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A-70s, A-100s

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I just today acquired 3pairs of Boston Acoustics. 2 pair of A-100's and 1 pair of A70's.

The 70's need re foaming. I took them out to send them out and find that they have different woofers. Both baskets are identical but the magnet assemblies are different. Also one is vented through a hole in the back of the magnet assembly. The other is notand has a porous dome making it front vented. The serial numbers are only 4 digits different and they look like original woofers...ie don't look like they've been out before looking at the screws. Unfortunately I don't know which woofer came out of which serial # because I didn't notice they were different till they were both out. I will not be an archaelogist or historian anytime soon!!!

I'll try to do pics tomorrow. I'm concerned that they will sound different. Will advise when they are refoamed.

The A-100's look to be an erly series because they have round basket dome tweeters whereas the brochure I have shows rectangular assmblies for the tweeters. Also the cabinets do not have the 2 1/2" pedestal base shown in the brochure and the cab bottoms don't have screw holes or glue remnants to indiscate there ever were bases.

I'll do pics tomorrow.. its too late now.

Appreciate input from anyone knowledgeable in these models.

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I have a pair of A-70s with the same woofer "rot'. Strangely, the woofers in mine are identical and they both have the same date of manufacture [which is even weirder]. The back piece on mine is flat and not vented. I also noticed that the front dome is porous like the one you're showing on the right. Come to think of it, Advent, Bose, and Radio Shack had woofers like this. I wonder if they were made by the same outfit?

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What you have is two different methods woofer manufacturers used to vent the voice coil to keep it cool. On the left is what's called a vented pole piece. All of the cooling air is taken in and out thru the back of the woofer by the pumping action of the dust cap. That design usually has a non-porous dust cap which you appear to have.

On the right is a screen type dust cap and the venting takes place thru the dust cap out the front of the woofer.

They may sould a little different. However, during music passages that difference may be hard to detect.

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