P-90 sized humbucker build

[pulpadded]

I am new to winding. I have mostly done Dimarzio style and rail humbuckers and P-90s. I had a friend ask me to make him humbuckers in a P-90 case, he is really only concerned with it being hum cancelling.

Doing some research on how they are designed, I had two thoughts"

- put a mini humbucker in a P-90 cover without holes

- build something between a p90 and a mini humbucker in a humbucker case similar to other designs, like this

Like one of these options, either one large magnet in the middle or one on each side

I would need to dry test to see if they fit, but any considerations on this idea?

[stratotarts]

The "large humbucker magnet" looks wrong. The magnetic field lies across its width, you have it connecting with the pole in the middle, as though the magnetization were along the shortest side, i.e. the thickness

The upper diagram shows a classic "sidewinder". It would work with the correct magnet orientation. If you don't want to go deeper, you could use Neo's there. Another option would be to use the same dual magnet scheme as the P-90, and it would be more authentic.

Tall coils turned sideways on a sidewinder won't be very efficient. Most of the coil will then be quite distant from the string field.

It will be very difficult or even impossible to reproduce P-90 tonal characteristics in this package because of the lower efficiency and difficulty in obtaining a high inductance. You might ask the person you're doing it for, about that, whether it matters to them.

[nuke]

Well, Gibson did this, in the form of the P100 pickup. It is a stacked humbucker, that fits in P90 form, though it is a bit taller due to the stacked coil design. They're not popular, mostly because they look like a P90, and people expected a P90 sound. 

As a result, you can pick them up pretty cheap. 







Here's a Bode plot of this particular pickup. 


 

[pulpadded]

Thank you for your feedback. As I mentioned, the user is not very concerned with the P-90 sound. Cutting hum is their bigger issue.

Where would the best place to put the magnets be on a sidewinder build?

[ms]

Lindy Fralin makes a P-90 sized sidewinder using Alnico rods (www.fralinpickups.com/product/hum-cancelling-p-90-alnico-rods/ )  Some discussion here: guitarnuts2.proboards.com/thread/8482/lindy-fralin-hum-canceling-alnico .

[pulpadded]

Thank you, I had read that post which is what made me consider sitting the bobbins on the side and magnetizing the poles using that.

Would that work as I drew it?

What would be the difference between that and sitting the bobbins upright? I was considering placing two mini humbucker bobbins with P-90 poles between them and a magnet beneath. How would that work?

My main purpose is to make as simple of a humbucking pickup that will fit in a P-90 case, if possible with P-90 poles in the center, as possible.

[ms]

May 9, 2024 13:19:30 GMT -5 pulpadded said:

Thank you, I had read that post which is what made me consider sitting the bobbins on the side and magnetizing the poles using that.

Would that work as I drew it?

What would be the difference between that and sitting the bobbins upright? I was considering placing two mini humbucker bobbins with P-90 poles between them and a magnet beneath. How would that work?

My main purpose is to make as simple of a humbucking pickup that will fit in a P-90 case, if possible with P-90 poles in the center, as possible.

I agree with stratotarts post.

As for putting the bobbins upright, both coils need their own poles or slug.  It might be a bit of a mechanical mess, but I guess you could mount minihumbucker components into a P-90 case instead of the normal metal one, but there might be some issues getting to work out.  Mini-HBs seem like a bunch of components stuffed into a cover.

Edit: I forgot the lower diagram in your original post.  The magnets would magnetize the slugs in the coils that  would magnetize the screws that would magnetize the strings.  I do not think you will get enough field to the strings.

[gckelloch]

May 8, 2024 0:45:23 GMT -5 nuke said:

Well, Gibson did this, in the form of the P100 pickup. It is a stacked humbucker, that fits in P90 form, though it is a bit taller due to the stacked coil design. They're not popular, mostly because they look like a P90, and people expected a P90 sound. 

As a result, you can pick them up pretty cheap. 







Here's a Bode plot of this particular pickup. 


