[sdiy] ot: 2b-or-not-2b was:audiophile cones

[harry]

Re... speaker coupling

Now maybe you want the room involved in the bass... maybe not.  The optimum
position for speakes in a rectangular room is (aprox) 1/5 the length of the room
AWAY from the wall, 1/3 the width of the room apart, and 2/3 (or 1/3 for sitting)
the height of the room.

This reduces standing waves (usually) to the greatest degree.  There are simulation
programs that can help tune this...

Your wives  (that's you plural, group... unless you live in utah?) will kill you if
you
try this placement.

Another solution is to chop holes in the wall, and mount the speakers flush... can't

be no back reflection because there's no back. The wall is effectively an extension
of the baffle board.  My small 13' x 13' x 6.5' studio does this... I cannot afford
to be
away from the wall....

Magnus pointed out the bass enhancement by locating at a wall (slight)  wall/floor
(moderate) or corner (large).  Do you want this...?

If you want good accurate bass... stay away from the corners. Get good speakers and
locate at the optimum points.

Have small (cheap perhaps?) speakers... go for the corner.

The foam and mass approach I mentioned is good for decoupling the speakers from
the structure (building). To work without screwing up the bass... the mass has to be

(er....) massive.  A sheet of foam, a piece of plywood... a layer of paving stones
(concrete) to crush the foam into some compression... another piece of wood
(don't want to scratch them speakers....).  If that won't do it... repeat the
process.
The bass will be fine (in your room) and will be MUCH better in the flat below
yours...

Some speakers (Klipshorn) for one... use the wall as the final flare of a horn
loaded cabinet. These MUST be in the corners !

H^) harry

Magnus Danielson wrote:

> From: harry <harrybissell at prodigy.net>
> Subject: Re: [sdiy] ot: audiophile cones was, Oh I wish I had never said that...
> Date: Sat, 27 Jan 2001 18:25:53 -0500
>
> > Hi Nick:
> >
> > My understanding is that they decouple the speaker vibrations from the
> > mounting
> > surface, mainly the floor. The low frequencies are poorly coupled by the
> > tiny
> > contact area.
>
> Strange... I've used to discuss how to make the speaker COUPLE to the
> floor and walls, basically letting them become baffles. If you have a
> bas-speaker in a room, put them tight up in two corners and you are
> basically there, that's good use of the rooms aspects. Doing that, you
> can pump less energy into the speaker for the same effect.
>
> If you place the speakers somewhere in the middle of a wall (say
> halfway to the corners from the center), then the speakers will have
> to emit energy into twice the space-angle as if they where in the
> corners. This is all classical schoolbook stuff.
>
> > Some folk like alternating layers of foam and something heavy.. like
> > wood... concrete
> > etc.
>
> That would form a good decouple of lowfreq stuff, but I wounder if the
> effect would be very prestine. These people tend to use vented
> speakers anyway, and then you've lost before you got started. Most of
> the stuff I've seen is passively filtered, then you have a big looser
> on your hands.
>
> Then you have manufactors that doesn't know what polarity means. Oh
> my. You *really* want to check polarity before you start doing
> anything, especially on bas-speakers. You sense more "punch" if you
> have the polarity right (that is, a positive going kick pushes air out
> of the cone and into your chest, just as a real bassdrum would).
>
> > I like laughing a little bit at this behavior...
>
> Please do, please do.
>
> Cheers,
> Magnus