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In the Forum: Horn-Loaded Speakers
In the Thread: Aporia - Silbatone Acoustics speaker

Post Subject: Not a hush hush secret or smoke and mirrorsPosted by Joe Roberts on: 1/15/2009

Quickly again, for the record, and The Google:

The back wave of the Manger has a much less flat response than the front wave. There are peaks out the back. It is not a symmetrical dipole.

This issue is only of interest if you are using the back wave, e.g. in a back horn. In a box, it probably doesn't matter as much. Maybe it does, not sure. Anyway, the rear output of the Manger is not optimal and Silbatone had to consider this problem.

Interestingly, the highs come out of different holes in the back of the driver than the lows, which allows for targeted treatment of back wave output. You can't just cover the holes with duct tape if you don't want highs or lows because this will mess up the front wave.

From my understanding of this procedure, the particulars of the trap or damper or whatever it is that is glued to the back of the driver also depend on the specific horn geometry and how the horn loads the Manger.

The horn curve attenuates mid frequencies for a mechanical xover effect, but traps and damping material in particular spots attached to the driver and inside the horn structure help to smooth out the response and help the integration of MF and LF in this particular design.

Also, the APORIA has a straight pipe directly behind the driver that provides space for this technique, but the Bulgarian Acousta IV backhorn plans might not allow this luxury, so beware.

This is not a CIA secret but it is too involved to relate in a snappy brochure. I am not even so sure that it is super-interesting because it is specific to this speaker design and not a useful generic tip, but I'm glad that I encouraged the question.

I don't know the exact frequencies and tunings involved but that is the general overview.

In short, the Manger is no zen nirvana easy money solution for a simple yet perfect single-driver full-range speaker. It is a demanding pain in the butt like all the rest of them.

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