Lightweight Cab building advice.

[Nev375]

I have a Hartke 410xl that I would like to convert to a pair of DIY 210xl cabs. Mostly because Im getting old and don't want to haul big 80lb. speakers anymore.

It should not be hard to figure out, the cab is already divided into 2 chambers and ported separately, I should just copy the internal dimensions right?

Looking at the construction of this cab, I can't hep but think there's a better way to do this for what i'm wanting.

I know ACME used thinner walls but tensioned then to reduce resonances, but I have no idea how that is done exactly.

I wonder if one took the time to honeycomb the internal sides with a drill to remove some material without going all the way through.... good idea or no?

Poplar plywood is lighterweight than others, can it be lightened further?

Thoughts? Analysis? Ideas? Professional advice?

[beatsbears]

I feel like there was a thread like this a few weeks ago about turning an 810 into two 410s. That is along the lines of what you were thinking about doing right?

As I remember most were against the idea. I think they cited there would be difficulties properly sealing the halves.

[mikeddd]

If your 410 cab is already internally divided and separately ported, then yes, all you would have to do, physically, is duplicate the dimensions of the chamber and port.

However, there's the crossover to consider. If you were always going to run BOTH cabs together, then just put the crossover in one cab and be done with it. But if you would ever run a cab by itself, then you would have to build two new crossovers from scratch taking into account 2 drivers, vs. 4 drivers and all the T/S parameter mess that goes with it.

[will33]

Most bass cabs just have the tweet highpassed with the woofers playing the full signal. If this is the case with yours it's a non-issue. If it also has a lowpass on the woofers, then you'd have to redo the lowpass half of the crossover.

Otherwise yes, cloning the size and port tuning will work as it does now. You could even change the footprint/dimensions as long as the internal volume/port tuning stays the same.

The only other issue is if it's an 8ohm 410 using 8ohm drivers in series/parallel. You would either make a pair of 16ohm 210's or a pair of 4ohm 210's and a series cable if your amp doesn't work at 2ohms.

1/2" baltic birch for the baffle at least, maybe poplar for the rest and good crossbracing will end up being stronger and lighter. Get it from a cabinet builders supply place or something. Most stuff at home depot or wherever has too many voids in it and extremely thin outer veneer.

[billfitzmaurice]

Originally Posted by Nev375

Looking at the construction of this cab, I can't hep but think there's a better way to do this for what i'm wanting.

There is, and this is it. Use 1/2" plywood.

[Nev375]

Originally Posted by billfitzmaurice

There is, and this is it. Use 1/2" plywood.

I was hoping you might chime in Bill. That diagram is quite helpful, but I have some questions.

Are those dowels under compression, pushing out on the sides of the cab? If so, how does one figure how much longer to cut them?

How are they held in place? screws from the outside? set into shallow holes? just glue?

What size dowel do you recommend for a 2x10?

[will33]

Ideally set in shallow holes with a healthy dose of PL Premium glue. It expands as it cures and is strong as hell. 3/4" dowel should be fine. You can cut them a hair long and force them into place using the same glue if modding an existing cab but if building from scratch, use a forstner bit and give them a little pocket to sit in.

[MuzikMan]

There have been some interesting Nida-Core cabs built around here. That material is supposed to be about 1/3 the weight of Baltic Birch.

[bgavin]

It is a lot easier to glue/screw a cleat to each side, then clamp a fitted flat brace to the cleat until the PL dries.

This method allows for less than a perfect length of the brace piece.
If you miss by a quarter inch, no big deal.

I prefer flat braces because they can be clamped and glued on their flat surfaces where they cross in mid-cab.
This is very effective when using 3/8" or thinner stock.

[will33]

Originally Posted by bgavin

It is a lot easier to glue/screw a cleat to each side, then clamp a fitted flat brace to the cleat until the PL dries.

This method allows for less than a perfect length of the brace piece.
If you miss by a quarter inch, no big deal.

I prefer flat braces because they can be clamped and glued on their flat surfaces where they cross in mid-cab.
This is very effective when using 3/8" or thinner stock.

Also a good way to do it. You can make the braces out of left over strips from panel cutting. Even put two together so they look like a T when viewed from the end...or an L like angle iron. You get grain running perpendicular that way...real stiff.

[dhomer]

Originally Posted by MuzikMan

There have been some interesting Nida-Core cabs built around here. That material is supposed to be about 1/3 the weight of Baltic Birch.

The nidacore experiment wasn't all that.. The weight savings were not that significant. However, some have figured out how to laminate pink styrofoam and build some pretty impressive cabs

Look here fEARful

[Robby Hoinsky]

Originally Posted by dhomer

The nidacore experiment wasn't all that.. The weight savings were not that significant. However, some have figured out how to laminate pink styrofoam and build some pretty impressive cabs

Look here fEARful

Nidacore would still be lighter, but the cost is pretty high and it is not easy to work with. I switched over to Epoxy/fiberglass over XPS foam. If you don't want to get into fiberglass, you can make a very ligfhtweight and stiff panel by laminating thin plywood (1/8") over XPS foam with similar, though a little heavier results to fiberglass. You sacrifice stiffness using lighter plywood and to regain it you have to add a great amount of careful bracing. IMO, a sandwich composite is the only way to truly achieve the best balance of light, stiff, and damped.

This 1212/6 cab weighs-in in he mid 40 lbs with a full metal grill and crossover.


Using this material:



Robby