 

Funny that people say they sound so different because that plot is virtually identical to the P90 LP plot in GuitarFreak 6.6 with 500k pots and the 10'/500pF cable option. I'm thinking there might be something about how ~1/2 the winds on each bobbin affect the sound and efficiency. My understanding is that a wider short coil increases inductance. The magnet also looks like ceramic, which would not avert the flux lines from the strings from entering the lower coil. Perhaps such a design with 1/2 height bobbins to spread the winds out (as in Bill Lawrence's no longer made noiseless Wilde L490 design), along with magnets of decent permeability like A2, A3, or A4 would make it more like the P90 sound? You might also cut and attach Steel spacers to the magnets at the bobbin ends to pull the outer string flux lines in. I could be way off on this last idea, but I don't think the screws or slugs in the bottom coil need to be magnetized. In fact, the flux going to the strings might be reduced if they are in or even touch the center bar the magnets abut.

[ms]

If the bode plots are the same, given the same measurement conditions, then the inductances are probably pretty close.  It is the upper coil that counts for signal output.  The goal is not get any flux from the vibrating strings into the bottom coil because it is electrically out of phase and causes a loss in output.  So if the "dummy coil" at best contributes no output but the total inductances of the P90 and P100 are the same, then we would expect the P100 to have less output.  That might be why people think it sounds different.

[gckelloch]

Considering the height of the peak of the P100 (~3dB?), with 500k pots and the 10'/500pF cable option, that P100 might be more like 6.5H than the 8.2H of the LP P90. I assume the thinner coil and/or loss from coil coupling in the P100 might account for that if it also has a total of ~8.5k of 42AWG wire.

Notice the P100 bode plot has some wavering above 2kHz. Could that be slight cancelations caused by outer flux lines coming off very short opposing phase string wavelengths? Is that indeed part of the sound of a P90, and would the effect be more pronounced if the coil were as wide as in a P90?

Perhaps shorter bobbins could be made with Fender flatware, and held together by glued-in Steel bushings that fit whatever magnetic Steel screws can be procured. Winding to ~10k might offset any coil coupling, but the output will still be a bit lower than an equal inductance P90 with the same flux strength, and let's not discount the effect of the AC hum harmonics. That could be the "airiness" of which some p90 users speak.

You could try placing Steel spacers above C8 magnets to both draw the string flux lines in and have strong flux, although the pickup would be a bit taller. . Again, I'd think the flux going to the strings would be reduced if the Steel poles in the bottom coil touch the center Steel spacer, but the alloy type and mass would have to be the same for both coils to get full hum cancelation.

The problem then becomes how to keep the whole structure together. You could possibly use double-stick tape until you get the wind count and magnet type where your client wants, and then glue it all. Sounds like a lot of time and work. Hope it's worth it for you.

[nuke]

So - I still have the P100 set I took out of a 1995 ES-135. 

I have the data from measuring them and that's one of the first Bode plots I took after getting the integrator box a few weeks ago. 

I'm not using the same setup everyone else is using. I have a Rigol MSO-5000 oscilloscope with a built-in Bode plot function which uses the scope's built-in arbitrary waveform generators.  I set it to create a very detailed plot with small increments between frequency steps, then exported the raw data to Excel to plot it.  The wiggles you see are likely just increased detail from the method I used, not very meaningful. I think the plots that most are plotting don't have as many steps as I used in this particular plot. (needless detail on my part).


P100 
Bridge:
Screws north, 420-500G, alnico bars,  positive coil phasing
Ls @ 100hz 5.6H
Q @ 1khz  2.6
Cp @ 100khz 224.5pf 
DCR 9.45k @ 73F

Neck:
Screws north, 420-500G, alnico bars, positive coil phasing
Ls @ 100hz 3.68H
Q @ 1khz 2.78
Cp @ 100khz 208.8pf
DCR 6.222k @ 73F



One thing I will add, in my opinion, the Bode plot and measured data are comparable between pickups constructed a similar way. When comparing a P90 single coil, to a P100 stacked humbucker, the magnetics and coil configuration is different. The bottom coil "bucks" the hum, but I don't think it contributes much to the signal output. Thus, the effective inductance is lower, probably about half the measured value. 


