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How to assemble a proper Euro cabinet
MUFF WIGGLER Forum Index -> Metasonix  
Author How to assemble a proper Euro cabinet
metasonix
First the cabinet itself. You can do a lot worse than Lamond.

Then the power supplies. 14 amps here, 20 amps there, not a big deal. No one gets a "gold star" for trying to run a substantial system from a cheap supply. This is what I'm putting in the Lamond cabinet. Linear for the +-12v and switching for the +5. (Did you know that Condor linear supplies have serial numbers and come with their own individual test reports? That's what those papers in front of the supplies are. Nice.) A GOOD power system, including these and plenty of #14 solid wire plus assorted hardware and connectors, only adds about $450 to the cost of the cabinet. There will be around $15k worth of modules in this damn thing so $450 is not really very much to power it properly. I also used Doepfer busses because they're not bad, but added filter capacitors to each one. There will be fusing on the primary mains and 5-amp polyfuses on all the DC lines. Using a MeanWell 20A switching supply for the 5v power because it only runs crappy microprocessors and R-55 tube heaters. Noise is much less of an issue on the +5 line. And blue LEDs suck. Ha ha ha.

Oh yeah, I bought one of those silly white LED lighting strips sold in auto-parts stores and stuck it under the lip on the cabinet above the top rail. $12 for pretty good cabinet lighting.
Joe.
Are you going to use OVP-12G's with the Conder PSUs?






.
metasonix
Joe. wrote:
Are you going to use OVP-12G's with the Conder PSUs?

No need, most of the modules I've seen can handle brief overvoltages and I guarantee Metasonix modules are not affected by it.

Why are you worried about that? I've heard very few complaints about modules being damaged by excessive supply voltage.
Joe.
I'm worried about everything (hides)

Thanks for covering it now though. Don't hesitate to add any other hints and tips, It's an interesting thread thumbs up





.
snakejaw
Eric, in this thread are you going to be documenting a cabinet that _you_ are building?
metasonix
That's the idea. How to do a good job (as opposed to the messes I see in the average home studio).

The wiring almost finished, just need to do the mains part. Spadelugs and push-on terminals are great and make it easier to replace things. Unfortunately those wonderful linear power supplies only have solder terminals.

I dunno: should I spend money on another barrier strip for the AC mains distribution or just solder and tape. Meh.

Sinamsis
Commenting mainly to subscribe. And been building a few cases myself. Personally I use single output switching supplies for the +/-12V lines and my distro boards generate the +5V if needed (MDLR boards. In my case I really don't have many modules that do require +5V. Yes they are cheaper than the linear equivalents. But mainly we do it for the weight and heat production, which lets us build the most compact folding case we can make. I've never really had issues.

Personally, I don't know much about your modules other than they sound badass and they have a decent power requirement. Perhaps this is a stupid question, but why such a large PSU for the +5V? Is that something unique to your modules? I guess I've been turned off by most of the multi output switching supplies because of the large output on the +5V line. I never thought I'd hit the minimum load to adequately regulate the output.
snakejaw
From the look of that big case, I can tell that you're not just the president of the Hair Club for Men, but you're also a member.
metasonix
Sinamsis wrote:
Commenting mainly to subscribe. And been building a few cases myself. Personally I use single output switching supplies for the +/-12V lines and my distro boards generate the +5V if needed (MDLR boards. In my case I really don't have many modules that do require +5V. Yes they are cheaper than the linear equivalents. But mainly we do it for the weight and heat production, which lets us build the most compact folding case we can make. I've never really had issues.

Lucky you. Other people have, and had no idea how to resolve it. Euro still suffers from this bizarre "cheapest power supply and enclosure you can possibly find" attitude. A good solution really isn't much more costly--people just labor under weird hangups.

Quote:
Personally, I don't know much about your modules other than they sound badass and they have a decent power requirement. Perhaps this is a stupid question, but why such a large PSU for the +5V?

That supply only costs $40. Got plenty of room so why not? Better too much than too little, okey dokey? Plus didn't you read this?
Quote:
Tubes briefly draw more current when they are cold, because the cathode heater in a tube has lower electrical resistance when cold than when hot. It's not like most analog solid-state gear, which draws the same power all the time.

Modern lightweight "switching" power supplies don't like this sort of "cold inrush" current, because they usually have no excess current capacity, and will only deliver exactly what they are rated to deliver (and sometimes less!) The tube heaters draw about 2 to 2.5 times more current when cold. In the "old days", electronics were powered with primitive linear supplies (usually transformers) which had built-in cold surge capacity, so this was never a problem.
metasonix
Here's how I wired the distribution from supplies to the busboards. All power wiring is 14 AWG solid copper 600-volt THHM "oil and gasoline resistant" blah blah, because it's QUALITY. All spadelugs and push-on lugs are crimped AND soldered; the plastic collet starts to melt when you solder, but it's only a problem if you leave the iron on it for an absurdly long time. Some practice might be required to do it correctly. If that doesn't last for decades, I give up.

Each +12, -12 and +5 line gets its own 14-ga wire directly from the barrier strip to each busboard, no "daisy chaining". And each ground/earth/return/etc. connection gets its own 14-ga wire, all going directly to a commercial grounding busbar. Crank all screws down HARD. Bundle and clamp long runs down so they can't vibrate or flop. Cable ties are cheap, use them copiously. Neatness counts esp. if someone else has to repair the thing many years from now.

The yellow things are polyfuse self-resetting fuses rated for 5 amps. They only come in PCB mount form but the wire-leaded ones can be attached to wires and spadelugs with some care and proper soldering technique. Polyfuses get very hot when they open so they have to be mounted to allow free air cooling and so they don't melt any plastic insulation etc.
metasonix
How to wire to a typical Doepfer/etc bus board properly. Slip-on terminals are crimped and soldered and covered with heatshrink tubing so there is no danger of shorts. On the other end of the board are pads suitable for attaching added 470 uf filter capacitors; I will goop them together with hot glue to keep them from flopping around. These caps are not "desperately needed" but one never knows. I will test the supply lines for high-frequency noise after completion, and if there is any substantial problem, adding filter chokes should not be difficult. Each of these busboards is only expected and designed to handle perhaps 2 amps continuous at most, so this is admittedly overkill.
metasonix
All done, plug it in, it works immediately. IF you're careful about assembly and check everything, there will be no problems. I installed a mishmash of Metasonix products adding up to 22 tubes and the power supply handles it. Also installed a couple of miniature speakers on the top row (hacked cellphone speakers). Unfortunately the busboards are a little short for this cabinet and power cables tend to be short, so I might need to get some adapters or longer cables to fill the cabinet.

If only the Keystep were smaller. Or if there were more euro-sized keyboards like that.

Sinamsis
Nice. Looks great. Did you do anything for ventilation?
bcomnes
Well if the pudding proof is in the tasting, patch something on that set up and let's hear it!
mt3
Some good "best practices" here.
Some nice "suspenders and a belt" safety factor applied.
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