Remaking The Horseshoe Bass Bobbin

[johnhall]

John Hall has stated a couple times that the only wire they ever bought for coil winding was 44 AWG but the lapsteel bobbin I have has closer to 42 AWG on it. The 1968 hi gain coil I have had a look at also looks to be heavier wire than 44 AWG.

Take a piece of that wire you think is #42 and soak it in lacquer thinner to dissolve the incredibly thick varnish these old magnet wires were made with. Then measure it and I think you'll find that it's closer to #44 than #42.

That thick varnish did have a positive benefit of making the wire less susceptible to stretching which can significantly reduce the effective diameter of the wire. Unfortunately, it can also increase the capacitance of the coil, given the extra non-copper space between windings, which dampens high frequencies.

I'll defer to the experts whether the skin effect is relevant to coils like this but the surface area per foot of #42 is vastly greater than #44.

[cjj]

That thick varnish did have a positive benefit of making the wire less susceptible to stretching which can significantly reduce the effective diameter of the wire. Unfortunately, it can also increase the capacitance of the coil, given the extra non-copper space between windings, which dampens high frequencies.

I'll defer to the experts whether the skin effect is relevant to coils like this but the surface area per foot of #42 is vastly greater than #44.

Umm, you've got the capacitance backwards. Capacitance is proportional to the overlap area of two conductors and inversley proportional to the distance between them. So, the smaller the distance, the larger the capacitance.

So, thicker varnish means lower capacitance and better high frequency response. The new thinner varnish will increase capacitance and cause more high frequency loss. Now, larger wire, with thinner varnish will be even worse since you have more width of overlap as well as closer spacing.

As for skin effect, this is directly related to the frequency of the signal on the conductor and presents itself as an increased resistance in the conductor due to the signal not running in the full diameter of the conductor. How deep into the conductor the signal flows is known a s"skin depth."

Doing the calculations for 20kHz (considered to be the highest frequency we can hear) and copper, we get a skin depth of 18214.4 micro-inches, or 0.0182 inches. Now, the diameter of 44 gauge wire is 0.00198 inches so, since the skin depth is about 9 times as large as the wire diameter, the entire signal will flow through the wire and skin effect will have no effect. The same would be true for #42 wire with a diameter of 0.00249 inches...

[teeder]

So ...... What wire should be used?

[xsubs]

Here is my winder. I sneak myself to use it when the "boss" is not home. (Hope she doesn’t see this )

That is priceless Geir... great photo!

[xsubs]

Many thanks for everyone.

When I said honestly, it tried in order that I may commission this project the specialist of a certain U.S. at the beginning, but since he was not so interested, I decided to do by myself.

Sean(Mr. Kelly), I also knew the thing in which Sergio's pickup is popular at the members of this forum.
Your pickup and are wonderful!

John(Mr. Alligaier), How do you think about the type of coil wire(types and gauges) for winding the Horseshoe pickup coil?
I have plan to choose 42 AWG Plain Enamel Copper Wire for winding to my bobbin since I would like to pursue the vintage sound.
My target DCR is 6.3k to 6.8k ohms at about 8,000 and more few turns.
However, I think difficulty in choosing the type of coil according to the tone and sound character.

Beautiful job Koji. Sergio wound mine to 6.8K exactly, and it sounds perfect... it also ended up a perfect match to my 7.4K toaster. The two balance really well. What DCR is your toaster at?

[cjj]

So ...... What wire should be used?

The wire that gives the desired results...

[chefothefuture]

Ronald, It has not felt like the ability of me to trust the direction of a mechanical counter rather than an electronic thing, either.
Although the thing of the system which resembled it with the electronic type could also be made, since it was troublesome, I decided to use a simplest and cheap thing this time.

John(Mr. Fay), It is not a silly question at all.
I have used Fillister head machine screws for the pole-pices of my bobbin, size is: #5-40 UNC. It is just same as replacement of Humbucker's.
For your reference: http://www.allparts.com/Nickel-Humbucke ... 53-001.htm
However, I cannot declare correctly whether it is that Ric was using the exact same screw for the Horseshoe Bass Bobbin as this.
For the moment, what I will make my bobbin in response to an order is not considered because I am not a professional pickup builder and I am only an enthusiast.

Interesting...
McMaster Carr has Drilled Fillister head screws in 6/32. The drilled ones are more like the ones Rickenbacker used.
Yours look great. I'm just looking to replace existing screws.
Good luck We're all eager to hear your results.

[johnhall]

Umm, you've got the capacitance backwards. Capacitance is proportional to the overlap area of two conductors and inversley proportional to the distance between them. So, the smaller the distance, the larger the capacitance.

Oops! Got it backwards- that's not at all intuitive to me.

Re: the sewing machine coil winder . . . in the early days here, Adolph used both sewing machines and a washing machine motor for coil winding so it's rather like back to the roots.

Note that some people think coils wound on a Singer sewing machine have better tone . . . the same people, of course, that think silver hook up wire sounds better.

So, which way is it on the skin effect? No guitar is going to hit 20kHz. Is a more typical 1.5-3kHz signal going to have greater or less skin depth?

[cjj]

Umm, you've got the capacitance backwards. Capacitance is proportional to the overlap area of two conductors and inversley proportional to the distance between them. So, the smaller the distance, the larger the capacitance.

