First post: Questions regarding ALTEC 612 enclosure - DIY

**Altec Best** · November 14th, 2012, 03:40 PM

Originally Posted by Geekstar

I once had an early 612 or 620 (forget which, been awhile) that had diagonally placed rigid fiberglass like the 618 photo below.

This stuff looks like Owens Corning 703 with a coat of varnish or lacquer to make it stiffer.

Check this 620 out

http://soundup.ru/images/stories/arc...ondition-7.jpg

Joe that looks like a 614 to me,which usually houses a 12" speaker.. A lot smaller than a 620 or even a 612. The driver in this photo is a 700 series full range driver 755 me thinks. A 612 or a 620 houses a 15" speaker and is twice the size of those cabs in my humble opinion..

http://altecpro.com/pdfs/vintage/Spe...net%20Plan.pdf

http://www.lansingheritage.org/image...pro/page14.jpg

**Tralalalala** · November 14th, 2012, 04:28 PM

Hi !

Music : difficult to say : varies a lot ... almost all genres ... it just have to trigger something.
For example I don?t like Bob Dylan very much , maybe I just have not figured him out yet... anyway: but I do love Nashville Skyline.

I still want to make the 612C cabinet with the front that GM posted.
Think I will go for 18 mm birch plywood.

Understand now that the damping of the cabinets is a matter of taste.

Will keep you up to date on how this goes.

**Altec Best** · November 14th, 2012, 05:34 PM

That is the original 612 that GM posted..Just follow the plans for the 612C with the different front baffle.The original doesn't have the bevel I believe.

**Geekstar** · November 14th, 2012, 10:13 PM

Trlalalala... Anyone no what it is???

Professor Longhair? Ike and Tina?

Being from Philly. I like The Delfonics "Lalalala...means I love youuuuu..." Major Harris RIP this past weekend.

Joe that looks like a 614 to me,which usually houses a 12" speaker.. A lot smaller than a 620 or even a 612. The driver in this photo is a 700 series full range driver 755 me thinks. A 612 or a 620 houses a 15" speaker and is twice the size of those cabs in my humble opinion..

The pic of the cab with the slanted pink insulation is my personal 618 (for 8"). I put it up to illustrate old school minimal damping technique.

The point I was making is that I had a bigger Altec cab years ago with the same damping tactic. I think it was a 612.

I am wondering if this is the sideways "thing" in the pictured old 612 plans? Doesn't seem to be a wood brace because it cuts the cab in half completely.

**Alien_Shore** · November 15th, 2012, 08:43 AM

Altec changed their nomenclature for these cabinets over the years.
The utility cabinets used to follow a naming convention with a suffix letter A, B, C, to denote the size of the speaker mounting hole. The size of the old 612 cabinet matches that listed on the drawing posted by GM, but back in the 60's, that would have been called the 612A for a 15" speaker. But even then, the 612 was the larger of the utility cabinets (6 CF), followed by the 614 (3 CF), and the 618 (2.3 CF).

Confusing, but that is the joy of vintage!

**Altec Best** · November 15th, 2012, 01:16 PM

Originally Posted by Geekstar

The pic of the cab with the slanted pink insulation is my personal 618 (for 8"). I put it up to illustrate old school minimal damping technique.

The point I was making is that I had a bigger Altec cab years ago with the same damping tactic. I think it was a 612.

I am wondering if this is the sideways "thing" in the pictured old 612 plans? Doesn't seem to be a wood brace because it cuts the cab in half completely.

Understood, thought you posting it as a 612.. The thing in the old plans is a slanted brace on edge that is mounted to the side panel I'm pretty sure.They don't usually post dimensions of the insulation AFAIK. Just thickness and location bottom,one side,back panel,etc..

Here is the 612 plans.

http://altecpro.com/pdfs/vintage/Spe...net%20Plan.pdf

And the 612C plans.

http://www.lansingheritage.org/image...closures05.jpg

IMHO both these plans are of the 612C.If you look at the front view you can see another slanted brace through the speaker opening mounted on the back panel.. In my original 612C cabinets there are 3 of these braces.One on each side and one on the back panel.

**Altec Best** · November 15th, 2012, 01:38 PM

Originally Posted by Tralalalala

Thank you all so much for your help !

ALTEC BEST: Just found the dictionary definition on bevel: in simpler english:
you mean the angled cut on the edge of the hole for the speaker element- correct ?

Your Welcome ! Yes. Altec used that bevel on all of their 612C cabs.

**Geekstar** · November 15th, 2012, 02:31 PM

AB:

OK, I never saw the side to side cross braces....does your cab also have a front to back diagonal brace as depicted in the middle drawing?

This 612 I once had was really old and had no diagonal bracing, only a piece of sideways rigid mineral board, which may or may not have been factory, and a little bit of cotton padding on the back and maybe the sides. It think it had a gray 603B in it. This was in the 80s which was many brain cells ago, but I remember it because of the diagonal mineral board, which is the first time I saw that.

**Altec Best** · November 15th, 2012, 02:43 PM

No diagonal front to back . There is a straight brace from front to back just below the driver opening,and just above the port.Check the photos I posted and that should give you a better idea.

**Geekstar** · November 15th, 2012, 02:54 PM

No diagonal front to back .

I checked out your pic. I think there are different eras of boxes in play here. Gradually they got more solid (and heavily damped), it seems.

If there is no front to back diagonal brace, then what is the diagonal "thing" in the middle drawing in the first blueprint above?

That is what I was thinking could be a mineral board damping panel. Note how it has square edges and is not connected to the walls. Can't be a sheet of ply because it would block off half the cabinet!