They Don't Call the Mouth of the Horn the Bell for Nothing

[toddalin]

I took a pic of the spectrum produced by tapping on an H92 with a small metal hammer. Note the two promenent frequency spikes. The decay time was on the order of a second.

[grumpy]

If you're able (and have time) to do the same test with the horn mounted to a
chunk of mdf (roughly baffle-size ), then, with it mass loaded on -both- ends
(attach a driver), it would be (more) interesting... either that or a lot less interesting.
Something to be learned, in any case.

[toddalin]

If you're able (and have time) to do the same test with the horn mounted to a
chunk of mdf (roughly baffle-size ), then, with it mass loaded on -both- ends
(attach a driver), it would be (more) interesting... either that or a lot less interesting.
Something to be learned, in any case.

A possibility once I remount the horns. But, at that point they will have a plasticized coating on them, so the test really wouldn't be valid.

At this point, I've already painted the inside of the horn used in the test (that had been stripped by a prior owner). I found with the finger taps that even the coating JBL puts on the horns provides some (but not much) deadening to the ringing.

(BTW, JBL certainly could have done a better job of casting these things. Once the paint is removed you can see all the flaws and seams in the metal-work.)

[4313B]

(BTW, JBL certainly could have done a better job of casting these things. Once the paint is removed you can see all the flaws and seams in the metal-work.)

They did what they were supposed to do. The old aluminum transducer frames also have voids which were undetectable until you start sandblasting them.

You could always have a pair made out of sonoglass.

[grumpy]

OK. I can see a weekend of playing with 2312's on the horizon.
I've got a contact mic to play with as well (pseudo-accelerometer).

Will be interesting to get your opinion on your 2307->2312 system mod
once completed.

[Beowulf57]

Me too...the battle of the horns is on. I'm all ears for the comparison!

P.S. The ringing is reduced by attachment to a baffle, but still present and some form of coating helps to deaden it even further. Attachment to a driver alone however, made very little difference as the horn is still hanging out there in space, ringing like a bell.

[grumpy]

Attachment to a driver alone however, made very little difference as the horn is still hanging out there in space, ringing like a bell.

... as one should well expect. Frankly, once mounted, I expect it to be difficult to
measure an audible, mechanical resonance, but it's an excuse to dust off some toys
and I might accidentally learn something