building 1x12 - internal bracing ?

Yes. Too late now, but for future reference well braced 1/2" plywood construction works better and is lighter in weight.

 

Really? With 3/4" and that small of a cab, I wouldn't have bothered with bracing either.

 

Even 3/4" doesn't take much pressure to flex. The hi-fi guys routinely build cabs of that size with two layers of 3/4" MDF, and they don't come remotely close to the levels that we do, but they don't have to move them either. OTOH 1/2" plywood braced to a maximum free span of 8" doesn't flex. With 3/4" I wouldn't run more than 12" free span.

 

How much? How do you test this?
I'm not arguing, but genuinely curious because I would like to test my boxes. I'm thinking that a 250w bass cab won't see more than 60-70w at the cab's resonant freq which wouldn't be that much pressure, or am I wrong?

 

I did not use bracing either, and no problem with the sound.
OTOH, i will never know how it'll sound with bracing.

 

Play a low E at normal stage volume with your hand in front of the port.

It's not so much a matter of hearing vibration as the energy loss that occurs when panels flex. Energy that's expended flexing the cab walls is energy that doesn't end up in the room as sound. With the very low electrical to acoustical energy transform efficiency of loudspeakers wasting any watts to cab flex can make a significant difference in your sound.

 

Is Braced 1/2" really good to use I've been using 3/4 thinking that it was the bare minimum. What type of bracing is recommended

 

my 112's are 1/2" braced. they weigh about 35 pounds a piece for a 2.25 net cf cab. (finished) not too shabby. a tip for 1/2" construction. line the braces up with the handle cuts so you have some extra meat to screw your handles into, and also put a front to back baffle brace next to your speaker hole between the ports/tweeter/midrange...

good luck.

 

Looks good.
Why did you not want to put a tweeter in?

 

That's the classic 'Knuckle Test'. When you rap your knuckles on a cab the sound should be a high pitched whack, not a low pitched thump as with a drum. The sound in the middle of the panel should not be all that much different than that at the edge. If it is the panels are too flexible, and you are losing tone and power. The vast majority of cabinets will fail the knuckle test.

 

So I decided I would do a little testing with the 1x12 cab I've been building. To test each panel I positioned that side face up and placed a penny in the middle of the panel. Then I played a loud E through the cab. Sure enough, the back panel, which measures 18x23 and is the only side bigger than 12" in both dimentions, buzzed the penny around. I'll be adding some bracing on that and the front baffle and also trying the "knuckle test."

 

Would you lose anything going from a 3/4" to a well braced 1/2" cabinet. In my mind it seems like the thicker wood would help the sound, not sure why though. I am about to build and 1/2 would save me some dough.

 

Cool. Love to see some progress shots.

I've been thinking about building one of these but got very confused when it came to selecting a tweeter. What are you using? .. and how did you calculate the crossover?

 

Only a lot of weight.