Short answer: the JBL Synthesis SCL-1 on measured sound quality, the JBL Synthesis SCL-4 on price. The JBL Synthesis SCL-1 ranks #15 of 28 in-wall speakers, rated 3.7/5, at $36,299.90. The JBL Synthesis SCL-4 ranks #16, rated 3.6/5, at $7,259.90, $29,040 cheaper.
The JBL Synthesis SCL-1 is the deeper-bass pick. JBL Synthesis’s flagship in-wall left, center and right speaker with two 12” woofers and a D2 dual-diaphragm compression driver on a large HDI horn. Its bass reaches about 53Hz before falling 3dB, against 83.7Hz for the JBL Synthesis SCL-4. Watch for: It needs a large wall cavity and at least 500W of amplification, and it is sold through JBL Synthesis custom installers.
Why pick the JBL Synthesis SCL-4: JBL’s own measurements show a 1.85 directivity-index deviation, the most even directivity of the JBL Synthesis in-walls, with 0.35dB average on-axis deviation. The catch: Bass is the weakest here, at 83.7Hz for -3dB and about 61.9Hz for -10dB in free air, so it needs a subwoofer.
Buy the JBL Synthesis SCL-1 if sound quality matters more than the price. Buy the JBL Synthesis SCL-4 if the price matters more than sound quality.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| JBL Synthesis SCL-1 | JBL Synthesis SCL-4 | |
|---|---|---|
| Price | $36,299.90 per pair | $7,259.90 per pair |
| Ranked | #15 of 28 in In-Wall & In-Ceiling Speakers | #16 of 28 in In-Wall & In-Ceiling Speakers |
| Drivers | 2x 12” C4 woofers, D2430K dual 3” compression driver on HDI horn | 7” aluminum matrix cone woofer, 1” 2409H compression driver on HDI horn (2-way) |
| Sensitivity | 94dB (manufacturer specified) | 91dB (2.83V/1m) |
| Impedance | 4 ohms | 6 ohms |
| Frequency Response | 40Hz-24kHz -6dB (manufacturer specified) | 45Hz-33kHz -6dB (manufacturer, on-axis) |
| Maximum SPL | 133dB peak (manufacturer specified) | - |
| Dimensions | 48”H x 19”W x 14.5”D (1218 x 482 x 368 mm) | 25”H x 16.1”W x 3.7”D (636 x 409 x 93 mm) |
| Weight | 177.5 lbs (80.5 kg) | 27.6 lbs (12.51 kg) |
| Bass Extension (-3dB) | 53.0Hz (measured, manufacturer data via spinorama.org) | 83.7Hz (measured, JBL data on spinorama.org) |
| Bass Extension (-10dB) | about 45.6Hz (measured, manufacturer data via spinorama.org) | 61.9Hz (measured, JBL data on spinorama.org) |
| Spinorama Preference Score | 4.03 | 3.56 |
| Spinorama Preference Score with Perfect Sub | 6.35 | 6.55 |
| DIY Kit | No | No |
| Enclosure | - | In-wall, integrated MDF back box |
| Power Handling | - | 200W RMS maximum recommended amplifier power |
| Crossover Frequency | - | 1.3kHz |
Frequency Response Compared
Both speakers’ spinorama measurements, overlaid. A flatter line is more neutral: peaks sound forward or harsh, dips sound recessed. Each curve is shifted so its average from 300 Hz to 3 kHz sits at 0 dB, so loudness differences between the two are removed and only the shape is compared.
Measurement data: JBL Synthesis SCL-1 (measured by the manufacturer) and JBL Synthesis SCL-4 (measured by the manufacturer), via spinorama.org.
Related Speaker Comparisons
How JBL Synthesis SCL-1 compares with other leading options:
- JBL Synthesis SCL-1 vs JBL Synthesis SCL-3
- JBL Synthesis SCL-1 vs Grimani Systems Rixos-L
- JBL Synthesis SCL-4 vs Grimani Systems Rixos-L
- Revel W228Be vs JBL Synthesis SCL-4
- JBL Synthesis SCL-3 vs JBL Synthesis SCL-4
Prices on this page were last checked October 11, 2026 at 4:59 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
JBL Synthesis SCL-1: $36,299.90 per pair Audio Advice eBay
Same family: the JBL Synthesis SCL-4 (smaller in-wall, ranked lower, rated 3.6/5), the JBL Synthesis SCL-6 (smaller in-wall, ranked higher, rated 3.9/5), the JBL Synthesis SCL-3 (smaller in-wall, ranked higher, rated 3.7/5), the JBL Synthesis SCL-7 (smaller in-wall, ranked higher, rated 3.7/5) and the JBL Synthesis SCL-5 (larger in-wall, ranked lower, rated 2.5/5).
