Pyle PDW21250

21" · 8 Ω · 1000 W · 95 dB · datasheet ↗

Thiele-Small parameters

Nominal size	21"
Impedance	8 Ω
Fs	22.4 Hz
Qts	0.33
Qes	0.378
Qms	2.6
Vas	703.8 L
Sd	1706 cm²
Xmax	9 mm
Re	6.3 Ω
Bl	26.39 T·m
Mms	296.959 g
Pe	1000 W
Sensitivity	95 dB

Alignment hint

EBP	59 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 196 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
18 Sound 21LW2600	27 +4.6	0.33 =	333 -370.8	14.6 +5.6	97 +2	usable		+
RCF LF21X451	28 +5.6	0.37 +0.04	385 -318.8	14 +5	97 +2	usable		+
Precision Devices PD2150	22 -0.4	0.19 -0.14	628 -75.8	19 +10	99 +4	usable		+
RCF LF21N401	30 +7.6	0.37 +0.04	374 -329.8	11 +2	98 +3	usable		+
Celestion NTR21-5010JD	30.2 +7.8	0.291 -0.04	341.215 -362.58	9 =	96.7 +1.7	usable		+
18 Sound 21NLW9001	31 +8.6	0.34 +0.01	272 -431.8	14 +5	95 =	risky	4 Ω vs 8 Ω: amp load changes	+
18 Sound 21NTLW5000	30 +7.6	0.32 -0.01	300 -403.8	17.5 +8.5	97 +2	risky	4 Ω vs 8 Ω: amp load changes	+
18 Sound 21NLW5300	31 +8.6	0.32 -0.01	325 -378.8	15.3 +6.3	98.5 +3.5	risky		+
B&C 21SW115	30 +7.6	0.37 +0.04	318 -385.8	14 +5	97 +2	risky		+
18 Sound 21LW1400	28 +5.6	0.24 -0.09	385 -318.8	9.5 +0.5	99 +4	risky		+

Compare the closest 3 against the PDW21250 →

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 (9)

FK BR 21subbass reflex
FK BR 21 Pairsubbass reflex
FK FLH 21subfront loaded horn
FK Sub BigVolsubfront loaded horn
FK Sub BR 21x4subbass reflex
FK Sub Heaviestsubbass reflex
FK Sub LowF3subtapped horn
FK TH 21subtapped horn
FK TH 21Bsubtapped horn