P100 vs P90 vs Mini-humbucker:


The P100 has alnico magnets, just like the P90 magnets and spacer bar assembly. They're just sandwiched between two P90 bobbins with longer screws. The P100 lacks a baseplate, and the keeper-bar is threaded. There's a copper tape around the lower bobbin, that's soldered to the shield wire and in contact with the keeper bar to ground the magnets and pole screws.

The P100 does not sound much like a P90. I had P90's in this ES-135 for a number of years. I eventually put the P100's back in for a few years. The 100's are somewhat brighter, lower in output, and don't have that kind of pronounced growl that P90's have. This particular ES135 is acoustically kind of dark sounding.

I have Gibson minihumbuckers in it now, which I like better. Very good hum-cancelling, a bit more bite and brightness. They look cool and fit right in, just like they do on Les Paul Deluxe, same metal mounting plate in the ES-135 that accepts either soapbar p90/p100's, or mini-humbuckers. 

[gckelloch]

5.6H with 9.5k of 42AWG is very low. I'm not sure how coil coupling works, so I only assume it's the Steel screw passing through both coils that reduces the inductance, but the proximity of the coils or any high permeability alloy near both coils might cause the same thing.

On third thought, it would be easier to just use two P90 bobbins as they are. You can get a slightly wider coil with the old double-insulation Heavy Formvar wire if you want. You might get higher inductance and output efficiency, as well as the least cancelation between coils by taping or gluing some very thin Steel plates on the top and bottom of C8 magnets. The distance from the Steel plates to the bottom coil might then be enough to eliminate coil coupling, and C8 will not conduct flux from the top to the bottom Steel plates. Probably best to ground all the Steel, but I again assume you'd want to keep the Steel in the cores separated to minimize and flux transfer. The bottom plates and screws should not touch the Steel center spacer bar, but you might need to ground them to minimize hum. I'm thinking Cu tape with a conductive adhesive side could be used to secure the entire structure? The inductance and output efficiency might end up a good bit higher than the old P100 at the same wind count, but I wouldn't be afraid to try at least 10k of HF 42AWG anyway. The slight increase in DCR should have no significant effect on the result.

[pulpadded]

I appreciate everyone's input, I want to confess a lot of what is being said is definitely beyond me currently. I am very new and my main concern is constructing something that works and sounds good, regardless of what kind of standard pickup it sounds like.

I am trying to determine the takeaway from what has been discussed to decide what the best way to wind these humbucking pickups in a P-90 cover would be. As the cover has slots for poles, I would prefer to use them. I could also cut down dummy poles and hope a mini humbucker would be high enough magnetism to work through the cover; I did that with a Dimebucker once under a Jazzmaster cover, but that pickup is much higher output and magnetism.

For an idiot, what is the big takeaway of the last few comments? Explain like I am a child. What would be the best, relatively simple, way to construct this pickup? Having a smaller pickup is a large cover doesn't bother me too much, I can glue it down before potting.

[gckelloch]

Oh, if he doesn't need it to sound quite like a P90, just do a mini-HB design. To get maximum hum cancellation, you should use the same poles or blades in each coil and wind each coil the same. Raising the poles or blade higher in one coil would make the string vibrations in that coil dominate the output without affecting the hum cancellation or inductance to make it sound more like a Steel core P90, assuming the inductance is in the 7~9H range. Who can say what magnet strength he prefers?

This Stew Mac Firebird PUP kit looks interesting:

www.stewmac.com/kits-and-projects/electronic-kits/pickup-kits/firebird-mini-humbucker-pickup-kit

The power at the top of the A2 bars should be ~500G, which is nearly 2x that of a typical steel pole HB with one A5 magnet, and the included Steel plates affect the results. The bottom plate draws the flux lines from the strings through the coils for increased "punch". The result will still sound brighter than a Steel core HB if you use plastic or NiSi P90 covers, so you might inquire if your friend wants 250k or 500k pots, and wind accordingly. The inductance will be much lower than a Steel core HB with the same wind count. I'd use a single-build insulation 42AWG or thinner wire for the most flexibility to increase inductance on those small bobbins.

[pulpadded]

I appreciate your help! I would probably assume he would drop in 500k.

I wonder if I could put C5 or C8 magnets in place of those.

Do you think the magnet would be strong enough to pick up through the case of the P-90 if I left off the cover of the mini?

