Re-building Boston speakers

[The Dali]

Hello all, as part of a general Home Theater/Music remodel, I am planning on taking my downstairs/basement speakers and building new cabinets for them. The reason is because the existing cabinets were originally an ash finish that the previous owner painted black for some reason. Plus, the bottoms of the speakers are beginning to breakdown. In addition, I want to create some beauty for the cabinets, a la Vienna Acoustics.

Ok, so the speakers I have:

Boston Acoustics 970 Series (Floorstanding, front)
Boston Acoustics HD-9 (Bookshelves, for use in the rear)
JBL Northridge USA Center Channel

I am planning on building new cabinets from a decent wood (haven't decided yet) so they all match. I am planning on reusing all the existing crossovers and connections, just building new enclosures.

Any thoughts or suggestions? This will likely be a few year-project (my overall media room) and I can use these as-is for the time-being, but wanted to start getting information on re-building.

I will likely just purchase a sub, as I don't have one beefy enough for this system and it would likely be easier and cheaper to buy something than to try to make it...

Anyhow... any suggestions on next steps? Wood type? Etc? Thanks!

 

[TLS Guy]

Hello all, as part of a general Home Theater/Music remodel, I am planning on taking my downstairs/basement speakers and building new cabinets for them. The reason is because the existing cabinets were originally an ash finish that the previous owner painted black for some reason. Plus, the bottoms of the speakers are beginning to breakdown. In addition, I want to create some beauty for the cabinets, a la Vienna Acoustics.

Ok, so the speakers I have:

Boston Acoustics 970 Series (Floorstanding, front)
Boston Acoustics HD-9 (Bookshelves, for use in the rear)
JBL Northridge USA Center Channel

I am planning on building new cabinets from a decent wood (haven't decided yet) so they all match. I am planning on reusing all the existing crossovers and connections, just building new enclosures.

Any thoughts or suggestions? This will likely be a few year-project (my overall media room) and I can use these as-is for the time-being, but wanted to start getting information on re-building.

I will likely just purchase a sub, as I don't have one beefy enough for this system and it would likely be easier and cheaper to buy something than to try to make it...

Anyhow... any suggestions on next steps? Wood type? Etc? Thanks!

I would use pre veneered 3/4" MDF or plywood. It is best to get it veneered both side.

You will need to have the enclosure dimensions the dam as they are now. You might want to add bracing, which will make the enclosures a little bigger.

I think these are what you have, with the passive radiator.

 

[GranteedEV]

Make sure you don't change the width of the baffle.

I wonder if Ultra-Light MDF is good for acoustic use. I'd imagine it would be, and it would make your job easier.

 

[The Dali]

The speakers above are not the ones I have... I'll have to take a picture for you.

I intend on using the exact same dimensions as the original speaker housing, just with different materials.

 

[bwilkinson]

Since I have not build speakers before, take this with a grain of salt, but in acoustics generally, mass is everything. I would believe that making a lower mass cabinet would allow the sound to penetrate through the body of the cabinet more than through the driver directly.

How much difference that makes is beyond me.

 

[GranteedEV]

Since I have not build speakers before, take this with a grain of salt, but in acoustics generally, mass is everything. I would believe that making a lower mass cabinet would allow the sound to penetrate through the body of the cabinet more than through the driver directly.

How much difference that makes is beyond me.

that's the thing though, if it makes a 2% difference in performance but weights 30-60% of regular MDF then i'd assume it's worth it as the right bracing can counteract that difference. There's a reason we don't make speakers out of concrete, after all! Well, some companies do.

A lot of people use baltic birch, which to my understanding is only slightly more resonant but way lighter and easier to work with. It's really expensive imo though for everyday DIY.

I'd really like to see some acoustic application tests on some of the Ultra-Lite MDF, the elemental Designs EFS wood, HDF, Baltic Birch, Maple Ply, etc just to know if there's viable alternatives.

 

[bwilkinson]

There's a reason we don't make speakers out of concrete, after all! Well, some companies do.

That looks like it would be a fun DIY project - if for nothing else than just to play in the mud!

 

[mattsk8]

Baltic Birch is about 50-60$/sheet, depending on when you buy it at most Menards stores. That's a 4x8' sheet. Don't make a mistake and get birch from Home Depot or Lowes, as its not the same. It has to be 'baltic' birch.

Because there's so many layers, the baltic birch will stay straighter and is a bit denser than the regular birch ply.

IMO, I would just use MDF. I think the only con to using it is the weight, and how often do you need to pick up your tower speakers? MDF is the densist of all of the possible plywoods and based on that I would think it would give you the best sound. One huge pro is a 4x8' sheet of MDF is 20$, as opposed to the baltic birch's 50$ range.

Veneer can get expensive though. I think Menards also sells some hardwood veneered MDF ply too. Cherry, Oak, Maple, and birch. But this is about 50$/sheet too. If your looking for something other than those types of wood, a store called Woodcraft is a great place if you have one near you. If they don't have it they'll certainly help you find it!

 

[The Dali]

I guess the question is... so you don't build speaker cabinets out of regular wood?

 

[mattsk8]

I guess the question is... so you don't build speaker cabinets out of regular wood?

Take this w/ a grain of salt because I've only built subwoofer boxes but I do know wood very very well...

One main problem w/ building speaker cabs out of solid hardwood is the inconsitency in density. Some hardwoods have knots, and even the one's that don't are inconsistent so it would be more likely to crack w/ the grain under pressure. Another is cost of solid hardwood but w/ veneer prices these days this is almost not an issue anymore!

Do you know what the cabinets are made out of now? Is it a veneer or a vinyl coating? If it's a veneer you could strip the old finish and just refinish them to your liking. If you like the way they sound you'd save a mountain of time going that route!! Even if it's a vinyl coating you could peel that off w/ a heat gun and just veneer it w/ whatever you want.

 

[highfigh]

I guess the question is... so you don't build speaker cabinets out of regular wood?

No, you don't. The density of solid wood isn't as consistent as MDF and cabinet resonances are a big problem because of this. If the bottom is crumbling because of moisture, you could stabilize it with epoxy or polyester resin (the stuff used when laying up fiberglass on boats and cars), making it smooth and flat, then veneering the whole cabinet.

 

[The Dali]

Right - I could simply re-veneer the cabinets with something to my likeing. I hadn't thought of that! That is an awesome idea!

As for the bottom... I think the bottom is actually a small 1" base that I could likely remove and replace.

 

[highfigh]

As for the bottom... I think the bottom is actually a small 1" base that I could likely remove and replace.

That's even better. If necessary, you could pretty then up and make a new base. Much easier than building new cabinets. Probably faster, too.