TC-615i in wall - fire hazard with blown-in insulation?

waxman
waxman Posts: 124
edited June 2008 in Speakers
Guys, I'm currently installing 4 TC615i's in my media room (paired with rti12 and an old cs350 (yes a new center is on the wish list for timbre match ;)

My question is regarding the backs of the tc615i's touching insulation. Is it a fire hazard? Since enclosures aren't required and it seems folks recommend putting the pink roll fiberglass insulation as backings to stuff any enclosure, I think I'm ok, but need someone else to nod their head so I can sleep better that I can have 2 of my speakers come in direct contact with blown-in insulation.

The setup- 2 in aflat rear wall. I put in an upper and lower 2x6 horizontal brace to form a type of enclosure using the drywall behind it as the back plate (it's not airtight, but it's solid). No insulation in the cavity, but I'm thinking of adding some assuming it's not a fire hazard.

The other 2 are the side surrounds, which will point down at a 45 degreee angle from the bevel in the vaulted ceiling (see pics- I have the template pinned to the 45 degree wall where I will cut my hole). These are open to attic above them. I could place a brace above and below the speaker connected to the joists, but I don't have a way to place a 'backing' to seal up the cavity- because of the vaulted ceilings I just can't wedge myself into a position to reach the speaker from the attic, let alone nail a piece of plywood to the joists to form a the back of a enclosure. So these speakers would basically be coming into contact with blown in insulation or the pink rolled stuff (if I decided to cram that in as I install the speakers.

So-- what'd ya'll think? Is insulation ok from a fire hazard perspective? I know the sound quality won't be as good without an enclosure with backing, but unless I shrink it isn't going to happen so I've got to make due. Thanks for your help and input.
Post edited by waxman on

Comments

  • disneyjoe7
    disneyjoe7 Posts: 11,435
    edited December 2007
    Well I don't think you what the loose stuff getting into the speaker itself, less of a fire hazard but a sound issue. I suggest placing bat insulation behind the speaker blocking the loose stuff from getting into speaker.

    Speakers
    Carver Amazing Fronts
    CS400i Center
    RT800i's Rears
    Sub Paradigm Servo 15

    Electronics
    Conrad Johnson PV-5 pre-amp
    Parasound Halo A23
    Pioneer 84TXSi AVR
    Pioneer 79Avi DVD
    Sony CX400 CD changer
    Panasonic 42-PX60U Plasma
    WMC Win7 32bit HD DVR


  • waxman
    waxman Posts: 124
    edited December 2007
    thanks Steve- I put in bat insulation at all four speakers, and got lucky and was able to form up something resembling an enclosure at each site.

    The two rears were basically in enclosures - albeit 8 feet tall, 14.5" wide, and 3.5" deep- the exact size of the 2x4 studs- so I put in 8 feet of 15" wide bat insulation and then installed the speakers. Haven't wired the other end yet at the receiver, but I plan on finishing that tonight.

    On the side surrounds, I was able to get to one of them on the attic side to form a 22" x 15" x 3.5" box using 2x4's and plywood, with bat insulation stuffed in, and on the one that I couldn't get to from the top, when I cut the hole from the room side, I had studs barely 10" apart so I could screw down braces through the hole and luckily the roof decking was just about flush with the studs (giving me a backing to the enclosure)- so I stuffed a 10" x 20" x 6" space with two layers of insulation and mounted the speakers. I'll see how they sound in a bit ;)

    One question though- it seemed like folks were recommending sealed enclosures if money were no object. On most of the polks I've owned (rt55i, rt800i,rti12,r10,etc), they've been 'ported' - somewhere on the box there would be a opening to allow air to get into the cabinet. The tc615i's have no ports- so if I sealed the box around them air tight, wouldn't I have killed the bass because the driver would be fighting negative pressure when it tried to move out and positive pressure when it tried to move in? Now, my enclosures are far from air tight, so I know my speaker enclosures won't run into this, but thought it was interesting reading the other posts. So what's your opinion on airtight enclosures for in-walls that have no ports on the speaker face?
  • disneyjoe7
    disneyjoe7 Posts: 11,435
    edited December 2007
    My feeling in general is the wall speakers are not port and designed for a sealed enclosure as there designed to sound decent even if just dropped in a wall, speakers can be ported or sealed in general it's what was designed by the Polk guru's. If I was going to the trouble to build a box for the speaker in the wall I would also seal the cabinet the best way I could. I thinking form sealer that expanding from stuff, it couldn't hurt IMHO.

