Mach 5 Audio FTW21

21.5" · 4 Ω · 600 W · 95.8 dB · datasheet ↗

Thiele-Small parameters

Nominal size	21.5"
Impedance	4 Ω
Fs	19.7 Hz
Qts	0.378
Qes	0.395
Qms	8.56
Vas	499.9 L
Sd	1640.3 cm²
Xmax	7.5 mm
Re	3.2 Ω
Bl	22.2 T·m
Mms	492.4 g
Pe	600 W
Sensitivity	95.8 dB

Alignment hint

EBP	50 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 200 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 +2.7	0.331 -0.05	703.8 +203.9	9 +1.5	96.2 +0.4	usable	8 Ω vs 4 Ω: amp load changes	+
CSS Audio Maelstrom 21 DVC by Exodus Audio	16.3 -3.4	0.389 +0.01	605 +105.1	16.3 +8.8	93 -2.8	usable		+
MCM Electronics 55-2985	25.9 +6.2	0.38 =	705 +205.1	6.9 -0.6	97.6 +1.8	usable	8 Ω vs 4 Ω: amp load changes · 300 W vs 600 W: lower power handling · Xmax 6.9 mm < 7.5 mm: lower excursion-limited SPL	+
RCF LF 21X451	28 +8.3	0.369 -0.01	385 -114.9	13 +5.5	97 +1.2	usable	8 Ω vs 4 Ω: amp load changes	+
MC Kenzie FRL-21/1200-LF	30 +10.3	0.378 =	374 -125.9	9.5 +2	98 +2.2	usable	8 Ω vs 4 Ω: amp load changes	+
RCF LF 21N401	30 +10.3	0.378 =	374 -125.9	10.6 +3.1	98 +2.2	usable	8 Ω vs 4 Ω: amp load changes	+
hertz Hertz Audio ML5400D	20.7 +1	0.303 -0.08	613 +113.1	8.5 +1	102.9 +7.1	usable	2 Ω vs 4 Ω: amp load changes	+
Mach 5 Audio FTW-LTE-21	19.8 +0.1	0.643 +0.27	526.1 +26.2	10 +2.5	92.8 -3	usable	450 W vs 600 W: lower power handling	+
Beyma 21PW1400FE	30 +10.3	0.343 -0.03	401.5 -98.4	10 +2.5	98.6 +2.8	usable	8 Ω vs 4 Ω: amp load changes	+
LaVoce SAF214.50 vp	30 +10.3	0.401 +0.02	311 -188.9	11.6 +4.1	96.4 +0.6	usable	8 Ω vs 4 Ω: amp load changes	+

Compare the closest 3 against the FTW21 →

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.