M19 crossover and isolation ?'s

[juniper]

Hello all, about to do my annual Altec speaker rotation, and cleaning, and have a few questions. My M19's came with copies of the original crossovers with "better" parts and patched into the mid and hi frequency controls, bypassing the originals xovers. They are attached with Velcro on the "shelf" above the horn and on a board that is about 6"x 12". Are the crossovers to close to the magnet of the 802 8g's and is the ground bypass modification necessary with this configuration? Also, I am getting some feedback from the house and a bit of loose bass because the 19's rattle the floor sometimes. I was thinking of using some 3' X 3' black granite slabs underneath them. Is this a good or bad idea? Thanks

[bowtie427ss]

802's are magnetically shielded to the outside world, no worries there.

I'd be inclined to put the granite slabs on top of the Nineteens vs under them.

If you're using a turntable for source, put the 3rd granite slab under it.

[zelgall]

The ground bypass is done because the originals used the aluminum plate as the ground plane and it corrodes, interrupting the ground path for the signal. If yors were rebuilt you should have a peek to see if they have hard wired grounds.
What kind of new crossovers were installed? Are they same as original but new parts or an "upgrade"? I have 19s and have used a variety of amps with them but I can't recall that kind of seismic disturbance in any of the 4 houses I've had them in. I'd like to copy yours if that's the reason.

[Altec Best]

The ground bypass is done because the originals used the aluminum plate as the ground plane and it corrodes, interrupting the ground path for the signal.

Yes mainly the ground bypass was necessary because of the rivets that the terminal bars are mounted with tend to loosen up and oxidize over time causing bad grounds..