fender neck pickup connected again.  I looked up the colour codes but is seems that Fenders can be reversed with the colours in some cases and I had it wired backwards.  We reversed the wiring on the neck pickup and it was fine.

There may be some confusion because on the Seymour Duncan pickups the black is hot whereas on Bare Knuckles black is ground

On Seymour Duncans the green is ground.

On Bare Knuckles the red is hot.

In both cases the bare wire must be grounded as well.

On Seymour Duncans the other two wires are white (north finish) and red (south finish), whereas on Bare Knuckles they are green (north finish) and white (south finish).  These are the wires you use for various switching options.

I think you can see the scope for your tech getting confused.

Check that the hot wire for the SD is black and the hot wire for the BKP is red on your guitar.  If you are not using coil taps etc those wires should be soldered together and insulated with shrink tubing, and the other wires should be grounded on a pot.

To keep the option of the phase reversal sound you could install a push-pull pot on your bridge pickup using the following diagram from BKP:

https://www.bareknucklepickups.co.uk/upload/support/1_hum_4_con_pushpull_pot_phase_reversal_with_another_hum_c8e3961.pdf

This mod simply inverts hot and ground and does not involve the green and white coil split wires.

[yanngiraud]

Thanks, Dave, this is really helpful.

[Dave Sloven]

One thing I would add: if you do decided to use a push-pull consider the height of the switch.  It may or may not fit under your control cavity cover depending on brand and type.  SG control cavities are quite shallow.

[yanngiraud]

Ok, problem solved! This was indeed an issue of wire interversion. Now I've got a real middle position, which sounds so much like a mix between the Seymour Duncan and the BK pickups that it proves they were a perfect match in the first place.
I hope to write more really soon. I can already that I love this new pickup. It sounds so much better than the Pearly Gates it replaced. More open, fuller and no dramatic loss of bass response when compared to its neck companion.