Where would I find an air coil?

toytech · #1 01-29-2008, 09:05 AM

A magnetless coil like alimbic uses in the series one, I have always wanted to try a set up like that in a build, maybe a set of big single
coils with the air coil in the middle for hum canceling only, and an Audere pre? just thinking out loud here..

newfuture · #2 01-29-2008, 05:10 PM

I think you might have to wind one yerself. I'm considering doing this...if anybody has any tips on how to do it, please chime in! My basic assumption is that it's just an antenna, and it'd need to be about the same impedance to the pickup, and without a magnetic core or pole pieces. Not sure if it needs to have any relationship to the size / shape of the PU's though. Would love to hear from someone with more knowledge on it.

toytech · #3 01-29-2008, 05:35 PM

I would not think the size would be too important, I thought about winding my own, I would still have to find or make the bobbin though. The ones on an Alembic are smaller than the actual pickups by about a third. Hmm, would be cool with a pair of darkstars...

Trevorus · #4 01-29-2008, 05:40 PM

Quote:

Originally Posted by toytech

I would not think the size would be too important, I thought about winding my own, I would still have to find or make the bobbin though. The ones on an Alembic are smaller than the actual pickups by about a third. Hmm, would be cool with a pair of darkstars...

I have a couple of coils from old pickups that you could fiddle with...

toytech · #5 01-29-2008, 07:05 PM

I did find some bobbins on stewmacs sight intended for building your own guitar humbuckers that would work, and I have a couple of off brand pickups from a washburn I used to have kicking around too, maybe I will go that route, maybe half a p pickup without the poles.

newfuture · #6 01-30-2008, 02:08 PM

I picked up one of the Turser '51 ('54?) copies...it's got a single coil in it that actually sounds good, just is a bit buzzy. Am thinking that I might be able to wind a canceling coil to the bottom of the existing PU...maybe just using some circuit board stand-offs for a bobbin...it'd interact with the PU a bit, but lacking a core and being much farther away from the strings than the functioning PU element, maybe it'd work? Next time I find some 42 gauge wire I may give it a try.

jim primate · #7 01-30-2008, 07:09 PM

i'm thinking of doing this as well. will probably just build my own.

Trevorus · #8 01-30-2008, 07:12 PM

Winding 42 wire is not easy, as it's prone to break. I would use a cheapo pickup, rather that bother with the winding part.

A9X · #9 01-31-2008, 02:10 AM

Quote:

Originally Posted by toytech

I would not think the size would be too important, I thought about winding my own, I would still have to find or make the bobbin though. The ones on an Alembic are smaller than the actual pickups by about a third. Hmm, would be cool with a pair of darkstars...

The reason Alembic get away with a different size/shape/impedance coil is the use of individual buffers (and adjustable gain/phase) for the pickups and the dummy. Anything else wil fail nicely.

otis_thick · #10 01-31-2008, 03:08 AM

Quote:

Originally Posted by newfuture

I picked up one of the Turser '51 ('54?) copies...
... Next time I find some 42 gauge wire I may give it a try.

http://www.stewmac.com/shop/Electron...ns/I-1465.html

I built a rig using an old film winder crank. In this case it was 4 revolutions per crank. I took a string and measured around the bobbin. In this case 6" = 24" per crank then apply that to the resistance per distance. I used some old fishing rod arms for guides. I eventually connected a hand drill and adjusted the motor speed screw until I got the right speed (without breaking wire). Use the above DC resistance check method noted on the Stew Mac site. 2 tips Number 1: Instead trying to scrape with a hobby knife, use a lighter and quickly wave the flame across the wire you will see the coating vanish and wipe wire with toilet paper ... do your DC resist check and recover with nail polish. Tip number 2: If you break the wire (especially after a few hundred turns) Using the lighter method above, remove the coating from a few inches on both leads and tie them in a knot. Clip as much of the excess as you can away. With volt meter, check for good contact and recover with nail polish.

Good luck

newfuture · #11 01-31-2008, 03:19 PM

Quote:

Originally Posted by otis_thick

I built a rig using an old film winder crank. In this case it was 4 revolutions per crank. I took a string and measured around the bobbin. In this case 6" = 24" per crank then apply that to the resistance per distance. I used some old fishing rod arms for guides. I eventually connected a hand drill and adjusted the motor speed screw until I got the right speed (without breaking wire).
Good luck

Thanks for the tips...I've got a good source for thin gauge wire in the bay area, a surplus shop called Halted, about half the stew mac price. The winder, a film crank like a bulk-film loader? Great idea...I've been winding sustainer coils with 32 gauge wire, so I'm familiar with the process, but yeah, 40 or 42 is wicked thin. Nice way to fix breaks, thanks!

Next question to the folks here: air coil in series with or parallel to the PU?

A9X · #12 01-31-2008, 10:47 PM

Quote:

Originally Posted by newfuture

Next question to the folks here: air coil in series with or parallel to the PU?

It can be either, usually series.

However to work well passively over a wide bandwidth, it needs to be the same construction (LCR) and number of windings.