Could I fit the poles of the P-90 between the coils, for cosmetics, since these coils don't need to be connected by a single magnet below them like a standard humbucker or mini deluxe?

[ms]

May 16, 2024 9:59:32 GMT -5 pulpadded said:

I appreciate your help! I would probably assume he would drop in 500k.

I wonder if I could put C5 or C8 magnets in place of those.

Do you think the magnet would be strong enough to pick up through the case of the P-90 if I left off the cover of the mini?

Could I fit the poles of the P-90 between the coils, for cosmetics, since these coils don't need to be connected by a single magnet below them like a standard humbucker or mini deluxe?

You might lose output level with the C magnets, hard to say.  The Alnico has low permeability but it is probably more than the ceramic.  The permeability of magnets in the coil helps guide the flux from the vibrating strings through the coil, increasing output.  I would stick with the A2. The stronger C might cause problems similar to a strat pickup too close to the strings; again, hard to say for sure.  Stew mac says the output of their firebird kit is more than a standard minihumbucker.  I am not convinced. Usually removing steel poles and slug decreases the output, but raises the resonant frequency and increases the Q.  Fake pole pieces?  Not for me, that's for sure.

The P-90 cover is plastic.  It spaces you down a bit, but it is not magnetic and does not alter the flux from the magnets going up to the strings, or the flux from the strings coming back down through the coil.

[gckelloch]

A2 also has higher permeability than A5, and I wouldn't even recommend A5. Two A5 bars so close together would create ~2x the string pull in the same portion of string as an A5 pole Strat pickup, which is already too much pull in my book. There may be slightly less pull if some of the inner flux lines from each bar are drawn directly to the other bar and the center Steel plate, but I'd stick with the A2 bars. With that level of flux strength into the strings and the increased efficiency the Steel plates add, I'd think it would be higher output than a typical PAF of the same inductance. Maybe Gibson Firebird pickups don't include the Steel plates?

Anything sticking out above the top of the P90 case will further limit how close the top of the A2 bars are to the strings. Generally, you want the tops of the bars to be not much more than 4mm from the low E and 2.5mm from the high, so you do the math. Separating the coils to put fake poles between them sounds like a hassle. Why not use gold foil or any very thin decorative sheeting on top of the pickup bobbin instead? Wanting the look of a P90 with fake poles regardless of the sound is an odd request anyway. I'd expect some level of compromise with this design.

The thin & short Firebird bobbins limit the total winds of 42AWG to the point that I don't think you can even get the inductance with AlNiCo bar cores up to a low PAF-type level of ~3.6H. You'd likely need at least one wire gauge thinner for that. The AlNiCo bars also don't roll off the high-end as Steel does, so they will be rather bright, like AlNiCo pole Strat pickups would be, with 500k pots. It would be easier to just wind them to Strat level inductances (~8k?) of 42AWG, or the equivalent in winds of thinner wire, and use 250k pots.

The max I've read of 42AWG on a Firebird bobbin is 3.85k/5071 winds with a machine. I'd think two of those with A2 bars in series would be in the low 2H's, which would be nice for the neck. 43AWG wire should allow ~1.35x the winds, which might allow up to a punchy 3.2~3.5H Tele bridge pickup, the bottom Steel plate increasing heft. People generally prefer that to a 2.3~2.8H Strat bridge pickup. You could forgo the bottom Steel plate for the neck pickup. It's a subtle difference in Strat pickups, but some prefer a less meaty sound in the neck. Your client can use a 1.5~2nF cap on the tone pot if he wants P90-like sounds with the pot down below 5. I recommend trying that anyway unless he's married to very dark sounds. I also recommend a low capacitance cable b4 the first preamp stage for a smoother extended high end with the tone knob up.

