Cornwall lll cabinet rebuild ?

[sasqwatch]

In the near future I will be building a pair of cabinets for the corn lll 's .

I understand the internal volume dim is to be kept the same.

I read somewhere that a more rigid cabinet is better,so I was thinking of 1" ply and some internal bracing.

If a more rigid cabinet is better , what is to be expected of the sonic improvement.

Also I picked up on some guys putting some type of padding on the inside ,would anyone share there insight as to what it does to improve sound.if I remember correctly it would only be used on motor board and sides.but the memory isn't what it used to be,not that it was all that special to start with. Thanks for any input.

[juniper8]

Bracing is always a good idea. If you are building from scratch you may want to look into Cornscala's.

[boom3]

We may not be asking the right question here..do you have two sets of Corn III components and you are building a cabinet from scratch?

The Cornwall traditionally either used a paper-based padding or like my Corn IIs from 1986, none at all. Remember that the Corns are vented and the internal volume is critical. Strongly advise you buy a measuring set-up first before you tackle a major build or major mod,

FWIW, my Corns have corner blocks and one 2x4 brace running front to back just above the woofer.

[sasqwatch]

Story is I bought a pair of corn lll on eBay.Ups destroyed one cabinet the other has two crushed corners.The insurance paid. I kept the one with the crushed corners.So I have one complete speaker to get my internal dim.I also have a pair of 84 corn ll that have the same bracing you describe,With no dampening on the interior.I guess what I am wondering ,since ill be building from scratch.

Would it benefit the acoustics of the speaker to build out of 1" vs 3/4 and ad some additional internal bracing.Or would it just be overkill .As far as the dampening on the corn lll it has what looks to be sheets of (shipping foam like I use at work).sort of draped from the top to both sides.I just dont know if I should try to replicate the factory dampening .Or maybe do a search on speaker dampening here,I recall a thread were someone was discussing some type of sound deadening mat. If anyone has any experience or ideas they would like to share please feel free to throw your two cents in. Thanks Stacy

[boom3]

Story is I bought a pair of corn lll on eBay.Ups destroyed one cabinet the other has two crushed corners.The insurance paid. I kept the one with the crushed corners.So I have one complete speaker to get my internal dim.I also have a pair of 84 corn ll that have the same bracing you describe,With no dampening on the interior.I guess what I am wondering ,since ill be building from scratch. Would it benefit the acoustics of the speaker to build out of 1" vs 3/4 and ad some additional internal bracing.Or would it just be overkill .As far as the dampening on the corn lll it has what looks to be sheets of (shipping foam like I use at work).sort of draped from the top to both sides.I just dont know if I should try to replicate the factory dampening .Or maybe do a search on speaker dampening here,I recall a thread were someone was discussing some type of sound deadening mat. If anyone has any experience or ideas they would like to share please feel free to throw your two cents in. Thanks Stacy

Yikes! You have my empathy about shipping mishaps. The first set of Corn IIs I bought were wrapped in bubble wrap and then grabbed with crate hooks by FedEx Ground. The seller refunded about half of my shipping fee and then tried to pursue a case with FedEx. They told him he was SOL due to poor packaging. Don't know if he ever got satisfaction out of the shipper.

My second pair was bought from a Forum member who used Craters & Freighters to package them correctly and they were delivered to my door by Saia Motorfreight in perfect condition.

If you are looking to duplicate the Corn IIIs then I would duplicate them exactly, measure and then start experimnenting with changes, one at a time. Be aware there is a difference between adsorbant filling and panel dampening. The function of the "curtains" of foam inside the box is to kill internal standing waves. The function of panel damping is prevent low-frequency energy from leaking through the walls.

If I were to rebuild my damaged Corns, I would probably use panel damping using constrained-layer sheets. The difference in internal volume will be negligable. I wouldn't use internal absorbstion. I would probably raise the woofer up to about the same position as is seen in the Corn III. I am told this reduces floor bounce and the Corn's tendency to excess energy in the 80-160 Hz octave.

As I've mentioned in other posts, I have 4 Corns in my HT set-up plus a Klipsch-derived center. I built a Ryhmik suibwoofer about 8 yrs ago and have it crossed over the Corns at 60 Hz (lowest point available). This has reduced the boom from the Corns and distortion as well since the woofers are now rolled off well before the Helmoltz resonance of the box, which is around 40 Hz.

[mark1101]

I seriously doubt that you would be able to actually hear the difference between 3/4" and 1" plywood boxes.

[sasqwatch]

Thanks for input guys ,since posting here I came across a post in two channel .which has several opinions on cabinet construction ie.bracing,stiffening strips on back dampening.it may be a couple of months befor ill have free time to build.so I been stock piling ideas .I'm leaning towards 1" ply just to add what rigidity it will provide .I agree probably wont here a difference,and I'm leaning towards replicating the bracing and dampening of the stock cabinet .as someone stated in the other post ,with the equipment and engineers at klipsch. Iwould tend to believe they have put together the best combination .

[Daddy Dee]

sasqwatch,

Yeh. think you are right. Just bone stock these speakers are already optimized as much as they can be by Klipsch engineering.