Re: How do firebird/minihumbucker pickups compare to regular single coils?
+1 about (vintage style) Firebird PU's as closer to single coils than (vintage style) mini-hum's.
Without getting too technical, let's say that (vintage style) Firebird pickups get close to Strat single coils when it comes to inductance and resonant peak, albeit their metallic cover and wider magnetic windows keep their sound in the HB camp.
Mini hum's (Epiphone / vintage style) enclose the same coils but their added metallic parts (mini screw poles + rail in one coil) and single horizontal mag give them more mids due to more inductance, less highs due to a flatter resonant peak and more eddy currents, plus a softer attack (less sensitivity)...
A Firebird PU has more treble and/or mid focus than a mini hum and a crispier attack... BUT IME, set in the same way (in the same guitar, when mounted instead of a mini hum with poles), it has also more bass because of the stronger magnetic field. It explains the BMT chart published by Duncan for mini HB models:
https://www.seymourduncan.com/pickups/guitars/other-guitars/mini-humbucker
NOTES
-it's possible to mimic 100% the rounder resonant peak of a mini hum with a Firebird pickup, by lowering the tone around 75%. It might explain why the SM1 is sold for age as a "mini hum" while it's technically a Firebird pickup (Seymour did know that a Firebird transducer can do the same than a mini hum after a few settings, I believe).
Conversely, a mini hum can't really copy a Firebird transducer, unless it's wired in parallel with an inductor in the Q filter style - but even in this case, the mini hum won't acquire the lacking sensitivity for structural reasons.
-That said, mini hum's have at least an advantage over FB PU's: being less sensitive, they are less microphonic.
FWIW (my experience and measurements. YMMV according to the precise models used).
