Specs or guidelines for DeArmond gold foil

[GlennW]

I bought a couple of dead ones on ebay. They're the style that Harmony used on their old Rocket guitars, but I'm going to use them on a bass project. They look kind of like l) S (l

Does anyone how much of what wire size was used on the Harmony H22 and/or H27 basses?

Thanks.

[Possum]

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I don't know exactly what wire was used in the H22 bass pickups not having taken one apart, if you can find out what the DC resistance of one is you can probably guess from that. The gold foil type DeArmonds used both 43 and 44 gauge wire, so you see some that are 8K and some then the more common ones at 10.5K or so. the more common ones used 44 gauge wire. If anyone here has rewound an H22 pickup then maybe they would know, but most here are hobbyists and don't bother to keep wire samples or own a micrometer of sufficient measurement capability (needs to be digital and read to 5 places) to really tell what gauge wire is used. Anytime you rewind a pickup or take one apart thats dead, SAVE THE MAGNET WIRE and label it, where it came from. Get a decent micrometer and learn to use it, you need a super light touch or while you are measuring the wire you can crush it at the same time giving you a totally bad reading.

You might periodically scout Ebay to find one of these pickups and see if they list the DC resistance. Most of those harmony pickups used the same size magnets and coils, magnets were either alnico or rubber ferrite.

[Mark Hammer]

Just so that I know, we are talking about those really shallow profile things where what looks like a row of adjustable polepieces along the edge is NOT another coil but is really a piece of the base bent upwards?

I have a busted one where the coil went long ago, but the base and cover remain, and a roll of both #43 and #44 sit happily unused on my shelf. Some specs would be nice.

[GlennW]

Thanks for the info. I have been watching ebay for specs, seems like most DeArmonds are in the 9+ through 13K range, with the majority around 10K from what I've noticed.

There's a bunch of Harmonys in the link...they're like the ones in the bottom left picture.

http://harmony.demont.net/model.php?id=150

I think a couple of those would look downright sporty in on an old hollow body bass.

I'm pretty sure I'll end up using 43 since I have some and don't have any 44. I've never been inside one, but have seen a couple of pictures. I'm expecting a P-90ish coil with the magnet in the center. I'm really not too concerned with duplicating anything - more curious than anything else.

[Sweetfinger]

A "gold" mine of info!

I've been measuring these when possible for a few years now. De Armond made several pickups for Harmony that were essentially variations on a theme. The ones I've been interested in are the thin, narrow, rectangular ones that came on Stratotones, Rockets, and Bobkats branded Harmony, Aldens, Airline, or Silvertone.

Here's what I got:

The "gold foil" without polepieces have all been "south" up in polarity,
8.8 K No date
10.92 K Jan 20, 1964
10.67 K Jan 20, 1964
11.2 K No date
11.2 K No date

"gold foil" with adjustable poles:
9.7 K South Sept 27, 1966

"Silver foil" with one large diamond on cover-
10.76 K South No date
10.79 K South No date

"Gold foil" from an Airline with several small vertical diamond shapes on cover:
14.9 K South April 14, 1965

"Solid shiny chrome cover"
3.88 K North Jul 24, 1957
3.52 K North 2 8 62

Solid cover with raised "pebble grain" rectangle-
3.51 K North probably late '50's or early '60's
9.15 K North same time period

It seems that the very early ones were not wound nearly as hot, and were North instead of south up. The plain chrome ones sound FANTASTIC on a Dobro style resonator, and fit well because they are "Wafer thin".

They seem to get hotter through the 1960's. The Airline at 15 K was a blaster! They also seem to have been wound hotter for the bridge position, but that might be just a couple of isolated cases. De Armond certainly made different assemblies with progressively taller bases for the different positions on multiple pickup guitars.

All the ones I have pulled apart have had alnico magnets and without exception, all sound great and have very low hum. De Armond is truly under appreciated in the guitar world- IMO they were as innovative and original as any other maker and every pickup they made was of high quality.

Hope my lil' show'n'tell has been helpful.

[GlennW]

Sweetfinger, thanks for listing all that stuff - nice to have stats.

The pickups arrived and I opened up one. I had all these plans for maybe making it differently, but the holes for the mounting holes would be in about the same places where the E and G rod magnets would go, and since there's no other way to neatly mount it I'll just try my luck at rewinding it with 43 and see what it sounds like.

