building Cabinets

howie461

I have a set of SDA-1A’s that I have carried around the world, only to have them fall victim to a flood. The damage is limited to the cases, if I close my eyes they sound perfect as the day I brought them home (1985), but visually they are a wreck. Has anyone had success building replacement cases? What are the pitfalls; I’m a fair woodworker and have a good electronics background. Is this worth doing or should I just close my eyes and listen?

NJPOLKER

By the time you get done building new cabinets and finishing them you will be into alot of time and money. However, pride of accomplishment is great and building your own SDA's cabinets would be a great accomplishment. If I were to re-make the cabinets I would carefully dismantle them and use the existing pieces to help replicate the original cabinets. I do not think it would be a good idea to vary anything in cabinet structure. The folks at Polk Audio did alot of research making sure everything is the proper structure and size/volume.
It maybe a good idea to post some pictures so we can be certain they are SDA1a's.
I am sure fellow Polk members will chime in.
By the way, Welcome to Club Polk
Drew

howie461

here, I was told that it was a factory upgrade from 1, to 1A is that correct? they don't show the damage but the bases fell off, and the bottom of the cases soaked up a lot of water. I plan on following the factory dimensions as closely as i can, I'm just not sure of the type of wood/MDF to use.

avguytx

If you get into woodworking, it wouldn't be that hard to duplicate those cabinets with the same interior volume and making them more attractive cabinets. Especially if you use some sort of cabinet grade wood. Or, you can always veneer over MDF.

They don't look that bad from the pictures I'm looking at. Are the bases able to be separated from the rest of it and just redo that part? It would make the job a lot easier? Plus, it would be nice to retain as much of the back panels as possible. Do you have some closer pics of the bottoms where the damage is?

howie461

the idea of building them doesn't scare me, of course that has gotten me into trouble in the past. I'm just not sure of the wood, does the it matter what kind, does that affect the sound? and I've thought of buying another set, or upgrading, but these have value beyond mere cost. the bases fell apart, and my wife threw them away ( I was in Iraq during the flood recovery), so if some one has a set of SDA's and could measure them for me it would be great.

Boywonder

As for the wood, use MDF and veneer over it. You could also use high quality cabinet grade plywood, (3/4" baltic birch, etc), but it may get cost prohibitive. If you don't like to veneer, you can rebuild them like SDA-1C's etc. with an MDF cabinet and hardwood tops and bottoms with grill mat'l front and sides.

Personally, I prefer the look of the hardwood end caps etc, but others prefer the older cabinet style like yours, it's all personal taste.

You need to use 3/4" (or thicker) MDF or cabinet grade plywood because you want the cabinet as sonically "dead" as you can make it, and MDF or highly laminated plywood fits the bill well) Thats why bracing is also required.

You could also use particle board (that is what the original cabinet is made from), but I strongly recommend MDF, it's higher quality, inexpensive, and machines very well.

It also has to be sealed well (although I see your SDA's are early ones with ports) You need to duplicate the ports with an otherwise air-tight cabinet or you will change the tuning of the speaker. You will also need to rabbet in the drivers so that they are flush with the front baffle.

I recently veneered my monitor 10's, and here is the link.

http://www.polkaudio.com/forums/showthread.php?t=61901&highlight=veneering

If it were me, I would keeps my feelers out for a pr of SDA-1C's for $350-$450, and sell the parts from your speakers to lessen the cost of the 1C's. Would certainly be less time and effort, but I understand that these have sentimental value.

I'm sure someone will also chime in here that you should upgrade the crossovers while you are at it, makes 20 year old speakers sound much better, but now we are talking scope creep for your project.

Finally, you could attempt to repair your existing cabinets if just the bottoms are damaged, saving a boat load of time.

Boywonder

A table saw and router are almost requirements for a quality job. You could get by with a circular saw and a straightedge if you are very talented. A dado blade helps immensely also.

How bad are the bottoms of the cabs? Can you post pics? Bases would be cake to build.

howie461

The bottoms are gone, and the base of the cases has swelled noticeably. I've heard that MDF/veneer is the way to go, and it is what they are made of now. I was thinking going with end caps, I have a stock of mahogany I've been carting around almost as long that needs a project. I figured that most folks on this group are purist and would burn me at the stake if I mixed my 1A components and a 1C case design. I'm not picky, my 1a's and my Akai 747 are all I have left from my original equipment (mover's robbed me blind), and I just want them pretty again

ben62670

Mdf with veneer is the only way to fly. I would go with a single tweeter. The early SDA1's with the dimensional tweeter had 1 stereo mid bass, 1 dimensional mid bass, and 2 bass only drivers. Mount the mids as they are, and mount a single tweeter in the center just like the newer ones. There is a 4 ohms resistor on the tweeter you may want to change to a 2.7ohm to make up for the missing dimensional tweeter. There is a reason Polk did away with the dimensional tweeter. If you need help with this mod shoot me a PM.

Ben

tx_polkhead

I say live with the swelling, rebuild the bases and re-invest the money you would spend rebuilding the cases on replacing the gear that the movers robbed from you. I say that since you say they still sound perfect.
either way good luck
abel

Boywonder

If the front baffle has not swelled, I would consider just replacing the bottom part of the cabinet, and reveneering the whole cabinet. It would take a steady hand and intestinal fortitude, but it could be done. A couple of correctly placed saw cuts, a couple of hammer whacks, and Voila! no more bottom.

Lifting those puppies up on the table saw to make the cuts would be a little unweildy, but do-able. Waxing the table saw surface with car wax before you start would help immensly.

Much less work than completely new cabinets.