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In the Forum: Horn-Loaded Speakers
In the Thread: Munich High End 2010
Post Subject: MangerhornPosted by Joe Roberts on: 5/18/2010
Moreart, somebody sent me this link last year. You are surely the DIY pioneer of back loaded Manger.

As you probably know this is a touchy speaker to work with.

Rated at 91 dB/W input by the factory, we measure ~91 up to near 92 dB/1W/1m in our two most recent tests in room in a horn! These are the numbers we are now publishing in our brochures.

One would think that the sensitivity would be at least the same in a backhorn...but maybe there is a reason why not that doesn't occur to me. Your results are even lower than ours.

Otherwise, we have found that our speaker is so sensitive to room placement and wall reinforcement that it is difficult to come up with "standard" response measurements. We don't have an anechoic chamber and that wouldn't be very useful info if we did. I can say that we are getting 30hz in-room down about 3-4dB from 100hz. Low end response and subjective quality is very dependent on distance to walls. Measurements are not repeatable site to site for the most part.

As for comparisons between your back horn and ours, your construction is much smaller and a folded horn of the Lowther style. Our horn is 9 ft long, no sharp angles, and relatively unconstricted. I don't know how to compare these theoretically with regard to expected specifications. It seems to me that ours should be somewhat more sensitive and produce lower bass since it is larger.

Again, we found that this driver is very tricky to play with in a backhorn and small tuning adjustments have a large effect. Ver small changes to the diffuser or internal taps totally change the presentation. Consequently, all constructions will vary and it is impossible to generalize.

As for maximum loudness, we recommend low power amps such as 300B SE with the Aporia. I would not overpower the Manger in a backhorn since it is not specified for this application. With a 300B, we get adequate volume for home applications and enough to compete with the high noise level at audio shows. With 8W, the amp typically clips before the speaker runs out of juice. At that point it is quite loud for routine living room listening.

At Munich, we cranked the Aporias up with a 20w 845 SE and they did not catch on fire but our goal for the speaker is "big horn sound in normal sized rooms"--and 8W will do that.

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