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Anatomy of a Firebird Pickup

hogy

Member
Joined
Nov 4, 2005
Messages
715
Hi there. There seems to be somewhat of a lack of knowledge of how a vintage Gibson Firebird is constructed. Today I got a chance to take apart a vintage '63 Firebird III pickup to repair a problem with a dead coil due to a faulty coil lead. The good news is that I was able to fix the pickup without having to rewind it. The better news is I have pictures to dispel all myths regarding the makeup of these things. They are not at all like a '70s mini humbucker. What they basically are, design wise, is two shrunken Melody Maker pickups wired as a humbucker.

First, the whole thing is held together by the cover and base plate, and a bit of glue.

Under the base plate are a couple of thin maple shims:

378024016.jpg


The dual coils are simply sitting inside the tight fitting cover. Under the wooden shims is a thin, ferrous metal plate:

378024020.jpg


Under that are two coils made up of thin, flimsy, translucent plastic bobbin formers. Inside each bobbin is a bar magnet. Picture a regular humbucker magnet cut in half horizontally. One coil has the North facing up, South on the other. The ferrous plate mentioned before is simply held in place by those magnets and is magnetically coupling them:

378024019.jpg


The coils themselves are wound with the typical, purplish/maroon Formvar wire as found on period or earlier humbuckers and P-90s. Each coil measures around 3.2k and they are connected in series like a PAF.

378024017.jpg


On the other side of the bobbins, the one facing the cover, there is another small strip of ferrous metal glued across the magnet bars. Again, apparently, to magnetically couple the two coils. On top of that there's simple transparent adhesive tape to insulate the magnets from electrical contact with the cover:

378024018.jpg


In a regular PAF style humbucker the magnet is in direct touch with the base plate, cover, and pole pieces. Obviously, the FB pickup's designer took efforts to avoid this. The wood spacers on the bottom and insulating tape on top of the bobbins ensure that the magnets have no contact to electrical ground. I'm no pickup designer and I'm not sure why this matters, but here it is.


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j45

Active member
Joined
Jun 14, 2002
Messages
9,081
I Bet J45/aka Kerry would love to see these.

Saw it! Unique pickup... unlike any other vintage Gibson p/u design. Now we need to open a few more and see when the PAF wire windings switched to the orange poly windings. My guess would be around '65 or so like PAT #'s but we won't know for sure until someone opens one up. Great post. i believe this may be a first. I haven't been able find a single internal pic of an original FB p/u anywhere....much less great shots like this.
 

tooold

Active member
Joined
Jul 31, 2006
Messages
2,071
Thanks for the effort and the photos, Barbarossa, this is great! It's good to see what's actually going on rather than speculation.

The coils are interesting - it seems like Gibson was always trying to use existing tooling to keep the costs of new models down - I wonder if these really are the same size as MM pickups?

Has anyone taken one of the repros apart (SD, Lollar) to see how they're made? It would be interesting to compare.
 

bigtomrodney

Active member
Joined
Nov 7, 2009
Messages
1,448
I've often wondered about how they differ from the Epiphone mini-humbuckers but haven't been able to find anything online. Thanks for posting!
 

jeffc

New member
Joined
Jun 1, 2005
Messages
1,720
Stupid question :
What are the wholes in the cover, in the first pic ? Didn't these PUs were without poles/ screws like 70's minis ?


BTW thanks for this great thread and pics :salude
 

Cody

Well-known member
Joined
Jul 23, 2002
Messages
4,494
The PU is face down, so that's the base plate you're looking at.
 

hogy

Member
Joined
Nov 4, 2005
Messages
715
Thanks for the cool pix!

But.... how do you "disseminate" a pickup?


Bad wording on my part. I hope the pictures do indeed help to disseminate knowledge about what makes a Firebird pickup tick, is what I meant. I think...

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Jason Lollar

New member
Joined
Jul 26, 2001
Messages
307
most of the parts are interchangeable- same baseplate, same bobbins, same cover but no holes, different magnets, as stated before the firebirds have bar magnets in the bobbins like a melody maker, minis have a steel slug in one bobbon and screws running through the other bobbin but unlike a PAF type bucker the minis do not have holes in the bobbins- they have a slot like a melody maker (that you could put a firebird magnet in if you are making a firebird).
So I disagree they are not at all like a mini bucker- they use alot of the same parts but they are a very different design in ways and sound quite different from each other
 
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