Short answer: the JBL 708P for better sound quality, the PSI Audio A21-M for the lower price. The JBL 708P ranks #21 of 48 powered bookshelf speakers at $4000. The PSI Audio A21-M ranks #22 at $3720, $280 cheaper.
What the PSI Audio A21-M gets right: PSI Audio deliberately skips DSP entirely, using a proprietary Coherent Phase Response analog circuit to keep phase alignment accurate without adding conversion stages, tracing its design back to the Studer A3 studio monitor. Set against that: The bass alignment measures a Q of 0.96, close to the point where a port tuned system starts to show a mild peak rather than a clean rolloff, worth knowing if placed near a wall.
The case for the JBL 708P: CEA2034 spinorama shows extremely good frequency response both on- and off-axis, with excellent horizontal directivity. Watch for: A port resonance creates a mild rise around 600-900Hz. Vertical dispersion is narrower than horizontal, so staying within a few degrees of the tweeter axis matters.
Buy the PSI Audio A21-M if the price matters more than sound quality. Buy the JBL 708P if sound quality matters more than the price.
Specifications Side By Side
| PSI Audio A21-M | JBL 708P | |
|---|---|---|
| Price | $3,720 each | $4000 |
| Ranked | #22 of 48 in Large Size Powered Bookshelf Speakers | #21 of 48 in Large Size Powered Bookshelf Speakers |
| Enclosure | ported | - |
| Drivers | 27mm handmade dome tweeter, 172mm cone woofer | 8" woofer, 2409H 1" compression driver |
| Dimensions | 9.8"H x 15.7"W x 11.8"D (250 x 400 x 300 mm) (9.9 x 15.8 x 11.9 in) | 17.2"H x 9.8"W x 11.5"D (438 x 248 x 292 mm) |
| Weight | 28.2 lbs / 12.8 kg (28.2 lbs) each | 25.1 lbs / 11.4 kg each |
| Power Output (Watts) | 335W total (280W woofer, 55W tweeter, Class A/B) | - |
| Frequency Response | 38Hz-23kHz -6dB | 41Hz - 25kHz (+/-3dB) (Manufacturer specified) |
| Bass Extension (-3dB) | 39.6Hz (measured, Audio Science Review) | 82Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | 33.2Hz (measured, Audio Science Review) | 62Hz (measured, Audio Science Review) |
| Max SPL | 110dB short term, 121dB peak | - |
| Crossover Points | 2.4kHz | - |
| Warranty | 5+1 years | - |
| Country | Switzerland | - |
| App | - | No |
| EQ | - | No |
| DSP | - | No |
| Output Power | - | 500W total (250W woofer, 250W tweeter) |
Related Speaker Comparisons
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- Neumann KH 150 vs JBL 4329P
- Genelec 8050B vs JBL 4329P
- Buchardt A500 vs JBL 4329P
- Genelec 8050B vs JBL 708P
- Neumann KH 150 vs JBL 708P
The Two Speakers In Full
PSI Audio A21-M: $3,720 each B&H Photo
Pros: PSI Audio deliberately skips DSP entirely, using a proprietary Coherent Phase Response analog circuit to keep phase alignment accurate without adding conversion stages, tracing its design back to the Studer A3 studio monitor. The sound power directivity index tracks tightly (standard deviation 3.39) and on axis deviation measures a moderate 0.375dB average, and it reaches a measured 39.6Hz extension point with a wide 80 degree horizontal by 30 degree vertical dispersion pattern.
Cons: The bass alignment measures a Q of 0.96, close to the point where a port tuned system starts to show a mild peak rather than a clean rolloff, worth knowing if placed near a wall. Sold as a single unit rather than a pair, a stereo set runs roughly $6,000 to $7,800 depending on retailer and finish. With no DSP or room correction on board, getting the most from it depends more on room treatment and placement than with a comparable DSP equipped monitor.
Full PSI Audio A21-M review and specifications →
| Bass Extension (-10dB) | 33.2Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 39.6Hz (measured, Audio Science Review) |
| Country | Switzerland |
| Crossover Points | 2.4kHz |
| Dimensions | 9.8"H x 15.7"W x 11.8"D (250 x 400 x 300 mm) (9.9 x 15.8 x 11.9 in) |
| Drivers | 27mm handmade dome tweeter, 172mm cone woofer |
| Enclosure | ported |
| Frequency Response | 38Hz-23kHz -6dB |
| Max SPL | 110dB short term, 121dB peak |
| Power Output (Watts) | 335W total (280W woofer, 55W tweeter, Class A/B) |
| Warranty | 5+1 years |
| Weight | 28.2 lbs / 12.8 kg (28.2 lbs) each |
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JBL 708P: $4000 Bhphotovideo
Pros: CEA2034 spinorama shows extremely good frequency response both on- and off-axis, with excellent horizontal directivity. Bi-amplified 500W design (250W woofer, 250W compression driver) handles an 8” woofer and JBL’s 2409H compression tweeter.
Cons: A port resonance creates a mild rise around 600-900Hz. Vertical dispersion is narrower than horizontal, so staying within a few degrees of the tweeter axis matters. Distortion climbs at 96dB SPL, with the tweeter reaching about 2.5% THD at elevated levels.
Full JBL 708P review and specifications →
| App | No |
|---|---|
| Bass Extension (-10dB) | 62Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 82Hz (measured, Audio Science Review) |
| DSP | No |
| Dimensions | 17.2"H x 9.8"W x 11.5"D (438 x 248 x 292 mm) |
| Drivers | 8" woofer, 2409H 1" compression driver |
| EQ | No |
| Frequency Response | 41Hz - 25kHz (+/-3dB) (Manufacturer specified) |
| Output Power | 500W total (250W woofer, 250W tweeter) |
| Weight | 25.1 lbs / 11.4 kg each |
As an eBay Partner, we may be compensated if you make a purchase.
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons