Peavey 121-4

10" · 4 Ω · 50 W · 95.4 dB · datasheet ↗

Thiele-Small parameters

Nominal size	10"
Impedance	4 Ω
Fs	44.7 Hz
Qts	0.462
Qes	0.52
Qms	4.18
Vas	51.7 L
Sd	335 cm²
Xmax	2.5 mm
Re	3.25 Ω
Bl	8.2 T·m
Mms	38.6 g
Pe	50 W
Sensitivity	95.4 dB

Alignment hint

EBP	86 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 38.5 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
Peavey SHEFFIELD 1035 4	44.7 =	0.462 =	51.7 =	2.5 =	95.4 =	close		+
Eminence LEGEND CA10	52.9 +8.2	0.456 -0.01	51.1 -0.6	3 +0.5	96 +0.6	close	8 Ω vs 4 Ω: amp load changes	+
Beyma 10BR60	45 +0.3	0.467 +0.01	47 -4.7	3.5 +1	91.3 -4.1	close	8 Ω vs 4 Ω: amp load changes	+
Dayton Audio PA255-8	46.4 +1.7	0.484 +0.02	59 +7.3	5 +2.5	94.6 -0.8	close	8 Ω vs 4 Ω: amp load changes	+
Eminence ELIMINATOR 2510	49.5 +4.8	0.472 +0.01	40.3 -11.4	3 +0.5	95.3 -0.1	close		+
Eminence BASSLITE CA2010	51 +6.3	0.505 +0.04	49 -2.7	3.5 +1	94.6 -0.8	close	8 Ω vs 4 Ω: amp load changes	+
STX W.25.300.8.MC	51 +6.3	0.483 +0.02	59 +7.3	4 +1.5	95.2 -0.2	close	8 Ω vs 4 Ω: amp load changes	+
Mercuriale PTR 256 M0	50 +5.3	0.498 +0.04	56.9 +5.2	3.5 +1	94.2 -1.2	close	8 Ω vs 4 Ω: amp load changes	+
Monacor SP-252E	42 -2.7	0.503 +0.04	57 +5.3	4 +1.5	93.7 -1.7	close		+
Eminence BETA 10 A	53 +8.3	0.489 +0.03	60.1 +8.4	3 +0.5	95.8 +0.4	close	8 Ω vs 4 Ω: amp load changes	+

Compare the closest 3 against the 121-4 →

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.