Pickups that sound alike that shouldn't

[roadtonever]

...Or should they? I stumbled upon Mike Stamper's Youtube channel that has a 400+ A/B tests of humbuckers. Curiously I spent an afternoon listening with the prospect of finding a passive pickup that sounds close to the venerable EMG 81 in the bridge position.

Unexpectedly it's the not a particularly modern model, and it's not bladed. Liked comments say "They both sound pretty sweet. I'd use either one" and "Realistically I think you can build a great sound with either of them"
You rarely, if ever, see discussion among musicians about interdependently designed products sounding equally good.

Ok, here's the reveal:
It's the Duncan Distortion.

Not much more than an overwound PAF with a ceramic magnet, and allegedly a Duncan JB with a ceramic magnet swap.

Let's compare specs
EMG 81
Magnet Type C/S
Resonant Frequency (KHz) 1.63
Output Voltage (String) 3.00
Output Voltage (Strum) 4.50
Output Noise (60 Hz) -100
Output Impedance (Kohm) 10
Current @9V (Microamps) 400
Battery Life (Hours) 600
Maximum Supply (Volts DC) 27
(from EMG)


Duncan Distortion
Series – 16.502 K
Inductance – 7.144 H
Split N – 8.365 K
Split S –  8.173 K
Parallel – 4.132 K
Magnet – Thick Ceramic
Resonant Peak – 5.5KHz (advertised)
(From http://darthphineas.com/2017/05/seymour-duncan-distortion/)

No obvious similarities other that dual coils and ceramic magnets.

The curves, don't look that similar either.

JB used here for illustration. Imagine the Duncan Distortion is a few dB lower from 1.3kHz and below.
Source: guitarnuts2.proboards.com/thread/8032/seymour-duncan-jazz-analysis-review



Source: www.electrosmash.com/emg81

You can get match at two discreet points of the curve depending on how they overlap vertically, but that's it. Maybe that's enough to provide a similar sound. EQ isn't always an intuitive thing.

[roadtonever]

Another humbucker with a sonic profile very close to the two above is the Fishman Fluence Modern Alnico, on voice #1.



Clearly not by design because it was made for the neck position. The bridge model uses a ceramic magnet and has a sound profile of its own.


Specs:
PEAK FRQUENCY
Voice 1: 630 Hz, Voice 2: 550 Hz, 8 kHz
MAGNETIC MATERIAL
Alnico V
MAGNETIC CIRCUIT
Bar magnet with blades
OUTPUT IMPEDANCE
2 k
CURRENT DRAW
2.5 mA
BATTERY
9-Volt or optional rechargeable battery pack
BATTERY LIFE
Up to 200 hours

Curves:

Source:guitarnuts2.proboards.com/thread/9480/fishman-fluence-modern-sustainiac-response

Only the ceramic version has been measured, so it can only be used as a rough guide.


So far all this suggest that if a popular type of voicing is required, there no requisite magnet or active circuitry. A skilled pickup maker could use a different BOM to achive the same voicing. At the same time a player can use passive components to transform generic import pickups. At least for high gain rhythm styles. Examples of transformations from this forum: #1 guitarnuts2.proboards.com/post/78836/thread #2: guitarnuts2.proboards.com/post/80974/thread


As an aside, with more robust data an argument could be made that a universal preference exists for humbucker voicing. As blasphemous as that sounds the Duncan Distortion and EMG 81 have held their place as one of the top 5 humbuckers in the last 40 years, don't shoot the messenger.

[antigua]

Some actives like the EMG rolled off the low end in order to make them sound "tighter", where as a passive pickup has no capacity to roll off low end (unless a cap is put in series with it), but if the pickup in in the bridge position, there's not a lot of low end to be had there, and so whether the low end it rolled off or not doesn't matter too much. In the neck position, it makes a much bigger difference, and in the case of the EMG 81 and 85, even though the 81 it often used in the bridge, IIRC the only difference is the type of magnet used, and so it was probably originally intended that either the 81 or 85 might be used in the neck, and so a low end roll off would be beneficial if either happened to be used in the neck. 

The other big difference between actives and passives is the high end roll off. The active pickups have a more gradual attenuation than a passive pickup, and you can really see that in the Fishman Fluence "vintage" versus "modern" plots. Since active pickups tend to have a softer slope, even if they technically have a lower resonant peak, they'll often sound like they offer more treble none the less. If you compare those plots, the "vintage" mode has a higher resonant peak (simulated) but it's treble slopes off much more abruptly. With the guitar that pickup is in, I can hear the different by just pulling a knob, and the "modern" sound simultaneously offers more treble and mid range. In some sense you could say the hard knee of passive pickups is a sonic flaw, but it's a flaw that everyone has come to accept as being the normal sound of an electric guitar.  

At the end of the day though, high and low roll-offs are just filtering the signal. How much difference you perceived depends on the source signal, which is to say, whatever sound the guitar strings are providing, and that depends on a lot of factors, like how and where you strum, where the pickup is located, how it's tilted the strength of the magnetic pull, etc. It's possible to play a guitar, or have the guitar be set up in such a way that the difference in high and low pass filtering is not as easy to appreciate, and vice versa. The rig and distortion pedals factor in also. A lot of pedals and amps will have their own built in low-end roll off, again in order to "tighten" the sound, and so the low end filtering of the active pickup will be harder to perceive.