HBs with filtertron look

[Peter Naglitsch]

Hi guys. First post here thou I have been lurking around for quite some time.

Some background: I build guitars and have started to wind pickups for them. In my ears they are decant sounding (at least as good as the generic stuff out there). Have done HBs, Strats, Tele,s and P90s. I have even tried T90s and slug pole P90s so I have some experience from experimenting also. This time I thought that I might save some time and ask you guys. I am building a Gretsch-looking guitar and would like to have the Filtertron look (not necessary the sound). I’m considering using a standard HB and swap the slug polepice bobbin for another screw polepice bobbin and another drilled metal spacer under the coil. Any thought of how it will change the sound?

Another question regarding the Filtertrons: I have found the information that they are “double singe coils” rather than traditional HBs. Does anyone have more info about the construction? I have tried searching this and other resources without luck.

Thanks for any help

[David Schwab]

Filtertrons are very similar to Gibson humbuckers, except they have two rows of screw poles.

I've made humbuckers with two screw bobbins... they might sound a bit brighter, if they even sound different at all.

[Peter Naglitsch]

Originally Posted by David Schwab

Filtertrons are very similar to Gibson humbuckers, except they have two rows of screw poles.

I've made humbuckers with two screw bobbins... they might sound a bit brighter, if they even sound different at all.

Thanks for the reply David. Slightly brighter seems to be in line with my picture of the Filtertron sound.

One thing puzzles me. In the book “Guitar Electronics for Musicians” Donald Brosnac claims that Filtertrons "resembles two single coil pickups joined together. There are two coils that each have six magnetic slugs" It’s the “magnetic slugs” part that makes me doubt Brosnacs claim (and think David is right). Anyone can se that the Filtertrons have adjustable pole pieces. Can anyone verify the fact that the Filtertrons are made the same way “ordinary” HBs are?

Can’t find much info on Fitertrons here so I post what I know and maybe someone that has more facts chip in:
Filterftrons are pretty low on the DC resistance side like 2K (TVJones classic ranging from 4.1 to 4.8 for complete pickup) for each coil and the coils are taller than ordinary Gibson style coils (up to 3/4”). The magnet is supposed to be as thick as ¼” and possible ALNICO II.

[David Schwab]

Originally Posted by Peter Naglitsch

One thing puzzles me. In the book “Guitar Electronics for Musicians” Donald Brosnac claims that Filtertrons "resembles two single coil pickups joined together. There are two coils that each have six magnetic slugs" It’s the “magnetic slugs” part that makes me doubt Brosnacs claim (and think David is right). Anyone can se that the Filtertrons have adjustable pole pieces. Can anyone verify the fact that the Filtertrons are made the same way “ordinary” HBs are?

I used to own a copy of that book. There are a LOT of errors in there. Both the Filter'Trons and the HiLo'Trons, which were half a Filter'Tron, used adjustable screw poles and a bar magnet. The Gretsch-DeArmond DynaSonic had adjustable magnets (slugs) for poles, but that was a single coil pickup.

Here's the patent for the Filter'Tron, invented by Ray Butts and patented in 1957: 2892371 (PDF)

You can see that it's pretty much made like a Gibson humbucker, except it has two rows of screws. By the way, the slot in the middle of the case is to help prevent eddy currents. He calls them "circulating currents" in the patent.

Originally Posted by Peter Naglitsch

Can’t find much info on Fitertrons here so I post what I know and maybe someone that has more facts chip in:
Filterftrons are pretty low on the DC resistance side like 2K (TVJones classic ranging from 4.1 to 4.8 for complete pickup) for each coil and the coils are taller than ordinary Gibson style coils (up to 3/4”). The magnet is supposed to be as thick as ¼” and possible ALNICO II.

I found this somewhere on the 'Net... don't know how accurate is is:

"Gretsch Filtertrons: 43 gauge Poly, 2000 CW turns; 2k average resistance DC per coil, Alnico 5, coils generally pretty loosly wound"

[Peter Naglitsch]

Thanks again David. That picture makes it very clear that Filtertrons are made very similar to Gibson style HBs, exept for taller coils and thicker magnet. So the ALNICO II was wrong. An ALNICO 5 magnet 1/4" thick must produce a quite strong magnetic field. That and the tall coils with few turns must be the main resons that the Filtertrons sound the way they do.

[bill raymond]

Newer (Baldwin-era) filtertrons have #43 wire, and total resistance (both coils) ca. 7.8k IIRC. Original (Ray Butts design) filtertrons had #42 wire ca. 4.4k total.

And, HiLoTrons aren't really 1/2 a filtertron, altho they are often thought to be. They were a Gretsch design (not Ray Butts') for a single coil to replace the old DeArmonds they had been using. You can find out a lot about the various Gretsch pickups (if you're interested) by perusing the Gretschpages forum.

Edit: And the screws are #6-32 filister headed screws. I don't remember the length, but it changed with the Baldwin era, as did the baseplates. More recent, made-in-Asia models use a similar sized metric screw.

[Peter Naglitsch]

Thanks Bill. My googling didn't result in any links to the Gretsch forum!!

Now for a question for anyone that might be able to help. I am looking for “open” type HB covers. Not necessarily open in the same way ass the original Gretsch. Any cover that reveals most of the tops of the bobbins so that I can get two rows of screws visible will do. I don’t really fancy the job of cutting ordinary covers for the Gretsch look. And I don’t think I can do a nice and clean loockin cut either. And the chrome will probably flake or discolour and the brass will show in the cut area… you get the picture. So I was hoping that somebody had a source for covers like the GFS Gretsch looking covers.

A loot of energy put into this just to get the look right, but this is for a customers guitar, and he wants the whole Gretsch look but not the Gretsch sound.

Anyway, I’m thankful for all your help this far.

[Peter Naglitsch]

Nwermind, I found these A bit pricy and not exactly what I was hoping for but they will do.

[Peter Naglitsch]

And a short time after ordering them a guy at the project guitar forum send me this link to axesrus:
http://www.axesrus.com/axepickup_files/hgates.jpg
So I had to order them too.

[Peter Naglitsch]

Here is the result (one of two):

And no, the finish is not buffed out

[David Schwab]

Very nice! Love the body too.