Firebird Mini Pickups - Extra bright?

[Lester]

I've never had a chance to play through them. Are they even brighter than mini-humbuckers as a general rule? Or does the full metal cover actually dull out some treble?

 

[guitartsar]

Depends on the year. In my experience vintage 60's ones sound better than later 70's. The design changed so that the coils lay sideways and they don't sound as good IMO especially the bridge pick ups that are quite weak and bright. The neck picks ups are more like the vintage design and sound much fuller.

 

[freefrog]

I've never had a chance to play through them. Are they even brighter than mini-humbuckers as a general rule? Or does the full metal cover actually dull out some treble?

IF both have the same coils, like vintage models (and as long as FB PU's are not the "sidewinders" evoked by guitartsar, therefore), yes, FB humbuckers are brighter than mini-HB's.
A mini-HB has a magnet under its coils and a "bar slug" + 6 screws in the coils. Consequence: weaker magnetic field, more inductance and a lower Q factor.
A FB PU has 2 bar magnets IN its coils, hence a stronger magnetism, less inductance and a higher Q factor. It's brighter and snappier - but not quite like Fender SC's, although it has practically the same inductance. IMHO, it's less due to the metallic cover than to the wider magnetic windows.

I have and use both. I prefer the FB model: with the tone pot set @ 7/10, it can sound close to a mini-HB. The opposite effect (emulating a FB PU with a mini-HB) is much harder to do IME. YMMV.

 

[ARandall]

A FB PU has 2 bar magnets IN its coils, hence a stronger magnetism, less inductance

Hang on.....maybe I've misunderstood inductance, but I always thought that was the capacity to produce a signal. So a stronger magnet (or magnetic field) in the same wind would mean more inductance hence a greater output for the same turn count.

 

[freefrog]

Hi Alex,

To sum up my thoughts simply (and not in a pedantic way, I hope), I'll say that in a pickup, a good amount of the inductance is due to its coil(s) and another good amount to its "ferrous content".
AlNiCo contains less iron than the slugs and screws of a traditional HB - and a mini HB is a reduced version of the big ones, with a "bar slug" instead of 6 slugs.
It's for the same reason that cheap single coils with ferrous slugs and a mag glued underneath exhibit more inductance than SC's with rod mags (if their coils are identical, of course).
And that's also why metal plates to put under SC's are sometimes called "inductance plates".

And to precise my previous post: a vintage correct Mini HB measures around 3H of inductance. A FB built with the same coils measures around 2.2H.

HTH.

It's already late at night here so I'm going to bed now. See ya!

 

[ARandall]

Yes.
Strat singlecoils have physically less magnet mass with rod mags. That goes along the line of a short magnet being a different animal to a long one of the same type.

What I'm specifically talking about is why you said a stronger magnetic field will mean less inductance.

 

[Lester]

So to make sure I'm visualizing this correctly:

- a mini HB has a traditional position would coil, ferrous adjustable screw type poles, and a bar magnet across the bottom - much like a modern bar magnet Fender single coil but with adjustable pole pieces (and dual coils, of course).

- an early FB pickup has a bar magnet in the center of the coil(s) where the individual pole pieces would be, but in bar format

- a later (?) FB pickup has the coil(s) turned at 90 degrees to the norm with a bar magnet in the core... like taking the early FBpickup and turning the coils on their sides.

Let me know if I have that much right, and I'll add some more questions.

 

[freefrog]

What I'm specifically talking about is why you said a stronger magnetic field will mean less inductance.

hi again Alex and good morning from Europe.

I've not said that a stronger magnetic field will mean less inductance. I've tried to share the fact that with identical coils, FB pickups have less inductance (as measured by a LRC meter) and a stronger magnetic field (as measured from the strings by a Gaussmeter or Teslameter).

The same absence of correlation can be noticed when we swap AlNi(Co) bars in a standard HB: A5 will give the strongest magnetic field and A3 the weakest, with A4 and A2 in between. Conversely, the inductance of the PU will be the highest with AlNi 3 and the lowest with AlNiCo 5, because A3 contains something like 11% more iron.