[gckelloch]

No doubt you've seen the cheaper Mimni-HB kit:

www.stewmac.com/kits-and-projects/electronic-kits/pickup-kits/deluxe-mini-humbucker-pickup-kit

I'd be surprised if the mass of the screws equals that of the bar, which would ensure max hum cancelation, but you can get those Steel bars:

www.stewmac.com/electronics/pickups/bar-slug-for-deluxe-mini-humbucker

Mini-HB bobbins are normally taller than Firebird bobbins, but both of these models use the same bobbin. The result with this kit should be ~2x the inductance of the Firebird PUP for the same winds plus the high-end roll-off the Steel bars cause. The string pull with an A5 magnet will also be ~1/2 of the Firebird. It will be much darker sounding and with a softer attack. 500k pots would be standard. You'd probably need at least 43AWG wire to get into Steel core 7~8H P90 territory-- maybe not with two Steel bars. Chrome-plated Steel spacers could be fit on either side of the magnet that the Steel bars can sit on. Steel spacers of various sizes can be found online. The Steel plates from the Firebird PUP are also available, but I'm not sure any minor improvement would be worth the cost, and the Steel bars will strongly attract the flux lines above them anyway. It may not be significantly louder than a ~1/2 inductance level Firebird PUP with 250k pots, but it will have less high-end extension and a softer attack. The high-end extension of the lower inductance Firebird pickup will ultimately be more versatile and with a more crisp attack character. I'd ask your client which they'd prefer b4 proceeding.

Lastly, I'm a stickler for aligning HB coils with the strings, especially at the bridge pos. If the PUP is tilted up even 1/2mm, that coil will dominate the sound. You might try to make a bar with two screw holes that can attach to one side of each pickup, or find a baseplate that already has that. Of all the nitpicky things we guitarists go on about, the combined effect of per coil + magnetic power is at least as valid.

[nuke]

May 18, 2024 16:39:23 GMT -5 gckelloch said:

Lastly, I'm a stickler for aligning HB coils with the strings, especially at the bridge pos. If the PUP is tilted up even 1/2mm, that coil will dominate the sound. You might try to make a bar with two screw holes that can attach to one side of each pickup, or find a baseplate that already has that. Of all the nitpicky things we guitarists go on about, the combined effect of per coil + magnetic power is at least as valid.

Have you done any tests or data you can share? I've not found it to be critical just listening to how they sound. 

I work a lot with Schaller humbuckers, which unlike most pickups, have mounting systems that allow for precise control of tilt along the string, as well as height, using a 4-screw adjustment.

Maybe I'll try looking at the coils individually on the 'scope to see how much difference it makes. 

[gckelloch]

No data. I just use my ears with amp sim software and headphones, and I can be a bit cork sniffy. I even found tilting my Tele Micro-Coil bridge pickup has an audible effect on the high E.

[pulpadded]

Thank you!

I mostly build from individual parts rather than kits. Could I use A2 magnets with in place of the pole pieces on a deluxe use a second bar?

[gckelloch]

May 23, 2024 12:05:38 GMT -5 pulpadded said:

Thank you!

I mostly build from individual parts rather than kits. Could I use A2 magnets with in place of the pole pieces on a deluxe use a second bar?

So, just an A2 bar in each coil? I don't see why not. You could also try Steel spacer bars below the coils for more punch. You'd need to figure out how to keep the pickup together if you don't use the NiSi cover. I guess you'd also need to drill holes through the P90 cover to access the pickup height screws and direct mount it?

I was mistaken about the small Steel plate in the Firebird kit. It's placed on top under the top two strings, perhaps to moderate the field? I don't see why that's necessary.

If your client wants the softer attack of a typical PAF, you could use a Steel Bar in each coil. For versatility, I strongly recommend winding to no more than a total of ~7.5k of 42AWG (or an equivalent of thinner gauge), and maybe less for the neck. 500k pots would then work well. An excellent quality low (~200pF) C 12' Sommer Spirit LXX cable with HICON noise-free connectors can be had for ~$25 from here:

store.haveinc.com/p-62046-sommer-cable-300-0091-sc-spirit-llx-low-loss-instrument-cable-per-foot.aspx

The low C cable will allow better articulation over 4kHz, and a 1~1.5nF cap on the tone knob can be used to get P90-like 2kHz bite when turned down, with other nice sounding options along the sweep.

[pulpadded]

I appreciate all of the input!

