Sound Dynamics Aluminium Horn repair

[farmerjack61]

Hello again to all my friends.

I have had a set of SD speakers for thirty years and finally killed them a couple of weeks ago.

The death was mourned for a week or so and I was overwhelmed by a tsunami of regret and anxiety, but **** happens and I got on with my life.

The tweeters were the problem, because I had carelessly broken the little fly leads from (&, which are) the voice coil winding. This encu wire is approximately .005 bees_dik_thik and will melt if you wave a soldering iron past them -fly wires fatigue if you are meddling inside the box all the time so I would suggest the user exercises great care when removing or re-attaching the 'spade' terminals on the diaphragm. And remember if it aint broke, don't fix it.

Anyway... here is the up-side of the story;

On the web one day
In a land far away
The king was browsing whilst bent
He looked on e-bay
And it blew him away
Cause speaker guy a Klipshch K-76 'phragm sent

Now, the 'king' was a pleb
but not off his head
cause the phragm he got almost fit
He pulled out the reamer
And increased holes di'emer
And the horn had a brand-new kit.

In other words "Good News" you can get a diaphragm for the SD aluminium horns with the phenolic domes - but be very careful fitting them and dont expect them to drop straight in - a bit of jiggery-pokery is required and if you're not at least a little dextrous get a mate with a steady hand to do it.

A couple of things to look out for:

• Make sure you poke that fibreglass insulation back into the dome cavity, it works as a spring and a dampener.
• The 'gap' in the magnet structure which houses the coil is very, very narrow on the SD, and if you are a bit careless like me you will burr the edges.
• Find a broom stick (get one off her - shes probably got a couple in a 'secret' place)
• While she's not watching drag out the tennon saw and chop ~4" off the end.
• Wrap some 240 - 360 grit emery paper around it and sand the groove out, dont worry I can guarentee you wont take too much because it's hard stuff.
• Now clean the groove out with some metho, but don'd drink it.
• Almost there...
• Get a 5/32 drill bit and enlarge the three smaller holes on the Klipsch diaphragm. Actually I used a tapered reamer because the material is pretty soft and fluffy - like cardboard.
• If you use a drill bit for the above I would exercise great caution in order not to jam the bit and cause the whole structure to spin in your hands thus mangelling the coil former and causing a great outpouring of emotion and perhaps even some cussing.
• Screw it all back together and hook it up as quick as you can because the fresh new coil will sound like the original that you listened to back in the eighties - and thats a whole lot better than your horns sounded like last week - I'll bet.
• BTW you will need a square 'allen key' but I couldn't get one from the tool joint, so just got a 3/16" allen key chopped the end off (don't use your tennon saw)! use a cut off wheel in your grinder and then fashion the end with the cut off wheel to make it square instead of hexagonal.
• Better get your mate to do that if you're and office worker because it takes a bit of dexterity and skill not to mention quite a bit of courage.
• Making your special 'allen key' is a last resort and could be seriously dangerous if you are not strong and confident, and this bit is very serious because if you get it wrong you could easily loose your eyesight or your fingers.

I hope this little article has helped to pay my debt to the site, because I love this joint and have learned heaps since signing up a few months back.

If you have any questions about the Sound Dynamics 100s horn repair give me a hoy through the site.

Bye for now, sincerely, Phil Elliott