Short answer: the JBL Synthesis SCL-3. It ranks #10 of 18 in-wall speakers by sound quality, rated 3.7/5, at $7,259.90; the JBL Synthesis SCL-4 ranks #12, rated 3.6/5, at $7,259.90. Close enough in price that the sound-quality gap is the deciding factor.
Why pick the JBL Synthesis SCL-3: JBL’s own measurements show 0.32dB average on-axis deviation and a 2.28 directivity-index deviation, and the preference score rises from 3.80 to 6.42 with a subwoofer. The tradeoff: Bass rolls off early, at 72.4Hz for -3dB and about 45.8Hz for -10dB in free air, so it needs a subwoofer.
What the JBL Synthesis SCL-4 does well: 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-3. It is rated higher for sound quality than the JBL Synthesis SCL-4 at the same price, which makes it the one to get unless you need something the other one does better.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| JBL Synthesis SCL-3 | JBL Synthesis SCL-4 | |
|---|---|---|
| Price | $7,259.90 per pair | $7,259.90 per pair |
| Ranked | #10 of 18 in In-Wall & In-Ceiling Speakers | #12 of 18 in In-Wall & In-Ceiling Speakers |
| Drivers | Two 5.25” aluminum matrix cone woofers, 1” 2409H compression driver on HDI horn (2-way) | 7” aluminum matrix cone woofer, 1” 2409H compression driver on HDI horn (2-way) |
| Enclosure | In-wall/in-ceiling, integrated MDF back box | In-wall, integrated MDF back box |
| Dimensions | 16.5”H x 16.5”W x 6”D (418 x 418 x 153 mm) | 25”H x 16.1”W x 3.7”D (636 x 409 x 93 mm) |
| Weight | 24.3 lbs (11.02 kg) | 27.6 lbs (12.51 kg) |
| Sensitivity | 91dB (2.83V/1m) | 91dB (2.83V/1m) |
| Impedance | 6 ohms | 6 ohms |
| Power Handling | 200W RMS maximum recommended amplifier power | 200W RMS maximum recommended amplifier power |
| Frequency Response | 65Hz-33kHz -6dB (manufacturer, on-axis) | 45Hz-33kHz -6dB (manufacturer, on-axis) |
| Crossover Frequency | 1.3kHz | 1.3kHz |
| Bass Extension (-3dB) | 72.4Hz (measured, JBL data on spinorama.org) | 83.7Hz (measured, JBL data on spinorama.org) |
| Bass Extension (-10dB) | 45.8Hz (measured, JBL data on spinorama.org) | 61.9Hz (measured, JBL data on spinorama.org) |
| Spinorama Preference Score | 3.80 | 3.56 |
| Spinorama Preference Score with Perfect Sub | 6.42 | 6.55 |
| DIY Kit | No | No |
Related Speaker Comparisons
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- Revel W228Be vs JBL Synthesis SCL-3
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- JBL Synthesis SCL-3 vs Miller & Kreisel IW150
- JBL Synthesis SCL-3 vs Revel W990
- JBL Synthesis SCL-3 vs Grimani Systems Rixos-L
Prices on this page were last checked September 26, 2026 at 11:14 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-3: $7,259.90 per pair Audio Advice eBay
Pros: JBL’s own measurements show 0.32dB average on-axis deviation and a 2.28 directivity-index deviation, and the preference score rises from 3.80 to 6.42 with a subwoofer. Two 5.25-inch aluminum woofers and a 2409H compression driver on JBL’s imaging horn give 91dB sensitivity, and the square baffle works in walls or ceilings. Bi-wire and bi-amp terminals and a paintable magnetic grille suit custom home theaters. Measured bass extension of 72.4Hz (-3dB).
Cons: Bass rolls off early, at 72.4Hz for -3dB and about 45.8Hz for -10dB in free air, so it needs a subwoofer. Listening-window smoothness is only 0.43 inside a 3.1dB reference band, rougher than the other JBL Synthesis in-walls. The data is manufacturer supplied and digitized from graphs. At $3630 each it costs twice as much as the better-measuring SCL-6.
Full JBL Synthesis SCL-3 review and specifications →
| Bass Extension (-10dB) | 45.8Hz (measured, JBL data on spinorama.org) |
|---|---|
| Bass Extension (-3dB) | 72.4Hz (measured, JBL data on spinorama.org) |
| Crossover Frequency | 1.3kHz |
| DIY Kit | No |
| Dimensions | 16.5”H x 16.5”W x 6”D (418 x 418 x 153 mm) |
| Drivers | Two 5.25” aluminum matrix cone woofers, 1” 2409H compression driver on HDI horn (2-way) |
| Enclosure | In-wall/in-ceiling, integrated MDF back box |
| Frequency Response | 65Hz-33kHz -6dB (manufacturer, on-axis) |
| Impedance | 6 ohms |
| Power Handling | 200W RMS maximum recommended amplifier power |
| Sensitivity | 91dB (2.83V/1m) |
| Spinorama Preference Score | 3.80 |
| Spinorama Preference Score with Perfect Sub | 6.42 |
| Weight | 24.3 lbs (11.02 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
JBL Synthesis SCL-4: $7,259.90 per pair Audio Advice eBay
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 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