Here is what I got:

- Two sets of bobbins www.mojotone.com/Mini-Humbucker-Bobbins

- Two sets of rails www.mojotone.com/Mini-Humbucker-Bar-Slug

- Two baseplates (I know they are the wrong kind but the slug should sit on it, they are out of stock of the firebird sort)  www.mojotone.com/Mini-Humbucker-Short-Leg-Frame-Nickel-Silver-50mm

- Two covers www.mojotone.com/Mini-Humbucker-Firebird-Pickup-No-Hole-Cover-Chrome

I also bought an assortment of magnets, from A2 to A8. Is everyone coming to the conflusion A2 is the best option? The customer plays a lot of doom metal but didn't want the pickups to be much hotter than the stock P-90s, only less noisy with gain.

I also bought these

i.ebayimg.com/images/g/aNoAAOSwqJJfOvzs/s-l1600.webp

And realize, if I am putting them in a soapbar route, they might need these.

i.ebayimg.com/images/g/zycAAOSwFglkwvgW/s-l1600.webp

I am thankful for all of the input. Compared to standard humbuckers, these are going to cost a good bit more per pickup.

[gckelloch]

I think you'll also need some type of spacers under the bobbins so they are supported. Steel spacers might increase efficiency and may spread out the aperture window a bit if on the outside edges below the bobbins. I don't think mini-HB bar magnets will fit between the Steel blades in the coils, so it will likely be half bar magnet and half Steel spacer under each blade. Not sure how that will affect the flux power going to the strings. Half the surface contact area to the blades vs shorter spacer bars might distribute the flux more evenly to each bar? I'm just speculating.

Assuming you will use the Steel blades as the poles, the flux from the strings won't be as strong as it would be with bar magnet poles. P90's have various magnetic strength, so which bar magnet to use is anyone's guess. With two covers attached to each pickup, you'll lose at least 2mm height from the top of the Steel blades to the strings compared to the top of a pole screw flush with the top of a P90 cover. You might go with the A8 bars in that case. If the client is expecting them to sound like P90s, you'll likely need to use at least 43awg to get the inductance into the 7~8H range. They will then be "one-trick-ponies" compared to ~4H pickups with a 1~1.5nF cap value on the tone knob. I'd ask the client what they think of that idea.

[nuke]

Just for informational purposes, here's a page with details of Gibson Firebird pickups, including both upright bobbin and side-winder versions and some good internal shots of them. 

They'll fit in soapbar routes too. 


www.heliotricity.com/firebird-pickups/ 

Be certain to watch the Jonny Winter video on that page for an idea of what Firebirds are all about.   

[gckelloch]

May 28, 2024 19:50:01 GMT -5 nuke said:

Just for informational purposes, here's a page with details of Gibson Firebird pickups, including both upright bobbin and side-winder versions and some good internal shots of them. 

They'll fit in soapbar routes too. 


www.heliotricity.com/firebird-pickups/ 

Be certain to watch the Jonny Winter video on that page for an idea of what Firebirds are all about.   

Cool article. I'm not sure the taller mini-HB bobbins would fit sideways in a cover with a typical width magnet bar between them. I don't get how a sidewinder cancels hum without canceling the string signal as well, but they do work. BTW, the "guy named Bill Lawrence" (Willi L Stich) eventually abandoned sidewinders for a type of magnetically isolated stacked SC design. It's essentially the same thing, but sometimes includes side and end mounted magnets between the coils. I guess the coils can be more completely isolated so the string flux doesn't reach the bottom coil at the bobbin ends?

There may be something to the sound of the thinner aperture window of a P90 if that is desired. A bar magnet could be used in the core of a stacked design with Steel bars surrounding it between the coils, and Steel bars on top and bottom, but the top bar could accept pole screws, maybe after being filled with solder and drilled out to the screw shaft width. Solo Guitars sells all shapes and types of such bars. You might need a more narrow bar magnet with P90 bobbins, but I don't think the coil widths are nearly as important to the sound as the aperture window, core alloy, and inductance. Again, you might need 43AWG wire to get 7~8H with stacked Mini-HB bobbins.

[ms]

May 29, 2024 3:29:19 GMT -5 gckelloch said:

May 28, 2024 19:50:01 GMT -5 nuke said:

Just for informational purposes, here's a page with details of Gibson Firebird pickups, including both upright bobbin and side-winder versions and some good internal shots of them. 

