john curl said:
I agree, but there are few-to-no circuits here in the hinterlands to "race" against. I had to smile when I saw your post in another thread about having others (whose hearing you trust) evaluate your work. I can number the audiophiles I know around here on one hand and have fingers left over...and not one of them has hearing I trust.
One of the practical problems with ugly--at least as I practice the art of ugly (and I practice it well, trust me)--is that a lot of my things aren't at all portable. The tube amps will never move, for instance. The water-cooled stuff, while better looking, is also effectively nailed to the floor. I'd like, just once, to have something I can pick up and carry around and that looks half-way decent.
I did manage to get a preamp over to a fellow's house so as to embarrass his CAT Signature preamp. That was nice, albeit a chore.
Well, all right, then...here's the windup...here's the pitch:
John,
Assuming limited access to materials or competent people to work said materials, what would be the best way to house a circuit?
--Plastic? To include Plexiglas, Lexan, etc.
--Wood? Anywhere from plywood to ebony. (Okay...ebony is expensive, but oak, walnut, cherry, etc. aren't that bad.)
--Synthetic materials? Faux marble, Formica, etc.
Yes, I know the very idea is difficult to swallow, but let's say that the economy completely croaks and you get a phone call from Parasound saying that market realities dictate that they commence design on a new downmarket line of product in order to stay afloat. They're not only asking you for a new circuit, but for suggestions as to what to use for a chassis.
Obviously, the vast majority of materials that fit into the above list won't have any EM shielding capability due to lack of metallic content, so let's assume the use of a metal sheath, conductive paint, or the like.
Your thoughts?
Grey
P.S.: I am equipped for, and quite good at, woodworking. However, that will not be true for the majority of readers, so relative ease of working should probably factor into the equation. Yes, this weighs against something like Corian, for instance, but perhaps Lowe's or Home Depot could be persuaded to cut it for a price.
Mr.Curl, unlike Blowtorch power supply, Parasound JC-2 preamp p.s.is not, according to high. res. photos, dual mono. Are JC-2 voltage regulators mutistage ( series,shunt,cap.multiplier) or simply series or shunt? What is common mode choke current rating?
Wood is also not very best as an electromagnetic shield 😉 , but the user probably does not care.
PMA said:
Not to mention that wood has a bad tendency to catch fire if something goes wrong
Magura 🙂
PMA said:
Note that I mentioned exactly that point in my post and proposed the use of a metal sheath (copper sheet would be a good start, aluminum foil is cheap and readily available although less than optimal--anything magnetic would be a double-edged sword) or conductive paint (carbon or aluminum being the most likely candidates).
Magura said:
Not to mention that wood has a bad tendency to catch fire if something goes wrong
Magura 🙂
True, but so do a lot of the other possibilities, like plastics. Build your circuit so it doesn't burn. There are a number of commercial products that employ various sorts of plastic as chassis sides and tops. If it's an amp, the heatsinks make up part of the chassis.
Something that occurred to me that I don't remember seeing mentioned before was the possibility of casting your own sides. I used to be able to get moderate quantities of epoxy locally, meaning a quart or so. Probably still can. I'm sure that car repair places have access to even larger quantities for repairing Corvettes and such. So here's my proposal: Using a large baking pan or cookie sheet (epoxy doesn't stick to metal nearly as well as they claim), or a large Tupperware container (which epoxy doesn't stick to at all), you could mix sufficient epoxy to make a 1/4" slab. This wouldn't be any better than, say, Lucite, and might even be worse except for the fact that as you're casting it, you could include metal flakes, filings, or something of that nature to block RF or EM fields. If you went to multiple laminations you could include an outside color layer, followed by a sheet of copper foil, then an inner inert layer that would be non-conductive.
John,
Your point about heat is valid, of course, but I'm assuming the inclusion of holes or slots for ventilation. In principle, it should be possible to cast holes in an epoxy casting, although I've never tried it. All the castings I've done have been things like pickups for my basses. That involves color layers that in turn support the pickup coils and magnets, then backfilling around that to fill the mold. At the very end, I put in threaded brass inserts so as to have a way to mount the pickup. It can't be that difficult to leave holes. I'm still pondering this one, but am interested in comments.
Grey
Please stick with thick alumunum. Aluminum foil will offer partial shielding, but you are throwing the baby out with the bathwater. Metal enclosures also are heatsinks to the outside world. We tried wood once, NEVER AGAIN, even with forced air circulation.
GRollins said:
Body putty, like Bondo, is good for filling/working/shaping etc.
Though it doesn't pour into molds.
Drills work good for air holes.
OOOHH, I can just see the smoke coming out of the volcano when the amp burns its guts out!😀 😉
Peace,
Dave
Peace,
Dave
The problem with using a chamberpot or spitoon design is that someone may mistake it for a commode.
Dave
Dave
Greek vase profile in brass? Many here think I am kidding, but I am not. I have already measured a brass prototype that looked like a 'spittoon'.
If you're seeking a chimney effect then on-end PVC pipe with something to space it at the bottom might be an option. Granted, no shielding effect, so you're back to metal foil or something. To forestall the inevitable, every time I mention PVC, someone pops up immediately afterwards and suggests that heavy cardboard tube stuff the name of which I can't remember at the moment. Ironic, given that they have--or used to have--a factory for the stuff not far from here. Sonotube? Is that it?
Ah ha! Got it! Copper pipe. I don't know how big a diameter you can get, but I've got 2" or thereabouts at the house that I used building a RIMS system for brewing. I'm pretty sure you can get bigger. Pretty good shielding. Excellent heat conduction. Easily worked. Okay, so the diameter will limit the size of your circuit. Don't fuss until the maximum diameter question is answered. If you need more cooling than the tube itself can provide, attach copper plate fins to the outside. See my old water-cooled amp thread for details. I just never thought of turning the thing inside-out before.
And copper looks good, too.
Grey
P.S.: Without even trying hard, I turned up 4" diameter Cu pipe on the web.
Ah ha! Got it! Copper pipe. I don't know how big a diameter you can get, but I've got 2" or thereabouts at the house that I used building a RIMS system for brewing. I'm pretty sure you can get bigger. Pretty good shielding. Excellent heat conduction. Easily worked. Okay, so the diameter will limit the size of your circuit. Don't fuss until the maximum diameter question is answered. If you need more cooling than the tube itself can provide, attach copper plate fins to the outside. See my old water-cooled amp thread for details. I just never thought of turning the thing inside-out before.
And copper looks good, too.
Grey
P.S.: Without even trying hard, I turned up 4" diameter Cu pipe on the web.
Use dbl sided bare copper circuit board material. You can even solder the seams (if any) from the inside. Easy to cut and drill.
BC
BC
- Status
- Not open for further replies.