Short answer: the JBL Synthesis SCL-3. It ranks #13 of 28 in-wall speakers by sound quality, rated 3.7/5, at $7,259.90; the JBL Synthesis SCL-4 ranks #16, rated 3.6/5, at $7,259.90. Close enough in price that the sound-quality gap is the deciding factor.
The JBL Synthesis SCL-3 is the deeper-bass choice. An in-wall or in-ceiling speaker with a horn tweeter, high sensitivity and bi-amp terminals for custom home theaters. Its bass reaches about 72.4Hz before falling 3dB, against 83.7Hz for the JBL Synthesis SCL-4. The catch: 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: A compact in-wall speaker with a horn tweeter, very even coverage and bi-amp terminals for custom theater installs. 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.
Prices on this page were last checked November 11, 2026 at 3:26 AM 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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Specifications Side By Side
| JBL Synthesis SCL-3 | JBL Synthesis SCL-4 | |
|---|---|---|
| Price | $7,259.90 per pair | $7,259.90 per pair |
| Ranked | #13 of 28 in In-Wall & In-Ceiling Speakers | #16 of 28 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 |
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