Altec A7 VOTT speakers - source for cabinet wood?

Hi everyone,

A group of us here in Sweden are interested in creating some clones/replicas of the classic Altec A7 VOTT speakers.

These speakers apparently had cabinets that used plywood composed of the following layers: Birch, Obechi, Pine, Obechi, Birch. We would like to use plywood of identical composition for our speakers.

Some questions:

1) Can anyone direct me to a source for purchasing this wood in the US (we will have it shipped over to Sweden)?
2) Would there be customs issues with shipping such wood, since it will probably not be treated for infestations etc?
2) Can anyone provide measurements for the layers?

Thanks!

Spiros

I think it is 18 mm Baltic Birch ply...

You might want to try these Folk's..

Europlywood | PLYWOOD, FILM FACED PLYWOOD, RUSSIAN BIRCH PLYWOOD, BALTIC BIRCH PLYWOOD, MDF, OSB, BOXES

From my 46 years use of Altec gear, and involvement with Altec, I have no clue where you got the info. AFAIK it is 100% wrong.
Altec used different plywood at different times, but all I have ever seen is just plain old domestic fir plywood. Some cabs were 5/8", others 3/4".

Altec made factory cabs and used contractors at a couple points I know of. IMHO you are chasing a fantasy.

Thread on A7 restoration here:

http://www.hostboard.com/forums/f700...e/index14.html

Hi,

Thanks to both of you for your responses.

One of my friends in Stockholm has an old, smashed VOTT enclosure. He sent me a wood sample where you can actually see different types of wood in the layers (I can upload a pic later). This was from one big theater in Stockholm. I believe it is 19mm thick. But if there really was a lot of variation, then we won't worry so much about replicating it beyond the birch layer. We thought perhaps that Altec choose this wood for its acoustic characteristics... but if we are wrong, then it's easier for us :)

Thanks,

Spiros

Quote:

---

Originally Posted by Old Guy

From my 46 years use of Altec gear, and involvement with Altec, I have no clue where you got the info. AFAIK it is 100% wrong.
Altec used different plywood at different times, but all I have ever seen is just plain old domestic fir plywood. Some cabs were 5/8", others 3/4".

Altec made factory cabs and used contractors at a couple points I know of. IMHO you are chasing a fantasy.

---

Quote:

---

Originally Posted by spiros54

Hi,

Thanks to both of you for your responses.

One of my friends in Stockholm has an old, smashed VOTT enclosure. He sent me a wood sample where you can actually see different types of wood in the layers (I can upload a pic later). This was from one big theater in Stockholm. I believe it is 19mm thick. But if there really was a lot of variation, then we won't worry so much about replicating it beyond the birch layer. We thought perhaps that Altec choose this wood for its acoustic characteristics... but if we are wrong, then it's easier for us :)

Thanks,

Spiros

---

No guarantee that is a factory cabinet. In fact likely not. Many local contractors built their own. Can you imagine the cost of shipping a plywood box from California to Sweden? The factory would cheerfully sell you VOTT decals in the old days. We built dozens and badged them as VOTTs.

A plywood REAL Altec box would certainly be .75 or .625 inch, not 19mm. Almost certain that was locally built.

See added line to my first post.

thanks OG, I will study your post!
regards
Spiros

Quote:

---

Originally Posted by spiros54

Hi,

Thanks to both of you for your responses.

One of my friends in Stockholm has an old, smashed VOTT enclosure. He sent me a wood sample where you can actually see different types of wood in the layers (I can upload a pic later). This was from one big theater in Stockholm. I believe it is 19mm thick. But if there really was a lot of variation, then we won't worry so much about replicating it beyond the birch layer. We thought perhaps that Altec choose this wood for its acoustic characteristics... but if we are wrong, then it's easier for us :)

Thanks,

Spiros

---

In the early 80's, JBL had a line of boxes called the Cabaret series .

The series started out being made with Baltic Birch ply & then ( without fanfare ) JBL switched to a different ( cheaper ?? ) type of plywood that they claimed ( when queried ) had many superior qualities to BB ( & by coincidence wasn't readily available to the rest of us, via normal retail channels ) .

They sent out ( educational ) circulars to the distributors ( who then passed this info / propaganda onto the dealers for mass consumption ) .
These circulars included some test results with formulas , etc. / so it wasn't all just junk science .

