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[BenFranske]

So I'm planning to replace a batch of 14 Soundolier FC104 70v ceiling speakers installed ca. 1986 with some QSC AD-CI52ST speakers. The good news is that the new speakers will use a 11.7" hole and the old speakers used a 6.25" hole. The bad news is that the old pre-installed backboxes need to disappear first. Of course access is only from below (except one can which can be seen from an access panel).

Any great ideas on getting the old backboxes out of the way? My best plan so far is to use a cutoff wheel in a die grinder to cut the sheet metal screws holding them in place and then try to pop them up into the ceiling, cut the larger hole and then pull them out.

Here's what the backcans look like, one of the few that's visible:


And here are the Soundolier FC104 speakers:

[Lee Douglas]

Any great ideas on getting the old backboxes out of the way? My best plan so far is to use a cutoff wheel in a die grinder to cut the sheet metal screws holding them in place and then try to pop them up into the ceiling, cut the larger hole and then pull them out.

I can't tell how those are held in place.  It kind of looks like plumbers tape in the picture of the back can.  In any case, if it won't come loose by simply turning the screw, your idea may work, although it seems like a lot of work.  Your next concern should be how you're going to maintain the integrity of the conduit to each of those speakers.  It looks like it was professionally done as most amateurs would not have ran the conduit.  Is conduit required in your jurisdiction? Is there a plenum requirement?  Is the existing wire plenum rated?  All good question to answer before you rip up the existing install.  Might be easier to find a replacement that fits the Soundelier (Atlas now) back cans.  Just some stuff to think about.

[BenFranske]

I believe it is plumber's tape on the backside of the can, the screws are run from the outside of the can in so the heads are inaccessible from the inside of the can. Conduit is not required here, and it is not a plenum space so the plan would be to simply put bushings on the ends of the conduits.

I am just pretty skeptical that a high quality speaker can be found to go in these vintage backboxes. This is not for a simple paging system, the speakers need to handle full-range audio at a pretty high quality. The existing speakers sound absolutely terrible hence the replacement project.

[Lee Douglas]

Oh right.  FC104.  That's not gonna happen!  I was thinking it was a bigger speaker and back box than that.  It's good to know code requirements before you get into something like that.  So, yeah, Dremel with a cutting wheel and then maybe a deburring tool to grind it down a little further.  Good luck!

[Scott Holtzman]

Oh right.  FC104.  That's not gonna happen!  I was thinking it was a bigger speaker and back box than that.  It's good to know code requirements before you get into something like that.  So, yeah, Dremel with a cutting wheel and then maybe a deburring tool to grind it down a little further.  Good luck!

My guess is that's a return air plenum and anything that goes into it has to be fire rated.  It's too clean and whoever did the install went to a lot of trouble to maintain the integrity.  It the ceiling was not a plenum you would see data, security, fire, controls etc. cables run in eyelets on clamps.

It's probably also not plumbers tape but some type of fire stop.

You will be in a world of hurt if you open that ceiling, install new LV equipment and don't get an inspection if the plenum comment is correct.

[BenFranske]

My guess is that's a return air plenum and anything that goes into it has to be fire rated.  It's too clean and whoever did the install went to a lot of trouble to maintain the integrity.  It the ceiling was not a plenum you would see data, security, fire, controls etc. cables run in eyelets on clamps.

I appreciate your concern but let me reiterate, this is not plenum space. I am familiar with plenum space identification and the requirements. There are in fact a several cables that are run in J hooks directly behind where I took that photo from. The fact is this is a building from 1986 and when it was built there were far fewer control circuits installed. There are no network jacks or communication lines in this portion of this building period so that eliminates a lot of what you might expect to see. As for the original being in conduit I think that has more to do with some interesting decisions made when the building was built than anything else. There is plenty more evidence of errrr, interesting decisions made by the original architect and general contractor.

[Scott Holtzman]

Cool....I don't know you so please don't take comments personally.    I would not want to see anyone make a dangerous and expensive mistake. 

[BenFranske]

Cool....I don't know you so please don't take comments personally.    I would not want to see anyone make a dangerous and expensive mistake.

No problem, as the guy frequently called in to fix messes I should appreciate it. In Minnesota we are required to be licensed and go through NEC continuing education training so we're familiar with the issues. Interestingly, power limited technology and communications circuits are exempt from inspection here in most cases.

[Jason Lavoie]

So I'm planning to replace a batch of 14 Soundolier FC104 70v ceiling speakers installed ca. 1986 with some QSC AD-CI52ST speakers. The good news is that the new speakers will use a 11.7" hole and the old speakers used a 6.25" hole. The bad news is that the old pre-installed backboxes need to disappear first. Of course access is only from below (except one can which can be seen from an access panel).

Any great ideas on getting the old backboxes out of the way? My best plan so far is to use a cutoff wheel in a die grinder to cut the sheet metal screws holding them in place and then try to pop them up into the ceiling, cut the larger hole and then pull them out.

Here's what the backcans look like, one of the few that's visible:


And here are the Soundolier FC104 speakers:

Once you loosen the conduit fittings and unscrew whatever you can a bit of brute force should take care of it.
the cans are only usually attached well enough to hold them in place until the drywall goes in, and especially with the conduit there to hold them I doubt they would have use more than one or two screws.

Jason

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