Bobbin Dimensions

[mr fab]

hi terry
allparts sell filtertron pickup kits, you may wish to ask them the dimensions.

https://www.allparts.com/PU-6991-000...it_p_4789.html

they look suspiciously a lot like firebird bobbins

fab

[big_teee]

I have some Mojo 8-string bobbins. I'll try to remember to take a look this weekend.

Any luck measuring the 8 string bobbin?
In inches decimal please.
Length?
Width?
Height?
Flange?

T

[rjb]

I have seen "vintage size" Filtertron bobbins for sale- but never with dimensions listed. Same old story.
Gretsch Filtertron Pickup Bobbins Nylon SET OF 2 ORG Vintage Size | eBay

I concur that a "hi-fi" Filtertron would have pretty low output. But the patent language makes it pretty clear that Mr. Butts' goal wasn't thick tone. I don't doubt that a Filtertron could be wound to have a loaded resonant frequency over 20 KHz- but I do doubt if many, if any, were sold.

** Sorry for not attributing you as finder of the Gretsch data. I just thought is was more expedient to link the pdf directly than to link to a link. (Note that I didn't attribute myself for originally posting the patent in an earlier thread...)

[big_teee]

Thanks, but really looking for pickup dimension data.
As in bobbin measurements.
This is a Bobbin Dimensions Thread!
Terry

**Changed post 8 from data to dimensions.

[rjb]

Been looking for Filtertron Data.
I have this, but if you have any other Filtertron data please post it here.

Here's some more info & hearsay from earlier posts.
http://music-electronics-forum.com/a...ickupsinfo.pdf
http://patentimages.storage.googleap.../US2896491.pdf
http://music-electronics-forum.com/t11489/#post89700
http://music-electronics-forum.com/t11489/#post90031

**I also read that some Filtertrons were wired in parallel instead of Series.
So if anyone has any info to add on Filtertrons in parallel, please let us know?

Here's some rumination on the above information:

We know the earliest Filtertron bobbins were narrower (and a little taller) than PAF bobbins. At any rate, they didn't hold much wire.
Consensus seems to be they were wound with ~3000 turns of #42, for a DCR of ~2K per bobbin.

A big selling point in Ray Butts' patent was that the pickups could be constructed to produce "hi-fi" output, with resonant frequency above 20 KHz. The patent states that the coils can be wired either in series or parallel, and hints they may be wound with less than 1000 turns of wire.

In order to achieve the "high fidelity" goal, one would use a low number of turns, and wire the coils in parallel.
I would venture such pickups would use no more than 3000 turns of #42 per coil (possibly quite fewer) and have a DCR no higher than about 1K. I would also venture that, as with the Les Paul Recording model guitar, few customers actually liked the hi-fi pickups. That would explain why Chet Atkins reportedly used a series-wired neck pickup (~4K), and had Shot Jackson drastically over-wind his bridge pickup.

Anyone who wants to experiment with hi-fi (low turns, parallel coil) Filtertrons can do so and decide for himself how he likes the result.

Excerpts from the Filtertron patent:

In accordance with the present invention pickups may be constructed which electrically reproduce the acoustical output of the vibrating musical members with full fidelity because they have response characteristics that are linear over a frequency range at least as great as that of the audible range of musical instruments. The resonant frequency of these pickups, in contradistinction to prior-art devices, which usually had a resonance within the audible range, is in the order of 20 kc. or more. Also, the electrical parameters of the new pickups of my invention are such that the linear response normally will provide the desirable constant velocity response characteristic, i.e., rises evenly and smoothly at 6 db per octave.

...the inductance and distributed capacity of the pickup are such that its resonant frequency is 20 kc. or greater. Even with the usual length of coupling cable and the amplifier input component parameters considered, the resonance is still outside the normal audible range.

The two ends of the wire forming coil C1 and the two ends of the wire forming coil C2 are connected in phase electrically, either by physically connecting them in parallel, or connecting them in series (as shown at terminals T1 and T2). In either instance, whether a series or a parallel wiring connection is made, the electrical phasing is such that the signals generated in coils C1 and C2 by any one movement of a string are effectively complementary and made to aid each other in either a voltage or a current sense.

Because several hundreds or thousands of turns of wire are used in each of the coils C1, C2,...

[big_teee]

I have some Mojo 8-string bobbins. I'll try to remember to take a look this weekend.

That would be great.
They show the bobbin but give no dimensions.
8 String Humbucker Screw Side Bobbin Black
Thanks,
T

[Jason Rodgers]

I have some Mojo 8-string bobbins. I'll try to remember to take a look this weekend.

[big_teee]

Been looking for Filtertron Bobbin Dimensions.
I have this, but if you have any other Filtertron bobbin dimensions please post it here.
Here is what I have come up with so far.
Thanks,
T
**Here is some Filtertron widing data to go with Dimension data.
http://music-electronics-forum.com/a...ickupsinfo.pdf

[big_teee]

If anyone has a pickup in particular that I can work up data for, let me know?
I'll see what I can do.
You will need the following bobbin data.
Core Length, width, height, and flange diameter, all data in Inches.
T

[big_teee]

Any 8 string bobbin data out there?
If anyone has a 8 string plastic bobbin they could measure, I'll put it in my Database.
Also any Music Maker bobbin core data would be appreciated.
Thanks,
T

[big_teee]

Here's some basic full sized blade humbucker info I just came up with, after measuring some old Guitar USA bobbins.
Not sure if these bobbins are like others currently available.
I also have 43, & 44 bridge data available if anyone needs it.
The Flange is actually .700" wide.
I use .5700" for calculations, because the wind channel is less on the end than on the sides.
Thus reasonably limiting the turns count available.
T

[copperheadroads]

I only have the one spacing which is 2.40"

[big_teee]

Thanks Copper.
Is that still a 61mm, or 2.40" spaced bobbin?
You can give that in inches or mm.
I presume neck and bridge bobbins are the same?
T
**edit
So that ends up with something in the ballpark about like this screen shot?

[copperheadroads]

WSC 7 string bobbins from Mojo
length of core 2.67"
H .233"
W .256"
Flange .690"

[big_teee]

Hi All:
I took a stab at 7 string bobbin dimensions. See Pic.
Can someone measure the internals of a 7 string bobbin and let me know if mine is correct?
So if need be, I can correct my Data!

Thanks,
Terry