[Milsurplus] Speaker

[Barry Hauser]

Hi Rick:

The LS-166 is both waterproof and concussion resistant.  It is in a sealed 
enclosure -- as if it were an acoustic suspension speaker, but those require 
special high compliance drivers and enclosures that are of certain 
dimensions to compensate for the resonant frequency of the driver, etc.  The 
LS-166 is very low compliance - very stiff suspension.

Some things to try --

Try it with the back left off so it works more like a ported speaker and 
alleviates the back pressure.  The concussion resistance comes from the 
stiff suspension and perforated "baskets" on both the front and back of the 
speaker frame to limit cone movement in the event of a nearby blast.  The 
one up front should be removable.  Try removing it and re-mounting the 
driver.  It's possible that the cone is hitting either the front or back 
basket.

If after all that, it still sounds unlistenable - -and even good ones are 
not easy on the ears -- the problem is probably in the voice coil area.  The 
suspension -- around the periphery of the cone, or the "spider" --  
corrugated flexible mounting near the voice coil -- may be warped.  Or there 
may be debris from flaking of the voice coil form or varnish/enamel/glue 
that secure the windings.  Short of reconing -- new voice coil-spider-cone 
assembly -- there is no fix and that's not practical on these.  You can 
check for the voice coil noise by gently pressing on the center of the cone 
while listening -- no signal.  If you hear a rustling or scraping noise, 
that's it.  If the surround, cone or spider is warped, you will find no 
noise if you gently press on the cone at certain points and pronounced noise 
at other points.

A lot of fiddling, but costs nothing.  If you are interested in 
authenticity, then the easiest thing to do is pick up another LS-166. 
They're fairly cheap.

You can match up a new driver that will sound better than the original.  If 
you do, I suggest leaving the front basket out as the cone or surround may 
hit up against it -- the replacement driver is apt to be more compliant and 
move in and out more.  And the shape of the basket may be wrong for it. 
Also would advise trying it with back removed or cut about a 1 inch diameter 
hole in the back cover if that's your preference.

Hope this helps
Barry

----- Original Message ----- 
From: "Rick Brashear" <rickbras at airmail.net>
To: <milsurplus at mailman.qth.net>
Sent: Sunday, April 09, 2006 11:05 PM
Subject: [Milsurplus] Speaker


>I have an LS-166/U speaker.  I can find no tears or bad spots on the 
>plastic (or whatever material it is) cone, but it is definitely not 
>producing a clear sound.  I realize these speakers are not designed for hi 
>fidelity, but this one sounds just like an old paper coned speaker with a 
>few tears in it or one that has worn very thin and broken away some from 
>the outer edge.  The unit is in great shape, the transformer (600:3) is in 
>fine working order as when I hook it up to a known good speaker the sound 
>cleans up nicely.  I really want to use this with my BC-342/BC-610 (I know 
>it's not the correct speaker) combination.  Has anyone here had experience 
>with this problem?  Has anyone replaced the speaker with a more modern 
>type?  I'd like to stay with the original if possible, but will replace it 
>if absolutely necessary.
>
> Thanks,
> Rick/K5IZ
>
>