Sunday, March 9, 2014

PVC Pipe Dreams (audio)

You have seen speaker enclosures I made from PVC plumbing pipes. For stuffing the pipes, I initially used heat pipe insulation (the grey stuff in the image below). It worked OK, at least to an extend I was surprised, concerning those tiny drivers.

speaker stuffing material

I experimented a bit with household cleaning cloth, as shown in the image... the stuff you would clean for bathroom with. The stuff was on sale, €1,- for 2 sheets.
What the hack, I rolled one up and stuffed it in the speaker pipe. Clearly, the mouth of the pipe now only did "mmmm mm mmmmm" (referring to very deep bass notes). The all over volume of the speaker went way down. I guess, I restricted cone motion quite a bit with that much mass.

This stuffing:
  • 0.5m of the insulation stuff
  • 1/4 sheet of rolled up cleaning cloth
was the next experiment.
Now the driver has got nearly half a meter of pure air column to breathe, followed by the insulation foam and some loose stuffing of soft cloth.
In a way, this is like tapered increase of acoustic density.

Again, the result is really interesting, seen the small / cheap drivers. Of course, you would not expect a hammering deep bass.

Still more to experiment, I pushed the cloth stuffing about half way into the PVC tube. This way, I think, the driver has to some volume to breathe from and the longer wavelengths, that made it through the stuffing, can form more homogeneous pressure fronts, before exiting the enclosure.
Again, some improvement could be noticed.

Speaker enclosures, made from PVC piping, seem to offer endless opportunities to experiment.