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Image Dynamics IDQ12 www.imagedynamicsusa.com |
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| Image Dynamic’s latest subwoofer offers big bass and tonal accuracy to boot. | |||
| by Brian Smith | |||
| The IDQ 12 is a 12-inch DVC woofer that was delivered for testing in a ported enclosure of about 2 cubic feet. The enclosure is constructed of 3/4-inch MDF and utilizes a 3.5-inch by 9.5-inch port. Features of the IDQ 12 include a composite cone with rubber surround, a stamped basket, 4-ohm voice coils, and a bumped back plate. Subjective The IDQ 12 did surprisingly well in our subjective evaluation, reproducing a wide variety of program materials with a high degree of accuracy. In most cases, a tuned system of this size will exhibit a bit of tonal coloration when it’s placed in the confines of an automobile. The low-frequency extension gained in free field conditions by tuning the system combines with the car’s transfer function and produces a nice lump around system resonance in the overall response. Based on outward appearance, I’d have guessed that this system would be a real boomer in the 60 Hz range, but this just isn’t the case. Upon removing the woofer, we discovered that the enclosure includes a relatively short but very constrictive labyrinth between the rear of the driver and the tuning port. This would explain the system’s unusual performance. The effect produced by blowing across the top of a half-empty soda bottle is roughly analogous to the operation of a tuned subwoofer. Now imagine how this sound would change if the neck of the bottle were stuffed with cotton balls. As with this system, the damped airflow minimizes the resonant coloration. Overall, the IDQ 12 performed quite well. Obviously, performance would vary according to the enclosure you choose for your installation. Objective The voice coils of the IDQ 12 were paralleled during both our subjective and objective evaluations. Impedance measurements for this unit show a maximum of 7.5 ohms at 45 Hz and a minimum of 2.6 ohms at 87 Hz. Average impedance measured 4.3 ohms. Out-of-car measurements show a rise of about 3.5 dB below 100 Hz, followed by a 12 dB-per-octave roll off below system resonance that is usually associated with a sealed enclosure. In-car measurements show a 1-watt sensitivity that averages 96.5 dB between 20 Hz and 50 Hz. Maximum SPL measured 122 dB at 36 Hz with 300 watts applied. In-car sweeps show a relatively smooth overall response and about 3 dB of power compression at 300 watts. |
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| Price & Contact: $209; 310-787-2399; www.imagedynamicsusa.com |
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