[PaulFolbrecht]

Anybody have experience doing something like this:

http://cgim.audiogon.com/cgi-bin/vs.pl?vaslt&1064799745&viewitem&o19

?

I think I'm going to try something similar.

[Russell Dawkins]

Are you aware of this configuration?

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=120&pos=6

I think it is the nicest implementation of the PHY/open baffle formula I've seen.

It is actually glass, but I think plexiglass might sound nearly as good.

[PaulFolbrecht]

I had.  They look very nice too.

I need to do some research on OB basics.  Like: what affect does the baffle width have?  And the wings?  Wings are clearly not "necessary".

I have a pair of Bastanis Promethes which are a very, very good OB speaker.  But those PHY drivers...

I cannot get the front of the baffle more than 4' from the rear wall.  That is probably not ideal.  But the Bastanis worked Ok.

I might barely have the room for a baffle width like the design you referred me to, but I also might get castrated by my wife if I try that.  Not sure.

[Russell Dawkins]

I might barely have the room for a baffle width like the design you referred me to, but I also might get castrated by my wife if I try that.  Not sure.

Only one way to find out!

[JLM]

Plexiglass has a low modulus of elasticity (flexes easily) and stratches very easily.  Lexan (the stuff used at attack resistant bank and other counters) would be a much better choice of material but find out what to clean it with.  Even tempered glass would be a better choice (but heavy and breakable).

[ecramer]

I believe Lexine is about $10 a square foot in the 1/4" stuff that stuff looks to be at least 1/2 and even plexy glass is expensive but with that said it both cut nice useing a melamine no chip blade on a table saw it routs good and can buy special glue made for joining plexy glass that aids on buffing out the seems giving it a pro look

[PaulFolbrecht]

Plexi can be bought online in thicknesses up to .75" in any dimensions desired.  The large pieces required for those baffles are about $175 each.

I'd like to find 1" thick stuff.  I think the driver probably be mounted in wood joined to the plexi as well, as here:

http://www.tonianlabs.com/Baffle_plan_nb.jpg

[PaulFolbrecht]

I read of ringing problems with plexi.  I doubt it would be severe with .75 or 1" material, but the best compromise might be wooden front baffles with plexi wings (hinged).  That would keep some of the illusion going that they're not really as huge as they are...

[Daygloworange]

Having worked quite a bit with plastics (years ago), I can offer you a few tips.

I'm not sure of the ringing problems, but know that cast acrylic is quite dense. I forget how dense lexan is.

But, yes, they are both quite flexible, being nowhere near as stiff as glass.

Both will scratch very easily. Matter of fact, they will scratch with just regular cleaning, never mind during the fabrications process.

Lexan is not UV stable, it will yellow, get foggy, and develop spider cracks over time.

Lexan is much easier to cut, you can cut it with a good, sharp blade designed for cutting melamine. Acrylic is much more difficult to cut it without chipping, or with the corners not breaking off as you reach the end of cuts. Acrylic requires a different blade.

If you manage to get chip free cuts, then you can sand the saw mark out, and use a torch to kiss the edges and flame burnish them to a shiny transparency. This requires practice to not distort the sharpness of the edges.

There is a glue for plastics that comes in a bottle with a syringe type needle for application, you fix two pieces together, and run the needle along the joint line, and they are permanently bonded. The fumes from the glue are quite hazardous.

Cheers

[samplesj]

As everyone has already alluded to you will have to use special solvent.  The acrylic "glues" melt the two pieces together.  The biggest brand name is weld-on.  Normally you'd want to use #4.  You could also use #16 if you need something a bit thicker (or you could just melt some scrap acrylic in #4 and use that mixture).

Do a LOT of reading first.  For the prettiest joints you want to use the "pins" method.  Here is one of the better descriptions http://www.reefcentral.com/forums/showthread.php?threadid=169326.

It is VERY important that you let it wick into the space properly.  If not you get a lot of bubbles in the seams (ask me how I know but luckily my ugly seams are hidden inside a stand).

I don't know if it matters or not, but you might want to look at the different types of acrylic you can use.  Extruded sheets aren't as sturdy as cast.  Also as you get thicker the flexibility goes WAY down.  A thicker sheet of cast isn't going to visibily flex.

[PaulFolbrecht]

Guys,

Thanks a lot for the pointers.  I am still going to build a baffle to play with with both PHY-HP and Supravox drivers, but in the meantime I came across a killer deal on a Supravox field coil OB system:

http://www.audiojunkies.com/blog/655/capilano-audio-tyee-speakers

That I'll be getting shortly.  Have never even heard the Supravox drivers.  I'm going on research and my experience with other field coil drivers, all of which have been intoxicating!

The baffles are the maple and they are gorgeous.  Much better job than I'd ever do on something home-made.  Still, acrylic baffles could look really cool.

But the first ones I'm going to build are large ones made for a single 8" to run full-range.  As in the ones PHY-HP recommends.