Selah Tempesta-Aluminum Enclosure

ChrisH

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Aug 25, 2015
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I've enjoyed reading this forum quite a bit and thought I'd show some pics of what I've recently assembled. This forum really helped sell my on using an active crossover solution.

http://imgur.com/a/roTMb#6

This project began about a year ago with a friend who builds aluminum boats for a living. I really wanted to upgrade my listening experience, and he was up for making something different. I talked extensively with Rick from Selah about what we were trying to build and he sold me on his Tempesta.

The front baffle was made using 1/2" aluminum plate and was CNC milled. The top, sides, bottom and back use 1/4" plate and were cut on a plasma table. The walls were then curved, this took 6,000lbs of pressure, and welded together. I'm pretty sure I can say that this is the strongest enclosure built for home use. The internal volume of the cabinet is 1.0003 cubic feet with no internal bracing.

About halfway through this experience I decided to make this whole system active. This led me to ClassD audio in California where I purchased and put together 3 stereo amps. A used Deqx 2.9P is used as the brains of the operation.

These cabinets are very much a prototype and I am working on building a finished set of these. We had to rush, as a few people wanted to the see the enclosures before they were really ready, so they were assembled in about 6 hours. This was a great project, and I learned heaps. If anyone has any questions about these, I'll try and answer as best I can.
 

amirm

Banned
Apr 2, 2010
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That's pretty cool:



This looks like three power supplies and six channels of amplification. Are you using this in a separate box to drive the speaker elements separately?
 

ChrisH

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Aug 25, 2015
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That's pretty cool:


This looks like three power supplies and six channels of amplification. Are you using this in a separate box to drive the speaker elements separately?

You are correct, 3 stereo amps all tied together. They are mounted now on a piece of steel while I'm building the rest of the box. 60w per channel into 8, and 120 into 4. They are dead quiet and for this application, more power than I could ever need. In total it weighs almost 60lbs, and will be 33" in length, 12" deep and 3.5" high.

To keep track of the output, I decided to use Deutsch connectors and their pin/socket terminals. The terminals are dust/moisture proof and give an excellent connection. I had to make and terminate all my chords. All of the wire is Ancor marine wire. It's pre-tinned, super flexible and each to work with. Would recommend for projects like this.

Once I get the slap echo fixed in my room, I'll post some measurements.
 

amirm

Banned
Apr 2, 2010
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Seattle, WA
I was wondering what the raw sheet of steel had to do with the elaborate process you described for your aluminum work :).

I use Ancor wire exclusively for my boat where its tin coating is essential for reliability which is paramount for a boat. Your life literally depends on that wire doing what wires do! They are expensive but of course not remotely the same as audiophile cables. Had not thought about using them for audio applications. That is a good idea.

So you have three-way speakers and those six channels power the two loudspeakers?
 

ChrisH

New Member
Aug 25, 2015
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My friend is putting 5 miles of Ancor wire into a boat he's working on right now, a research vessel for University of Michigan. Let's say, I got a good discount for what I needed.

Yes, this is a 3 way active system, one amp channel to each driver. The Deqx is doing the crossover, using 96db slopes. The Raal has a cap soldered on the + side, other than some OC705 and what I used to kill the resonance in the cabinet, that's all that is inside the speaker enclosure. There is no audible ringing up to 110db, I haven't gone any louder. I'm hoping to send these cabinets out for real testing soon, I really want them on an accelerometer. This would really let know what I'm dealing with concerning resonance. Then I can fix what needs to be fixed, I'm sure there's something I can't hear. Beating them with a hammer produces a very dull sound, no metallic ringing. The results, so far, have been quite spectacular. The opening of Mahler 8 at high SPL is really something to hear.

Basically, this cabinet could be immersed in salt water for 200 years and come out looking as it does today. The fabricator, he's also an engineer, figures that we could set about 5 tons onto each cabinet before they buckle. We may actually try this when he gets a large shipment of metal in.
 

amirm

Banned
Apr 2, 2010
15,813
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Seattle, WA
I hear you on resilience of aluminum. The builder of my aluminum boat dropped it from 10 stories high and then took it to water and it was leak proof and ran as if nothing had happened! This is 1/4 inch aluminum with welded joints by people who know what they are doing with great bracing.

I am surprised though that you have managed to get it to be so resonant free. I have been meaning to make a PVFD based accelerometer but just haven't gotten around to it.
 

ChrisH

New Member
Aug 25, 2015
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I'm not really at liberty to talk about how we solved the resonance problem, my fabricator and I may try to sell a hand full of these cabinets. We did this without adding mass, too. They weigh about 60lbs each.

I had no idea you could build your own accelerometer, that is very interesting.

Now, I'd just like find someone to hear them that actually is into this stuff.
 

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