Pics Altec VOTT A7 using CAD and CNC

**atilsley** · March 4th, 2014, 10:47 PM

Whilst I'm developing a smaller Altec bass horn for my own system, I'm using part of that experience to do a CAD/CNC Altec VOTT A7 cabinet.

Attached are the initial drawing from my engineer CAD mate.

This will be built in Euro Birch Ply, 19mm.

A significant change over the original is the central baffle which is rebated into the sides, top and bottom of the cabinet.

The horn sections will be bent by CNC'ing the multiple grooves into the back of the ply. This creates an easy bend. CNC'd brace supports are used as the template for the 31 inch radius curve.

The back 2/3 of the cabinet will be fixed, while the top 1/3 will be removable.

As a decorative feature, we'll create an oval shape port at the front, which will sit in a removable panel, per the original design. This way we can add different size ports to suit the tuning of the cabinet. The initial sizing is smaller than the original A7?and the current pic shows the oval cut out too large. We?ll target a size of approx 30cm x 7cm (12 inches x 2.75 inches).

And yes, I've purposely gone to town on the cut-outs for the inner baffle/support, including CNC'ing the letters VOTT into the panel.

Altec 515's will be used in this version.

I suspect the cabinet will be heavy, with as little cabinet resonance as possible.

What extra things should I be looking for in the design...?

Photobucket links here also -

Front
Top
Back

Kind regards.
Andrew

**endeeinn** · March 5th, 2014, 12:12 AM

You attachment says 4 views but only 1 came through

**atilsley** · March 5th, 2014, 12:56 AM

Originally Posted by endeeinn

You attachment says 4 views but only 1 came through

Only the one attachment (PDF)...but the other three are URL links to Photobucket. Please click on the words, Front, Top, Back per above.

Kindly

**endeeinn** · March 5th, 2014, 10:18 AM

I was only looking at the pdf and completely missed the front, back and top. Great cad drawing. Thanks.

**VolvoHeretic** · March 5th, 2014, 01:38 PM

How do you calculate the bottom cut for the curved side horn flare so that after cutting a flat piece of plywood and bending it, it has a straight bottom face where it meets the angled bottom flare of the horn? I assume the cut is some kind of curve, maybe some kind of ellipse segment?

Edit; maybe it's just a straight line and I am trying to think too hard.

**Altec Best** · September 26th, 2015, 10:42 PM

GMason he hasn't been on the board since May.. You may want to send him an email.

GM · September 28th, 2015, 12:30 AM

These? Altec VOTT A7 using CAD and CNC - diyAudio

GM

**GMason** · September 30th, 2015, 08:40 AM

Yes, exactly. Thanks a lot!

**Altec Best** · June 30th, 2014, 04:09 PM

Looking Very Nice ! You should be proud, as you have done a beautiful job on those Vott's...

**atilsley** · July 1st, 2014, 02:00 AM

Thanks...it's my first pair. I've been working on tweaking the CAD plans if I build another pair. Some things worked out very well...other things needed some adjustment...eg, you can't put in the panels once the side walls have been glued...! Dumb. Needed to remove the protruding 'lugs' on one end to insert the relevant panels. I'd also dispense with the horizontal shelf...simply not needed. I'd remove some of the fancy bracing on the main large baffle piece....more intricate means more turbulance.

The things that worked well are:

bracing for the large back panel
pre-drilled screw holes everywhere
horn section supports...nice and thick 25mm MDF
the 3-way adjustable front vent with oval, fixed and open positions (I've only tested oval and open so far)
the CNC'd grooved horn flare pieces for easy bending
the lovely Euro Birch ply in 18mm (it would be quite expensive to veneer this with Walnut etc....the ply sheets would triple in price...I used 5 panels/pair)

I'd also CNC the driver mount holes for the relevant driver. Last night, I created a cardboard template taken off the 515G. This driver has 8 holes...but I only used 6 holes for mounting due to the exposed location of two screws holes at the horn throat.

I'd probably make the back panel 2/3 fixed (bottom), and a 1/3 removable panel at the top. The current panel has about 30 screws each...and is nicely connected with the vertical and horizontal braching (which also connects to the baffle board).

It's certainly been an enjoyable build though....

I have a new smaller bass horn to start in a week or two...which has similar top section to VOTT A7...but different cab. I'll start a separate thread on that.

Andrew