It's a question of permeability of core materials and remains true with mini HB's vs FB pickups: The A5 bars used in a FB humbucker are less magnetically permeable than other AlNi(Co) alloys while AlNi(Co)'s are themselve less permeable than low carbon steels used to make slugs and screws. And permeability works as an inductance booster, so to speak.

Sorry to have avoided this explanation at first: I'm always (non magnetically) "reluctant" to dig too much of physics on a forum for musicians.

 

[freefrog]

So to make sure I'm visualizing this correctly:

- a mini HB has a traditional position would coil, ferrous adjustable screw type poles, and a bar magnet across the bottom - much like a modern bar magnet Fender single coil but with adjustable pole pieces (and dual coils, of course).

- an early FB pickup has a bar magnet in the center of the coil(s) where the individual pole pieces would be, but in bar format

- a later (?) FB pickup has the coil(s) turned at 90 degrees to the norm with a bar magnet in the core... like taking the early FBpickup and turning the coils on their sides.

Let me know if I have that much right, and I'll add some more questions.

I wouldn't want to sound pedantic by monopolizing your topic so I'll just provide a link towards the info generously shared by Dougie on MLP a while back:

Dissecting more Firebird pickups (pic heavy)

Had the opportunity to gut an '82 Firebird pickup and rebuild it, so I thought I might share some pics. These are the same laid over sideways pickups found in the '76 Bicentennial Firebirds, and they also did the Bicentennial Thunderbird bass pickups the same way. The coils are wound pretty...

www.mylespaul.com

EDIT - and here is a dissected Mini HB (not a FB one): http://www.guitarattack.com/winder/hum1.jpg

To compare with... https://music-electronics-forum.com/filedata/fetch?id=845630&d=1496383130

And to achieve to make my contribution forgettable (LOL): https://www.premierguitar.com/articles/Humbuckers_and_Mini_Humbuckers

 

[Lester]

Thanks all. The links above and some more googling gave me good understanding of the pickup construction. I was under the mistaken impression that a Humbucker (mini or not) had two magnets. Like two Fender single coils just strapped together back to back. I see now that it's one magnet and an integrated design.

Also, I was under the impression that a Firebird pickup was essentially a Mini with a full cover. I see now that either the old or new FB design is completely different from a standard humbucker.

 

[Lester]

The same absence of correlation can be noticed when we swap AlNi(Co) bars in a standard HB: A5 will give the strongest magnetic field and A3 the weakest, with A4 and A2 in between. Conversely, the inductance of the PU will be the highest with AlNi 3 and the lowest with AlNiCo 5, because A3 contains something like 11% more iron.

I could use some basic info on this.

I know that stronger magnets typically lead to greater output... i.e. replacing you Fender A2 pole pieces with A5 pole pieces give more agressive output.

I'm weak on the inductance aspect. I know a lot of (most) folks evaluate pickups based on DC resistance. So a coil with more windings (given the same wire gauge) has a higher resistance and likewise higher output. But I understand that's inaccurate and that's it's inductance that really should be measured.

What's confusing me is the statement above: "Conversely, the inductance of the PU will be the highest with AlNi 3 and the lowest with AlNiCo 5, because A3 contains something like 11% more iron.". My weak understanding of traditional magnets (A5 has more output than A3) tells me the A5 pickup has stronger output.

But, if inductance is higher with A3, and output is lower, my understandings are at odds. Does higher inductance result in lower output?

 

[freefrog]

What's confusing me is the statement above: "Conversely, the inductance of the PU will be the highest with AlNi 3 and the lowest with AlNiCo 5, because A3 contains something like 11% more iron.". My weak understanding of traditional magnets (A5 has more output than A3) tells me the A5 pickup has stronger output.

But, if inductance is higher with A3, and output is lower, my understandings are at odds. Does higher inductance result in lower output?

Hello,

More inductance = more output.
BUT only if nothing changes magnetically.

A3 causes an higher inductance because of its ferrous content but generates a lower output level than A5 because the magnetic field of a normally charged A3 is noticeably weaker.

To come back on topic... I prefer FB pickups but it has a possible downside as everything in our human lifes.: It' might be more sensitive to high pitched squealing than an Epi style mini-HB.