It looks like the top bobbin and the baseplate are glued to the magnet, and I think I'll be better off leaving that stuff alone. After the wire is removed, I'll try to get some tape on the magnet side of the baseplate so the wire won't be on it. It looks like the coil will be about 0.2" tall.

The thing that has me all confused is how it was all held together. I drilled out the two rivets? from the baseplate side to take it apart. I can't figure out how the rivets held the coil in the cover. I don't think they were attached to the cover - maybe they were. If anyone knows, please enlighten me.

I tried to include a picture, but it didn't come up. I'll try again.

[GlennW]

I couldn't leave bad enough alone, so I dismantled it. The magnet flaked apart next to one of the screw holes. I don't think it's alnico because I couldn't get a reading on the ohmmeter. It also seems to be soft. I'm going to try to replace it with a ceramic bar magnet from a Peavey pickup which feels a lot stronger. It had the end of the beginning of the coil soldered to the little prong in the baseplate, and then a small piece of tape over that. Also looks like top of the baseplate was coated with white enamel or something.

[Joe Gwinn]

I couldn't leave bad enough alone, so I dismantled it. The magnet flaked apart next to one of the screw holes. I don't think it's alnico because I couldn't get a reading on the ohmmeter. It also seems to be soft. I'm going to try to replace it with a ceramic bar magnet from a Peavey pickup which feels a lot stronger.

I bet it's a plastic magnet, such as used by Lace. Plastic magnets are ferrite magnet dust dispersed in a plastic binder. A hard ceramic magnet may be too strong, or DeArmond may have picked plastic magnets because they could be cut to fit with scissors, or punched from sheet goods.

It looks from color that the core is wood.

[GlennW]

Wooden magnets? Maybe that's where the real sound is?

It's flexible, like the kind that are on refridgerators. Would that be a plastic magnet? I don't know what it is, but it's seen better days.

I wonder how many drill bits it'll take for me to drill those two holes.

[Possum]

its rubber

I thought I mentioned that before? The gold foils were rubber magnets, probably over time they get dried out or something. Basically ferrite embedded rubber is all it is......

[Joe Gwinn]

It's flexible, like the kind that are on refridgerators. Would that be a plastic magnet? I don't know what it is, but it's seen better days.

Yes, it's a plastic magnet. Same material as used on the back of magnetic signs, but magnetised differently.

I wonder how many drill bits it'll take for me to drill those two holes.

If you are drilling holes in ceramic magnets, use the same bits and procedures as are used to drill holes in glass. Diamond-tipped drills, always used wet, work very well. Regular twist drills won't work on glass or most ceramics.

Here are two suppliers:

http://www.drillglass.com/index.html

http://www.gordonglassusa.com/listing.htm?cd=301

[David Schwab]

I bet it's a plastic magnet, such as used by Lace.

And Rickenbacker too. The 4000 series basses' treble pickups have rubber magnets.

[GlennW]

Thanks for the further input. I ordered a 1/8" bit from the first link - very good salesman.

Rather than just wait for the bit, I got to thinking about Plan A with the alnico rods. I'm going to try that, but have a question about the mounting screws being in contact with the magnets. Will they just become an extension of the magnets and act as pole pieces themselves? I think they will, but am just guessing. If there's something wrong with that approach let me know.

I'm asking that because I've never seen a pickup with a screw in contact with both the north and south poles.

As far as the original coil goes:
wire diameter is about 0.0016"
weight is about 217.4 gr

[jason lollar]

not all gold foils have rubber magnets.
I had a batch of alnico magnets made for making copies of these- they sound really good.

There are two ways to deal with putting them back together- #3-48 machine screws and nuts- the cheezey way or make your own eyelets with brass tubing- quite easy actually if you get them cut accurately to be slightly longer than the height of the pickup and dont peen over the end too hard at once or youll split them- that way youll have what looks like stock and you can run mounting screws through it.
I used to use machine screws but once I figured out how easy it was to rivet together I never went back

[GlennW]

Thanks Jason. After reading your post I went and took a closer look at the one I haven't taken apart and sure enough, you can see the rivet from the cover end - guess I didn't look hard enough before.