A new Cab design; Part II!!!

EdRo · « **on:** 28 Sep 2016, 02:30 pm »

Okay guys. I wasn't happy with some of the results of my latest build, so I had to change things. A big part of this new cab design is the build method; if I can't make this cab as flawless and as repeatable as possible then I can't afford to build it. Thats part of the fun of a new cab design, right? The basic shape will stay the same. My first two build methods haven't given me the results I need, so it's taking me a bit longer to get the prototype done than I expected. I have to hurry though; the corian order will be ready for pickup on Thursday. I don't mean to string everyone along. I'm going to get this thing beat into submission!!!
STAY TUNED!!!

EdRo · « **Reply #1 on:** 11 Oct 2016, 02:10 am »

Well, my cab build method looks solid. Now if I can just get laminating corian right! This cab has all the right elements, and experimenting with corian it seems 20 times as rigid as MDF and very dead. Combined with my cab material (top secret) and drivers that will be used, I think this speaker will be my next step up. I'm betting that I have some pics by next Monday, the good Lord willin' an the creek don't rise! As far as drivers go, the Transducer Labs magnesium oxide dome behind a 1.5" deep waveguide looks promising. The 8" Acoustic Elegance might be the right woofer, might not. I also have some interesting ideas for stands. Crossover parts will be top shelf, too. I really want this to have the potential for being a statement monitor. What's cool is that because of the construction method, if someone would rather have a tower with possibly 2 woofers, and a to design, it could work. Flexibility will be the key to this effort.

Folsom · « **Reply #2 on:** 11 Oct 2016, 02:30 am »

Is it hard to laminate two flat pieces of corian?

Norman Tracy · « **Reply #3 on:** 11 Oct 2016, 03:07 am »

Nothing is hard on the internet.

In the Real-World(tm), not so much.

My favorite scenario.
-First time works
-Second time works even better
-Third through sixth time works. Sign off on production.
- X weeks pass
- Seventeenth time "What the !@$!!! why isn't this epoxy curing?!! The mix ratios were correct to plus or minus one gram and we mixed for five full minutes prior to application!!!!

gregfisk · « **Reply #4 on:** 11 Oct 2016, 06:56 am »

I believe when gluing corian on the flat side you have to take the sheen off. At least that's what the guys did when they put the edges on my counter top in my daughters bathroom.

EdRo · « **Reply #5 on:** 11 Oct 2016, 11:19 am »

The West Systems epoxy guys found that roughing up both mating surfaces with 80 grit sandpaper before applying epoxy worked best. My problem was using their G-5 epoxy, and it started to cure before I could get everything fully clamped. Oops. Learning experience.

jtwrace · « **Reply #6 on:** 11 Oct 2016, 02:14 pm »

Quote from: Folsom on 11 Oct 2016, 02:30 am

Is it hard to laminate two flat pieces of corian?

No, not at all. Two flat pieces of anything is quite simple with the right technique.

Chu Gai · « **Reply #7 on:** 14 Oct 2016, 03:56 pm »

Other than perhaps looking cool, if you google the terms corian+acoustic+properties, you find that corian has been used in sundry musical instruments. Further, it appears to have less internal damping than MDF. Given that, what is the motivation for using it in this manner? Couldn't you achieve something similar appearance wise with the plethora of thin laminatable kitchen and bathroom veneers?

rajacat · « **Reply #8 on:** 14 Oct 2016, 06:53 pm »

How about laminating Omega-Bond to form a very stiff baffle? Too expensive?
http://www.laminatorsinc.com/sign-panels/products/omega-bond

Folsom · « **Reply #9 on:** 14 Oct 2016, 07:08 pm »

Quote from: Chu Gai on 14 Oct 2016, 03:56 pm

Other than perhaps looking cool, if you google the terms corian+acoustic+properties, you find that corian has been used in sundry musical instruments. Further, it appears to have less internal damping than MDF. Given that, what is the motivation for using it in this manner? Couldn't you achieve something similar appearance wise with the plethora of thin laminatable kitchen and bathroom veneers?

Links?

Also what is corians resonate frequency by comparison, that could be a factor even if dampening isn't better.

Chu Gai · « **Reply #10 on:** 14 Oct 2016, 10:12 pm »

Google not working?

EdRo · « **Reply #11 on:** 14 Oct 2016, 10:17 pm »

Corian is dense, easily cut with a cnc, and doesn't react to humidity. Once it is cut, it just needs buffing. It's initially more expensive than MDF, but the finishing is easier, and the finished product is much more resilient.

Folsom · « **Reply #12 on:** 14 Oct 2016, 11:27 pm »

Quote from: Chu Gai on 14 Oct 2016, 10:12 pm

Google not working?

Google gives different results to different people, I couldn't find the instrument company, for example.

Chu Gai · « **Reply #13 on:** 15 Oct 2016, 01:01 am »

https://www.google.com/patents/US7482518

http://www.drummagazine.com/gear/post/fords-corian-snare-drum/

Comments by Genesis: http://www.genesisloudspeakers.com/downloads/G2.2_Fact_Sheet.pdf

Maybe it won't matter so much if it's thick. Maybe. Maybe the differences in thermal expansion between Corian and what it's attached to aren't so different that that joints would lossen over time.

Folsom · « **Reply #14 on:** 15 Oct 2016, 02:59 am »

How much heat are you expecting?

Solid cast acrylic seems like a neat option for certain things.

Chu Gai · « **Reply #15 on:** 15 Oct 2016, 12:42 pm »

It's not the heat, it's the magnitude of the ratios of thermal expansion coupled with time.

EdRo · « **Reply #16 on:** 15 Oct 2016, 05:50 pm »

The ratio of thermal expansion would have more impact if the corian surface were mounted to a dissimilar frame material. The Aurora II cab has no frame. It will have ano inversion layer applied to the inside walls of the cabs, and to the back of the corian "inner baffle". The corian bottoms and baffles being the same material should minimize the negative effects of the thermal ratio of expansion. Am I thinking right? I'm going with it anyway. A year in Vietnam will help me test this concept.

Pete Schumacher · « **Reply #17 on:** 16 Oct 2016, 04:51 am »

Quote from: Chu Gai on 15 Oct 2016, 01:01 am

https://www.google.com/patents/US7482518

http://www.drummagazine.com/gear/post/fords-corian-snare-drum/

Comments by Genesis: http://www.genesisloudspeakers.com/downloads/G2.2_Fact_Sheet.pdf

Maybe it won't matter so much if it's thick. Maybe. Maybe the differences in thermal expansion between Corian and what it's attached to aren't so different that that joints would lossen over time.

I find it interesting that you would cite a PDF with this observation . . .

There is now almost absolutely zero vibration in the cabinet
structure of the G2.2 – either in the midrange/tweeter wings or the
woofer towers. Even when playing loud music, vibrations cannot
be felt with the fingertips.

Chu Gai · « **Reply #18 on:** 16 Oct 2016, 01:28 pm »

You have remarkable fingertips.

EdRo · « **Reply #19 on:** 16 Oct 2016, 03:05 pm »

I worked in the power plant industry for 21 years. Believe it or not, all supervision had to go to "smoke school" to get their eyeballs certified for degrees of opacity in case of a failure of emissions monitoring equipment. They were trained to read percentages of opacity coming out of the stack. If a person can be trained for that, then fingertip oscillation certification might be the next training all audiophiles need to get!