[Bob in St. Louis]

Wouldn't that make yours a horn too? I'd like to avoid the discussion that went on awhile back on Decware where several folks were "chatting" about what's a horn, what's a T.L......
Just curious. 

Ok, here's another wild idea..
Scotch tape five (or more) large balloons to the drivers mounting flange. Edge diffraction is eliminated, you've still contained the wave (for the most part), it won't be SOOOO directional that it would beam. You'd have to run tape all the way around the balloons to keep them stable.
You've only spent a few minutes, and haven't spent any money.
I know you have balloons John, you've got kids!!

Whatcha think of that!?!?

Bob

[JohninCR]

Actually I throw balloons away whenever I find them in the house due to the 3yro.  When I was a teenager a friend of the family's kid choked on a balloon and died.  I don't ever want to have to try an emergency tracheotomy, although I think I could if I had to.

If you could find a long 4-6" diameter one like used to twist into animals but bigger, then you might approximate the diffraction ring thing.  Waveguides need to have specific depths and mouth sizes, and the roundovers don't count toward that.   We do have one of those long cylindrical foam swimming pool floats laying around that has almost be sacrificed in the name of speaker advancement on quite a few occasions.  Thanks for reminding me.  This may be the one.

If I wanted to do something temporary, I'd use a serated knife and cut them out of styrofoam sheeting that I have.  I was saving that for later to maybe make a form easily to create something out of fiberglass.  I'd rather work with wood for now, glass and resins can get nasty.

[doorman]

Don't quit your "day job" Bob!

[tminus]

I've been wanting to do waveguides frnt and rear for OB's with fiberglass baffles.  It would be similar to this times two for the frnt and rear guides:

http://www.putfile.com/pic.php?img=4008408

The man who did these is truly skilled, however, glassing these shapes is not difficult.  The pic shows the baffle just after the sealer was sprayed.  The drivers would be sandwiched between the front and rear baffle cutouts and decoupled from both.  Then the area between the outer edges of the baffles could be filled in with some nice hardwood panels and filled with sand or what-have-you to add mass - or layered up MDF with a veneer applied.  Mine will be figure 8 shaped instead of the rectangles pictured.

The OB dispertion pattern is figure 8 shaped, which causes the lame sound off axis.  My intention for the wavequides both frnt and rear is to cause the figure 8 dispertion pattern to move closer together, or "overlap" - something closer to a double cardoid pattern.  This should produce the most benefit in the lower registers, but I think the midrange can benefit allot as well.  Guess I'll be finding out.....

Patrick

[tminus]

My apologies to Mark in Canada.  I just scrolled through this thread and I see that it morphed into a "waveguide" thread.  None of us have addressed his questions iirc.  I'm going to copy my post to a new "OB waveguide" thread.   Sorry, Mark in Canada.  I don't have experience w/ the B200.

Patrick

[mcgsxr]

tminus, no worries about the new thread (though I do see it active), as I was asking for ideas for a new baffle, and this clearly qualifies as something I have not done!

Great idea flow!

[goo]

your not kidding
I think some of the most creative ideas are coming out here

Hey Bob,
when I was developing a polymer for the USNSeals we used a Latex form (balloon).
I think I may try this. All I have to do is nail the solids, and monomer ratio....etc ZZZZzzz
Imagine a Wg or horn made out of a polymer that mimicks human flesh.....ok what's in this cigar I am smoking
Q

[JohninCR]

Hey Goo,

Do fiberglass resins eat latex?  What about the plastic/vinyl that are use for inflatable beach toys, like a childs lifering or beachball?

Here's a cheap and easy one for a complex baffle shapes that I've seen some car audio installers use.  Take that cheap carpet-like material used to cover car audio boxes and frame it into the shape that you want.  Put some resin on with a paintbrush.  Add fiberglass and/or carbon fiber in additional layers for strength and added rigidity.

[goo]

Not all, it depends on the solvent used, (MEK,2-p, ipa,etc). Unfortunately for diy hobbies we don't work with anything with an epoxy type cure.
Great work on those WG's by the way. Once I finish the Content baffles (final rev). I will be going down the path you are. aa
q

[Bob in St. Louis]

Don't quit your "day job" Bob!

