Trade Secrets!

Upgrading an inexpensive semi-hollowbody with P-90 sound


Issue 166 June 07, 2012

Minor investment, major upgrade

Upgrading an inexpensive semi-hollowbody with P-90 sound

My customer, Nathan Moore, loves the way his Epiphone Casino plays, but he’s not so crazy about the sound of its pickups.


Nathan plays in a local band, Sport Fishing USA.

Sport Fishing USA

Talking after one of their gigs, Nathan told me the pickups in this Epi are considerably overwound. They don’t give him the P-90 tones he feels the guitar should have.

He wants to get that sound without sinking a lot of money into this guitar.

We discussed whether to rewind the stock pickups or replace them. Nathan wanted to switch to Golden Age P-90s – Parsons Street model.

They’d be perfect except that they’re soapbars, not mounted in dog-ear frames like his guitar’s pickups.

Soap bar 1
Soap bar 1

Lucky break:

As it turns out, it’s pretty easy to transplant a Parsons Street into a dog-ear frame if the polepiece spacing matches the holes in the cover. Here’s how I did a quick P-90 transplant:

measuring

Out come the stock pickups

They were soldered to their covers, but a quick hit with a soldering iron broke the joint easily:

Unsolder 1
Unsolder 2
Unsolder 3
Unsolder 4

The bobbins unscrew from their metal frames

I removed the two screws holding the dog-ear frame to the bobbin and unsoldered the ground wire:

Removing the pickup
Removing the pickup 2
Removing the pickup 3

Parsons Street transplant

Two screws held the P-90’s bottom plate, too. I took those screws out, but didn’t remove the plate:

Disassembling a P-90
Assembling a P-90

I left this plate on to show how simple this swap can be. Removing the plate would be no big deal: I’d just have to resolder a ground wire to the Epiphone’s dog-ear frame. But the P-90 screwed right onto that frame, baseplate and all. It fit tightly, with the metal plates establishing a good ground. Easy!

P-90 and cover

Reassembly

Now it's time to solder the cover back on. Using a couple of spring clamps to hold the frame tight to the cover, I reflowed the solder joints that hold the cover and frame together.

Soldering the cover
See this album on our Facebook photos page See this album on our Facebook photos page See this album on our Facebook photos page

What about rewinding?

The Epiphone’s neck pickup was way overwound, reading over 12k on my multimeter! It sounded super muddy. Modern Epi P-90 neck pickups use a different string spread than the bridge pickup, even though vintage Gibson P-90's are the same string spread for both neck and bridge positions. This means we can't transplant a Parsons Street P-90 in this dog-ear cover. The polepieces wouldn’t match the holes.

Finished pickup

The thing to do here is to rewind the stock pickup to get a more usable DC resistance. I cut the wire off the coil and broke down the parts. I underwound the coil with about 8,500 winds of AWG wire to give it more clarity and punch.

Broken-down pickup

It came out right around the high 6k range; that’s a perfect complement to the 8k Parsons Street bridge pickup. A little less power on the neck pickup has a balancing effect, since there’s so much more string motion at the neck position compared to the bridge.

Pickup winding


Tip:

For details on winding P-90s, check out our free pickup kit instructions.


The P-90 transplant and the rewound pickup dropped right back into the guitar. They look factory, but they don’t sound factory.

Finished installation

Since I had the guts out anyway, I took this chance to redo this wiring harness with vintage push-back wire, CTS pots and a Switchcraft jack.

Wiring

Nathan’s stoked: his Casino is finally sounding the way it should. Rock it, man!

Nathan Moore

Don't miss an issue!

Get Trade Secrets delivered to your inbox. Only from StewMac.