I am installing Jamo 10.5k4 ceiling speakers... These are 4-way speakers with a monster 10" sub. I am making the back box out of 17mm plywood.
My dilemma is do I put in fibreglass insulation inside the box ?
The second issue is do I cut out a port / vent beside the speaker facing down into the room ?
The ceiling drywall is not yet in, so I set it up and tested them by closing off the front with a sheet of plywood cut out to suit the diameter of the speaker... When cranked up, there was wind (literally) rushing out the edges of the box where there were small gaps !!
Someone please help me, as I am really baffled and need some advice FAST before the builders get the drywall ceiling installed.
First, do you have the plans / size for the recommended box? Is the box design for sealed or ported? IF sealed, than sealed it is and wind whooshing out cracks is BAD. IF ported, than you'll need the port dimensions, both diameter and length. Sealing all seams is important, in either case. Speaker boxes (enclosure, more properly) should also be internally braced. I suppose if the enclosure is out of site, buried in the ceiling, you could also use external bracing. The walls must be stiff and not flex under heavy bass pounding. Rapping a knuckle on the finished enclosure will give some idea of its 'liveness'. In any case, I'd recommend Polyester fill from the local fabric store NOT fiberglass. Both enclosure types should have some....and are generally 'filled to taste' as the last step. If you are concerned, get thee to 'Parts Express' or 'Madisound' and check out speaker building supplies....they'll have the stuffing you need.
17mm plywood? I hope it is void-free multiply. It is expensive here in the states but I think in about that thickness....3/4" it is 9 ply. Properly braced, that is probably minimum. Since I believe that 'too much is never enough', I'd be tempted to use 25mm=1"....
Just went to the Jamo site. Quite an in-ceiling speaker!
It LOOKS like they do not recommend an enclosure....I think this is what is called 'infinite baffle'. The implication is to sturdily mount the speaker on a nice, thick baffle board and flush mount. I'd put some insulation behind the speaker, but wouldn't obstruct the motion or airflow to the back....some restriction with the fill you use will be inevitable, but not a deal breaker.
I'd personally think about making a removable panel the speaker mounts into.
NOW:: Do You Have a Dealer? That SHOULD be your first source for good information.
Hi Leo... Thanks for the tip to the right direction mate. Much appreciated.
I did go to the dealer and they have the most amazing A/V / home automation / luxury top end of the world set up there. Apparently cost $ 750,000 to set up and they use it as a show piece to get rich folk to sign cheques for bragging rights to having the best in the city !!
The guy there's the local expert and his advice was basically seal the back box to kingdom come. Even silicon sealant around the speaker wire hole. So, I've sealed every side of the box (there's 8 sides to the box without a lid). Twice.
The Jamo site does suggest a back box, and their recommended size is 26 litres.
I've mounted the boxes into the ceiling cavity between joists and kept them such that they will be flush against the jib (drywall) that goes up to form the ceiling. After the cutting the holes, I will also apply silicon sealant to the box where it rests against the ceiling inside the cavity.
And yes, very firmly screwed in against the 12" x 2" timber that the joists are made of. On both sides, firmly in place.
As regards the inside padding, that was up in the air. The final suggestion was to avoid it for now, and we can always re-visit that at a later date, if the need was felt.
I did set up to test the speakers with a temporary front to mount the speakers into. One with padding, one without. Very carefully listening to some very deep and heavy drum&bass lounge music, I came to the conclusion that there was in fact a better delivery from the speaker WITHOUT the padding.
At the end of the day, my guy opines, keep it simple. Just follow what the manufacturer suggests as they know their product best. The manufacturer suggests a back box, but does not suggest padding. So, that's what we go with for now.
Good. Time enough later for experiments with a moderate amount of 'fill'. That should be fluffed out and an even amount per enclosure. 26L is less than 1 cubic ft, so it's in the ball park for a sealed enclosure.
The NEXT step, for fanatics only, would be to get the Thiel / Small parameters of the woofer and run them thru a box design calculator. That way lies madness, and I get the feeling you just want it to work well......
OH, forget it! Stay with the manufacturers design.
However, I must seek your kind indulgence for a few more weeks till the over bearing burden of stress weighs a little less on my weary shoulders...
I feel I am running, uncontrollably and at tremendous speed, towards the brick wall of time.....
The house needs to be ready for us to move back in by last week of April... The place we are renting - the landlord has sold and the new owners move in soon. Plus, my mother-in-law is coming to stay at the same time. Plus, my mother is coming to stay too ! You can well imagine the burden I bear....
This is a very interesting forum. Not silly and childish like most floating around, but mature with wit and repartee. I thank you gentlemen for a warm welcome and am honoured to be in your midst.
MINE at least, speaks NO English and knowing what a case her daughter is, sides with me unconditionally and before she even knows what the issue is. 'No Returns on Sale merchandise' was communicated to me from the MIL on my wedding day.
He was a keyboard player not a bass player. Whomever shot him was unidentified so it could not have been me Nuck. There is no reason for me to shoot you either so it really is safe to come back here. This week would have been ideal with Marsh away for 12 days.
VRG, maybe you can put the mother and mother-in-law up in a nearby hotel, single room, twin beds, for a few nights. That way you only have the burden of the one that does not flee first.
Normally that would not be my first message to a new forum member but you are here for advice and did indicate "the burden I bear..."