Guest analouge Posted September 2, 2005 Report Share Posted September 2, 2005 I'm not really sure where to put this topic... but I end up putting it here in Design Consepts...I have been searching the net for 19" rack DIY stuff... But eithere there is no on the net - wich I seriously doubt - or it is my searching that sucks - that's closer to the truth I guess :PSomeone knows how to build a 19" rack? Coz I don't have one available to take mesurements from, and I don't have any rack units yet so... I guess it's 19" wide, but is it like 19" wide between the the alu/steel mounting brackets inside the rack or is it 19" wide between the inner walls? Just examples of what I need to know before starting. I bought some mounting brackets to place inside the rack (the ones that u put all the screws into when putting equipment inside)...Someone knows places on the net where I can find out how to build it? Or someone can tell me how?Thanks! Quote Link to comment Share on other sites More sharing options...
Synapsys Posted September 2, 2005 Report Share Posted September 2, 2005 Hi,There are several manufacturers of racks and panels that have drawings of thier products with dimensions. Here are a couple of links that may help you.http://www.hammondmfg.com/pdf/RCBS1900313.pdfhttp://www.hammondmfg.com/pdf/PBPA_PBPS19001BK2.pdfThe horizontal dimension (i.e. srew hole to screw hold distance of 18.5") and the vertical single space dimension (1.75" for a single space) are really the only standards. The depth of the enclosure varies depending on intended use. There is an Electronic Industy Association (EIA) standard you may want to look for, EIA-310, that is the industry standrad for rack mount equipment.Hope this helps you :)Regards,Synapsys Quote Link to comment Share on other sites More sharing options...
Jidis Posted September 3, 2005 Report Share Posted September 3, 2005 Ingebret,I've built more than I care to think about ;)I learned from bad experiences to be a bit generous on the i.s. dimensions. I usually go 19 &1/8" on the inside width. The rails are really easy to shim inward with a couple thin strips of cardboard or rubber, and you won't notice it at all. There's nothing worse than going the exact dimension and finding one piece of gear who's ears are a tiny bit wider than the others.I give them a fraction more at the top and bottom as well. The rails will give you the proper space to space dimension, with the exception of that one device with the "tall" chassis screws that seems determined to destroy all your other hardware.-Good Luck Quote Link to comment Share on other sites More sharing options...
Guest analouge Posted September 5, 2005 Report Share Posted September 5, 2005 Hey!Thanks a lot!!I have another question... a little more "technical" than dimensions :DOK... I've got a digital yamaha mixer that I use for live applications. And I also just got hold of an old phonic mixer. I thought of using it for multitrack recording into a hd recorder or so... or maybe as a seperate monitor mixer...And as the good DIY person, I started to search for solutions for splitting the signals from stage to both mixing consoles. I noticed that it was a problem just splitting microphone or similar sources by just splitting the cables (because of the resistance in the microphone and the resistance in the pre-amp or something...). I was stupid enough to think that it was that simple... But when I started to think I realized that it wasn't that simple - OF COURSE! So I started to read theory about Lo-Z signal splitting and isolation.And somewhere along the line I read that cables can function as RF antennas if enough RF energy is fed to the cable... Don't know if I understand it correctly, but... As I understood the theory you can reduce the RF stuff by using "natural" shielding in the room or - RACKS - etc... Like steel enforced concrete floors, walls etc - AND steel/alu racks.First I thought of building the rack from plywood or so, but when I read about the RF stuff I started to think that a steel rack would be better for reducing noise in the system... Does it really help? Or did I understand this totally wrong? I am NOT an electronic engineer expert kinda guy like our beloved TK :), so I am pretty much not sure of anything yet :). I considered buying splitters also, but as I said, I like to make the stuff myself - much more funny :D. And I suspect that it would be very expensive to buy splitters for 16 channels :P - maybe expensive to build it myself too - don't know - but at least I will have fun doing it :P.Since I usually work with fairly big live applications, a lot of the time I have problems with noise from all kind of equipment around the space - like dmx lightning, dimmers, RF "noise" etc.. SO I pretty much want to build things the right way, so that it doesn't pick up more noise than it have to :).I guess this was a pretty long post... But if someone knows if a steel rack can help shield RF signals better than a plywood rack, I appreciate all tips I can get :)...Anyway - if someone has some tips on how to build splitters - like theory - parts - online resources - anything - I really appreciate that too :)Thanks for the help again guys - really useful :)Ingebret Quote Link to comment Share on other sites More sharing options...