    Merry Christmas

    Steve

    Speakers
    Carver Amazing Fronts
    CS400i Center
    RT800i's Rears
    Sub Paradigm Servo 15

    Electronics
    Conrad Johnson PV-5 pre-amp
    Parasound Halo A23
    Pioneer 84TXSi AVR
    Pioneer 79Avi DVD
    Sony CX400 CD changer
    Panasonic 42-PX60U Plasma
    WMC Win7 32bit HD DVR


  • 4406bbl
    4406bbl Posts: 194
    edited December 2007
    It depends,I doubt the seal will be good enough to bother them. If you had about a 1/3cubic ft behind them perfectly sealed them maybe you need a port. The higher line Polk inwalls do use a power port,if I recall it is a slot in the back that feeds 2 holes in the front. You could try a port,but it may huff if too small.In the old days Polk used a 7x13x5 box with a 1 x 3 port with a 6 1/2 driver,try it and let us know.
  • waxman
    waxman Posts: 124
    edited December 2007
    Merry Christmas as well Steve. I had to go see the folks for a few days so I'm wiring the speakers at the amp-end right now. Thanks for the insight on air-tight in-wall enclosures- I can't actually make them airtight without pulling down drywall, so I'm just going to make due :) but it's nice to hear the theory behind such things.

    FYI, made my annual day-after run to Frys here in Austin-- they have about 10 TC615i's that they've marked down to $50. Not advertised, and no longer on fry's.com. They seem to have just gotten in some TC265i, too- they aren't sale priced yet (still $400) but when they get a lot of the same speaker in, it tells me they are going to sell them cheap in the next week or two, just like when they were getting 20 rti12's a day before they went on sale. If you got a frys near you, keep your eyes peeled :)
  • zengel442
    zengel442 Posts: 21
    edited December 2007
    I see you guys are talkin the rectangular in-wall/ceiling speakers. Is there a reason for using one vs the other? Does the rectangular have better sound than the round? What dictates the use of one or the other? Personal preference or performance?
    And location... is in the wall better than ceiling?
    Room is roughly 15'x15' with the side of the room being open to another space.
    Oh, and I've prewired for ceiling... but could be convinced to change..
    Frank
    Ma System Upstairs
    Sony 60" RearP LCD XBR
    Infinity cc-1 Center
    Rti10's Frt
    Rti8's Rear
    Infinity SM85's surround
    SVS PB12-Plus/2 SubW
    Ma System Downstairs
    Nothin yet
  • mflesher
    mflesher Posts: 4
    edited December 2007
    From what someone has told me, if you box in the speakers in the attic, the sound is greatly enhanced. I can definitely understand how this would be the case. If it's installed in a vaulted ceiling or a place with limited access, there's really not much that you can do about it, but if you're in an attic, I'd definitely take some 3/4" plywood and cut a box and box those puppies in to enhance the sound. That way there's no question as to whether or not it would be a fire hazard (which it probably wouldn't anyway).
  • readonly
    readonly Posts: 12
    edited June 2008
    Good suggetion
    mflesher wrote: »
    From what someone has told me, if you box in the speakers in the attic, the sound is greatly enhanced. I can definitely understand how this would be the case. If it's installed in a vaulted ceiling or a place with limited access, there's really not much that you can do about it, but if you're in an attic, I'd definitely take some 3/4" plywood and cut a box and box those puppies in to enhance the sound. That way there's no question as to whether or not it would be a fire hazard (which it probably wouldn't anyway).