Description
Audio Pro Allroom Subwoofer in silver
RRP $799.00. – Our price $249.00
How does such a small subwoofer deliver such a large sound? Our patented ace-bass technique allows us to produce small subwoofers with small drive units without losing any bass performance. It
delivers the same deep, clean and rapid bass as its bigger brothers while its downward firing bass port ensures maximum connection to you. It also benefits the rest of your sound system by taking on all low bass information, thus letting the ALLROOM focus on what it does best.
(Please note image of the rear panel is in white; this item is silver, not white).
Specifications:
150 W Acebass amplifier
Auto standby
Line and speaker level inputs
Woofer: 6 1/2″ long-throw
Effective freq. range: 30-100 Hz
Lowpass: 50-100 Hz, variable 24 dB/octave
High Pass: 100 Hz, 6 dB/octave
Dimensions (WxHxD): 280x290x300mm (excluding spikes)
ACE-BASS – DEEP BASS FROM SMALLER CABINETS
In Elektronikvärlden (a Swedish hi-fi magazine) No. 8, 1988, Bertil Hellsten wrote a very good and instructive description of the ace-bass technology. Below is an abstract of the article:
General
There are many ways to accomplish good bass in a loudspeaker. One is to have a large cabinet and a large woofer.
In practice, the lower limit for a woofer is set by the lower resonance frequency, which can be lowered by increasing the membrane’s mass. By adding weights, you can go lower and lower in frequency. But, at the same time, the speaker will respond increasingly slowly. In addition, the membrane’s compliance and damping will no longer match, so the result isn’t useful. To achieve a very low limiting frequency in a small woofer, a combination of mass, compliance and damping is needed, and this is impossible to achieve mechanically.
Audio Pro’s solution – electronic mechanics
Seen from the amplifier’s point of view, the loudspeaker is an electrical component with its mechanical attributes transformed into electrical magnitudes. The mass corresponds to a capacitance, and the compliance to an inductance that is in parallel with the capacitance. The attenuation corresponds to a resistance that is in parallel with both of the above. By adding more inductances, resistances and capacitances, one should easily be able to change the loudspeaker’s mechanical attributes. This is the main idea behind Audio Pro’s ace-bass loudspeaker constructions. But there is a catch. The drive unit’s voice coil has a resistance that lies serially with the parallel ‘mechanical’ components. This means that we can’t parallel-connect directly to the woofer’s mechanical parameters. It is not connected to the amplifier firmly enough. If we were to increase the damping by parallel-connecting the amplifier output with a resistance, we would still never get a lower value than what the voice coil’s resistance gives, and that is not good enough. The same thing happens to the other attributes. They are ‘hidden’ by the voice coil’s (and the speaker cable’s) resistance.
Negative resistance
The solution is to serially connect the amplifier output with a negative resistance. But you can’t buy that at your nearest electronics parts shop. It can only be achieved by positive feedback in the amplifier’s output stage.
There are several sensitive factors that can easily cause the system to self-oscillate. However, correctly trimmed, you can achieve a system that exactly equalizes all the resistances that are in series with the drive units’ properties. In this way, you can also reach and affect the loudspeaker’s mechanical attributes electrically.
You can also choose to let this influence decrease with increasing frequency, where it’s no longer needed.
By using this feature fully, Audio Pro maintains that you can decrease the speaker’s physical volume by 90%, compared to a conventional bass reflex box!
ACE-BASS is an abbreviation for Amplifier Controlled Euphonic Bass.
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