First-time post for me. I'm the AV tech at our church, and have cabinet making skills. I recently purchased a Micca M-8C 8" 2-way in-ceiling speaker for our church's front entrance foyer. We have a 100+ year-old building with Lath & plaster ceilings. Using a 16-element stud finder, I thought I located an area free of obstacles. I drilled a 3/8" hole, but when I attempted to cut two lines out from the center of the hole found an electrical conduit on one side and a ceiling joist on the other side.
I want to construct an enclosure for the speaker that will be mounted to the surface of the ceiling. I need some help in understanding the acoustics involved in speaker box construction. The outer dimensions of the speaker are 10.7" diameter, with a mounting depth of 3.5". I am imagining a box that 12" square and 4" high with slots (instead of one or more round port holes) on two or four sides, say 1/4" x some length less than 12" long. Someone indicated I need to obtain the Thiele/Small parameters in order to proceed with a proper design. I've requested this information from Micca. I'm looking for advice on how to proceed. For example, does this box need to be tuned? What do I do with the Thiele/Small parameters if Micca provides them? Thank you! Link to Micca M-8C.
I want to construct an enclosure for the speaker that will be mounted to the surface of the ceiling. I need some help in understanding the acoustics involved in speaker box construction. The outer dimensions of the speaker are 10.7" diameter, with a mounting depth of 3.5". I am imagining a box that 12" square and 4" high with slots (instead of one or more round port holes) on two or four sides, say 1/4" x some length less than 12" long. Someone indicated I need to obtain the Thiele/Small parameters in order to proceed with a proper design. I've requested this information from Micca. I'm looking for advice on how to proceed. For example, does this box need to be tuned? What do I do with the Thiele/Small parameters if Micca provides them? Thank you! Link to Micca M-8C.
In-ceiling loudspeakers usually have high Qts Thiele-Small parameter, so vented enclosure (with slots - as in your picture) is out of question. If slots are very thin, it may work as aperiodic box, which is fine, but it is impossible to design it correctly without acoustic measurements, so do not make any slots - make your enclosure simple closed-box. Put some stuffing (poly-fill, etc.) inside the enclosure, install the speaker and call it a day.
Thank you all for your helpful feedback! I wasn’t please to find we had a lath and plaster ceiling. There have been many updates over the past century, and we never know what we’ll find when we do maintenance or wiring. We are now keeping a notebook with images to track what we find and the work we’ve done. I appreciate your help.
Sonce has nailed it.
https://www.miccatron.com/shop/product/micca-m-8c-8-inch-in-ceiling-speaker-each-white/
The receipe for a driver like this is:
Build as large a box as you can. Given the mounting you probably don’t want too heavy, so i’d use 15mm (or even 12mm ) quality plywood. Windsor Plywood, noit Home Despot.
Shape: The driver is meant to be mounted in the ceiling, essentially a real large baffle. So bigger baffle is good, and i’d put angled sides on it to make it blend more smoothly into the ceiling (acoustically & esthetically). I susxpect acoustics could be a mess no matter what you do.
Stuff it. If you want to get fancy, email me and i can arrange some acoustastuff (saves shipping from Madison, WI)
If you find too little bottom (unlikely) put somethign insdie the box to reduce the volume… if there is too much, make the box aperiodic. That is a rabbit hole. Sonce hinted at it with the real skinny, high aspect ratio vent. Easier and much more tunable is to drill some small holes (as far as you can get from the driver), starting with a few and then adding more until it sound about right. Make sure the insides of the holes are heavily covered with damping. Probably best to do this with it temporarily mounted on a wall to make it easier (and safer( to get at).
dave
PS;which church
https://www.miccatron.com/shop/product/micca-m-8c-8-inch-in-ceiling-speaker-each-white/
The receipe for a driver like this is:
Build as large a box as you can. Given the mounting you probably don’t want too heavy, so i’d use 15mm (or even 12mm ) quality plywood. Windsor Plywood, noit Home Despot.
Shape: The driver is meant to be mounted in the ceiling, essentially a real large baffle. So bigger baffle is good, and i’d put angled sides on it to make it blend more smoothly into the ceiling (acoustically & esthetically). I susxpect acoustics could be a mess no matter what you do.
Stuff it. If you want to get fancy, email me and i can arrange some acoustastuff (saves shipping from Madison, WI)
If you find too little bottom (unlikely) put somethign insdie the box to reduce the volume… if there is too much, make the box aperiodic. That is a rabbit hole. Sonce hinted at it with the real skinny, high aspect ratio vent. Easier and much more tunable is to drill some small holes (as far as you can get from the driver), starting with a few and then adding more until it sound about right. Make sure the insides of the holes are heavily covered with damping. Probably best to do this with it temporarily mounted on a wall to make it easier (and safer( to get at).
dave
PS;which church
Our church is New West Community Church.
I just received this back from Micca tech support.
"Thanks for contacting us. Unfortunately, we don't have the T/S parameters for our speakers. If you would like to build an enclosure for the M-8C, make sure it is at least 1.5 cubic feet in volume, and lightly stuffed with some type of fill such as fiberglass insulation. The larger the box you build, the more even the bass response of the speaker will be, but 1.5 cubic feet is the smallest we recommend before the bass response becomes too over-damped."
If I set the height to 5.5" and the width to 12", the length of the enclosure will be about 38". I picked this location on the ceiling of our foyer because it is a straight drop down from one of the walls in the AV Studio. The reason for the speaker is that we have a couple of guys sitting in the foyer to watch at the front doors during the worship service, and some of them have a difficult time hearing the spoken word from the main house speakers in the sanctuary. I'm going to re-think this.
I just received this back from Micca tech support.
"Thanks for contacting us. Unfortunately, we don't have the T/S parameters for our speakers. If you would like to build an enclosure for the M-8C, make sure it is at least 1.5 cubic feet in volume, and lightly stuffed with some type of fill such as fiberglass insulation. The larger the box you build, the more even the bass response of the speaker will be, but 1.5 cubic feet is the smallest we recommend before the bass response becomes too over-damped."
If I set the height to 5.5" and the width to 12", the length of the enclosure will be about 38". I picked this location on the ceiling of our foyer because it is a straight drop down from one of the walls in the AV Studio. The reason for the speaker is that we have a couple of guys sitting in the foyer to watch at the front doors during the worship service, and some of them have a difficult time hearing the spoken word from the main house speakers in the sanctuary. I'm going to re-think this.
Large box = under-damped, smaller box = underdamped.
The tech got that wrong. And the damping should be quite dense to maximize the apparent volume.
I’d make the width/length a little closer together, to minimize eigenmodes. Say 16 x 28.5.
dave