They'll fit in soapbar routes too. 


www.heliotricity.com/firebird-pickups/ 

Be certain to watch the Jonny Winter video on that page for an idea of what Firebirds are all about.   

Cool article. I'm not sure the taller mini-HB bobbins would fit sideways in a cover with a typical width magnet bar between them. I don't get how a sidewinder cancels hum without canceling the string signal as well, but they do work. BTW, the "guy named Bill Lawrence" (Willi L Stich) eventually abandoned sidewinders for a type of magnetically isolated stacked SC design. It's essentially the same thing, but sometimes includes side and end mounted magnets between the coils. I guess the coils can be more completely isolated so the string flux doesn't reach the bottom coil at the bobbin ends?

There may be something to the sound of the thinner aperture window of a P90 if that is desired. A bar magnet could be used in the core of a stacked design with Steel bars surrounding it between the coils, and Steel bars on top and bottom, but the top bar could accept pole screws, maybe after being filled with solder and drilled out to the screw shaft width. Solo Guitars sells all shapes and types of such bars. You might need a more narrow bar magnet with P90 bobbins, but I don't think the coil widths are nearly as important to the sound as the aperture window, core alloy, and inductance. Again, you might need 43AWG wire to get 7~8H with stacked Mini-HB bobbins.

Sidewinder: Flux from the vibrating magnetized string comes away from the strings  between the two coils.  Since magnetic flux lines have no ends, they must curve back to the string, passing through the two side-mounted coils, but in opposite directions.  (One points "left", the other "right".)  Therefore the coils must be wired with opposite polarity so that signals add.  Flux from hum sources is much farther away than the strings, and therefore lines are much straighter.  The sensitivity is to flux pointing through the two coils, but since they are wired with opposite polarity, the hum signal cancels.

I can find no indication in the article of what the core is of the firebird sidewinder pickup coils.  Without knowing its approximate conductivity and permeability, there is no way to analyze how they would sound.

The firebird side by side should sound similar to a strat pickup because the core material has low permeability (compared to steel) and low conductivity (also compared to steel).  Therefore, the inductance is lower than a standard mini hb and so the resonance is higher in frequency, and Q is higher because of the lower eddy current loss.  When setting up to get the sound you want, it is usually easier to throw out highs rather than to bring them back (except through more distortion; that is easy but the highs are not the same as those from a pickup itself).  Output is lower with such a pickup, but nothing is easier than getting more gain.  Therefore, firebird pickups should be flexible.

[pulpadded]

It looks like, from the kits I can find, Deluxe mini hbs use one magnet making contact with the slug and poles.

Firebird minis use two alnico magnets in place of slugs.

What would the difference be? How is the Firebird magnet oriented?

Could I use a Deluxe mini build but with two slugs, no poles, and a magnet below?

[nuke]

Here's a link to the patent, with claims and details of the design. 


patents.google.com/patent/US3902394A/en 

It's a short read, informative. All the coils and components are described as interchangeable, the pole pieces are described in the patent as, "iron" and the magnet is ceramic. It seems to be an exercise in minimizing cost and easing manufacturing. 

I don't think there's any magic there.  

The regular Firebird pickup has the typical vertically oriented bobbins with blades. They tend to be bright and crisp, kind of strat like, low-output, while being humbucking. 

[ms]

May 29, 2024 15:41:15 GMT -5 nuke said:

Here's a link to the patent, with claims and details of the design. 


patents.google.com/patent/US3902394A/en 

It's a short read, informative. All the coils and components are described as interchangeable, the pole pieces are described in the patent as, "iron" and the magnet is ceramic. It seems to be an exercise in minimizing cost and easing manufacturing. 

I don't think there's any magic there.  

The regular Firebird pickup has the typical vertically oriented bobbins with blades. They tend to be bright and crisp, kind of strat like, low-output, while being humbucking. 

OK, so the "sidewinder" firebird pickup (the subject of that patent) uses iron core coils, and therefore does not have a high Q bright sound, maybe with the intention that this pickup would be used with much larger amounts of distortion that the neck pickup.