Doorman - My day job affords me the luxuries I've become accustom to. In addition, the day job is unable to keep me busy for the full eight hours that I'm there, which is why I'm able to hang out in places like these and annoy people. During my 'down time', some of these useless ideas come dribbling out of my head and I've got to "air them" in order for them to go away (be disproven). John and I have a history of me coming up with off the wall silly shit, and him being the consummate professional explaining why it won't work. It's become a mission for me to come up with some bizarre idea that he actually uses (I'll be able to die happy then). Granted having a half dozen balloons taped around a magnet mounted driver would look like something from a circus, but it might just have a sonic benefit, if so, a fellow could fashion something that looks more masculine (Use all black balloons  ). Who knows. Hell, it wouldn't look much worse than having a swimming noodle wrapped around your driver. I've seen guys do some pretty silly stuff in order to improve their sound.

John - I understand the aversion to balloons after hearing that story. That sucks! In addition to swimming noodles, you can also use the foam insulation that folks install around water pipes. The dark gray, fairly stiff stuff that's split halfway through.
I've seen the car guys on TV fashion up some pretty cool looking fibreglass sub enclosures. Thought about making some cool looking baffles out of it too. Also thought about creating a mold using the 'lost wax meathod', making a baffle out of lead. Talk about your dead baffle materials. (Automotive repair shops have a never ending supply of wheel weights).

Goo - I've known for awhile now what your day job consist of. I just made the connection to your screen name. If you ever change your name to, "Iglowinthedark", I'll know you've moved on from polymers to "other stuff".

Have a good day gentilemen
Bob

[goo]

Gentilemen
how did you know I was goyim

The "other stuff" will require a higher clearance Clarence
happyjoy

[JohninCR]

Not all, it depends on the solvent used, (MEK,2-p, ipa,etc). Unfortunately for diy hobbies we don't work with anything with an epoxy type cure.
Great work on those WG's by the way. Once I finish the Content baffles (final rev). I will be going down the path you are. aa
q

I use epoxies any time the need arises, most recently a very liquid version to bond wood to concrete and to prevent the moisture from the concrete from damaging the wood as the concrete cured.  It's about the consistency of latex paint, and even a thin coat on both sides of styrofoam makes it strong and rigid like wood.  Now that I think about it, I'll use it to make some experimental dipole waveguides next week.  Just add in some fiberglass mat for strength, and I can build any shape or angle with just a knife.  I'll try some on a balloon while I'm at it, which presents some interesting prospects for circular forms and roundovers.

[goo]

John,
you probably have already tried this, if so just ignore me.
Think about what Shapers use for surfboards. The trick will be finding a blank large enough to shape into a bowl. (15" finish diameter with 2" thick lip...Dude ...just guessing ). I wonder how much$$ a blank of foam say 24" sq would cost. Then you can shape that T curve to your hearts content. yes

oh one more thing with the epoxy I'll give you some tweaks on how to cure to a target duro...just got to bug me boss...he's in India right now and was the principle chemist on the product type you are using. I am more of the UV/Gamma cure guy..oh well
I throw all of this out there to try and provide something to you guys (I'm not as intertaining as Bob). I have learned so much from all of you. So if you need some compounding help, that's what I do ....I am Goo

[JohninCR]

John,
you probably have already tried this, if so just ignore me.
Think about what Shapers use for surfboards. The trick will be finding a blank large enough to shape into a bowl. (15" finish diameter with 2" thick lip...Dude ...just guessing ). I wonder how much$$ a blank of foam say 24" sq would cost. Then you can shape that T curve to your hearts content. yes

oh one more thing with the epoxy I'll give you some tweaks on how to cure to a target duro...just got to bug me boss...he's in India right now and was the principle chemist on the product type you are using. I am more of the UV/Gamma cure guy..oh well
I throw all of this out there to try and provide something to you guys (I'm not as intertaining as Bob). I have learned so much from all of you. So if you need some compounding help, that's what I do ....I am Goo

Goo,

How about gallon size samples, including some that remain the consistency of clay for an hour or so, to allow perfect shaping and smoothing before it hardens?  Sanding to shape is a bear.  Finding anything down here is also a bear.  I continually find things used for something else.  eg The only epoxy, other than tiny amounts, that I can find is one used to bond new concrete to old concrete.

How would you recommend an easy way to do this, for example?:
Create a general shape that is rough and strong, using styrofoam, some type of resin, and fiberglass or carbon fiber.  Then add something to create a perfect and smooth shape, before a final coat with something like gelcoat.  Something like Bondo would be good if it had a longer working time.  Could I use something like modelling clay, which doesn't harden?

