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-   -   Impressive built vintage laminated speaker cabinet (http://www.diyaudio.com/forums/multi-way/102630-impressive-built-vintage-laminated-speaker-cabinet.html)

binarywhisper 28th May 2007 04:06 PM

Impressive built vintage laminated speaker cabinet
 
I mentioned some time back that I had made a deal with my wife that I would get rid of many of the ends and odds that I have collected over the years as I pursued my interest in vintage speakers.

For the most part that means stripping down many of the speakers I have and throwing out the cabinets. Don't worry as these various yard sale finds all have severally damage cabinets.

SOOoooo anyway I take apart these old large Wharfdale 2 ways (w60's I think). I've always thought these speakers were too darn heavy even given their considerable size.
http://www.cancompute.com/postedimag...wharfdale1.jpg

I pulled the back panels and as I handled the panel I though that just isn't right. Its way to flippin heavy. So I had a look at it.
http://www.cancompute.com/postedimag...wharfdale2.jpg

It is not unusal for old speakers to have composite panels but I noticed this one had plugged holes in one end.
http://www.cancompute.com/postedimag...wharfdale3.jpg

I got some tools and carefully pulled the lamination apart and low and behold its filled with sand.
http://www.cancompute.com/postedimag...wharfdale4.jpg
http://www.cancompute.com/postedimag...wharfdale5.jpg
You know as you look at the build quality of these old Wharfdales you can not help but be impressed. Unfortunately this pair got wet in a flooded basement and then had several coats of house paint applied before I found them.

Anyway I thought it was interesting and thought I'd share.

Willitwork 29th May 2007 01:48 AM

:eek:

binarywhisper 29th May 2007 02:00 AM

I had a good look at the rest of the cabinet and it appears its only the back panel that was constructed this way. I will know for certain when I take the cabinets out back tomorrow.

So I guess this was done just to add some weight vs resonance control.

binarywhisper 31st May 2007 12:59 PM

I'm a little surprised this didn't generate more interest. I certainly found it surprising

badman 31st May 2007 01:42 PM

It's interesting, but what's to say? Nice to see that kind of effort in a cab...

Willitwork 31st May 2007 03:45 PM

Quote:

Originally posted by binarywhisper
I'm a little surprised this didn't generate more interest. I certainly found it surprising
I've seen posts here that wouldn't get any replies for like two years and then all of a sudden it's back on top with 5 pages of comment and 3 or 4 heated controversies going on at once.

Regarding the Wharfedales I'm not really surprised about the sand because it's commonly done for deadening walls in recording studios but I was astonished that such a costly technique would be used in relatively affordable speakers. The W60's cost about $250.00 in the mid-1960's. That may sound like a lot for the era but one must remember that kitchen radios sold for over $100.00 in those days and a small color TV went for over $500.00 so the W60 itself was a bargain even though the electronics required to drive it properly probably cost an arm and a leg.

binarywhisper 31st May 2007 04:26 PM

It grabbed my interest not only because I was surprised to find it but because it is an easily duplicated method for the DIY'er.

I may very well try it on an upcoming project although I'm still leaning more toward hidden compartments that I can drop lead ingots into. (Only because I can remove the lead to make moving the speakers easier)

If I was to use the Whardale method I was thinking of making all of the panels this way including the front baffle. The additional weight offers obvious benefits but how much benefit do you think it offers in controlling resonances?

Willitwork 31st May 2007 05:02 PM

Quote:

Originally posted by binarywhisper
The additional weight offers obvious benefits but how much benefit do you think it offers in controlling resonances?
Hard to say. I'm inclined to think that the reason this method was used is either because MDF wasn't commonly available at the time or to avoid the increase in cabinet size that a braced MDF construction would require for the same given volume, or because of sand's inherent acoustic properties. I'd be intrigued enough to build a sandbox and see for myself. Even if from a manufacturing point of view the method appears prohibitively expensive this is not really a factor for the DIY'er because the materials aren't that costly. However, I imagine that with all the carving and layering process involved in creating airtight hollow walls it'd be a time consuming project.

I'm not sure using lead ingots wouldn't have an effect on the sound, because sand itself has different sonic properties (progressive damping I imagine) than purely reflective metal. That may be the reason why Wharfedale opted to use sand, and this is really what I'd like to find out.

banana 31st May 2007 05:37 PM

One thing puzzled me... How to ensure the cavity to be fully filled without void? Did they fill sand through the little plug hole??

I can imagine the panel play like a Maracas if there is void within.

binarywhisper 31st May 2007 06:38 PM

Yes they filled it though the hole(s) at the top of the panel. There were two holes. AS long as the interior shape is designed with a bit of thought there is no reason to not be able to fill it totally. You could also use a vibrator (palm sander with no paper would work) to make sure there were no air pockets.


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