Rickresource Rickenbacker Forum

ken_j wrote: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.

The "lipped" bobbins are fairly willowy affairs. The plastic is thin and where the screws pass through , a bit of the surrounding plastic is drawn in . The screws are what hold the two plastic pieces in place.
They are wrapped with a layer of electrician's tape prior to winding.
The same is true for the later resin bobbins. Jason Lollar(when he made a horseshoe) used a fiber bobbin with a solid center. To my ear there's not a great difference in tone but perhaps Jason took that into account.

Does anyone have pictures of an original bobbin/internals.

ken_j wrote: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.

Ken, It is very good question.
Yes, I also feel fixed importance about the center core piece of this bobbin.
In fact, for making by handmade of the bobbin, I think difficulty is lower for making a later types(does not have the center section).
However, I decided to copy the composition of the type of this time and the early type of Horseshoe bobbin and not the later types.
The bobbin made from bakelite of Lap Steel has a center section(injection molded).


I built the bobbin with the thickness of 6 mm for this center section at the beginning (Above is side view of my Version-1 bobbin - Already introduced to you).
In order to give fixed intensity to a bobbin, since the thickness which is not damaged when letting a screws pass is required, it is the numerical value which I deduced.
Pole piece screw(#5-40 UNC) diameter: 3.15 mm
Bobbin mount screw(#6-32 UNC) diameter: 3.48 mm

However, the thinner possible one considered that I was more good, then I remade the center section by the thickness of 5 mm.
This is my Version-2(It is the just completed yesterday.):


Since I do not own a high-precision machine tool and I am not a professional work engineer, this is a limit of my manufacturing skill.

Koji, your manufacturing skill is certainly not limited, nice work indeed.

i'm not sure of the internals of the later HS, but 69 on when they went to the standard pup, both upper and lower plates were threaded meaning a bobbin wasn't needed, how this changed the sound, again I have no experience with the original HS, all interesting stuff though.

Thank you, Sean(Mr. Singleton),

I am not sure details of the bobbin internals of the early type Bass Horseshoe I has not seen it, but I am sure in Bakelite Lap Steel bobbin has the center section I have seen.
About the difference in the sound quality depended on those without/with this center section, I do not know for a however big difference to come out yet. Since it is thin if it is version-2 bobbin which I made, I think mostly that it is same now.
Moreover, it is also possible to make this center section still thinner and to make from the design to which a polepiece and a coil are touched. However, I thought whether it would become a different type of the bobbin.

You obviously have the dimensions at a minimum which was hard to tell from the photos. I know current RI toasters and high gain pickup bobbins have a center section. I personally don't know enough to say what the difference would be between the two methods. I was just putting the question out there hoping that someone with more experience and knowledge may know are share that with us.

Seans wrote:Does anyone have pictures of an original bobbin/internals.

Here's an original bobbin, that has been rewound.

Good thread BTW!

cjj wrote: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).

You have been warned!
:
OK, you're safe now, the Techno-Geek portion is finished...

Thanks cjj
"Clarity" hm? I guess it’s higher frequency overtones.
I always try to pull out some simple principles to remember, and from what you’re saying I get
More turns -> higher output, higher inductance, higher capacitance
Higher inductance -> reduced high frequencies response
Higher capacitance -> reduced low frequencies response (?)

Wiker wrote:

cjj wrote: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).

You have been warned!
:
OK, you're safe now, the Techno-Geek portion is finished...

Thanks cjj
"Clarity" hm? I guess it’s higher frequency overtones.
I always try to pull out some simple principles to remember, and from what you’re saying I get
More turns -> higher output, higher inductance, higher capacitance
Higher inductance -> reduced high frequencies response
Higher capacitance -> reduced low frequencies response (?)

No, that is wrong. Higher capacitance -> increased low frequencies response
hm...

Both higher capacitance and higher inductance lead to reduced high frequency response...

Koji, if I was to make a pickup myself I would make it like yours. I would much rather have adjustable pole pieces like that, as it seems magnetic horseshoe pickups are very sensitive distance between string and poles.

ken_j wrote:You obviously have the dimensions at a minimum which was hard to tell from the photos. I know current RI toasters and high gain pickup bobbins have a center section. I personally don't know enough to say what the difference would be between the two methods. I was just putting the question out there hoping that someone with more experience and knowledge may know are share that with us.

I don’t have "more experience and knowledge" , but what I’ve read is that having the wire closer to the core increase output (and high frequency response ?). But the center of the bobbin is not the only factor determining the width of the coil. Thicker wire will make the coil grow fatter. Also, the width is affected by how tight it's wound - how much tension is put on the wire when winding it up.
On the toaster I once unwound the wire filled the bobbin almost to the rime. When I rewound it myself with the same number of turns it ended up much smaller, so I obviously had more tension on the wire (and/or the wire I used had thinner varnish).

The width of the coil affects the tone in some way, which is beyond my comprehension. In my mind I get the idea of a wide coil responding to a wider section of the string, whatever the result of that is.

cjj wrote:Both higher capacitance and higher inductance lead to reduced high frequency response...

Ah , I had to re-read the last sentence.

cjj wrote: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.

Wiker wrote:Koji, if I was to make a pickup myself I would make it like yours. I would much rather have adjustable pole pieces like that, as it seems magnetic horseshoe pickups are very sensitive distance between string and poles.

Problem there is if you adjust them ( like any of the pre 73 pups) you take the pole away from direct contact with the shoe ( or Magnet), which in turn will affect the transfer of magnetic power away from the pole. Not to mention on those 69-73 versions where you turn the E or G pole and cut the coil .

this is a great thread ! are there any fotos of an un-wound original bass bobbin coil ?