>1. Isolation occurs because of the iron core.
That is useful... I take it my two ART 9v pre's would NOT be isolated from one another, which sounds bad. One is an electric guitar line (single coil pickups) which triggers all kinds of noisiness...
>2. Full wave Rectification of a 9 VAC voltage yields about 12 VDC. It's basically VAC * 1.414 or the sqrt(2). It's very coom that the first thing an instrument does is rectify the input. It would not work, if the instrument created a +-6 V supply internally just through rectification.
Em..... Not that english is not my language, I would probably even get less of it in french. Seems informative and useful though. i'll make sure and try to make sense of it and see how I can use it in that context.
>3. The torroidal xformers mount with a rubber and metal washer.
Good. That 1U pc case was already abused beyond insanity and will surely not mind a couple additional drillings...
>4. I had a custom one designed for me once: 4x35 V @ 3A secondary.
Ouch! you do not deal in two channels pre's now, do you ?
>5. Audio would tend to rectify, get 12V and then take the newly created "reference" to be 1/2 the supply voltage (aprox. 6 VDC). Then Connecting all of these together from a single power supply may or may not work. One might be at 6; another at 6.5 and another at 6.1 V
Back at >2... sorry about that. I will have to scrapbook this one and read on until I see the light...
>6. Each components DC supply would be slightly different due to component tolerances if run from a single AC supply.
Is that good or bad? I mean, those pre's are probably though little things and the wall wart is usually the one that goes first, heavy as it is. Hence I can relate to the tolerance thing. Now I don't like that one pre would not get the same current supply as the next. I like my sound steady and predictable. It's more than subtle a thing to speak about... Well I still like cheap gear, not that I have a choice. But I'd rather move and pay a lower rent than lose those subtleties. Am I threatening my sound with current inconsistencies?
>7. Custom is possible. e.g. specified as ? VA, and say 6 x 9 VAC @ ? Amps ; so you would get 6 windings at 9 VAC. What you get is smaller/lighter and more expensive.
I am definitely on the market for smaller, lighter and more expensive. I'll add cooler/quieter on my own authority
.... Well, we all have our own notion about expensive now, don't we ? ...
>8. PTC (Positive Temperature Coefficient) Thermister/fuse protection would not be a bad idea.
>9 one AC input fuse would be OK too.
>10. One ZNR across the AC line would work for surge protection.
I need to get fluent in that PTC stuff and implement the idea. AC input fuse, dead stupid as it sounds, my rack is still lacking. Not proud about that. Good for me visiting here...
I use surge protection in the form of a multiple outlet. not sure how good these cheap things are...
Note that people building and using racks similar to mine (bigger, more professional, in the sound engineer scene) all have Furman like devices and even UPS. The scene I'm talking about is
SAC . I'm way behind them on that area. But they are sound engineers with trucks (well SAC removed the "S" few years ago) and seriously paid gigs, while I'm more of your basic troubadour who just can't cope with Mackie stuff or worse any more. Not in 2012. I definitely won't ever use a UPS (don't care if power gets cut, I'll just break and have a well deserved beer. AC regulation is appealing though and I wish I had room for one of those; say 1U. In the end, it's more my ignorance preventing me from making the jump... "How good will those be to me any way?" kind of ignorance...
Oops, feel like I'm preying for more here
>11. Putting the wall warts inside of a rack case is also an option
Right. Only they are heavy, a pain to secure, get hot, often underspec'ed, and need an actual socket to be connect to (which I just don't allow in my racks). Plus I do want total control on their location, down, to the inch, due to the insane amount of emissions they're outing, along with their fellow out cable... Sorry how this comes out : even I can feel the french accent there...
>12. Usually you put a separate panel in the case to act as a chassis.
This sounds professional. I wish I could visualize an illustration. I'd still want to spread EM emissions where they hurt less, in a super-confined environement. I suppose the pro version of my rack would not have to be so tiny and constricted. But the fact is that I like to have one speaker in one hand, one bag on one shoulder, the rack on the other and the guitar in the back. Remaining hand doubles as mic stand handler and bartender greeter...
I'm not ready to join my gigs on a bike but that's close. I can definitely use a cab. Handy when they remove my driver license, which I am entitled to, driving mostly after bars just closed...
This is where I make the connection between rack design and driver license. Phew...
>13. In one design I used: I took the back off the rack case and replaced it with two rods. I was able to use a lathe to create the holes in the ends and tap them. The case then was mounted on a slide and magnets held the lid. The rods strain relieved the wires coming out. Tied with zip ties.
Sounds nice. My designs rely heavily on those tricks. Actually, the current one was factory-designed with those ideas... zips and all. I solved the wires problem by basically suppressing them. Only thing out of this rack is mains. Apart from midi connection, a small snake connection on top is all their is. CAble wight relief seems way to go, I'll keep that in mind for further designs. I have that idea of a bigger rack to offer high end mixing with my own SAC system. Those guys are actually experiencing the future, albeit in a a weird, rebelious, off-standards community, and I sure would like to be part of it. Totally disgressing here...
>14. LMB Heager makes some very nice and the cheapest I found rack cases.
Good to know. I'llgo check on them.
That's serious food for thoughts
Thanks! You know how they say simple is beautiful ? I like the idea of stupid simple, a lot. How comes it takes so much planning and dedication to achieve that pure, simple, light and efficient design that looks stupidly so ? Note to self : "when you have kids, don't ever let them jump school... Sometimes I wish I wasn't me. Well that might be overstating it a bit
Good day all. I'll get back to the thread after some work. So far, this has been a fruitful one, amazing inputs! I'll probably have to edit some of these posts, get the syntax right and dump some of the foreign language stuff.Don't be offended if you notice, I'll like my posts readable, if not pertinent
Roger.