I am building some relatively large PA subs and I am hoping for some guidance on how to make the front bracing removable to be able to access the driver as well as how to get a grill on this sub and still looking "pro". Keep in mind that the enclosure has not been glued up yet. I am using 3/4" plywood and the nominal mouth opening is 15 3/8" x 21".
Below is my current plan on how to make the bracing removeable.
The sides of the braces that can be accessed from the outside of the cabinet will have 2 threaded inserts side by side, everything will be countersunk so everything still fits flush. The top of the vertical braces are a bigger question mark for me. Current idea is to have 1/2" Neodymium magnets countersunk in the top of the braces and in the face of the mouth, should allow for relatively easy removal of the front brace. However I am not sure the "connection" between the 2 magnet pairs will be strong enough for the brace.
Does anyone have any ideas on how to design a better removeable front brace? How about thoughts on this idea? Concerns?
Below is my plan for the grill.
My current plan is to make a 3/8" rabbet cut with a router at the depth of the grill so everything is flush. I then plan on countersinking 3/8" Neo magnets in the locations specified on the picture. I am worried that they might rattle in the corners and off the center of the bracing in the mouth.
Anyone have any better ideas? I also have toyed with the idea of countersinking a pair of 1/2" magnets on the actual corners of the mouth and in the center of each side. Countersinking them below the actual depth of the grill. Any hints or other ideas on how to accomplish these objectives would be greatly appreciated!
By the way, does anyone know a good place where I can purchase a metal grill for this specific purpose (and have it cut to size)?
Below is my current plan on how to make the bracing removeable.
The sides of the braces that can be accessed from the outside of the cabinet will have 2 threaded inserts side by side, everything will be countersunk so everything still fits flush. The top of the vertical braces are a bigger question mark for me. Current idea is to have 1/2" Neodymium magnets countersunk in the top of the braces and in the face of the mouth, should allow for relatively easy removal of the front brace. However I am not sure the "connection" between the 2 magnet pairs will be strong enough for the brace.
Does anyone have any ideas on how to design a better removeable front brace? How about thoughts on this idea? Concerns?
Below is my plan for the grill.
My current plan is to make a 3/8" rabbet cut with a router at the depth of the grill so everything is flush. I then plan on countersinking 3/8" Neo magnets in the locations specified on the picture. I am worried that they might rattle in the corners and off the center of the bracing in the mouth.
Anyone have any better ideas? I also have toyed with the idea of countersinking a pair of 1/2" magnets on the actual corners of the mouth and in the center of each side. Countersinking them below the actual depth of the grill. Any hints or other ideas on how to accomplish these objectives would be greatly appreciated!
By the way, does anyone know a good place where I can purchase a metal grill for this specific purpose (and have it cut to size)?
You can add a firring strip around the opening to mount the grill.. that won't have any impact on the boxes performance.
Neodymium magnets are typically very brittle. If you get vibration in that area that's stronger than the holding force, two brittle magnets vibrating against each other may chip. Same issue if they snap together during assembly. If you get magnets strong enough to really do the job here, the chances of chipping during assembly go up.
If you separate the magnets, force goes down dramatically with distance (even small ones).
For something like this, I would try for a more significant mechanical connection.
Pocket screws or biscuits/dowels/whatever seem like some other possible approaches. A pull saw or similar would remove very little material if you need to undo a biscuit/dowel-type joint later. It would take a little reworking to re-install, but I assume you aren't planning on blowing drivers every other day.
With a furring strip added, wouldn't the grill "protrude" from the actual dimensions of the box? Maybe I am not picturing what you are describing correctly.
Yeah I was kinda worried that they wouldn't be quite up to the task.
Looking at it again it appears that I only will have to remove the horizontal brace to be able to service the driver. That could make things a bit easier since I can access both sides of the horizontal brace from the sides of the cabinet.
The furring strips would be recessed enough to allow the grill to sit flush with the exterior.
The grill should rest on foam tape or simlar or it will buzz, this makes holding it with magnets tricky as they will have not enough 'grab' due to the increased foam distance. Recommend the furing strips approach with wood screws and foam tape behind the grill. Also put grill foam on to stop liquid getting in the sub.
If you are in the UK I do, Its best to buy in whole sheets. You can cut it to size with a hand held angle grinder.
Metal would be best, but support or reinforce the center area of grille to avoid resonances or buzzing.
Mounting the grille edges with some rubber neoprene sheet cut into strips, sandwiched between grille and cab will do a better job dampening the grille over its entire mounting surfaces.
I also use neoprene sheeting to seal driver flange mounting surfaces. The driver flange fasteners will retain their torque more consistently/evenly and reduce the chance of deforming or snapping when the cabs are handled roughly in transit.
If your drivers don't have double spider suspension, be careful torquing the screws evenly to avoid deforming the baskets, causing the VC to become misaligned and possibly rubbing on the outer pole plate - bad news for the driver and amp when this happens.
Mounting the grille edges with some rubber neoprene sheet cut into strips, sandwiched between grille and cab will do a better job dampening the grille over its entire mounting surfaces.
I also use neoprene sheeting to seal driver flange mounting surfaces. The driver flange fasteners will retain their torque more consistently/evenly and reduce the chance of deforming or snapping when the cabs are handled roughly in transit.
If your drivers don't have double spider suspension, be careful torquing the screws evenly to avoid deforming the baskets, causing the VC to become misaligned and possibly rubbing on the outer pole plate - bad news for the driver and amp when this happens.
Thank all of you for your responses.
I have ordered some grills for the subs, they have a 1/2 inch hem, the sales guy said they should be rigid enough for the opening. The grill dimensions are 3/4" bigger than the mouth dimensions, allowing for a 3/8 inch rabbet cut. I think I am going to go the furring strip method but might be tough since cabinet wasn't built perfectly square.
Picture below shows the final assembly of the mouth and braces.
Last question, looking at the braces, would there be enough support for the middle of the grill to avoid rattling? Is the furring strip method still viable? I believe the grill is 18 gauge.
I have ordered some grills for the subs, they have a 1/2 inch hem, the sales guy said they should be rigid enough for the opening. The grill dimensions are 3/4" bigger than the mouth dimensions, allowing for a 3/8 inch rabbet cut. I think I am going to go the furring strip method but might be tough since cabinet wasn't built perfectly square.
Picture below shows the final assembly of the mouth and braces.
Last question, looking at the braces, would there be enough support for the middle of the grill to avoid rattling? Is the furring strip method still viable? I believe the grill is 18 gauge.
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If the grills come into contact with the braces they will make audible noise, but a grill flexing in free air doesn't