Speaker cabinet design

[M6NTL]

So what is the consensus on the Plaster of Paris used by Max Townshend in my old Glastonburys as a cabinet material?

Sent from my LG-H850 using Tapatalk

[Pharos]

Unusual, not that heavy a material, maybe quite self damping, probably cheap, but then there are numerous attempts at cabinet designs involving innovative approaches.

Wilson uses 'kitchen tops', ATC uses now quite a lot of aluminium, and I feel sure that certain polymers would make very good cabinets, and be easy to manufacture, but of course plastic has a name associated with cheap and nasty.

I am thinking about using 1' drain pipe for a project.

[walpurgis]

I am thinking about using 1' drain pipe for a project.

I've had similar ideas. Using multiple lengths of 1" pipe each cut to a different length around the quarter wavelength of 35Hz and installed into a cabinet, effectively giving an acoustic column with a broadly spread line resonance around 35Hz instead of the usual transmission line 'hump'. It may be a rubbish idea, but I don't recall seeing it tried.

[danilo]

Apparently this has digressed into the odd materials arena. Fastcal is a superior (harder stronger cheaper than plaster of paris) plaster casting goop.
Some are reporting seriously decent result from enclosures glued together from 1" DOW insulation foam.
Initially adopted for v quickly/cheaply assembled proof of concept enclosure builds.. results have shown that many now view the resultant foamies as keepers.
Who woulda thought?

[Pharos]

I thought that the OP wanted clarification on material choice.

I was thinking Geoff, of 1/4 wave as well, and possibly a passive at the bottom facing the floor.
Pipe may have to be blue or yellow - seen on the street side. Very dead and very tight.

[walpurgis]

I was thinking Geoff, of 1/4 wave as well, and possibly a passive at the bottom facing the floor.

A passive radiator at the exit end of an acoustic line has also crossed my mind in the past. However, I think it may give a somewhat loose bass, as it will rely on the slightly dissipated wave energy from the end of the column.

[walpurgis]

I've also considered an open baffle with an acoustic column pipe at the rear, relying on energy from the rear of the adjacent driver to excite it. The pipe would be open at both ends and would be length tuned to the required resonance. It does not take much energy to stimulate resonance in a pipe. This means the benefits of an open baffle are retained, but a little lower bass reinforcement is provided.

[Qwin]

A few current production speakers are using a sandwich of MDF and Chipboard. (eg Quad, Wharfedale).

MDF on the outside for finish and jointing, Chipboard on the inside for acoustic properties.

DIY possibilities if you can clamp up the sandwich well when glueing them.

I've considered this over 24mm Birch Ply for my next build, still to decide which.

[RothwellAudio]

A few current production speakers are using a sandwich of MDF and Chipboard.

Yes, layering materials seems like a very good and practical idea to me too. MDF and chipboard with a layer of plasterboard between the two might be even better.
Less easy to do but possibly very effective would be two layers of some something (MDF, chipboard, plywood etc) with a void between the two which can be filled with builder's expanding foam.

[walpurgis]

Less easy to do but possibly very effective would be two layers of some something (MDF, chipboard, plywood etc) with a void between the two which can be filled with builder's expanding foam.

Or kiln dried sharp sand? You'll end up with floorstanders that weigh a thousand pounds, but they'll sure be inert!