1 X 12 Speaker cabs: Open Back and Closed Back

Karel-Mars

Hi all

I am building two speaker cabs currently. One open back and one closed back. I do not have the speakers with me yet, but the rest is ready for assembly. I would like to share the project; maybe someone who is planning such a project, can gain some ideas. Maybe they can share it with us; I could learn something too ?

The brief was to build two cabinets with dimensions 600X500X300mm from 19mm pine and using 12mm pine ply for the baffle and the rear panels:

This is what I got back from the wood supplier:

and this

and some essential extra's:

I stood the panels up for a prelim:

and

Ok: Let's get busy

I cut some cleats to the right length:

Put some glue on...

Screw it down...

Do both sides....

Do another one the same way and then mount the bottom panel...

Check the join :-\

Next is the top panel...

I did the second cab exactly the same and I call it a day...

to be continued ?

RobK

What a coincidence. I've just thought of bulding my own cab, so I'll be watching. Thanks for sharing.

PeteM

@Karel - I'm interested to hear why you're using pine. I'm led to believe that one should stay away from timber because of its resonant properties that could induce unwanted frequencies in a speaker enclosure. For this reason, marine ply and MDF have become more popular. Some guys also use polyurithane glue. which fills in the holes better than a cold glue at the join - this ensures that no air can escape - a specific requirement for a sealed enclosure.

aja

You could also fiberglass the inside to seal it perfectly, something the car sound guys often do

Gearhead

+1 PeteM on both the glue and the plywood/timber. I would guess Karel is going for the aesthetics here.

I tend to rout all the sides to be glued with a straight router guide so I can use white glue; this only requires an hour or two of clamping before you can do the next assembly step. The time it takes to rout is easily less than the drying time of polyurethane glues; they foam first, adhere and then shrink before getting their strength.

aja wrote You could also fiberglass the inside to seal it perfectly, something the car sound guys often do

... and the car guys invariably tend to forget that their flat panels are so flexible that sealing the case still does not do the work. A flabbing panel acoustically is the same thing as a leaking one.

aja

Gearhead wrote ... and the car guys invariably tend to forget that their flat panels are so flexible that sealing the case still does not do the work. A flabbing panel acoustically is the same thing as a leaking one.

Nah you just put carpet on the outside and it works nice after that!!! ? ?

Karel-Mars

PeteM wrote @Karel - I'm interested to hear why you're using pine.

Pine is actually quite commonly used in musical instrument cabinets. For the exact reason of it's resonant properties ?arty: Throw out the rule book for hifi speakers. The baffle also does not need to be sealed air tight. The resonances enhances the tone ??? Closed speaker cabs are a bit different though. They are more air tight, but still resonant. I am actually using 12mm thick baffle boards to accentuate resonance.

A Blackface Twin has a pine cabinet and a chipboard baffle that is mounted free standing in a groove along the bottom of the cabinet and two screws at the top corners. The more the baffle flops around, the better the sound. You do not want any audible vibrations of loose parts rattling around though :-[

PeteM

@Karel - interesting thanks.
It sounds to me like the chipboard baffle might have been an afterthought in an attempt to cancel out standing waves. But what do I know? - all I know about is studio monitor speakers.
I can sort of understand now that using resonant timber on a guitar amp will add colouration offering a property specific to that enclosure making it an instrument in it's own rite.
What about PA speakers - I would have thought that they would need to be flat like studio monitor speakers?

Karel-Mars

We are having some weird weather in the Cape. Some days very hot and windy....

So here is some updates on the speakers:

I glued the boxes together

Routed the corners

Painted contact adhesive

Cut a strip of vinyl and gave it a cote of contact adhesive

Covered the cabinet

Time for upholstery skills with a sharp knife

Here I check how the corner is going to look

more to follow...

shadow1

looking like its going to be nice and SOLID ? awsome

knapie

Great work Karel!

I was always scared of attempting a cab due to the lack of tools, but it looks like you can get away with the bare basics.

Where do you source the vinyl, grille cloth and corner protectors from or is that a trade secret...

Thanks for sharing, will attempt to give my little Laney LC15 a 12" for a bit more bottom end.

Karel-Mars

I have a few more pics to share to show how the project came out:

Open Back hot of the press

And the Closed Back

Here's some detail on how I fitted the castors

And Voila! Rock and Roll. Check the Speakers in action at the Blues Summit!