AliExpress Epi ProBucker Mini and Firebird Humbuckers review

[antigua]

I had another cheap guitar with mini humbucker sized pickups that I was looking to replace with a proper Gibson style version. AliExpress had both a Mini Humbucker and a Firebird Humbucker for pretty cheap, both sets $33, or $16.50 per pickup. 

1 Set MINI ProBucker Alnico Electric Guitar Pickups For EPI (PMHNHB) - AliExpress www.aliexpress.us/item/2255799918900394.html (Mini Humbucker)

1 Set MINI ProBucker Alnico Electric Guitar Pickups For EPI (FB720NI) - AliExpress www.aliexpress.us/item/3256804922220638.html (Firebird)

I had ordered Epiphone Probuckers on AliExpress a few years back, and found that the quality was all over the place. The gold colored humbuckers mostly had brass covers with odd shades of redish gold, but the chrome covered humbuckers turned out to be really nice, nearly vintage correct for a sub $50 price. When you buy anything on AliExpress, there's a coin toss of a chance that the goods will be inauthentic, and it's a matter of fact based on this prior experience that some (maybe all?) of the Epiphone ProBuckers sold on AliExpress are inauthentic. I also don't have an authentic example of either on hand to compare them against, so this is really just a question of whether they're good pickups and worth the $33 per set. 

But to my surprise, both of these, the Mini and Firebird, are really nice.  

Here's my usually work up of pics and measurements:






"Epiphone" Probucker Mini Humbucker
AliExpress "1 Set MINI ProBucker Alnico Electric Guitar Pickups For EPI (PMHNHB)"

Bridge
- DC Resistance: 7.926K ohms (7.9k stated)
- Q @1khz: 2.32
- Measured L: 4.733H
- Calculated C: 120pF
- Gauss: 350G (AlNiCo)

Neck
- DC Resistance: 6.476K ohms (6.5k stated)
- Q @1khz: 2.20
- Measured L: 3.680H
- Calculated C: 158pF
- Gauss: 350G (AlNiCo)

Bridge unloaded: dV: 5.4dB f: 5.67kHz (black)
Bridge loaded (200k & 470pF): dV: 2.8dB f: 2.73kHz (blue)
Neck unloaded: dV: 4.3dB f: 6.21kHz (red)
Neck loaded (200k & 470pF): dV: 2.8dB f: 2.73kHz (green)




The Q factor in the bode plot indicates that it has a nickel silver cover. That part alone runs $10 on eBay. For only $6 more you're getting a whole pickup.

The inductance being 3H and 4H, and a loaded resonant peak being around 2.7kHz for the bridge and 3.2kHz for the neck makes these clearer, less "hot" as compared to full sized humbuckers. Some say Mini Humbuckers sound half way between a Fender single coild and a Gibson PAF style humbucker. These specs land in the middle of those averages, combined with the more "mini" magnetic profile, and combined with the somewhat stronger magnetic field, it seems reasonable to perceive that they would sound like a cross between a "single coil" and a "PAF"

Something I never realized until now is that the second coil of a mini humbucker is supposed to have an AlNiCo bar, as if to use one of the coils from a Firebird humbucker. The construction of this $33/set appears to use all the right vintage correct materials, except that the bobbins are clear plastic, and the magnet wire is probably something modern. A Gibson version is apparently supposed to have a spacer on the screw side, but this pickup doesn't have one. 

These pickups came with Molex connectors, which is a hint that they might be authentic Epiphone, as Molex connectors are used in their stock wiring. 















"Epiphone" Probucker Firebird Humbucker
AliExpress: "1 Set MINI ProBucker Alnico Electric Guitar Pickups For EPI (FB720NI)

Bridge
- DC Resistance: 7.990K ohms (7.9k stated)
- Q @1khz: 2.64
- Measured L: 4.156H
- Calculated C: 114pF
- Gauss: 300G (AlNiCo)

Neck
- DC Resistance: 8.062K ohms (7.9k stated)
- Q @1khz: 2.54
- Measured L: 4.077H
- Calculated C: 145pF
- Gauss: 300G (AlNiCo)

Bridge unloaded: dV: 6.9dB f: 5.87kHz (black)
Bridge loaded (200k & 470pF): dV: 4.3dB f: 2.73kHz (blue)
Neck unloaded: dV: 7.2dB f: 5.00kHz (red)
Neck loaded (200k & 470pF): dV: 4.3dB f: 2.73kHz (green)






The two Firebird humbuckers are designated with a neck and a bridge model, but they're intended to have the same specs. The loaded resonant peaks are the same at 2.73kHz, but the unloaded peak was lower for the neck pickup, on account of it having a longer lead cable, which adds more capacitance. This really demonstrates the value of the loaded measurement. 

