MCM Electronics 55-2985

21.5" · 8 Ω · 300 W · 97.6 dB · datasheet ↗

Thiele-Small parameters

Nominal size	21.5"
Impedance	8 Ω
Fs	25.9 Hz
Qts	0.38
Qes	0.426
Qms	3.509
Vas	705 L
Sd	1706 cm²
Xmax	6.9 mm
Re	6.3 Ω
Bl	22.9 T·m
Mms	218.5 g
Pe	300 W
Sensitivity	97.6 dB

Alignment hint

EBP	61 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 286.3 L

EBP 50-100: works in either a sealed or ported alignment.

Rules of thumb from T/S parameters only. Verify against a real simulation before cutting wood.

Substitute candidates

Driver	Fs (Hz)	Qts	Vas (L)	Xmax (mm)	Sens (dB)	Fit	Notes	Compare
Pyle Audio PDW21250	22.4 -3.5	0.331 -0.05	703.8 -1.2	9 +2.1	96.2 -1.4	usable		+
Beyma 21L45	25 -0.9	0.275 -0.1	660 -45	9 +2.1	98.7 +1.1	usable		+
Mach 5 Audio FTW21	19.7 -6.2	0.378 =	499.9 -205.1	7.5 +0.6	95.8 -1.8	usable	4 Ω vs 8 Ω: amp load changes	+
RCF LF 21X451	28 +2.1	0.369 -0.01	385 -320	13 +6.1	97 -0.6	usable		+
MC Kenzie FRL-21/1200-LF	30 +4.1	0.378 =	374 -331	9.5 +2.6	98 +0.4	usable		+
Cabasse 55NDS	23.5 -2.4	0.369 -0.01	975 +270	4.2 -2.7	98.7 +1.1	usable	200 W vs 300 W: lower power handling · Xmax 4.2 mm < 6.9 mm: lower excursion-limited SPL	+
RCF LF 21N401	30 +4.1	0.378 =	374 -331	10.6 +3.7	98 +0.4	usable		+
Beyma 21PW1400FE	30 +4.1	0.343 -0.04	401.5 -303.5	10 +3.1	98.6 +1	usable		+
hertz Hertz Audio ML5400D	20.7 -5.2	0.303 -0.08	613 -92	8.5 +1.6	102.9 +5.3	usable	2 Ω vs 8 Ω: amp load changes	+
CSS Audio Maelstrom 21 DVC by Exodus Audio	16.3 -9.6	0.389 +0.01	605 -100	16.3 +9.4	93 -4.6	usable	4 Ω vs 8 Ω: amp load changes	+

Compare the closest 3 against the 55-2985 →

Ranked on parameter similarity only (Qts, Fs, Vas, Xmax, sensitivity). Same nominal size required. A hint, not a simulation, model the swap before cutting or buying.

Used in enclosures (0)

No enclosure in the catalog uses this driver yet.