1/2 inch lightweight plywood?

[Stewie]

My favorite amp is an old Fender BXR300C. It makes my upright sound like an upright, and can get very loud without distortion.
The problem is the weight. Fender advertised it as 78 pounds, but it pushes 120 easy on my bathroom scale.
I would like to rebuild the cabinet to the same internal specs, but with braced 1/2 inch plywood to cut it back to a more manageable heft.
I'm a retired carpenter/cabinet maker, so I have the necessary tools and experience.

I was wondering if anyone knows what the amp manufacturers are using when they state "lightweight plywood"

Thanks for your help

 

[BassmanPaul]

I was wondering if anyone knows what the amp manufacturers are using when they state "lightweight plywood"

Thanks for your help

Plywood that sin’t heavy?

All joking aside I’d take a look through the fEarful threads and see how they handle the bracing. Good luck with the project.

 

[Passinwind]

I was wondering if anyone knows what the amp manufacturers are using when they state "lightweight plywood"

Poplar and Arauco are two fairly common choices.

 

[beans-on-toast]

Lightweight can mean one type throughout or it can mean lightweight core.

For a speaker cabinet you want void free plywood. Otherwise, it can develop rattles inside the ply. You also want strength.

Many use 12mm baltic birch. Compare the published weight persquare foot to 12mm poplar which is lighter. Hardwood vs lighter softwood are available.

Weights are here:
https://www.wolstenholme.com/pdf/Baltic Birch Plywood Specifications.pdf

Lightweight poplar plywood

 

[Luckaz]

Lightweight can mean one type throughoutor it can mean lightweight core.

For a speaker cabinet you want void free plywood. Otherwise, it can develop rattles inside the ply. You also want strength.

Many use 12mm baltic birch. Compare the published weight persquare foot to 12mm poplar which is lighter. Hardwood vs lighter softwood are available.

Weights are here:
https://www.wolstenholme.com/pdf/Baltic Birch Plywood Specifications.pdf

Lightweight poplar plywood

+1
Link Removed

 

[Stewie]

Thank you all.I've used a lot of 3/4 inch poplar plywood to make cabinets that would be painted. I like it better than birch or maple veneer because they give you a wee more than the 3 microns of actual Birch. I'll look into what I can get from the local plywood distributors

 

[jallenbass]

I get Sandeply at Home Depot. It's really light and with some well placed bracing makes a very solid cabinet.

 

[Stewie]

Is that the stuff that smells like lobster when you cut or machine it?

 

[alaskaleftybass]

Somebody would make a million bucks if they could reverse-engineer Gallien Krueger's MB and CX series cabinets. They are 1/2" lightweight, but very sturdy and sound excellent for what they are. I own a GK MB108 practice combo and kicks butt on anything else in its size. It will KILL any 8" bass combo.

 

[dbase]

I wonder what a Balsa wood cab would sound like? It would be very light I'm sure but just don't sit on it .

 

[Rune Bivrin]

I wonder what a Balsa wood cab would sound like? It would be very light I'm sure but just don't sit on it .

I think you'd find balsa to be quite strong. After all, it's used to build functional airplanes. But it might get dinged somewhat too easily...

Invalid Link Removed

 

[beans-on-toast]

I’ve used aircraft grade plywood. It was made out of spruce. They do sell hardwood veneer sheets that help protect softer woods.

Here are some examples of aircraft grade wood.

Aircraft Plywood

 

[popgadget]

Baltic Birch is my wood of choice. It checks all the boxes, very stable, void free, dense ply count, excellent panel stiffness, and durable. But it’s got to be true Baltic Birch, not “Birch Plywood” from a big box store. It’s usually only available from lumber wholesalers or larger lumber yards, and comes in 5x5 sheets.
If you have to have lighter weight, then I’d suggest Okoume. However, it’s 3 times the cost, about 20% lighter, and a softer more easily damaged surface.
The weight savings obtained from dumping the “particle board”, should be sufficient without resorting to exotic wood.

 

[beans-on-toast]

Baltic Birch is my wood of choice. It checks all the boxes, very stable, void free, dense ply count, excellent panel stiffness, and durable. But it’s got to be true Baltic Birch, not “Birch Plywood” from a big box store. It’s usually only available from lumber wholesalers or larger lumber yards, and comes in 5x5 sheets.
If you have to have lighter weight, then I’d suggest Okoume. However, it’s 3 times the cost, about 20% lighter, and a softer more easily damaged surface.
The weight savings obtained from dumping the “particle board”, should be sufficient without resorting to exoctic wood.

Interesting to note that these 5x5 Baltic birch sheets use a urea based adhesive while 4x8 sheets use a phenolic based resin. Phenolic resins are used in waterproof marine grade plywood. I’ve used both formats for cabinets and didn’t notice a difference.

https://www.wolstenholme.com/pdf/Baltic Birch Plywood Specifications.pdf

 

[thehindteet]

i wonder what percentage of the total weight is the cabinet itself? have you had the driver out of it? I remember lugging some of those 90s fender guitar combos around, sweet jesus. I used to wonder if they hid bricks inside.

 

[Coolhandjjl]

Okume is another choice

 

[CRich0205]

My sealed 212 is Baltic birch and with eminence delta 2s or whatever is only like 50 ish pounds. Really strong and light stuff.

 

[interp]

I’ve used the 5x5 Baltic Birch for cabinet building with pretty good success.

 

[singlemalt]

I use 1/2 Baltic birch, about $37 for a 5x5’ sheet.

I made a little jig so I could use my biscuit jointer. Makes a really solid box. PL premium glue works really well for glueing up cabs.

Duratex is really nice for a tough, easy, roll on finish. No smell and warm water cleanup.

Here’s an apres build shot. FEarful 12/6 cube, glued up after a lovely afternoon in the shop. 1/2” Baltic birch.

If you have the itch to build a cab, I’d suggest you check out Greenboy’s fEarfuls. All the plans and info are on the site, Speaker Hardware is you one stop shop for parts.

 

[Stewie]

I'm pretty stuck on the original design as a combo. Like I said, My upright sounds like an upright through it. It can fit in the bed of my Tacoma along with my upright, PA head. mic and speaker stands. I thought of making it a head/cab set up, but there are no sides on the amps case. I have a great Ampeg stack for anything the combo can't handle.

Baltic birch box? does anyone feel that braced 5/8, or even 1/2" stock would be stiff enough to handle the vibrations from the low end?, or should I stick with the tried and true 3/4" stock?