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Mirage SM-1s or "Marky Plumbs the Depths of Low-Rent Speaker Repair"

mhardy6647

mhardy6647

Lunatic Member
Kids, don't try this at home.

Back story: many years ago, I found a nice pair of Mirage SM-1 speakers (Mirage's first offering, I believe) at our town dump. They were in pretty nice condition, albeit needing woofers refoamed, of course. As it turned out, one of the woofers has "issues"... it will play, but the output is low and there is no bass. The cone does not move freely in the gap; either the cone is dragging or there is "crap in the gap".

I refoamed the good woofer and confirmed that these are pretty nice sounding speakers indeed.

DSCN5566.jpg


The original woofer is a pretty unimpressive driver.

SM1wooferfront.jpg

SM1wooferback.jpg


This weekend, out of a mixture of desperation and whimsy, I decided to refoam an equally unimpressive, utterly generic 8" woofer I had taking up space. Sealed box designs are generally fairly forgiving of T/S parameter mismatches. Put this refoamed thing into the other Mirage box. Hooked up the pair to a Sherwood integrated ss amp I got from JoZmo and gave a listen. Not too bad; not bad at all, as a matter of fact.

DSCN5567.jpg


Note that no duct tape was involved in this travesty (at least so far)...
 
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I once knew a guy who "refoamed" a pair of old advents with the elastic off of his underwear!

Shockingly, it kind of worked...

Not so shockingly.. his mom was really pissed! HAHA

Evan
 
If I understand things properly. The one thing that duct table should not be used on is, well, ducts. Apparently with large changes in temperature, they are prone to catastrophic failure.

Probably work poorly on speakers also, unless you needed, for some reason, to increase damping by a factor of 100 or so.
 
I found the problem with a few dump speakers is that the magnet has shifted from being thrown around, and is still sticking itself to the backplate whilst being mis-aligned. Might be worth checking that...but as you said, the original woofer does look a tad wimpy.

They look to be in pretty good condition otherwise - nice find! :thmbsp:


RayW said:
Imagine how good they could sound if you did use duct tape!

Ray
Click to expand...
I "repaired" the surrounds on a pair of a friend's car speakers...the foam had rotten after 20 years of dashboard sun exposure. He didn't want to buy new ones, and it seems like a good experiment.

Amazingly, they're still going strong after just over a year. Truly, there is nothing duct tape cannot fix! :D
 
MunkeyQ said:
I found the problem with a few dump speakers is that the magnet has shifted from being thrown around, and is still sticking itself to the backplate whilst being mis-aligned. Might be worth checking that...but as you said, the original woofer does look a tad wimpy.

They look to be in pretty good condition otherwise - nice find!

:D
Click to expand...

Excellent point! Given old Polk drivers' proclivity to do this, I shoulda thought of that!

Yes, they are in pretty darn good condition (and they really do sound pretty nice).
 
I remember having a pair of SM-1's many years ago and I pulled a woofer out to look it over. The magnet did seem kinda small, but the bass was quite impressive for such a small cabinet. They always marketed them with short, angled stands to put the tweeter at the correct angle and height. Also there was a felt pad on the grill cloth right in front of the tweeter supposedly to aid in dispersion and to smooth out the tweeter's strong output.
 
lab said:
Also there was a felt pad on the grill cloth right in front of the tweeter supposedly to aid in dispersion and to smooth out the tweeter's strong output.
Click to expand...

Thanks for pointing out the tweeter thing; I was too lazy to type that! The instructions on the back clearly state that the speaker is meant to run with the grille on for just that reason.

yez can see the wool felt circle in front of the tweeter dome in this photo. That circle fits into the cutout in the wool felt pad around the tweeter (see photos above); it's a simple but effective solution to a problem, I guess. Interesting to note that these speakers also have a tweeter level control on the back panel.

DSCN5564.jpg
 
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