2.7kHz is a common loaded resonant is similar to a lot of "neck" PAF humbuckers, where as the "bridge" models tend to be closer to 2.3kHz. They're going to sound thinner than your average PAF set, but thicker than Fender single coils. 

The construction looks pretty clean, similar to the Mini Humbucker with clear bobbins instead of black. It has two AlNiCo bars, one in each coil, and a steel pace under the coils, and all sit on top of two wood spacers, and the wiring connections are tucked in between the two wood spacers. It's nice to see that they use real wood, and didn't leave out the steel plate. There should also be a metal shim connecting across the top, touching the two magnets together. The coils were kind of stuck inside of the cover, due to the wax, and I couldn't easily scoop them out to see if that metal piece was in place or not. 

Long story short is that both sets are close enough to vintage correct that $33 per set is a steal (figuratively I hope). 

[frets]

Antigua,
Thank you for this thorough review. I too have purchased the ProBuckers you have referenced and can attest to the quality of sound. They are a robust pickup with balanced tone.

In my experience, Chinese pickups have dramatically improved. For the price point, they are an excellent value.

Although I have no personal experience with the Firebird, I have a good friend who put one in a guitar and was very happy with it.

[gckelloch]

The inductance for the Firebird models seems too high for the DCR of 42AWG and the Gauss too low for any type of AlNiCo bar in the coils. The bars look black and wider than usual from the bottom. Maybe those are rubber Ferrite bars, or something? Far be it for a pickup maker to mislead.

[David Mitchell]

Jul 9, 2024 3:38:29 GMT -5 antigua said:

Something I never realized until now is that the second coil of a mini humbucker is supposed to have an AlNiCo bar, as if to use one of the coils from a Firebird humbucker.

I've read over and over that mini-humbuckers are not at all the same as Firebird pickups, often with illustrations showing how each is constructed. I don't remember ever seeing that half-and-half design. But that's what it's supposed to be? Wild!

[antigua]

Jul 9, 2024 15:18:44 GMT -5 frets said:

Antigua,
Thank you for this thorough review. I too have purchased the ProBuckers you have referenced and can attest to the quality of sound. They are a robust pickup with balanced tone.

In my experience, Chinese pickups have dramatically improved. For the price point, they are an excellent value.

Although I have no personal experience with the Firebird, I have a good friend who put one in a guitar and was very happy with it.

Yeah I put some well made Firebird pickups from a East European makers in a guitar sized for them, and they sound good, clear and strong. They make a good clean pickup, but they were marketed towards rock musicians. 

[antigua]

Jul 9, 2024 16:05:05 GMT -5 gckelloch said:

The inductance for the Firebird models seems too high for the DCR of 42AWG and the Gauss too low for any type of AlNiCo bar in the coils. The bars look black and wider than usual from the bottom. Maybe those are rubber Ferrite bars, or something? Far be it for a pickup maker to mislead.

The inductance looks OK to me, it's not greatly different from PAFs of similar values, and they're joined closely with that steel plate on the bottom, which probably increases the mutual inductance.

The Gauss is measured with the covers on, so there's some gap. I did touch the probe to the magnets with the covers off, mostly to see if they were steel or AlNiCo, they measured around 400G directly. They're definitely AlNiCo bars, based on the color and the machining marks, and if they were steel I'd expect the Gauss to be closer to 200. The bars in the coils are shorter than P-90 / PAF bars, and AlNiCo loses strength when it's polar faces are closer together relative to its overall width. That's due to their lower coercivity compared to modern magnets.  

I should take the pictures during the day time, but I usually have free time at night. 

[antigua]

Jul 10, 2024 11:46:24 GMT -5 David Mitchell said:

Jul 9, 2024 3:38:29 GMT -5 antigua said:

Something I never realized until now is that the second coil of a mini humbucker is supposed to have an AlNiCo bar, as if to use one of the coils from a Firebird humbucker.

