Replacing damaged SDA speaker enclosures

AFVET

I recently had to total a set of SDA-CRS+ and SDA-2s due to the cabinets being stored in a damp basement after my water lines broke. I would like to take out the drivers and cross-overs and build new custom cabinets. My understanding is the key to doing this is to get the interior dimensions correct. Can anyone verify this or give me the interior dimensions on these speakers. I did get the money to replace with decent current day technology, but I want to treat them like the bionic man and rebuild them...maybe even better than before.

Rivrrat

I would say yes to the interior dimensions. My old 10B's are particle board, if I were to do it, I would go with MDF and veneer the outsides.

I would think if you have the right tools (I do) it wouldn't be that difficult. After all it's just a box.

I'd measure the exterior dimensions, minus any means of raising the enclosure, assume 3/4" walls for the enclosure, and reduce your figures accordingly.

ben62670

It would be better if properly braced.

honda cber

ben62670 wrote: »

It would be better if properly braced.

or at least, it certainly *should* be.

i love science and technology as much as anyone, but sometimes, some things are hard to explain.

a

Boywonder

The interior volume is the most critical (for box tuning), including the volume of any bracing. It's probably a good idea to keep the front baffle dimensions the same also, although you could get creative. MDF is the material of choice, particle board is used in production for cost reasons. The cabinets also have to be air-tight or you'll get little or no bass. The stiffer you can make the cabinet the better. You want to hear the drivers and not the cabinet.

Rabbetting in the drivers flush to the baffle is also a good idea, this requires a router with a circle template/jig.

Parting them out and finding another pair is by far the easiest solution.

If you have the skills, MDF/wood veneer would be a very nice solution. You could also entertain thicker MDF for increased stiffness (comes up to 1 1/4" thick if you search around locally enough). If you make the baffle dims and internal volume the same, you would just need to increase the depth of the cabs with the thicker material. MDF machines like butter and is easy to work with, but it's dusty and is a little tough on blades. A good laminate saw blade cuts plywood, MDF and particle board wonderfully and is highly recommended.

Rivrrat

Lasareath wrote: »

Would the speakers sound the same?, Some people have stated here that if you build the cabinet out of MDF and it was originally particle board that you may not get the same sound.

Particle board is maybe a bit softer, so maybe it'll absorb a bit more, but I doubt it. especially once you put some kind of damping inside. Although, internally bracing the stiffer MDF would be a good idea to cut down on the vibrations.

I'd actually be somewhat interested in trying it, as if I needed another project. :rolleyes:

AFVET

When you say I would need to increase the depth of the cabinets because of the thicker MDF you are only speaking of the overall external dimensions? My understanding working with a guy who built custom speakers is that as long as the interior/open area of the speakers matched the cabinet would be in tune with the drivers and I would be fine. I just want to make sure since both sets of speakers have the passive radiators.

Joe08867

You need to increase the volume of the cabinet according to how much bracing you use. Although I can't see an X brace taking up to much space. It all depends on how you brace it. Although you could probably skip bracing such a small cabinet if you use biscuits in the joints.

ALSO: AFVET, you posted in the schematics thread that asks we don't post in it. This is a reference thread and not a discussion thread. Please read the whole post before doing stuff like that again.

Thanks,

Boywonder

AFVET wrote: »

When you say I would need to increase the depth of the cabinets because of the thicker MDF you are only speaking of the overall external dimensions? My understanding working with a guy who built custom speakers is that as long as the interior/open area of the speakers matched the cabinet would be in tune with the drivers and I would be fine. I just want to make sure since both sets of speakers have the passive radiators.

If you want to keep the same front baffle height and width, the only dimension left to make up for the thicker cabinet material is the depth. The total cabinet internal air volume needs to be the same as the original cabinet. As Joe and others stated above, if you add bracing you need to make the box bigger (to get back to the orig cabinet internal air volume). Tuning the cabinet boils down to the spring rate of the air volume behind the drivers; larger air volumes are more compliant, ie are lower rate springs and smaller air volumes are stiffer springs.

A smart speaker building trick is to purposely oversize the cabinet by 10% or so, and then glue in a hunk of 2x4, 4x4, brick, etc to reduce the cabinet volume if needed. Making the internal volume smaller is easy, making it larger is impossible, ie you have to start over.