Omni source

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Chris Notton - 05 Apr 2006 03:10 GMT

Any advice?
Faced with the difficulty/expence of obtaining a Dodecahedron speaker I
am thinking of building my own omni(ish) source from inexpensive home
cinema NXT system's. I think that these might be quite effective because
of their nice dispersion charateristics.
I was thinking of mounting an array of NXT's around a cylinder which
could be supported on a speaker stand. The l.f. would be provided by a
seperate sub.
Comments invited!

Pip pip

Signature

Chris Notton
Replace "nospam" with my surname to reply by email
Sostituisca il "nospam" con il mio cognome per rispondere
}<////(*>

Reply to this Message

Angelo Campanella - 26 Apr 2006 19:13 GMT

> Faced with the difficulty/expence of obtaining a Dodecahedron speaker I
> am thinking of building my own omni(ish) source from inexpensive home
> cinema NXT system's. I think that these might be quite effective because
> of their nice dispersion charateristics.

    The basic duodecagon comprises 12 flat pentagons (72 degree or 108
degree sides, depending on how you look at it), joined at all their
edges to form a cloased globe-like volume. That is the way they are
fabricaeted in practice.

    The key work is to select the size (to accommodate the selcted drivers,
their bolt circle, and their circular opening plus assured clearance
inside for their magnet and terminals), their material (plywood, OSB or
plastic sheet), the mount point (often either one of the 12 flats or a
"corner" if you want the 12th flat to be also a speaker. and the edge
joining detail (often the most difficult task as they should be
hermetically sealed).

    Since the load impedance that is presented to the drive amplifier is a
factor, viz, for 8 ohm speakers, form four strings of three to make six
ohms when paralleled, or three strings of four to make 11 ohms when
paralled as the impedance the drive amplifier sees, etc.

> I was thinking of mounting an array of NXT's around a cylinder which
> could be supported on a speaker stand. The l.f. would be provided by a
> seperate sub.

Approximations can be a cube (6 sides), or a
tetrahedron (all triangles, 4 sides).

Angelo Campanella

Reply to this Message

Chris Notton - 26 Apr 2006 22:34 GMT

Thanks for the input,

I think I'll try a few experiments with commercially available NXT
systems to see how they measure up before entering into the difficult
task of building a Dodec!

Unless anyone knows of a dodec. sitting unused in a dusty cupboard? ;o))

Pip pip

> > Faced with the difficulty/expence of obtaining a Dodecahedron speaker I
> > am thinking of building my own omni(ish) source from inexpensive home
[quoted text clipped - 24 lines]
>
> Approximations can be a cube (6 sides), or a

> tetrahedron (all triangles, 4 sides).
>
> Angelo Campanella

Signature

Chris Notton
Replace "nospam" with my surname to reply by email
Sostituisca il "nospam" con il mio cognome per rispondere
}<////(*>

Reply to this Message

Natural Science Forum / Physics / Acoustics / April 2006

Omni source