Altec Cabinets…episode 2, the Big Easy 620

[Phillip Jeffries]

Coming along nicely! And don’t feel bad, I mitered my 604 cabinet panels and still veneered over it.
How about staining the existing plywood (unless you have a nicer veneer in mind)? Maybe even inviting the Mrs. input on the color (helps get larger cabinets into the home).

yeah, I guess you get more glue area than the butt joint, which is nice. There’s a great veneer I really like, so I’m excited about that. Problem is, it’s 17 3/4” wide which means I have to trim off my excess 1/2”. I thought, no problem with my diy router table, but now my router died again! Seems permanent this time…and I still have 3 panels to trim. Going to need to find a decent router, now. Don’t want to try the circular saw, having better luck with the router table/fence setup.

 

[Phillip Jeffries]

I’ve got some sound files for you guys of the two different cabinet volumes. I recorded them on my little Zoom iphone mic adapter pointed straight at the woofer about a yard away. The 32b horn is also going, but it’s above and behind the speaker, so it’s mostly the woofer running full range. Unfortunately, I had to compress the files to get them off my phone. I think the uncompressed wav files capture the difference pretty well, but I haven’t compared to m4a’s too closely.

Moment’s Notice 9.2 cubic feet
Moment’s Notice 6.7 cubic feet
Taxman 9.2 cubic feet
Taxman 6.7 cubic feet

WARNING- there’s some loud digital noise about a minute into one of the taxman’s. Don’t listen loud on delicate gear.

What’s interesting is that it’s not just a difference in bass. The bigger cabinet is a touch more dynamic and flatter.

I did a couple quick tests with pink noise

6.7 cubic feet



9.2 cubic feet



On taxman, the smaller cab has more abrasive mids on the guitar than the larger cabinet. May be standing waves coming into play, since there is less overlap with the larger dimensions.

Also, the big cabinet sounded better for mono, more depth and width to the sound.

 

[billfort]

What is the baffle size on the smaller cabinet?

 

[Phillip Jeffries]

What is the baffle size on the smaller cabinet?

25” x 41” on both.

 

[Phillip Jeffries]

Got another router going and was able to trim off 1/2” fairly adequately. Got a bit wavy on one or two panels, but I’ll put those ends on the rear.

Planning out the baffles…



The centers of the woofer and horn are going to be 10” apart. Also, cut the vents in the bottom and got some gluing started…



Took some advice on clamping from this thread…thank you!

Bought a thin plywood panel at Home Depot. Going to try to make a template for the horn. Planning on cutting it with the dremel then using the template with a flush router bit. Hopefully do the template and glue the next box tomorrow.

 

[MrEd]

I want see how ypu make your pattern for the horn, do the cut out.
I have a pair of the same and plan on a build soon.

 

[Phillip Jeffries]

Template started…



And…it’s not even 9 am?!?!

 

[Audionut]

Template started…

View attachment 63668

And…it’s not even 9 am?!?!

View attachment 63669

Coming along nicely! At this rate you will be listening by supper!

 

[Phillip Jeffries]

The template is promising. I bought the dremel cutting kit which has a little router base and some bits. That thing really cut through the 1/4” ply easily. I had to do a bit of damage control in some areas with some wood putty, but I think it worked out. Need to order a flush bit, I thought I bought one at harbor freight, but it was a trim bit, which I already had.

I’ve got one extra baffle to practice on. Want to cut the horn before the woofer, so that the board stays as flat as possible.

 

[Phillip Jeffries]

Ready to finally get some work done on this project…

Here is the template….



Kind of giving away that I’m going for a polished aluminum look on the visible portion of the horn. Got it sanded to 220 right now…more on that later…I’ll just say…the paint matters…ringing a lot more now…

But, what’s interesting is that this template fits one horn one way! The other horn is slightly bigger, so even after cutting to the template, I’m anticipating a bit of customization. Seems like there’s a bit of variation in the casting of these horns.

Also, made a trip to my favorite lumberyard, Riverside, for material for the inner braces.



That’s mostly beech…some of it is kind of wavy, filled in with a couple pieces of poplar.

I was reading a pdf on cabinets from the BBC that someone posted here and they found beech to be superior to pine. So, I wanted to get some 1x1 that was not pine. Poplar is actually not that hard, but I was happy to find the beech. $20 for the lot.

My plan was to do the reinforcement of corners and the front panel Shindo style, with a bunch of little triangular pieces. However, I have concerns with the flatness of the baffle boards. I need the front to fit in as flush as possible to get the fronts flat for the veneer. There’s not going to be any edge banding…would have been smarter to have the baffle go straight to the edge, but that wasn’t the initial plan.

