OHM Acoustics "Walsh F" Speaker remakes

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#381
That's funny, I could have sworn there was a post from Loquatious put up about his very well researched Infinity Walsh tweeter thread over on Audio Karma. I was going to suggest you all check that out, because there are some photos of the Walsh Tweeter there. Checking these out would be helpful to you.
You folks will have to bear with me- I am buried in a amp project I am designing for laser show use. Sort of looking at a deadline.
I'll get some links put up here in the next day or two.
 
#385
Forgive me if I haven't read the last pages and am repeating something here. I read the first pages and had an idea and was didn't have the patience to read a further 8 pages! Anyway, just thinking, you could take the flare off an atc midrange dome, and face upwards, then conventional bass driver configuration from 350hz down? The atc mid domes can do high frequencies well enough? Could build the bass with four drivers on each face of the box?
 
#387
lejockey said:
Forgive me if I haven't read the last pages and am repeating something here. I read the first pages and had an idea and was didn't have the patience to read a further 8 pages! Anyway, just thinking, you could take the flare off an atc midrange dome, and face upwards, then conventional bass driver configuration from 350hz down? The atc mid domes can do high frequencies well enough? Could build the bass with four drivers on each face of the box?
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You'd get a ceiling flooder, mostly, except if you mount some kind of wave guide over it, which is done successfully, on occasion.
 
#391
Just re-reading the 14" driver thread and noticed that there was already a discussion there about this thread - I had not remembered that. I wonder if anything has ever come from this thread or that one? And by the way, the Pioneer driver originally mentioned by Mamboni is no longer available.
 
#393
GRollins said:
The standing joke was that it took 200W to get the original Walsh speakers to make sound and 201W to blow them up.
The Ohm versions were poor copies. They were basically a one trick pony. They could do that weird where's-the-speaker imaging thing, but the sound quality was sad compared to other speakers. The shop I worked for bought something like two dozen pairs of the stupid things and we could hardly give them away. For all I know, they still have a pair or two.
The basic idea is simple enough--just turn a driver face down into a box so that you're listening to the back of the cone with no cabinetry. It images well, and is close to omnidirectional. So far, so good. The problem is the frequency extremes. The way they got anything like reasonable frequency response out of the original Walsh was to vary the makeup of the cone from (as I recall) metal at the voice coil to paper at the surround. Each ring of material had to be bonded to the next quite carefully. Note that the metal and bonding agents increased the mass of the cone considerably, and transients suffered as a result.
The Ohm speakers used really cheap drivers and treated them.
Of the two approaches, the Ohm strategy is going to be more practical to the average DIYer. I'd reccommend getting a case of really cheap "buyout" paper cone drivers from Parts Express--the 99 cent specials--and experiment with different treatments. Your goal is controlled cone breakup, which is a difficult horse to ride. Once you set different parts of the cone in motion, things are going to get complicated fast.
Suggestions for paper treatments: rubber cement, super glue, varnish, polyurethane, etc. Also consider the careful application of water to loosen up the paper fibers and make the cone more floppy. Your goal is to have the cone as stiff as possible up near the voice coil so that it acts like a tweeter. As the frequencies decrease, you'll need to assign more cone area to radiate.
You'll end up trashing a lot of speakers in the beginning, which is why I suggested starting with really cheap ones.
On the other hand, you might just decide that you like the sound of an ordinary driver upside-down, in which case you're done.

Grey
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I'm sorry, I know this discussion is many years old, BUT: Man, you're talking without knowing exactly what. The principle on which the operation of the Ohm F Type driver is based, because only if you talk about this speaker can be the subject of discussion, is far above your knowledge, which you expose here in a very childish and ignorant way. If you want to discuss this topic, please at least read in the literature of those times, where you will find simplified technical explanations, so that almost anyone can understand.
 
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