Short answer: the Ascend Acoustics CBM-170 SE2. It ranks #114 of 222 bookshelf speakers by sound quality, rated 3.8/5, at $468; the Dynaudio Special Forty ranks #148, rated 3.5/5, and costs $3,600, so there is little reason to consider the other one.
The Ascend Acoustics CBM-170 SE2 is the more accurate option. On-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that. Its measured preference score, a predictor of how neutral it sounds, is 6.30 against 4.73 for the Dynaudio Special Forty. Watch for: A narrow dip in the on-axis and listening-window response appears in the 3-5kHz range (down to about -2.7dB), mirrored by a matching dip in the directivity index at the same frequencies: likely a brief widening of dispersion right at the tweeter/woofer crossover.
The Dynaudio Special Forty is the deeper-bass choice. Smooth, “buttery” overall tonal character consistent with Dynaudio’s house sound. Its bass reaches about 54Hz before falling 3dB, against 70Hz for the Ascend Acoustics CBM-170 SE2. Watch for: A glaring, sometimes sibilant quality around 3-4kHz was the most noticeable issue in listening, the one thing the reviewer would want notched out with EQ.
Buy the Ascend Acoustics CBM-170 SE2. It is rated higher for sound quality than the Dynaudio Special Forty and costs less, so only choose the other one for a particular feature it does better.
Looking for alternatives? See the complete Passive Home rankings.
On-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that.
Ascend Acoustics $468 eBay
Smooth, “buttery” overall tonal character consistent with Dynaudio’s house sound.
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Specifications Side By Side
| Ascend Acoustics CBM-170 SE2 | Dynaudio Special Forty | |
|---|---|---|
| Price | $468 per pair | $3600 per pair |
| Ranked | #114 of 222 in Large Size Bookshelf Speakers | #148 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) | 54Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) | 39Hz (measured, Erin’s Audio Corner) |
| Sensitivity | 86.8dB (2.83V/1m, measured, manufacturer spinorama data; 87dB manufacturer specified) | 83.5dB (measured, Erin’s Audio Corner; 86dB manufacturer specified) |
| Drivers | 27mm custom SEAS soft dome tweeter, 6.5” proprietary composite polygel cone woofer | 5.9” MSP (Magnesium Silicate Polymer) cone woofer, 1” Esotar soft dome tweeter |
| Dimensions | 12H x 9W x 9.5D in | 14.1”H x 7.7”W x 12.1”D (358.1 x 195.6 x 307.3 mm) |
| Weight | 15 lbs (6.8 kg) each | 17.9 lbs (8.1 kg) each |
| Impedance | 8 ohms | 6 ohms nominal (4.9 ohms minimum above 80Hz, measured, Erin’s Audio Corner) |
| Power Handling | 200W continuous, 400W peak | - |
| Woofer Cabinet | ported, rear | ported |
| Spinorama Preference Score | 6.30 | 4.73 |
| Spinorama Preference Score with Perfect Sub | 8.66 | 6.74 |
| DIY Kit | No | No |
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. The two were measured by different sources, so small differences, especially in the bass, can come from the measurement setup rather than the speakers.
Measurement data: Ascend Acoustics CBM-170 SE2 (measured by the manufacturer) and Dynaudio Special Forty (measured by Erin’s Audio Corner), via spinorama.org.
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