I've read over and over that mini-humbuckers are not at all the same as Firebird pickups, often with illustrations showing how each is constructed. I don't remember ever seeing that half-and-half design. But that's what it's supposed to be? Wild!

Here's a diagram of the two from Stewmac, which I stake Stewmac's reputation on assuming this is true to Gibson's design. Apparently this is just the way they are made. 

[David Mitchell]

Jul 10, 2024 13:02:53 GMT -5 antigua said:

Jul 10, 2024 11:46:24 GMT -5 David Mitchell said:

I've read over and over that mini-humbuckers are not at all the same as Firebird pickups, often with illustrations showing how each is constructed. I don't remember ever seeing that half-and-half design. But that's what it's supposed to be? Wild!

Here's a diagram of the two from Stewmac, which I stake Stewmac's reputation on assuming this is true to Gibson's design. Apparently this is just the way they are made. 

SPOILER: Click to show

Either I'm misremembering, was misreading, or others were misinformed. Thanks for the education!

If you know, what impact does the bar have, compared to slugs? Would a full-size humbucker made this way sound different from standard ones?

[antigua]

Jul 10, 2024 13:26:09 GMT -5 David Mitchell said:

Jul 10, 2024 13:02:53 GMT -5 antigua said:

Here's a diagram of the two from Stewmac, which I stake Stewmac's reputation on assuming this is true to Gibson's design. Apparently this is just the way they are made. 

SPOILER: Click to show

Either I'm misremembering, was misreading, or others were misinformed. Thanks for the education!

If you know, what impact does the bar have, compared to slugs? Would a full-size humbucker made this way sound different from standard ones?

The AlNiCo pole piece gives a slightly stronger magnetic pull than slugs, with Gauss 300 and upwards versus slugs, being around 250, more often, when paired with AlNiCo underneath. In either case that seems small, but since there are two magnetized coils, it's doubled, relative to a single coil. The stronger the pull, the more induced harmonics come from the guitar string, but this is offset by how high or low the pickups are from the guitar strings. More harmonics means more treble, in practice.  

AlNiCo is less permeable and conductive than steel, so the inductance is lower and the Q factor is higher with AlNiCo, compared to steel. Lower inductance means higher peak frequency, and higher Q means higher peak amplitude, so more treble on both accounts.

But comparing steel and AlNiCo in that way is "like for like", but the slugs/screws have a lot of air between them, where as the AlNiCo bar is solid from end to end. The greater mass of the AlNiCo bar might cause the inductance and Q factors to end up being similar, because the air gaps between the screws will greatly lower inductance and raise the Q factor also. Not only that, but these screws are rather small. I should unsolder the coils and measure them each by themselves to see how they compare in isolation.

Another difference is that because steel is more permeable than AlNiCo, it lowers the reluctance path between the magnetized string and the coil, which is analogous to having a more efficient antenna, so with the steel you would usually get more output, all others things being equal, but again, the small size of the screws might counter balance against the larger size of the AlNiCo magnet. When you compared like for like, say a Strat pickup with AlNiCo pole pieces, and a Strat pickup with steel slugs and ceramic magnet underneath, then because the geometries are alike, these material differences have a much bigger impact on the resulting tone. 

Finally, when you have a long bar magnet instead of slugs, the side to side movement of the guitar strong is cancelled out, since the guitar string's side to side movement is occurring in a homogenous magnetic gradient, where as the up and down movement is moving in and out of the magnetic fields, resulting in a difference over time that causes in a voltage. Since the slugs have spaces in between them, the magnetic field becomes stronger and weaker with respect to all directions of string movement, and that results in a harmonic, which again means a little bit more treble, so little that it might not even be audible. 

If I compare the Mini Humbuckers coils bit themselves, I can get some answers. I can do that later, and I ordered another set to actually use in a guitar, so that I can rip this one up and not have to worry about it going back together perfectly, with all the wax and what not.  

The bode plots show that the Firebird has a slightly higher Q and a slightly lower inductance, despite a similar DC resistance (indicating similar coils in each), even with a steel baseplate underneath. Therefore I suspect that the AlNiCo bar will result in a higher Q and a lower inductance than the screws, despite the fact that there is so much air in between those screws. I suspect when Gibson made the first Firebird pickup, they thought is sounded too thin and weak, so they added in the steel plate underneath to lower the reluctance path and increase the output, but because that steel plate is underneath the coils, it's not as effective at its job as the steel screws are.


