A5 cab construction. DIY or Original?

[similost]

I went and looked at a pair of A5's tonight. I have a question about the cab construction. They were made from MDF.. looks like maybe 1/2"?

I know the older A5 cabs were made from plywood. Did Altec make any from MDF? If so, about what year did they start this? Also, would a MDF cab or a plywood cab be more desirable sound wise?

These had pine fillets in all of the corners, and they were cut in triangular shape. Sitting at a 45 in the corners as fillet brace would in a weld. Hope I am making it clear?

Is there anything that would tell me if they were original cabs or DIY?

I thank you in advance for any information you can give me.

[edfallon]

Altec did make A5 cabinets in MDF. Not sure when they switched over but probably mid to late 70's. I had a pair of A5 in 3/4" MDF with 1505B horns and while the horns can sound great with a Hiraga crossover or digital eq, I never did think the MDF bass bins sounded very good. The MDF has a lower resonance frequency than plywood and is readily excited in the woofers passband. For hifi purposes, plywood is easier to brace and damp and ultimately sounds better to me. That said, rigid bracing will do wonders for MDF too.

-Ed

[mlr]

Yes they made gobs in MDF. They're 3/4" or whatever oddball dimension that MDF seems to be made in (13/16th's? 47/51th's? mmmm math... brain exploding, must stop thinking...). I think started around the late 1970's or early '80's (based only on memory, not a fact).
I think the MDF cabs are superior to the ply's for several reasons. First they are denser, and I think yield a better sound. Second is that they are less susceptible to manuever damage. I can't recall ever seeing a "perfect" plywood cabinet, even new ones upon delivery. They just are very easily scratched. They seem to have been made better too. No flat head nails to be found loosely tacking down the horn bells, and better bracing (still not enough though). I also like the paint that they used on the MDf's over the battleship grey primer look.
They may have painted some in that grey, but I can't recall ever seeing an example. As far as I have seen, the colors were a silvery grey, and I think at the very last days they used a sort of Bronze color, both are low gloss, verses the older flat grey. I've owned several early 210's as well, and the oldest pair (probably '49-'52/5-ish), an A2 with wings, was painted either a super dark grey, or black. That A2 had either a painted VOTT logo on each side, or it was something much finer than a sticker... pretty sure a multi colored paint dealio... (an effect not unlike that which a silk screened stencil might yield).. different on so many levels from the later striped stickers. Artistic comes to mind, as well as 'pride in craftsmenship'... those bad boys just said "take note... here you have met quality... let all others rise to meet the challenge". Brings to mind a quote from Merle... ""when a Ford and Chevy, would still last ten years like they should...".
anyhoo, I digress... I still have examples of both Bronzeish, and sil./grey A5's. I think the silvery grey looks better. Both are more of an automotive sort of paint... easy to keep clean, and resistent to scratches, and liquids. Can't recall ever seeing an MDF cab with altec side stickers. Probably determined that they were not cost effective (why they ever did I don't know. A5's were almost 100% placed behind theatre screens, either in cubby holes, or on platforms 8-12 feet up... who's to see the advertising?). Maybe also, from my experience, the sticker guy was not the most skilled worker at the Altec factory. It's hard to find a cab made after say 1970 with a smooth, level, and centered decal.
I also don't remember an MDF cab with a small rear panel (again just my memory). I've had them with back rails, and without, but always full panel.
I know they still used plywood for the A7's, but might have switched those to MDf too, but I've never seen a factory A7 in MDF. But all my MDf's do have the little back panels for A7 sort of crossovers, and a small format horn mounting bar planted in the horn cavity.. so maybe A7 version was planned, or perhaps executed, beats me.
I think probably all the MDF cabs will be cut for 16" frame LF's.
Same exact size as similar vintage (probably older vintages too) plywood cabs. But they weigh a good bit more.
Also all the MDf cabs I've had (or that were installed at shows I worked at) have had the grill peg inserts, regardless of grill/no grill. Never had, or seen one with horn opening 'screened' either. The opening itself is completely different than the Ply versions, as is the larger removable panel above as well.

I think you should be safe that upon examination, you should easily be able to tell a factory cab, from a homemade. If not then that MDF cab should be given the benefit of doubt. Can't imagine someone creating an example intended to decieve... just too much work to accomplish, and for what possible gain?

Just my 2 cents, which is just that.... worth about 2 cents given inflation. HA HA. Now I'm off... I'm the official taste tester for the candy my 6 kids will scare up tonight, and adult on hand to squash the fun of the other 12, or 15 scary kids that have decided to join our ghastly procession. I'll be dressed as a stressed out, father of 6.. yearning for the safety of chair, ottoman, and **** -tube. Happy Halloween you freaky old brainiacs! HA HA HA (in a dastardly manner with wringing of hands and arched back).

