Rockford Fosgate SPP-184

18" · 4 Ω · 350 W · 99.2 dB · datasheet ↗

Thiele-Small parameters

Nominal size	18"
Impedance	4 Ω
Fs	27 Hz
Qts	0.266
Qes	0.3
Qms	2.37
Vas	353 L
Sd	1141 cm²
Xmax	6 mm
Re	3.5 Ω
Bl	18.9 T·m
Mms	179.6 g
Pe	350 W
Sensitivity	99.2 dB

Alignment hint

EBP	90 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 58.2 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
Celestion FTR18-4080F	28 +1	0.265 =	383.3 +30.3	6 =	98.6 -0.6	close	8 Ω vs 4 Ω: amp load changes	+
RCF LF 18G400	28 +1	0.273 +0.01	360 +7	9 +3	98.3 -0.9	close	8 Ω vs 4 Ω: amp load changes	+
RCF LF 18X400	28 +1	0.255 -0.01	360 +7	9 +3	98.6 -0.6	close	8 Ω vs 4 Ω: amp load changes	+
RCF LF18G400	28 +1	0.27 =	360 +7	9 +3	97.5 -1.7	close	8 Ω vs 4 Ω: amp load changes	+
RCF LF18X400	28 +1	0.27 =	340 -13	9 +3	97.5 -1.7	close	8 Ω vs 4 Ω: amp load changes	+
RCF LF 18X400 v2	28 +1	0.278 +0.01	340 -13	9 +3	98 -1.2	close	8 Ω vs 4 Ω: amp load changes	+
Eminence PS18-6008 vp	28.1 +1.1	0.239 -0.03	354.1 +1.1	5.5 -0.5	98.9 -0.3	close	8 Ω vs 4 Ω: amp load changes · Xmax 5.5 mm < 6 mm: lower excursion-limited SPL	+
Electro-Voice EVX-180A	29 +2	0.27 =	416 +63	6.4 +0.4	99.5 +0.3	close	8 Ω vs 4 Ω: amp load changes	+
Electro-Voice EVX-180B	29 +2	0.27 =	416 +63	6.4 +0.4	99.5 +0.3	close	8 Ω vs 4 Ω: amp load changes	+
Celestion FTR18-4080FD	26 -1	0.27 =	395.56 +42.56	6 =	97 -2.2	close	8 Ω vs 4 Ω: amp load changes	+

Compare the closest 3 against the SPP-184 →

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.