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Cases and enclosures: What are the constraints?

post #1 of 19
2/9/10 at 6:44pm
Thread Starter 
I'm interested in building and designing cases for custom diy projects. I have access to a metal shop, wood shop and machine shop to some extent, so i was wondering what I should take into consideration with my designs. Are there any particulars i should know about materials? I know heat dissipation is a big issue, but what else is there, other than size and position of components?
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post #2 of 19
2/9/10 at 6:54pm
Do not put low level inputs near high voltage AC or transformer.

Depending on the amp design you need to account for grounding and not grounding certain components to the chassis. This is per design and configuration of each build.
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post #3 of 19
2/9/10 at 7:14pm
It's easy to think that you should use the thickest materials you can, but the effort required to panel-mount most things in, say, 2" wood is... non-trivial. It can be done, but it's kind of a pain. Also remember that unless your (school?) shop has the correct tools, making non-round holes - IEC jacks come immediately to mind - can be a double-plus unfun challenge, especially in thicker metal.

Head-Fi users seem to obsess over heavy, overbuilt aluminum enclosures, but don't be afraid to use whatever materials you prefer. I tend to prefer a simple kind of retro late-1950s look - light or moderately light wood, like cherry with a tung oil finish, with aluminum or acrylic front panels and large, low-profile knobs - but that's very much not everyone's cup of tea.

Oh, yeah, important final piece of advise: Never build a project enclosure you can't reasonably easily reopen later. There's nothing quite like saying "you know, in retrospect, maybe wood glue wasn't such a good idea"...
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post #4 of 19
2/9/10 at 9:59pm
Can you specify more about what you have access to in terms of equipment? Also, what is your experience level?

In terms of metal, there is rarely a reason to use a material other than aluminum (shielding is one exception that comes to mind). It is cheap, light and workable. Steels (especially stainless steel) are much harder to work with and will dull even TiN-coated or cobalt steel drill bits and taps relatively quickly.

Choose some sizes that would be useful...I would recommend something like 12" x 12" and 12" x 17" footprints, with and without heatsinks.

Ventilation is very important - a nice-looking design is no good if it cooks the circuit inside.
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post #5 of 19
2/9/10 at 11:23pm
Once complete, test the enclosure with a cheap transformer (new Triad or the like). This will vibrate the chasis, and there should be no rattles, squeaks or ringing. Mechanical noise is a very bad thing for an audio enclosure, and, will lessen the premium you can charge for an otherwise custom piece of kit.
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post #6 of 19
2/10/10 at 12:43am
Another thought is to integrate heat sinks into the sides. Most off the shelf units do not have this built in (at least at the lower price points). I had to go to Italy to modushop.biz to get the big monster enclosure with integrated heat sinks for my B24. But I can see a market for smaller enclosures with approrpiate heat sinks for sigmas, betas, M3s, and a number of other applications.
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post #7 of 19
2/10/10 at 5:26am
Thread Starter 
This is all really great info. Thanks everybody. It didn't occur to me to check for vibration, but thats a really good point. Ive been eyeballing designs in the forum for ideas on how ventilation and sinks can be incorporated into design. Whats the deal with dust? is it better to have side and bottom vents?

I've got access to a pretty extensive set of tools and machines. The machine shop is the same that the university uses for its maintenance and lab departments. While nonstandard holes (oval/square) will be a pain in the ass, I'm pretty sure that we've got the equipment to handle it. I'll be starting by building enclosures for my own diy projects so I dont have to subject anyone else to my errors, but I may eventually do some custom work for folks on here, or start turning over some finished amps and such for cost+time. Im not really interested in making any money, mostly to fight off boredom and hone my skills without ending up with a huge pile of amps or empty boxes.

I do most of my metal working in copper, silver and steel. I have extensive welding experience and some machining and woodworking. I've been really drawn into foldforming recently and I'd like to see if I can incorporate that into a couple of designs. I think theres a lot of potential in some organic forms, not just the standard "jewelry box" design, which are quite nice but a little sterile. I'll be starting with some headphone stands to get into the design mode, and I'll make sure to post the results up here for all to see.
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post #8 of 19
2/10/10 at 5:46am
i'm using wood and premade stamped metal dishes for all my future 'boxes', aluminium seems expensive and way ott for an average joe like me to machine.

got a drill, a coping saw, sandpaper, rulers and pencils, etc, cheap simple things, works great! not to mention wood looks a million times nicer than aluminium and is far more workable and forgiving :P
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post #9 of 19
2/10/10 at 6:38am
You have to take a look over at AMB's Beta22 page, there's a gallery of Beta22 builts and some done a really nice job there. Maybe some inspiration.
AMB Beta22
Greetz
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post #10 of 19
2/10/10 at 2:11pm
Rounded edges would be a nice feature that no one seem to offer right now... differentiation factor is important when you're starting a "business"
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post #11 of 19
2/10/10 at 9:43pm
"Removable sub-panels" is my tip. Makes building, upgrades, repairs so much easier. Having one big welded structure or a thick 'screwed and glued' wooden box is a pain in the nuts. Make the front and rear panels, and either the top or bottom, easily removeable. : )
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post #12 of 19
2/11/10 at 7:55pm
Thread Starter 
Great stuff! Lots to take into consideration. Anybody hear of any "vertical" builds? Something like the Stax SRM-300. Intersting visual presentation potential, though i would think the fact that heat rises might cause some issues, as well as the fact that you'd have to do some hefty soldering.

How much of a problem is vibration? Is that the main reason amps are built so heavy? Or does that have more to do with transformers, heat sinking, and all that jazz? This is particularly of interest when adding in panels and other removable parts.
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post #13 of 19
2/11/10 at 8:29pm
There is a vertical build in the Utah meet impressions thread built by ericj.

If you can weld aluminum, we seriously need to talk. You have a PM.
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post #14 of 19
2/11/10 at 9:48pm
Quote:
Originally Posted by oneplustwo View Post
Another thought is to integrate heat sinks into the sides. Most off the shelf units do not have this built in (at least at the lower price points). I had to go to Italy to modushop.biz to get the big monster enclosure with integrated heat sinks for my B24. But I can see a market for smaller enclosures with approrpiate heat sinks for sigmas, betas, M3s, and a number of other applications.
I picked up one of these a while ago. Haven't used it yet, and attaching devices to the case might be a bit tricky, but there are definitely cheap options out there. I have one of their GK8 enclosures on order, and have high hopes for it.

I also got a pair of these heatsinks sometime last year, and plan to use one as the top of an otherwise wood power supply enclosure I'm making. Should be pretty slick, when it's finished.

I'm sorely tempted to use the other for a low-power (desktop/bookshelf speakers only) gainclone, inside a 3.5" USB hard drive enclosure with a fan. Just have to find the right enclosure...
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post #15 of 19
2/12/10 at 5:09am
Be sure to pick up the Morgan Jones book on building valve amps. It's chock full of amazing advice on building amps. The information carries over to solid state, as well. Be sure you have good isolation between the power supply and amp section. A power supply can be noisy and you want to control for that.
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