Refoam of a 200003 AR11 MK1 woofers

[Giorgio AR]

Yesterday I refoamed a pair of 200003 AR11 MK1 woofers belonging to a friend of mine, these had the wrong foams in all sizes (which unfortunately is very common in Italy), these made strange noises at high volume!
First thing noticed was the cable mounts on the baskets in an improper position with the cables themselves dangerously close to the baskets, easily fixed.

Before

after

I decided to do the job using shims and then I removed the dustcaps to check if there were any problems with the coil formers and to my surprise, I expected to find them in aluminum, instead these are in Nomex, the same as the AR3a.

The date imprinted on the woofers indicates 7602, therefore consistent with the other speakers of these AR11.

I also add below the photos to compare the suspensions: on the left the "filthy" one removed

Here the differences are better understood... none of the measurements of the previous suspensions are consistent with our beloved 12"woofers

[AR55]

On 9/1/2023 at 6:48 AM, Giorgio AR said:

I removed the dustcaps to check if there were any problems with the coil formers and to my surprise, I expected to find them in aluminum, instead these are in Nomex, the same as the AR3a.

You just missed it.  AR started using aluminum formers in their 12” woofers with the introduction of the AR9.  The AR-11B was released about the same time as the AR9 and its woofer also had an aluminum former.