Free Advent project.

teal'c

Nuclear Cardiac Parent
I'm still not done with my first speaker project, but that's OK.
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Almost didn't go since the ad was an hour old, glad I did.

Are there supposed to be positive/negative stickers at the speaker terminals?
 
My favorite looking Advents.
Won't take much to make them look new and sound great.
 
Since I'm getting ready to order foams I opened these up, and they're filled with block foam.
Are they supposed to be?
Sure takes up a lot of air space.
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These three were stacked behind the woofer, and there are two more behind the tweeter.
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Single cap. Checked the tweeters through the back connections and both worked.
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Weird things going on with the grills. One chewed upon by something and the other with a weird cut out.
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Since I'm getting ready to order foams I opened these up, and they're filled with block foam.
Are they supposed to be?
Most certainly. Acoustic suspension speakers like these along with their forebearers from Acoustic Research, KLH, etc. all required that for the design to work properly.
 
The grille cutout almost looks like it was made to allow the grille to be inverted and still fit around the tweeter (stackable Advents?).
 
The foam inside actually slows down the back wave of the speaker tricking it into behaving as if it were in a LARGER cabinet.

If they used a cabinet sufficiently sized for the woofer it would be too large for most potential buyers. The foam allows for a smaller, more marketable cabinet size.

There is no Red/Black or +/- designation for the speaker terminals. IIRC the 0 is negative. Many people modify these by replacing the existing connections with color coded binding posts.
 
+ and - only matters if you're a believer in 'absolute polarity'. <backs away from open can of worms>

But I would have guessed 0 was negative anyway.
 
The grille frame is a stock frame. It's just been modified, probably for the reason jberger stated.

Also read up on why acoustic suspension systems are filled with fiberglass or foam. It IS to make the cabinet seem larger to the woofer, thus extending low frequency response.

Doug
 
Also read up on why acoustic suspension systems are filled with fiberglass or foam. It IS to make the cabinet seem larger to the woofer, thus extending low frequency response.

Doug

I am familiar. However, it was my understanding that you wanted to reduce air movement while keeping as much volume as possible. That was why you "fill" with poly-fil, not pack tight with poly-fil. With the solid foam it seems you're reducing a lot of the volume that you want to keep. This setup seems like trying to put in a non-designed baffle system by just tossing in wood chunks.

Wouldn't foam pieces like this be better?
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15 PPI open cell foam
You don't loose as much air space while still drastically reducing the air movement resulting in an even "larger" volume cab.

Looking around, it appears this type of foam wasn't invented until the 80's so they couldn't have used it.

Any thoughts on it as an upgrade?
 
IIRC, five pieces of foam, 2” thick x 12” x 12”. Works great. Still using the foam in my home-built double advents. All drivers from 1977/78.
 
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