[Russell Dawkins]

I use epoxies any time the need arises, most recently a very liquid version to bond wood to concrete and to prevent the moisture from the concrete from damaging the wood as the concrete cured.  It's about the consistency of latex paint, and even a thin coat on both sides of styrofoam makes it strong and rigid like wood. 

John,
could you be a little more specific about this epoxy (name, source)? Sounds like it would be handy to have around.
Russell

[JohninCR]

I use epoxies any time the need arises, most recently a very liquid version to bond wood to concrete and to prevent the moisture from the concrete from damaging the wood as the concrete cured.  It's about the consistency of latex paint, and even a thin coat on both sides of styrofoam makes it strong and rigid like wood.

John,
could you be a little more specific about this epoxy (name, source)? Sounds like it would be handy to have around.
Russell

Russell,

There are lots of epoxies.  The one I found down here is a spanish name branded product for binding old concrete to new concrete, probably like one of these http://superiorepoxies.thomasnet.com/viewitems/construction-products/new-2-old?&forward=1.  I was putting concrete inside a plywood speaker, and thought I should protect the wood.  First I drove some screws partially into the wood leaving the heads exposed.  Then I applied the epoxy over the area of wood the concrete would touch, and put the concrete in.  The rest of the cab might come apart due to differences in expansion and contraction of the concrete and plywood, but those panels aren't ever separating from the concrete.

Reading about the New2Old, I saw you can make a mortar by mixing sand to epoxy, so maybe I can get a clay-like consistency that way or maybe by adding sawdust instead.

Now if I can just find large blocks or sheets of foam similar to surfboard blanks (very shapeable), instead of the bonded beads like a styrofoam icechest that I used before....Maybe some of the foam that starts as mixable liquid....Easily finding exactly what I want using the Yellow Pages is something I sorely miss by living in a developing country.  I can't even find sonotube down here despite the fact that concrete is the most common building material.

[goo]

John
I've surfed Jaco beach before and remember a couple of guys that could fix dings in that area. This goes back more than 10 yrs so the memory is faded a bit. Can't remember some of the other spots we went. Does Guancastle sound right? I think that was an area we hung around. Povones..hmmm..sucks getting old
Anyway, if you could tap into the local surfing comunity and find a local Shaper. He might be able to help you with supplies. I learned how to shape a little fixing my boys boards. Once you cut the foam and sanded it to the final shape you start the fiberglass and epoxy coat. There was never any need to add anything else for a smooth surface. The "Glass" would level perfectly. Once the surface has cured, you could add a layer of whatever to damppen the inside of the horn mouth ...WG mouth You have already learned how to "Tweak" viscosity by adding sand or what ever. With this type of Epoxy you can add a binder/filler. Sorry can't remember exactly what it was. Silica works great(Don't work with any of this stuff without a Respirator..please ). The blanks may not be thick enough for a WG so gluing them together isn't a problem (you probably already figured that out)...oh one other option for supplies got any boat builders down there? They may be of use also

[JohninCR]

Goo,

I'm in the central valley, so Jaco is a couple of hours away, but next time I'm there I'll try to find some broken surfboard blanks for cheap.  I always look for the easiest quickest path.  I'm looking to quickly cut a soft material like styrofoam or cardboard to make panels that I'd tape into the shape I want.  Then add a quick layer of epoxy and fiberglass to get some strength and to glue it together.  That gives me the basic form for a pair within an hour or two.  At that point I'd want to fill in and smooth interior corners.  If I can use clay for that, then cover the clay with just resin before the final gelcoat if they work well, I can foresee that being easier than something with time constraints on workability.  Once I get something optimized sonically, then I'd be willing to invest the time for perfect surfaces and making molds.  In the meantime, I need quick and dirty prototyping.

[goo]

cool
sounds like you got a good plan
I still owe you and others a report on the Firewire 410 vs Behringer boxes
haven't forgoten
Can't wait to see what you come up with
cheers
q

[Bob in St. Louis]

Now we're talking...
Remember as a kid making paper mache`?
Create your "negative" with the paper mache`, then use the epoxy over the top of that. The paper mache` stuff is cheap, easy to use, and easy to clean up.

Bob