Hey all,
I am new to this forum, seems like a lot of good exchanges from my search, glad to have found it.
I am planning to build some enclosures for a friend of mine who DJs. The theme is see-through.
I was considering plexiglass, clear acrylic sheets. Any idea how thick it should be for the proper stiffness? Anyone know of this being tried and how it worked out? Does plastic stand up to the rigors of gigging?
Because the idea is to just see the driver inside the box, i am struggling with design issues of a substitution for internal bracing and the lack of damping material inside the enclosures. Any ideas?
thanks
Dan
I am new to this forum, seems like a lot of good exchanges from my search, glad to have found it.
I am planning to build some enclosures for a friend of mine who DJs. The theme is see-through.
I was considering plexiglass, clear acrylic sheets. Any idea how thick it should be for the proper stiffness? Anyone know of this being tried and how it worked out? Does plastic stand up to the rigors of gigging?
Because the idea is to just see the driver inside the box, i am struggling with design issues of a substitution for internal bracing and the lack of damping material inside the enclosures. Any ideas?
thanks
Dan
Acrylic may be too brittle, especially for PA stuff that gets knocked around. Not sure about PET or its relatives (used for fizzy-drink bottles), it could be good. Polycarbonate would probably be the best due to its immense impact strength (used in bullet-proofing applications), though it's still just a plastic and can be scratched. Of all readily available plastics polypropylene is one of the best for absorbing vibrations, but it's not transparent (it's a creamy yellow), and don't even think about it. PP is only good for melting and moulding into shapes, once you start cutting or drilling it, it'll be such a gooey mess and such lot of effort that you'll wish you were never born!
The best thing would probably be to find a plastics merchant who has his/her own proper cutting tools, and get them to cut the plastic for you.
Glueing is another question, maybe the pieces should be bolted together and silicone be used to make everything airtight.
You shouldn't need to go much above 10mm or 12mm (11/24"), and remember that what looks good are good design practices. If it needs lots of bracing, then add lots of bracing. If it needs pillow stuffing, then add that too. Someone could argue that sports cars look ugly because of their aerodynamic design. People should be able to see why the speaker sounds good, not why it sounds bad.
The best thing would probably be to find a plastics merchant who has his/her own proper cutting tools, and get them to cut the plastic for you.
Glueing is another question, maybe the pieces should be bolted together and silicone be used to make everything airtight.
You shouldn't need to go much above 10mm or 12mm (11/24"), and remember that what looks good are good design practices. If it needs lots of bracing, then add lots of bracing. If it needs pillow stuffing, then add that too. Someone could argue that sports cars look ugly because of their aerodynamic design. People should be able to see why the speaker sounds good, not why it sounds bad.
You will need at least 12.5mm ( 1/2 inch) thick material to be strong enough, and it will need plenty of bracing. It will cost lots of money, and be very heavy.
You will also need to be very careful when moving them around, as the plastic will scratch easily and start to look tatty very quickly.
However, if this was for a permanant install, where the above factors are not important, they could look quite cool.
You will also need to be very careful when moving them around, as the plastic will scratch easily and start to look tatty very quickly.
However, if this was for a permanant install, where the above factors are not important, they could look quite cool.
How about compromising a bit, and making the cabs out of MDF or whatever, with plasic windows in the walls? If these were inset, they'd be better protected from scratching (you could even make clip-in 'shutters' for transport), and the whole thing would be easier to make, and a lot lighter too.
You could also incorporate concealed coloured lighting in the cabs (like some people use now on computer cases), which might look quite cool!
You could also incorporate concealed coloured lighting in the cabs (like some people use now on computer cases), which might look quite cool!
Bull, beat me to it.
The drivers are P.Audio BM-12CX38 and a crossover that makes them +- 2dB is available from www.proaudioparts.co.uk . Look under http://www.proaudioparts.co.uk/page19.htm . They are said to be very loud by Rog Mogale (the designer) and almost indestructible (ie survive kamikaze DJs) becasue of the 3" vc compression driver (1.5" exit). Search Ro'g forum (www.speakerplans.com)
The drivers are P.Audio BM-12CX38 and a crossover that makes them +- 2dB is available from www.proaudioparts.co.uk . Look under http://www.proaudioparts.co.uk/page19.htm . They are said to be very loud by Rog Mogale (the designer) and almost indestructible (ie survive kamikaze DJs) becasue of the 3" vc compression driver (1.5" exit). Search Ro'g forum (www.speakerplans.com)
Cool.
It depends on the dimensions of your cabinets, but essentially, as thick as you can afford. You may want to look up some basic engineering info, and calculate it so that it's about equal to 3/4" birch ply.
I would recommend polycarbonate, since it is tougher and less resonant. I built a front horn from it once. Acrylic is more expensive, and easily cracked. OTOH, polycarbonate (lexan) is more flexible. Either could be made to work.
First of all, if it were me, I would curve the sidewalls to maximize stiffness and minimize cost and weight. Polycarbonate will bend cold, acrylic will need heat.
Damping material? Yeah, what's the point if you have to fill it with fiberglass.... Bubble wrap would work OK. How about getting some mesh colanders to make balls, stuff them full of fiberglass or polyfill, and hang them inside the boxes? Could look kool.
GB
Glass?
What about glass?
Surley there'll be some sort of glazing company who will cut glass pannels for you? Glass is hard (more scratch resistant than most/all plastics) and ridged (little bracing needed). On the other hand it is also very brittle (so may not be so great for moving about unless you are very carefull) and not a very good absorber of sound either I'd immagin.
What about glass?
Surley there'll be some sort of glazing company who will cut glass pannels for you? Glass is hard (more scratch resistant than most/all plastics) and ridged (little bracing needed). On the other hand it is also very brittle (so may not be so great for moving about unless you are very carefull) and not a very good absorber of sound either I'd immagin.
This project sounds like it could be a good candidate for open baffle! A number on this forum have used acrylic baffles for this with some interesting results ... an open baffle array crossed to a vented bass cab ...
A big issue with plastic is scratches and that is going to compromise the finish in a PA setup. Glass is much more scratch resistant and can be made extremely tough. If you use plastic you can do things like laminate layers together for rigidity, and curve them. Select a thickness that allows bending, and bend them around some bracing which will act as template for the curves. Then laminate the thin layers together with an adhesive that sets clear. You can protect the plastic from scratching with perforated metal, which will still retain transparency.
Now if you want to get really trippy (I'm now visualising those night clubs in scifi movies)... Another interesting idea would be to incorporate lights into the speakers - LEDs, neon lights and UV lights. You can get ink that responds to UV light and put it on parts of the drivers.
A big issue with plastic is scratches and that is going to compromise the finish in a PA setup. Glass is much more scratch resistant and can be made extremely tough. If you use plastic you can do things like laminate layers together for rigidity, and curve them. Select a thickness that allows bending, and bend them around some bracing which will act as template for the curves. Then laminate the thin layers together with an adhesive that sets clear. You can protect the plastic from scratching with perforated metal, which will still retain transparency.
Now if you want to get really trippy (I'm now visualising those night clubs in scifi movies)... Another interesting idea would be to incorporate lights into the speakers - LEDs, neon lights and UV lights. You can get ink that responds to UV light and put it on parts of the drivers.
The way I know DJs, that woofer will have a sudden urge to reach for the walls in an open baffle. The trend is for the DJ monitors to be very loud (sometimes louder than the PA for smaller venues) so that the DJ is the only deaf person at the end of the night and the dancing masses get to hear for another day ;-)
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