The ( newly substituted ) plywood was a special 9 ply, Maple/Poplar mix ( with 5 Maple plies & 4 Yellow Poplar ) .

The alternation of a denser hardwood with a softer wood had some superior ( claimed ) properties ( ie; less shattering upon dropping from 12" , a slightly lighter weight, a bit better damping/sound transmission & a harder surface / though with slightly more over-all flex ) .

All in all, JBL was really proud of their innovation, though ( I believe ) the perception of industry standards had them switch back to baltic birch for their follow-up ARRAY series of boxes .

A google search for Maple/Poplar plywood, reveals that Ludwig has used this plywood mix, for decades .

:)

Interesting. the Israelis were looking for a cheap way to armor vehicles. They did sheet metal/styrofoam ad infinitum layers...well really only a few layers. Anyway- metal spreads the force over a large area,foam absorbs energy, repeat as necessary. The result was made from two cheap available items and would stop sizable fragments or bullets.

Gotta wonder if the differing wood layers performs likewise.

I am not a techno geek, I just play one on TV.

Yes I agree, it's all pretty interesting ( the whole constrained layer damping thing ) / just not quite interesting enough to have me search it out & use it instead of Baltic Birch .

:)

Quote:

---

Originally Posted by Earl K

Yes I agree, it's all pretty interesting ( the whole constrained layer damping thing ) / just not quite interesting enough to have me search it out & use it instead of Baltic Birch .

:)

---

Yeah that sounds too much like work. I fish these days.:cool:

Quote:

---

Originally Posted by Old Guy

Interesting. the Israelis were looking for a cheap way to armor vehicles. They did sheet metal/styrofoam ad infinitum layers...well really only a few layers. Anyway- metal spreads the force over a large area,foam absorbs energy, repeat as necessary. The result was made from two cheap available items and would stop sizable fragments or bullets.

Gotta wonder if the differing wood layers performs likewise.

I am not a techno geek, I just play one on TV.

---

i think i'll stick to ballistic panels. :D

Quote:

---

Originally Posted by Phil-G

i think i'll stick to ballistic panels. :D

---

What if you are stuck somewhere and gotta make it out of what is available? People do what they gotta...

Quote:

---

Originally Posted by Old Guy

Almost certain that was locally built.

---

+1. Altec continued the business plan developed by W.E., so need to find out if there's a plywood local to Stockholm that was available back when the cinema opened. Here in Hotlanta, I can't recall ever seeing a VOTT cab shipped to the distributor, though of course I wasn't over there there very often. CMC Stereo OTOH ordered pallet VOTTs [unassembled]. These cabs were so cheap that they were pretty much more trouble than they were worth to tweak them for HIFI, though fine for MI apps.

GM

hi guys, I will use 25mm MDF, any thought's about?
Here is a friend's VOTT

MDF may well be superior for cabinets that are not hauled around. The are low formaldehyde MDF's available...worth it for health reasons of you can find.

Baltic Birch is the only thing I will ever use anymore.. :cool2:

MDF or Baltic Birch? Which is the best if we agree the loudspeakers don't move at all.
And why please!

if you are going for a furniture grade end product then use furniture grade wood.

Only sonically benefits account in my case!

Then it's Baltic Birch IMHO !

......and 13 ply at that.

GM

What I try to focus here is the effect of the vibration and not the kind of coloration av the tree sort. For me it is very important to avoid the coloration's(vibrations). Is it any computer analyze in the behavior of the VOTT?

Sand-filled, double-skin, panels may be worth investigation.

Quote:

---

Originally Posted by spiros54

What I try to focus here is the effect of the vibration and not the kind of coloration av the tree sort. For me it is very important to avoid the coloration's(vibrations). Is it any computer analyze in the behavior of the VOTT?

---

Not aware of any computer analysis, but once the cab's Fs is pushed either below or above its intended pass-band enough, there's nothing to excite it, ergo is acoustically 'dead' WRT any vibrations except from driver movement and an 825/828 will be plenty heavy enough with braced 19 mm/13 ply BB plywood to be acoustically inert and 'ring' well above 500 Hz. If you prefer to push its Fs below ~25 Hz, then mass load it with enough sand filled cavities or better yet, construct them in place out of Portland cement and/or marble, slate or similar massive construction.

GM