Jidis Posted September 5, 2005 Report Share Posted September 5, 2005 Hey again,I think it can help, but it's effectiveness will depend on the signals and frequencies you're trying to block. Hopefully someone more knowledgeable here can explain. I had to laminate sheet aluminum to both of my isolation cabinets in the control room due to the fact that I was running "caseless" computers. Years ago I wanted to shield either a CRT or a speaker, and a tech here explained that in order for it to be effective in that range, I'd have to use expensive mu-metal, or go with some ridiculously thick stuff. Shielded speakers supposedly use a specially designed magnet which counters the emissions. I'm guessing balanced transmissions and proper distance are the most realistic solutions.-- Sorry if you already knew all that ;)George  PS--- I just remembered that with certain noise, any little gap can allow passage. I had to couple metal screening to the inner shields where my fans were. In other words, I'm not sure a rack which was wide open on two sides would defeat the purpose. I know there are a lot of them in the server/network industry, but it may be more for the durability.PSPS------ Also remembered your mention of lighting/dimmer noise. Another thing to try might be isolating your gear from the noise makers. I've got variac dimmers in both my rooms to kill the regular dimmer buzz. An iso-transformer or some filtering may help if it's "safe" enough. I've got one here as well, but I think it makes as much acoustic buzz as anything it knocks off the power line. ;D Quote Link to comment Share on other sites More sharing options...
moebius Posted September 6, 2005 Report Share Posted September 6, 2005 You're probably talking about EMI here as RFI shouldn't bother anything but sensitive high speed systems..Analog Devices Application Note "AN-347: Shielding and Guarding" is still a nice reference for sorting out some problems, even in studio environment.Some tips: Keep power and signal cabling separated.EMI should follow an inverse-square law - so doubling the distance between the EMI source and what ever it's picked up by should make the field to be only 1/4th.Fluorescent lighting is bad, m-kay.Bye, Moebius Quote Link to comment Share on other sites More sharing options...
Martin_Haverland Posted September 7, 2005 Report Share Posted September 7, 2005 So i want to bring a little light into a more professional way to handle all kind of noises from the stage and studio points of view.If i understand it right, you use almost exclusively unbalanced consumer level (-10dB) line signals and want to have them splitted for mainly live use i.e. gear to FoH mixer/recording mixer/monitor mixer.The pro version of what you want would cost you a big amount of money. The highest level would be an active transformer splitter box with every channel having a transfomer with a primary 600 Ohm (line level? check your gear for this in the manual) impedance winding (mics would be rated 150 Ohm normally) and optimally THREE secondary windings (all 600 Ohm to match line or 150 Ohm). I really don't know a standard splitter transformer having more than 2 secondary windings. But nothing is impossible...just didn't heard of. You can buy lams and bobbins and stuff and end up winding yourself (diy!) - resulting in a bad sounding 100 tons heavy box...Other option: get a 2x splitter transformer, standard model with one primary 600 Ohm to 2 secondaries 600 Ohm per channel (leaving out either monitoring or recording) and pay around 50-60$ (per channel) without mounting hardware and stuff.Last option: an active transformerless splitter. (search the net for this and "diy", you will find various options for this, many of them quite professional!) May be opamp based or even discrete transistor tech. fairly easy circuits but must be made with a good will of perfection as you will route all your signals at the earliest stage thru them.BTW, a fairly pro level splitter is for example available from whirlwind (with trafos i think). Costs: approx. 350 to 450$ for 4 channels to split. A pro 24ch split (complete small console) is rated at 3k$ normally...Other question: Steel rack for shielding your signals...My opinion: nearly useless to think about that...it's the least important factor for noise rejection (otherwise all live racks would be steel racks i think ;D).Gear placed into racks is almost EVER shielded by it's own casing. Most sensible part is the cable works in the rack and proper grounding. Each device has to be checked for hums due to a ground loop (most evil in a live situation). For decent description read the AN's of Jensen Transfomers Inc. . Lots of info about that. In fact one could write books about this, really...Organize your psu and signal cables on the backside of your rack to avoid noises (keep both types AWAY from each other as far as you can and fix them).Use good and stable wallwart psu's (if you have to). Often reduces noise ALOT.And last but not least think about using symmetrical signals when leaving the rack! Get a decent DI box. Again, a good (and i mean good = pro *usable*) DI Box is transformer based and *really* expensive (100 EURO per channel is absolutely a kind of standard, the trafo itself normally cost 60 Euro without the active electronics, mounting, etc...).On the other hand especially in live applications symmetrical/BALANCED signals tend to be a milestone for a good noise rejection. (signal is doubled with diametral phase, at the receiver phases are paralleled again, so (nearly) all noises from external influences are killed when the signals were summed again - just in short and bad english).A cheapy recommendation is the exeptionally cheap and small (1 rack unit) Etek 16x DI Rack unit. More awful than behringer in terms of solidity and inside electronics but i was really surprised - it's fairly usable! (Maybe i would buy a decent single DI for bass signals...)I hope it helps you a little with your decisions...Kind regardsand happy DIYMartin Quote Link to comment Share on other sites More sharing options...
Guest analouge Posted September 12, 2005 Report Share Posted September 12, 2005 Hey.I'm happy to see that there is people here that knows something about this stuff... I really don't know very much, so I'm very glad you guys do :) Thank you!Well... A lot of answers here. I really appreciate it guys!What I didn't think about is one thing you said Martin. That the rack equipment is shielded itself, and that it is the cables that are the real danger for picking up noise... Did I understand you correctly there? When I think about it, I should have known :-[I read everything I can find about the Jensen transformer stuff.... REALLY good resources there!! :DI have some more questions and explaining what I mean, but first I need to clear things up in my head... :) hehe. Thank you again! All you guys have helped me a lot in my quest of understanding what I need and what I have to do. I hope you can help me some more when I come back with some questions later...Cheers!HAVE FUN!Ingebret Quote Link to comment Share on other sites More sharing options...
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