Rerurn to Romy the Cat's Site
In the Forum: Horn-Loaded Speakers
In the Thread: Jessie Dazzle Project
Post Subject: Decisions decisionsPosted by jessie.dazzle on: 7/25/2008
Thanks guys for all the suggestions.
Klaus wrote :
"...there are a lot of questions, but if one thinks to much, then he will end up like this lynn olson, pages and pages of endless talk and no horns..."
Very true, I need to get cracking, but I'm currently sort of stuck : I need a means of calculating for rectangular (I don't mean square) exponential horns.
I guess I could stop being lazy, and just extrapolate from the data given for square horns. I would imagine that in transforming a square horn to a rectangular horn, one need only maintain constant area for each section given for the square horn. In other words, take a section of a square horn that measures 2 X 2 feet; it will have an area of 4 square feet... To adapt this data for construction of a rectangular horn, it seems one could make that same section 1 X 4 feet, or 1.34 X 1.5 feet, or whatever, as long as the resulting area comes out to 4 square feet, and as long as the same height-to-width ratio is applied to all sections (there is probably a limit somewhere around the point where the mouth starts taking on the proportions of a slit).
The plan is to dimension the mouths of these horns such that they would contact the room on three sides; this means mouths that go from floor to ceiling and contact one side wall. So the long sides would stand about 8 feet tall, and the short sides would be whatever they need to be.
Never mind the fact that the current room does not allow for this sort of coupling (the ceiling is inclined and too high, and coupling with the side walls is not really possible)... This is a sort of "end of life horn system"; I will find it (us) a good home once the project is done.
Next step is to commit to a construction process and buy materials.
Romy wrote:
"...So, if I was in your shoe I would discard whatever Romys and others say and would talk to the guys who build the horns... Do not take anything that anyone say as the fact but rather use it as background to make you own decision..."
This is my intention. Advice, intuition, time ticking away, physical, financial and logistical considerations, illogical superstitions, they will all conspire to point me toward a decision.
Romy wrote:
"...So, way do not leans hot [why do we not learn how] to make “interesting” horn with proper balance of damping and “Resonance Oops” properties? I do not say that it is a good direction to think but the benefit would be so cool: to have a quick and light, literally collapsible bass horn that could be installed for a few seconds. It might be a wall ornamentation in living room during a “normal time” but when you wish to listen music a few walls might be unfold and the bass horn might be formed. I would even go for such a stupid idea as inflatable horn. Sure it will resonate; the inflatable resonances should be included into the design… somehow…"
Romy, dude, pass that Cohiba over here! I'm naive enough to think that I could tune a resonant horn wall to get a desired effect... This is one arguement against making the walls of the horn too thick. On the other hand part of me agrees with Paul and Tuga, when they mention that all resonance is best kept well in check. If I could, I'd probably make these horns as heavy as a gospel choir. Again, all this will weigh when deciding on construction method and materials.
Tuga wrote :
"...Carbon is used by Audiotekne in a variety of products, from vinyl claps to a speaker with a 35mm carbon front baffle. Some guys in Italy compared the same housing configuration built in wood using the same driver and they swear it's so much better..."
Which one do they claim to be better; wood or carbon?
Paul S wrote :
"...Nor have I yet heard anything good coming from fiberglass or carbon fiber drivers. FWIW, I think there are "better sounding" materials for those purposes..."
Apart from harboring an ilogical reluctance toward the use of man-manipulated materials on this project, I will pass on carbon purely out of financial considerations. It's surprising that one pair of 45-50Hz horns (made from two layers of carbon + foam + two layers of carbon), would require more than one complete 100m roll of carbon. At 40€/m X 100m, we are into the sort of cash that I'd rather put toward real estate (the kind with enough space to properly install such horns); what's more, we would probably need an additional half roll of carbon to finish the job.
The quickest and most cost-effective way to increase rigidity in a composite-sandwich (provided one has the space) is to increase the thickness of the middle part, in this case, the foam within the sandwich; alternatively, generous stiffening ribs might be molded onto the outer surface.
Paul S wrote :
"...I sometimes use a cementatious material that has added to it a fair amount of foam-ish beads and acrylic. The stuff sets up like cement but is MUCH lighter than cement or plaster, perhaps 2/3 lighter. I mention this because I still think moulding/forming with substantive inert material is the way to go..."
Sounds like what we (over here) call aerated concrete, which I used in the form of pre-cast blocks to make the lower bass enclosures. Yes it's way lighter than normal concrete, but still ended up with over 500 lbs of blocks in each enclosure. The best part is... I get to do it all again! One of the enclosures has developed cracks (I think the blocks were defective; the other enclosure is fine). The new versions will use double plywood walls, spaced for sand filling.
Thanks again,
jd*Rerurn to Romy the Cat's Site