Oops! Got it backwards- that's not at all intuitive to me.

Re: the sewing machine coil winder . . . in the early days here, Adolph used both sewing machines and a washing machine motor for coil winding so it's rather like back to the roots.

Note that some people think coils wound on a Singer sewing machine have better tone . . . the same people, of course, that think silver hook up wire sounds better.

So, which way is it on the skin effect? No guitar is going to hit 20kHz. Is a more typical 1.5-3kHz signal going to have greater or less skin depth?

Skin depth gets smaller with higher frequency. Pretty much anything below RF (radio frequency) can safely be ignored as far as skin depth is concerned...

[Moonie Man]

Beautiful job Koji. Sergio wound mine to 6.8K exactly, and it sounds perfect... it also ended up a perfect match to my 7.4K toaster. The two balance really well. What DCR is your toaster at?

Sean(Mr. Kelly), Like your indication, I consider that I should also take matching with Toaster Top and Horseshoe into consideration enough.

I have checked again DCR of my pickups - "Reissue Toaster Top" on front of my RM1999 Reissue Bass.


And, my "Reissue Horseshoe".

[Moonie Man]

Although I should have trying this first to the very first .... It replacing my old Horseshoe with the bobbin of 8-Pole Lap Steel experimentally at this time.


Surprisingly, although the space between a magnet and a pole piece of Lap Steel bobbin was very slight, it can be played without buzzing at all frets by me!

The original Horseshoe sound is wonderful.
It is very natural and there is clear string sound with a feeling of air.
It is very acoustic low bass tone.
(I used strings is set of Pyramid flat wound)

And, there has no noise.
That my old Horseshoe pickup assembly for Lap Steel functioned completely till present.
If this is used as an original for Lap Steel, I think there will be very wonderful sound.

However, the output was high a little for the Bass.
Here is checking DCR:

Or this result is considered to be a thing for the spatial relationship of a magnet, a string, and a polepiece being too near.
Sound will be distorted shortly after picking strongly for this reason without any FUZZ pedal like a "Think For Yourself" tune of young Beatle McCa played.


Anyway, I reconfirmed that there is value of enough which carries out my project by this.

[Wiker]

Balancing pickups, you probably know this already, but just in case.

As far as I know:

Regarding output strength it’s the number of turns that is interesting, not the resistance. Measuring resistance is mostly an indirect way to get an idea of the number of turns, but hard to compare between two different pickup bobbins.
With the same number of turns and same size wire, a smaller bobbing (like neck toaster) will have less resistance than a larger bobbing (like RI horseshoe). Then larger wire will have less resistance, so that two similar bobbins wound with the same number of turns but with different size wire, the one with the thickest wire will have less resistance.

More windings generate higher voltage - stronger output.
More windings increase inductance - loss of clarity.
Higher resistance leads to loss of bass clarity. (Then a thicker wire should give better bass tone clarity.)

I feel I’m in deep water here, so – CJJ, HEEELP!

[Moonie Man]

Geir, Your description is very intelligible. Many thanks!

[cjj]

Yes Geir, you are pretty close. Resistance is a function of the length of the wire and the diameter. For the same length, a smaller wire will have more resistance. And of course, longer length will be more resistance. The size of the core will determine the length of wire per turn (you must remember that as the wire builds on the core, it will take more wire for each turn, and thinner wire will not build up as fast).

If you don't want to read a bunch of Techno-Geek speak, quit reading NOW...

You have been warned!

For a given core material/size/shape and magnetic field, more windings will generate more output. More windings will also increase inductance, but inductance is very dependent on the core material too. A big chunk of iron as a core will have more inductance than an air core for the same coil of wire.

Now, as for the "loss of clarity", I'm not exactly sure what that means as it's not really a term used in electronics. But I'm sure it is related to the frequency response and resonance of the coil. All factors of the coil will affect this, the resistance, the inductance, and the inter-winding capacitance. The capacitance happens because you have a lot of wire close together and it acts like a capacitor.

The resistance has the least affect because resistance is constant over frequency. Inductance and capacitance act like frequency dependent resistors. For inductors, the higher the frequency, the higher the "impedance" (a fancy word that means frequency dependent resistance). For capacitors, the higher the frequency, the lower the impedance.

Now, since the signal travels through the coil, it will look like the resistance of the coil gets higher as the frequency increases because of the inductance. More inductance will mean less high frequency can get through the coil and out to the amp.

The same thing happens with the interwinding capacitance even though its impedance gets lower with rising frequency. This is because the capacitance is between the windings and is essentially shorting out the windings at higher frequencies, causing them to produce a lower output voltage.

OK, you're safe now, the Techno-Geek portion is finished...

[ken_j]

The only thing I would question with this, is the design of the bobbin. This bobbin has a center plastic section. Some pickups are wound directly on the pole pieces or maybe just a layer of tape on the pole pieces. I am not sure how the original HS pickups were constructed. I would think that a thicker plastic bobbin core would result in the windings being further away from the pole pieces. This would affect the inductance of the pickup and ultimately its performance. I am in no way implying that this is not a good design. I am just throwing this out for discussion as I am certainly no pickup expert but I do have a good understanding of how an inductor works.