Pros: JBL Synthesis’s flagship in-wall left, center and right speaker with two 12” woofers and a D2 dual-diaphragm compression driver on a large HDI horn. Sensitivity is very high at 94dB, and JBL rates it to 133dB peak. JBL’s measurements show a preference score of 4.03 that reaches 6.35 with an ideal subwoofer, with 0.39 listening window deviation.
Cons: It needs a large wall cavity and at least 500W of amplification, and it is sold through JBL Synthesis custom installers. Bass reaches 53.0Hz (-3dB) and about 46Hz (-10dB).
Full JBL Synthesis SCL-1 review and specifications →
| Bass Extension (-10dB) | about 45.6Hz (measured, manufacturer data via spinorama.org) |
|---|---|
| Bass Extension (-3dB) | 53.0Hz (measured, manufacturer data via spinorama.org) |
| DIY Kit | No |
| Dimensions | 48”H x 19”W x 14.5”D (1218 x 482 x 368 mm) |
| Drivers | 2x 12” C4 woofers, D2430K dual 3” compression driver on HDI horn |
| Frequency Response | 40Hz-24kHz -6dB (manufacturer specified) |
| Impedance | 4 ohms |
| Maximum SPL | 133dB peak (manufacturer specified) |
| Sensitivity | 94dB (manufacturer specified) |
| Spinorama Preference Score | 4.03 |
| Spinorama Preference Score with Perfect Sub | 6.35 |
| Weight | 177.5 lbs (80.5 kg) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
JBL Synthesis SCL-4: $7,259.90 per pair Audio Advice eBay
Same family: the JBL Synthesis SCL-6 (larger in-wall, ranked higher, rated 3.9/5), the JBL Synthesis SCL-3 (larger in-wall, ranked higher, rated 3.7/5), the JBL Synthesis SCL-7 (larger in-wall, ranked higher, rated 3.7/5), the JBL Synthesis SCL-1 (larger in-wall, ranked higher, rated 3.7/5) and the JBL Synthesis SCL-5 (larger in-wall, ranked lower, rated 2.5/5).
Pros: JBL’s own measurements show a 1.85 directivity-index deviation, the most even directivity of the JBL Synthesis in-walls, with 0.35dB average on-axis deviation. The preference score rises from 3.56 to 6.55 with a subwoofer. A 7-inch aluminum woofer and 2409H compression driver on JBL’s imaging horn give 91dB sensitivity, and bi-wire and bi-amp terminals suit custom home theaters. Measured bass extension of 83.7Hz (-3dB).
Cons: Bass is the weakest here, at 83.7Hz for -3dB and about 61.9Hz for -10dB in free air, so it needs a subwoofer. Listening-window smoothness is 0.59 inside a 3.1dB reference band, and the data is manufacturer supplied and digitized from graphs. At $3630 each it costs twice as much as the better-measuring JBL Synthesis SCL-6.
Full JBL Synthesis SCL-4 review and specifications →
| Bass Extension (-10dB) | 61.9Hz (measured, JBL data on spinorama.org) |
|---|---|
| Bass Extension (-3dB) | 83.7Hz (measured, JBL data on spinorama.org) |
| Crossover Frequency | 1.3kHz |
| DIY Kit | No |
| Dimensions | 25”H x 16.1”W x 3.7”D (636 x 409 x 93 mm) |
| Drivers | 7” aluminum matrix cone woofer, 1” 2409H compression driver on HDI horn (2-way) |
| Enclosure | In-wall, integrated MDF back box |
| Frequency Response | 45Hz-33kHz -6dB (manufacturer, on-axis) |
| Impedance | 6 ohms |
| Power Handling | 200W RMS maximum recommended amplifier power |
| Sensitivity | 91dB (2.83V/1m) |
| Spinorama Preference Score | 3.56 |
| Spinorama Preference Score with Perfect Sub | 6.55 |
| Weight | 27.6 lbs (12.51 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons