Baltic Birch Question ???

[just me now]

so, is this that perfect world, where no compromises are necessary?

:big grin:





good quality stock to start with & additional bracing are important in my mind...

[Mustang Marvin]

Usually compromises are always necessary. That doesn't mean we can't strive for something a little better. Also, the perfect world is a matter of opinion. That's what I look for here. Some of these guys have a vast amount of experience. I have found that experience is better than opinions.

Relating to this topic, someone may say they have heard material A is superior to most other materials. Then someone else may chime in that in their experience where they have USED material A, material B has proven a better choice. At this point someone else may chime in that in their experience material C is better. This is not only enlightening, it is usually very entertaining.

In the end, we all learn something and hopefully make the BEST choice for our project. Does this make sense, or am I making too much of this? (as usual)

[oface1]

Thanks for the link OG, is is a good price of 4x8 plywood, and it is available here.



-chris

[Altec Best]

Hi Marvin, But that is why I posted the question as I never built my own cabs so I have NO experiance with these materials.I was hoping to tap that vast experiance of others who have used this stuff before and can help guide me in the right direction.I think what is just as important as what to use is what NOT to use as I have been told not to use MDF it doesn't sound as good as BB plywood.And really appreciate the help Thank You Regards ~ JOHN

[Mustang Marvin]

Exactly John,
Keep us informed. I'm not ready to start my project yet, but I'm very interested in materials and construction tips.

[Altec Best]

Update on the BB plywood I went to the lumberyard today instead of calling much better service that way I was there when he called their distributor 1" thick Baltic Birch Ply only comes in 4x8 sheets which was right the first time at $6.05 a sq ft so it is $193.60 a sheet,now the 3/4" BB ply only comes in 5x5 sheets and are much cheaper at $ 37.25 a sheet or $1.49 sq ft. at that price I'll be grabbing that and stocking for future projects as well and think I may grab 1 sheet of the 1" I like the thought of making the baffles out of the thicker grade.

[NKF]

I build cabinets and furniture for a living. Baltic birch is the material I always use for any box project, always for speaker boxes. To give you an idea of its toughness, before Katrina, I purchased a pair of 80HZ Edgar horns made of baltic Birch. My home is in Waveland, MS, the eye passed over our little town. My home had 5 feet of water in it. The Edgar horns floated around in salt water for a few hours and then baked in the house in 100 degree heat for 3 months. I took the horns to the car wash, bleached them and hosed them down. They are still perfect today.

32.00 is very cheap for 5 by 5. I pay $50.00 here.

Nick

[oface1]

Hey Altec Best,

Yeah, stay away from mdf, it is the dust which is a pita... plus all the glue & formaldehyde isn't too good, especially when all this stuff is turned into nasty little dust particles that you breath in.....

I used it a long time ago and regret ever using the stuff....I will always buy the ply instead..



-chris

[Panomaniac]

Well here is my little A7/A5 story.

Back in about '87 I "upgraded" a pair of these for my friend and mentor, Jean Hiraga. I wanted a great P.A. for the jazz acts I was touring with. Mr. Hiraga said if I would help him rebuild a pair, he wold let me use them for a while. I did, and he did.

It was along time ago, but this is what I remember:
We took the standard cabinet and stiffened the walls substantially. We used Nantex, a very dense, very hard marine plywood. So dense and strong it was like cutting and drilling cast iron, not wood. Never seen a harder wood. Do not remember if it was 18mm or 25mm. But it was heavy.

Some some of the inside walls were doubled with the new ply, some cross braces added, non-hardening tar was put on the back of the horn flair, 100% wool felt was used for damping. Not sure, but there may have been a brace from the rear of the woofer to the back wall. It was no longer the flimsy, resonant box it had been. A big change.

The rebuilt box was topped with a 1505 horn driven by a 50's vintage Westrex driver. Cabinet got a 416, IIRC. Later replaced with a hybrid Westex/EV. Port area was reduced for proper tuning.

The results? Startling! It sounded soooo good. Clean as a whistle. It became my favorite speaker. The rebuilt cab had no box sound at all. It is one of the very few I've ever heard that sounds like real musical instruments. Not like a speaker at all, no hint of speaker flavor.

I wish I could remember more of the rebuild details, but it was too long ago.
The speakers live on, tho. See my avatar. They are still the reference system for the French "Revue du Son" magazine, all these years later. All other speakers are judged in comparison to them, as well as being used as a test bed for electronics.

So the box can sound wonderful, if done right. More info (in French, bien sur) is here:
MELAUDIA :: ?coute Revue du Son - juin/juillet 2005

[Mustang Marvin]

Pano,
Thanks for the info and link. I would suggest you consider hypnosis so you can recall the exact procedure for the cabinet bracing, HA. Just kidding though I would really like to get the best sound from my A7's (flimsy 5/8 in 825's). I have done only what the original specs called for. Very little acoustic material and no bracing. I did shrink the port size as per GPA's recommendation. I am torn between remodeling my original A7's or building totally new cabinets. I hate the idea of destroying these original gems, so I am leaning toward new cabinets. Still, proper bracing appears to be necessary for really great sound reproduction.

I know Bowtie and others have A7's. What have you guys done to yours?
Thanks..

BTW, great pictures. I would love to have a poster size to hang on my wall...