After I do the cutouts in the baffles, I’m going to test clamp them to see if I can glue them in flush. If not, I’m going to build a frame at the front and clamp the baffle so the frame holds it flush. The usual way, essentially.

 

[Audionut]

Coming along nicely! I’ve done the polished aluminum look on a project (BeePre2) and have two more to go (amp and TT), I like it very much (but tons of work!!).
Maybe some dynamat-like material to reduce ringing?

 

[Phillip Jeffries]

Coming along nicely! I’ve done the polished aluminum look on a project (BeePre2) and have two more to go (amp and TT), I like it very much (but tons of work!!).
Maybe some dynamat-like material to reduce ringing?

Yes, it sure seems to require a bit of elbow grease. I wasn’t going to post about in the event I throw in the towel and paint them black!! Plus, there’s a lot of imperfections in the casting…I don’t think they’re ever going to be like mirrors, but hopefully I get something more interesting than black. I’m not a fan of the bow tie’s aesthetics…a bit too Star Wars tie fighter when done vott style, and a bit strange, like a big crack or crater, when mounted in a baffle, at least when it’s black on black, which is all I’ve seen. I’m thinking the silver horn against the reddish veneer I picked out will look nice…maybe polished aluminum feet, rather than the Shindo sticks.

I bought a can of DEI Boom Mat vibration killing paint I’m going to use on the back. I think it’s silver colored. Then I will use clear lacquer on the front once I’ve got it all sanded and polished…which may be a couple weeks of sanding!!! Hopefully, that combo will get me back to normal.

The veneer looks to be a bigger project, since it will need to be flattened piece by piece. It’s looking to be a slow process in that front, so I will have time to sand.

 

[Phillip Jeffries]

Ugh!! I am telling you…these horns are snowflakes! The template only works one way on one horn!! I accidentally did my practice baffle backwards, and there is no way to reverse it without big gaps.

I think I am going to have to go to Home Depot and get another piece to make a template for the other horn.

The template worked well. There would have to be way too much slop around the horn for it to work on both horns.

 

[Tsingtao_1903]

ringing a lot more now

If I may ask, what is the average wall thickness of the horn? My experience, the thinner the wall, the higher pitch is the ringing (more audible).

 

[Phillip Jeffries]

If I may ask, what is the average wall thickness of the horn? My experience, the thinner the wall, the higher pitch is the ringing (more audible).

I don’t have a set of calipers that can fit in there, but it’s pretty thick. Sticking it on the baffle muffles it pretty well, but I’m going to try the anti vibration paint, too.

 

[Phillip Jeffries]

Last weekend, I got the second template done and managed to do the horn cutouts. They came out pretty well. I’m satisfied, not perfect, but no real outrageous gaps. I may do a bit of touch up with some putty before the veneer, since the opportunity to do a touch more damage control does present itself.

This weekend, I did the woofer cutouts and made the decision to just do the frame to set the baffle in. I think having that frame will add some rigidity, since the horn and woofer are going to be heavy. Glued that front frame in both speakers…managed to get enough straight beech for all of it. Unfortunately, I do have to do a bit more sanding to get everything as flush as I’d like. There’s enough wave in the baffles, that I don’t think it would have worked without the frame to clamp against.

Here’s a progress shot…the baffles are not glued in yet…



The internal frame…



Also, here is a shot of the veneer…



I think that strong grain is going to give it a bit of the Shindo vibe. It’s wide enough for the sides and so I only have to do two pieces in the front. Never tried that before. But, I got it from veneersupplies.com and bought their flattening spray, a roller, and their glue. Not going to try to use hide glue again.

In fact, I’m really liking the titebond…the extra working time makes a ton of difference.

 

[Phillip Jeffries]

I was fortunate enough to acquire a real pair of original 612 cabinets, so I’m going to need to rehome these…don’t have the room for two enormous pairs of speakers.

Here’s what they look like as is…can be sanded, stained, oiled. In their raw birch state. The drivers are for display, only, because I’m planning on still using them vott style with my other cabs.

Hoping someone is interested…got a thread in the emporium…

 

[Phillip Jeffries]

Haven’t gotten much interest in these, so I did a bit more work…going to see what these sound like…hold off on the veneer for now.

So, I worked up a crossover.



That’s no cabinet damping, just a curtain of cotton batting. Altec style series crossover 1.25khz, Bessel, with the horn coming in a bit over 1.4khz, into a T pad attenuator. The Emilar needs the T, not the L.

Going to try to get the other side going tomorrow, then eventually compare against the duplexes.

Edit: took a better measurement…

 

[MrEd]

I am really interested in this project because I have pair of these and have a speaker build planned for Lucy's livingroom system.

 

[Mike414]

Curios why you say the Emilar needs the T pad attenuator. I've never tried the T pad version. Can you share the crossover you are using?

Thanks