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In the Forum: Horn-Loaded Speakers
In the Thread: The Macondo’s Upper Bass Channel: what is next?
Post Subject: Damping, back-chamber and the cool 10 incher.Posted by Romy the Cat on: 11/2/2007

 op.9 wrote:
I agree, there is probably very little to learn luthiers that is directly applicable. However, I've always been interested in the similarities between good speaker cones and thin lacquerd spruce. Sort of a crispy pingy sound even with just a gentle tap. Anyhow, its not a BaD way to make an enclosure.. stiff as you like - with very little stored energy. Also, the resonaces of a violin front are many and chaotic, having the affect of spreading out the resonances. I thing it will be fun to play with the back-chamber back - adding little very light stiffening bars accross - in the manner of a bass bar on a violin. I plan to get lucky!

What I did detect that absence of moisture in cone is very critical. There are many ways to removed moisture from cone, some of them work very nice, still an cone with moisture has no good upper bass. Make an experiment – get a good sounding upperbass driver and just sweep it once with wet price of cloth. You will instantaneously loose the upperbass transients and for a good couple of weeks…
 op.9 wrote:
   When I said PR107 i meant PD107 of course
Very-very interesting driver – I never have head them. Pay attention that they are 10” but the outer spider is very wide, so it has more like 7-8” cone.
 op.9 wrote:
I'm interested in the amp damping discovery. I will be able to experiment with this too.  Would electrically over damping affect the optimum size of the back chamber do you think? I still am not sure what size to start with anyhow...

More loaded plate = more harmonics, more power. Less loaded plat = less power, less harmonics. When you ridiculously unload the tube you strip all harmonics and sound become zippy, unnaturally contrasty and very hasty  - it is hardly listenable – or something that Jonathan Valin calls “the best sound he ever heard”. However, if you driver do not produces HF, over-damped with back chamber and have tendencies to run sit on crossover point too close to the horn rate then the “holding” the driver from amps does produces an interesting result. It is very important here do not go very far and the channel if you go too far in the plate idling will loose the natural upperbass “bloom”. I also presume that each driver would react differently. In my case 4 time higher impedance works fine. Probably 3.5 times higher would be better but I have no such an option on my transformer.

The Cat

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