[sdiy] semi ot: loud speaker for synths

[Harry Bissell Jr]

It would seem that they are not suitable for anything
BUT bass... The displacement should be better, but
it might not be so bad as you think.

You might (in a sealed box) get more displacement
without distortion than might be obvious. The
additional
damping of the cabinet air would help.

Another configuration that might benefit you (in this
case) is to mount two speakers FACING each other...
wired out of phase. They would them trap a slug of air
between them... making the pair of cones quite
stiff...
and wired out of phase they would electrically handle
twice the power, with both cones moving in the same
direction.

One of these speakers needs to be "inside" the sealed
enclosure... the other can be in free air. this makes
for a mechanically 'weird' looking system. It is only
good for Bass (highs would get scrampbled by the
speaker
frame etc.

You might cut the cabinet size almost in half.

Another classis "bass" system is the Ampeg SVT
system...
they used eight 10" speakers. Each pair of two
speakers
shares the same sealed enclosure (there are four
separate sealed chambers in the one large cabinet -
this
makes the whole assemby VERY stiff and heavy).  Each
pair is operated in a WAY too small enclosure... the
resonant frequency is in the hundreds of Hz. The
response falls sharply (but smoothly) below that, and
is compensated by brute force power and gentle EQ.

The transient response of the system is considered
excellent (for bass).  But its really BIG and really,
really HEAVY !!!

If I were to try a bass speaker today, I'd use a
variant 
of a folded horn, with two speakers in the facing each
other config (I believe the in folks call it
'adiabatic'
configuration)

H^) harry

(but if I had the speakers for free, I'd knock a quick
cabinet together and see how they work. I doubt you
could get a good design the first time without a lot
of luck.  I was never *that* lucky :^)



--- Czech Martin <Martin.Czech at Micronas.com> wrote:
> > It seems your speakers are intended for a sealed
> > box...
> > is that what you are planning ?   They should be
> OK
> > with the additional loading of the box.
> 
> Well, I do not know yet.
> Perhaps they are not suitable at all for low
> frequencies,
> because they are so displacement limited...
> I fear I need a 18" speaker....
> Perhaps I can use them as a 2x2 array, which was the
> original idea.
> The VAS would then climb up to completely over the
> top
> 4*180 litres.... wowwww.
> 
> > 
> > Some of the 'electronic' means of restoring or
> adding
> > low frequencies to bass cabinets do not sound so
> good
> > IMHO.  They may use some pretty high Q filters to
> > extend the range, and the damping is bad.  I have
> the
> > electronic equalizer for my ElectroVoice System
> 200
> > speakers... I only used it once (and was NOT
> happy).
> 
> Hmm, this is really a danger...
> 
> m.c.