Jack 212 build

[NoGraveConcern]

Here's what I've been working on for the last few weeks.

Started ripping some 1/2" birch:

The baffle...I was just barely able to get one $10 piece of expanded metal to cover everything, hence the top port hole grills are facing a different direction.

The box has taken shape:

Gluing in the driver spacers and throat reflectors:

This is a picture of the bracing that surrounds the back of the cab. The plans call for a completely open back except for the 1" wide border that the back panel screws into. I modified the design to use 3" tilt back castors and an angle handle in the back, hence the two ~5" pieces on the top and bottom. The flat piece added to the top also made a good spot to put a speakon connector. I ended up using the version that has the sealed 1/4" jack in the middle of the speakon since my current amp has only 1/4" outputs. I need to get a picture of the completed back.

Finished. I used the detalites. My impression of the sound is that it is very smooth and even and loud. I need to break the drivers in more before commenting on the lows.

 

[Sparks55]

Very nice work! You should seriously consider becoming a commercial builder of Bill's designs.

You are making me drool. One of these on top of a tall Tuba with a nice horn on top and you'd have a killer PA.

Mark

 

[5StringPocket]

Nice build! I've wondered what a Jack 212 would look like. I think the 3" castors and handle are a good addition and will make this easy to transport. A shot of the back would be appreciated (when you get a chance) to see how the castors, jack, and handle turned out. What are the dimensions and weight of this cab?

 

[NoGraveConcern]

Thanks for the compliments. I'll be sure to get a back shot and put it on the scale. The wheels really make this setup. It's too awkward to schlep any distance, but with wheels it's oh so easy. Dimensions are 22w x 18d x 36h (w/ 1" feet and castors).

 

[rpsands]

It ought to weigh around 70lbs by my numbers Just a ballpark figure.

 

[PaulNYC]

looks great.

 

[NoGraveConcern]

It ought to weigh around 70lbs by my numbers Just a ballpark figure.

Close, but a little high. Actual weight is 61.5 lbs.

 

[NoGraveConcern]

I cut out a hole for the speakon and backed it with a piece of 1/2" ply with a circular hole. This made a clean mounting spot for the speakon that is flush with the back of the cab. Got a little heavy on the duratex in that one spot. Maybe because this part was upside down when I was painting it.

Rear view:

Side view:

 

[rpsands]

Close, but a little high. Actual weight is 61.5 lbs.

That's pretty impressive My Birch J112 weighs in at 44 or so.

 

[NoGraveConcern]

Yeah, it's not too bad. Especially with wheels.

 

[MX21]

Nice. Very similar to my fEarful 1212/6. I did the wheels and handle the same way.

What are the dimensions for the Jack 212?

 

[kesslari]

What's the story with the wooden circles in the speaker grille?

 

[rpsands]

Phase plug =)

 

[NoGraveConcern]

Nice. Very similar to my fEarful 1212/6. I did the wheels and handle the same way.

What are the dimensions for the Jack 212?

See post #4. The wheels added an inch.

What's the story with the wooden circles in the speaker grille?

What rpsands said, although that still doesn't explain what a phase plug does. I think they keep the out.

 

[rpsands]

Smooths out the midrange a little bit.

 

[pgk]

i'm confused, is that the same style jack 2-12 that marko ursin built? yours looks significantly taller at 36", and really nice btw.

 

[funkytoe]

i'm confused, is that the same style jack 2-12 that marko ursin built? yours looks significantly taller at 36", and really nice btw.

As I recall, Marko built an Omnitop 2x12. Vintage style PA top. This cab in this thread is the Jack 2-12.

 

[NoGraveConcern]

i'm confused, is that the same style jack 2-12 that marko ursin built? yours looks significantly taller at 36", and really nice btw.

Not familiar with marko's cab, but thanks.

 

[dcodym]

I love the 90 degree recessed handle and the recessed wheels. The runners on the access panel are nice touch as well.

I was planning an O15 TB build and was going to employ this idea, but then when I started leaning towards the J212, I settled on just handles. You have me rethinking this again.You just cleared up for me as well how to modify the design so that the handle and the casters can fit in there. THANKS!

I do have one quick question, though. When you had the handle and the casters, how do you ensure that they are air tight? Do you glue them in with PL (or whatever) or are they backed some how?

For that matter, I'm still not clear on how to ensure an airtight seal on the access panel.

Either way, your thread here just cleared up a lot of questions I was having before starting my build - Jack212 it is!

 

[gregoire1]

That looks fantastic and very loud!