HBR - Type of plywood?

[TexDrone]

What type of plywood was used to build Heresy HBR cabinets? I understand that it's Birch,  3/4" thick, and it appears to be 7 ply... but what about fillers, grade, etc etc.

 

thx 

[DrTUBE]

Well @TexDrone, the only thing that I can tell about my Heresy I HBR is that the plywood is quite brittle...

 

 

 

Even if I use a brand new router bit and I go slowly, radiusing the edges to eliminates bumps and cracks...

 

 

Cheers,

[Dave A]

It is birch veneer plywood and for some reason I thought made of Fir except for the veneer. No idea on specs though. True Baltic Birch plywood looks like this.

 

 

"Well @TexDrone, the only thing that I can tell about my Heresy I HBR is that the plywood is quite brittle..."

Nope the plywood is not brittle. Try dropping a heavy cabinet like that with MDF and you will see brittle. Remarkably little damage for a corner drop on hard surfaces.

 

[Klipschguy]

Early Klipsch speakers, from my observations, used fir plywood, the plywood in your pictures look like fir to me.  I think later they used Baltic Birch plywood for their raw cabinets and veneered lumber core (poplar) for their fine veneered cabinets.  The one to ask is forum member HDRBuilder; he has great knowledge because, depending on the year, it is quite possible he built your Heresy speakers.  What year are your Heresy speakers (or what is the "letter" in the middle of your serial number stamped into the top, back edge of your cabinet)?

[DrTUBE]

Hi @Klipschguy

 

Here are the mentions found on my Heresy I HBR pair :

 

 

 

They are also stamped "USA" : I noticed this today...

 

I'd rather agree with @Dave A : it looks like Fir or Pine plywood, looking at the edges and the way it reacts under the radiusing bit of the router...

 

Below :

Upper cabs are made from laminated-glued Beechwood : hard and abuse resistant.

Center cabs are mad from Pine plywood : quite resistant, but not not as good as Birch, indeed.

Lower cabs are made from Fir wood planks, covered with tolex : tender like buter, poor resistance, but lightweight.

 

 

Cheers,

[Klipschguy]

1983 Heresy speakers - very nice.

 

BTW, good work on the other cabinets; thank you for posting the pictures.

[DrTUBE]

Thanks @Klipschguy !

 

Question : I saw that the cabs of my Heresy I are assembled by outside nailing and internal stapled bracing in the angles. But do you know if in addition these cab panels were also factory glued ?

 

Yes, I'm tempted to build a pair of Heresy cabinets using Laminated-Glued Beechwood. This wood is consistent to machine, mechanically resistant, and offers easily a nice natural finish just by oiling it - hence my small "The Cube" - where I used kitchen worktop oil :

 

 

 

 

Cheers,

[Klipschguy]

Beautiful woodwork; it would a fantastic looking subwoofer!  If memory serves me, I seem to recall HDRbuilder saying they used white glue on the joints (more working time versus yellow glue + easy clean up).

[DrTUBE]

OK - I see. Thanks @Klipschguy !

 

Cheers,

[JJkizak]

You can get top of the line finished one side cabinet grade 3/4" plywood (Cherry, Walnut) for about $250 to $450 bucks per 4 x 8 sheet. That was in 1970. So I am a bit behind the times.

It might be $1000 now.

JJK