Only pretty regularly. If they are mounted like in a Model 19, this damps the bells somewhat, but not enough. Plus, when you move back into the horn where it really counts, they ring like crazy until you get back near the throat even when clamped like in the consumer models, so it's worse with the A7's metal brackets. If mounted only on one flange, then obviously it's much worse. To ~effectively damp these requires several pounds of oil based clay, or better still, build a box for them and fill it with either sterilized sand or Portland cement, filling the bells also. Or if you're lazy, just toss a bag of kitty litter on top of them.

This still doesn't address the stress issues due to welding that can only be resolved by cutting out the vane welds and interior vertical brace, filling the vane's voids with a lossy material and adding exterior stiffeners (if you don't do the filled box tweak).

GM

It depends. If it's not highly stressed, it's a subtle difference, but quite a few I've 'liberated' were so stressed it made a big difference. Some are so bad that the vanes don't line up once cut. Sustained notes, such as in organ music, is where it's the most obvious.

Some folks prefer them with the vanes removed, or at least the two outside ones like some early W.E. lens, but HF dispersion suffers even more, requiring a super tweeter IMO.

GM

I heard this kind of resonance on some of Johan Van Zyl's speakers during a recent trip to Dallas. It sounded just like the speakers were slightly underdamped, or a panel was unbraced. I mean, it really sounds like the speakers. But I knew that the amp he was using gave a little bit of bass bloat just like that, because I had one just like it for a couple years. It sounds good, but tends to make speakers have an underdamped sound. It's a pretty good match for very small high Q single drivers, but it's a little thick for larger, more balanced speakers. So I went out to the car and brought in one of the amps I took to show and viola! Perfect! No more bass resonance. Swapping out the amp to one with more bass control gave his speakers the balance they really needed.

I like your amps, and think they sound nice in the mids, and provide deep, full bass. That's a nice change from some of the other low power SET amps that don't have any bass response. But the bass is a bit bloated, and it will be hard to tell that symptom from speaker resonance. Trust me, it isn't all the speakers.

But I have found the aluminum horns (511B/811B) to sound more lively and sound better with the very low powered amps.

I'm glad that there is plenty of opinions and ideas on what to do with these VOTT systems, that way Tim and Colin can take them all in and decide what direction they want to go.

I may be wrong, but I advised both of them to listen and enjoy them for awhile before starting to tweak those systems. The sky is the limit on tweaking the A7 VOTT, but either way they sound pretty good in stock form.

Dr Bruce Edgar when asked to compare his "Edgarhorn" system to the VOTT's replied that the VOTT's are good at "vintage horn" sound vs his "modern horn" sound. I have had both and like most things in life they both have their good points.

I like wood horns now but still enjoy a good listen to a pair of A7's now and then. For the money though it's hard to beat a pair of used VOTT's if you search for ther parts at their best prices.

Ron

Rated at "109 dB in their passband" I'd have thought 40 WPC would be plenty enough to make them happy. But this weekend I moved them up to 100 WPC and the harshenss is gone - you can crank them to 11 without adding any strain whatsoever to the sound.

Another point is that the Altec horns were made to be screwed down, but most people just plop them on top. With the flange screwed tight to the bass box there's a world of difference, even without additional damping of the horn itself.

Altec introduced the concepts of pattern control and driver interaction, and some of their early thrusts in this regard were included in the VOTTs. The sectional horn was designed to put the sound where they wanted it, and their method of adjusting its position was a way to improve summing through the crossover range. Altec developed the Manta Ray horn, which was one of the first constant directivity horns. We're really only just now starting to move past the Manta Ray, and there are a lot of modern production horns that still employ its design features. So I'd say Altec actually used more modern design approaches.

I don't think the difference in sound is due to modern verses vintage as much as it is due to implementation, to the differences between two-way and three-way loudspeakers and due to diferences in equalization used.

Two-way speakers have the advantage of simplicity and coherance over three-way systems, much like single drivers have this over two-way speakers. But the disadvantage is that frequency extremes are harder to push. A midwoofer in a two-way loudspeaker has to run clear into the upper mids and overtone region, and it also has to go deep in the bass. Altec chose a large two-way for their VOTT system, and they weren't expected to be used with soundtracks having deep bass rumbles or much content above 10kHz. Edgar prefers to run three-way systems, because horns are relatively narrow bandpass devices and his speakers are intended for home hifi use, covering a wider total audio band.

Another thing is the equalization curves in each of these speakers. The VOTT is horn loaded through the midrange, and uses an even more efficient horn loaded tweeter. Bass is generated by simple direct radiation from the woofer, loaded by a bass-reflex rear chamber. So the system has rising response, with a few pretty distinct steps. But most people don't use equalization with VOTT speakers, so they can sound somewhat strident. Bruce's basshorns are generally used with equalization, which helps ensure the bass response is deep and full. So there are a lot of differences in implementation that make any comparison less one of vintage verses modern and more really just an apples and oranges thing.

Beyond that, I think the sound difference is due to the characteristic response of the VOTTs. That particular family of loudspeakers was made to be used in theaters with a large number of people, and the most important thing was good coverage over the majority of the audio range, roughly from 100Hz to 10kHz.

What I'm saying is that I don't think it's a vintage verses modern thing here. I think the difference is due to configuration. Take a couple of Edgar's horns, make a two-way loudspeaker for theaters and compare it with the VOTTs. Or take a 511 or Manta Ray, a 100Hz Altec midhorn and a subwoofer below it, setup for balanced response and compare that with one of Bruce's three-way systems. I think that's a more valid comparison.