Altec Design 20 Repair- worth it?

[AudioJuice]

Found someone giving away a vintage pair of Altec Lansing Design 20 speakers yesterday. He said they needed new woofers as they were “dry rotted”. At first glance, I see they just need new foam surrounds. I’ve replaced foam once before, so can tackle that project!

BUT- as I took out the woofers, I see the top one in both speaker boxes has no magnet or wires connected to it. Question 1: Are they supposed to be that way? A bit of a newb question perhaps, but I find it odd that a woofer cone would exist without a magnet/power.

Question 2: think these are worth the cost and time of replacing the 4 foam surrounds?

 

[twiiii]

Go to Midwest speaker Repair and order re-foam kits. Maybe replace the caps from Parts Express. no big deal.

 

[alteclipsch]

That magnetless woofer is a passive radiator.

 

[AudioJuice]

That magnetless woofer is a passive radiator.

Thanks! I’m learning plenty.

 

[AudioJuice]

And I may end up using these in the garage.

 

[AudioJuice]

I also see these speaker boxes are hollow inside. I previously repaired a set of old Heathkit speakers that had boxes filled with insulation-like foam.

Is there a sound benefit to the insulation inside a speaker box? Or does it depend on the individual design?

 

[62caddy]

The majority of loudspeakers have sound insulation material of some kind but not invariably and to answer your question yes, it does depend on the individual design.

 

[Katalyst]

When you do the re foam .Start with the passive ones. The ones with the magnets second. Make sure there is no coil rub.

 

[AudioJuice]

When you do the re foam .Start with the passive ones. The ones with the magnets second. Make sure there is no coil rub.

Will do, thanks! Why do you suggest it this way? Better to practice on the passive ones first?

 

[mhardy6647]

Will do, thanks! Why do you suggest it this way? Better to practice on the passive ones first?

Exactly so.

 

[Katalyst]

There was probably foam in there at one time. The dust/debris on the inside is the remnants.

 

[Katalyst]

Try them out with foam on the back at the least.

 

[swechsler]

With sealed (usually called "acoustic suspension") speakers, the stuffing/foam is part of the design. With ported speakers (a passive radiator acts like a port) the foam is basically there to prevent internal reflections. This wasn't an expensive speaker to begin with so they might have dispensed with the internal foam; I don't see any indication that there used to be some (you'd normally see some remnants of adhesive if nothing else). I'd repair the surrounds first and see how they sound. Afterwards you can experiment with putting some acoustic foam on one or more internal panels. I suspect it won't make a huge difference in sound.

ETA: looks like these aren't all that great and don't have much value. They'd probably be good for a garage or workshop, but I wouldn't use them with my main system. I'd probably buy generic surrounds from HES (measure the current surrounds, and confirm all measurements via email with their customer service before purchasing) rather than spending money on the good ones.

 

[AudioJuice]

I'd probably buy generic surrounds from HES (measure the current surrounds, and confirm all measurements via email with their customer service before purchasing) rather than spending money on the good ones.

Thanks for the info and advice. Yesterday I ordered a foam replacement kit from Simply Speakers’ eBay account. I thought $32 was a good deal for the 4 foam replacements + glue. I’ll have to keep HES in mind for future projects though.

 

[Nat]

It looks like there is a layer of foam at the back of the enclosure. It might make sense to put a layer on two of the sides, but the decision not to put it in originally may have been deliberate - so be prepared to remove it if it makes the speaker too damped.
They look like an inexpensive version of the Bolero, with two tweeters for more power handling. I wouldn't assume that they would not be good.
Remember that for a passive radiator system to work optimally, it must be completely sealed - no air leaks at all. So check the edges of the crossover panel ond of the tweeters and seal, if needed, and use gasketing when installing the woofers.

 

[AudioJuice]

Remember that for a passive radiator system to work optimally, it must be completely sealed - no air leaks at all. So check the edges of the crossover panel ond of the tweeters and seal, if needed, and use gasketing when installing the woofers.

Glad you mentioned this. The cap on the back of one of the speakers, that holds the connectors where the speakers connect, wasn’t attached at all. It just needs glued back on, and I have some extremely sturdy glue that I can use. But since you mentioned it, I’ll take extra care that I get glue coverage around the entire piece.

 

[AudioJuice]

OP Update:

Foam surrounds replaced! I managed to install them without any rubbing. Some extra glue remnants remained on the outside of the foam (you can see a little in the bottom photo). This was just my 2nd foam replacement project, so I still have room to improve!

Thanks for all the input!

edit: and- These sound ok, but not as good as a pair of Heathkit AS-1363s that I have. (For vintage comparison)

 

[Nat]

If they don't rub and are sealed, no need to apologize for anything. They weren't going to be beautiful, ever, and there is a reason for grill clothes. I'd give the surrounds some time to break in, and also check for leaks, which will have a significant effect on the tightness of the bass produced by a passive radiator system. And if you haven't recapped, that might be a good idea.

 

[carls06]

Older thread,,, but i just picked up a set of these that were re foamed.... Will be testing them out against some Technics SB4500A , that i have here..

 

[Nat]

It might be worth recapping them - I suspect the crossover is pretty simple, so some Dayton caps wouldn't cost much, and might improve the sound considerably.