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9842a cabinet question

J

jackson

AK Subscriber
Subscriber
Howdy, I need advice on repairing a set of Altec Lansing 9842a monitor cabinets. Someone had removed the original 12" drivers and enlarged the opening for 15" Radio Shack woofers.

I have a set of the original Altec woofers just renconed at GPA.

How can I repair the opening to original size? I have correct dimensions as I have a set of Model 14's.

Attached is a picture of the front of the cabinet.

Thanks Jackson IMG_20230412_194216.jpg
 
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Two plywood rings, the first cut to precisely fit the current opening with the inner diameter being the proper cutout for the original woofer, and the 2nd ring dimensioned to bridge the gap between the back of the first ring and the baffle. Glue and clamp excessively.

I would use a high quality plywood purely for it's tensile strength in this application.
 
Thanks for the reply. I have a hard time envisioning things like this. This is sort of what I was thinking but My only question is how can I get the 2nd ring inside when it will be larger than the hole? Unless I am thinking wrong?
 
If it won't fit diagonally through the horn opening, then you could make a single radial cut in the interior ring and feed it through the baffle opening helically, kind of the opposite of how you slip rings onto a piston. That single radial cut isn't going to compromise the strength of the part the way it's being applied. It probably wouldn't even matter if the inner ring was installed in 2 or more pieces.
 
I think I’d make the inner rings in two pieces. Hopefully when the person enlarged the hole the did a decent job of making it round.

I think these speakers are worth the effort to make them whole again. Post some pics when you’re done with the surgery
 
Thanks hole is out of round will be a challenge
elitopus said:
I think I’d make the inner rings in two pieces. Hopefully when the person enlarged the hole the did a decent job of making it round.

I think these speakers are worth the effort to make them whole again. Post some pics when you’re done with the surgery
Click to expand...
 
I had some modified 828 cabs that I used a bit of bondo on. It stinks, but it works great.

If you ever want to keep your wife out of the garage just open up a can of bondo ;)
 
As I prepare myself to try this project, I see the MDF in the cabinet is actual 3/4" but isn't all 3/4 plywood thinner? Can you get actual 3/4 plywood?
 
bowtie427ss said:
If it won't fit diagonally through the horn opening, then you could make a single radial cut in the interior ring and feed it through the baffle opening helically, kind of the opposite of how you slip rings onto a piston. That single radial cut isn't going to compromise the strength of the part the way it's being applied. It probably wouldn't even matter if the inner ring was installed in 2 or more pieces.
Click to expand...
Single cut worked perfectly. Have both inner and center rings in place. Thanks will update progress with pictures and info soon.
 
Question on the protection circuit on the crossover board- a couple resistors and a diode are burnt on one board. Pics attached. I can't find a schematic for this anywhere. Any input appreciated. Thanks cabinet restoration coming along better than I expected fir a novice woodworker. All advice appreciated. IMG_20230506_180928.jpgIMG_20230506_180923.jpg
 
Can you get the resistor values from the good board? Or maybe just bypass the protection circuit :)
Probably not needed for home use anyways.

That’s the “automatic power control” circuit I think.
 
I’ll be impressed if someone can find that :D

I read the description and it sounds interesting. Something about over 75 watts and it starts limiting power to the drivers. Sounds like it’s not very good for SQ.

Is it like a compression circuit?
 
Try
elitopus said:
Can you get the resistor values from the good board? Or maybe just bypass the protection circuit :)
Probably not needed for home use anyways.

That’s the “automatic power control” circuit I think.
Click to expand...
Trying In the morning thanks
 
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