Regards,
Mike

[Audio_by_Goodwill]

Originally posted by mlr:
I think the MDF cabs are superior to the ply's for several reasons. First they are denser, and I think yield a better sound. Second is that they are less susceptible to manuever damage.

<font size="2" face="Verdana, Helvetica, sans-serif">This has been kicked around several times before. MDF may be more dense, but it is a lot less rigid than plywood.

Less susceptible to damage? That is the exact opposite of reality. I don't have any first hand knowledge of touring rigs, but I doubt you'll find any made of MDF. MDF will be heavy, and not durable enough.

[similost]

Some good information, and I really appreciate it.. good chance it wasn't 1/2", but that odd size... I knew it wasn't 3/4" though.. but close..

I am not trying to start a debate between everyone about what is better and more desired, but I did get an idea of the reasons some like one type of wood, and others like another. Please don't turn this into anything other than a personal opinion instead of a slugging match.

I think my best bet is to just follow my heart, and figure out what these speakers are worth to me, and the rarity of how ofeten they turn up in my area as configured... I wished I could have given them a listen, but it wasn't possible. I do think though, in the configuration they are in and being a local pickup, there is a little more value to them to me, than they would be to someone that would pay freight..

[Old Guy]

Hey as far as slugging matches, everybody usually learns something.

I won't use MDF. It has formaldehyde in it. I don't even want it in my house. There is a more expensive similar prduct that doesn't.

Value to yourself is the best wy. I have bought stuff as investments, but I still try to buy stuff I like in case I do get stuck with it.

[Old Guy]

Originally posted by similost:
I went and looked at a pair of A5's tonight. I have a question about the cab construction. They were made from MDF.. looks like maybe 1/2"?

Did Altec make any from MDF? If so, about what year did they start this? Also, would a MDF cab or a plywood cab be more desirable sound wise?

These had pine fillets in all of the corners, and they were cut in triangular shape. Sitting at a 45 in the corners as fillet brace would in a weld.

<font size="2" face="Verdana, Helvetica, sans-serif">1/2" is DIY for sure.

Altec made MDF cabs in the 80's and 90's. 70's were still plywood.

Only other thing to do is get the prints and look for bracing inside.

The "pine fillets" you mention don't sound Altec to me.

Bear in mind, much new lumber is undersize, but not by 1/4".

From what you've guven, my vote is DIY.

It doesn't matter that much, I would prefer cabs I built to factory.

Silly people who pay 600 to $1000 for empty cabs feel differently. But a lot of them are probably getting fakes.

In the 1950's and early 60's Altec prints included the part numbers for emblems and decals to make it easy to buy them and put them on your home made boxes. Altec stopped that in the '60's.

[bowtie427ss]

Mr Dickinson needed the internet.

Here's a link to 1970's Altec plan for 828 cabinet.

http://www.lansingheritage.org/images/altec/plans/1970's-lf-plans/enclosures11.jpg

Careful review of this drawing will reveal the thickness of the cabinet material at 5/8, and not 3/4. Indeed the only part of that box using 3/4 inch material is the full section woofer mounting baffle, the dimension is referenced at least twice on that drawing.

Interesting that it shows the one piece back, 2x4 braces(dickinson says 2x2), and full section baffle that Dickinson mentions in his article, but 3/4 inch stock hasn't made the scene yet.

It's sad that all these plans were published as basic working drawings rather than bonified blue prints, or facsimiles thereof which would have included a key, material and finish specs and tolerances, and the author's name.

Just my .02 y'all understand..................

[gamalot]

I've always liked the sound from cabinets made with MDF.

My rule of thumb was if they are going to be in one place most of the time then MDF is fine.
If they are going on the road then Plywood is the only way to go.

Who ever said the MDF holds up better is completely misinformed!

Gary

[Old Guy]

The 70's were an odd time at Altec. Sometimes cabs came in 5/8, sometimes 3/4". I was there and bought a lot of them.

In the late 70's they dropped the braces behind the horn curve completely- a bad move.

2 x 4 bracing, as Bowtie mentions, is correct, not 2 x 2. It was there to protect the flimsy 771 biamp which usually just blew up. Horrible little thing.


As far as formaldehyde, theere is a product just like MDF witout it. And there is much less of it in plywood.

Also, plywood tends to make sawdust whereas MDF makes a fine dust that goes right thru breathing masks.