  

[nuke]

Curiously, there were several versions of the Firebird pickups. 

They had a reputation for being thin at the bridge position. In the mid-70's, the "Bicentennial", Gibson changed the bridge version of the Firebird pickup to a sidewinder with a ceramic magnet in the center, designed by Bill Lawrence. His name is on the patent application. 

Some good background info, sound clips and tear-down photos here:


www.heliotricity.com/firebird-pickups/

[David Mitchell]

Jul 10, 2024 16:06:28 GMT -5 antigua said:

Jul 10, 2024 13:26:09 GMT -5 David Mitchell said:

Either I'm misremembering, was misreading, or others were misinformed. Thanks for the education!

If you know, what impact does the bar have, compared to slugs? Would a full-size humbucker made this way sound different from standard ones?

The AlNiCo pole piece gives a slightly stronger magnetic pull than slugs, with Gauss 300 and upwards versus slugs, being around 250, more often, when paired with AlNiCo underneath. In either case that seems small, but since there are two magnetized coils, it's doubled, relative to a single coil. The stronger the pull, the more induced harmonics come from the guitar string, but this is offset by how high or low the pickups are from the guitar strings. More harmonics means more treble, in practice.  

AlNiCo is less permeable and conductive than steel, so the inductance is lower and the Q factor is higher with AlNiCo, compared to steel. Lower inductance means higher peak frequency, and higher Q means higher peak amplitude, so more treble on both accounts.

But comparing steel and AlNiCo in that way is "like for like", but the slugs/screws have a lot of air between them, where as the AlNiCo bar is solid from end to end. The greater mass of the AlNiCo bar might cause the inductance and Q factors to end up being similar, because the air gaps between the screws will greatly lower inductance and raise the Q factor also. Not only that, but these screws are rather small. I should unsolder the coils and measure them each by themselves to see how they compare in isolation.

Another difference is that because steel is more permeable than AlNiCo, it lowers the reluctance path between the magnetized string and the coil, which is analogous to having a more efficient antenna, so with the steel you would usually get more output, all others things being equal, but again, the small size of the screws might counter balance against the larger size of the AlNiCo magnet. When you compared like for like, say a Strat pickup with AlNiCo pole pieces, and a Strat pickup with steel slugs and ceramic magnet underneath, then because the geometries are alike, these material differences have a much bigger impact on the resulting tone. 

Finally, when you have a long bar magnet instead of slugs, the side to side movement of the guitar strong is cancelled out, since the guitar string's side to side movement is occurring in a homogenous magnetic gradient, where as the up and down movement is moving in and out of the magnetic fields, resulting in a difference over time that causes in a voltage. Since the slugs have spaces in between them, the magnetic field becomes stronger and weaker with respect to all directions of string movement, and that results in a harmonic, which again means a little bit more treble, so little that it might not even be audible. 

If I compare the Mini Humbuckers coils bit themselves, I can get some answers. I can do that later, and I ordered another set to actually use in a guitar, so that I can rip this one up and not have to worry about it going back together perfectly, with all the wax and what not.  

The bode plots show that the Firebird has a slightly higher Q and a slightly lower inductance, despite a similar DC resistance (indicating similar coils in each), even with a steel baseplate underneath. Therefore I suspect that the AlNiCo bar will result in a higher Q and a lower inductance than the screws, despite the fact that there is so much air in between those screws. I suspect when Gibson made the first Firebird pickup, they thought is sounded too thin and weak, so they added in the steel plate underneath to lower the reluctance path and increase the output, but because that steel plate is underneath the coils, it's not as effective at its job as the steel screws are.

Again, thank you for the education! That was a very detailed reply to a rather uninformed question. I don't understand all of it yet, but I'm learning.

I had already had my eye on these pickups after a TDPRI thread about them a while back. Curiosity got the better of me....



I ordered from XIYANGJUAN-guitar on eBay, who accepted an offer which made the price about the same as the AliExpress seller linked above, and the pickups got here in three days, which was nice! They appear to be the same as the ones you tested. I can't measure inductance, but when I checked the resistance, they measured at 7.98K for the bridge and 8.01K for the neck. 

Now I need to figure out what to put them in!