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Gear / Technical Help => Microphones & Setup => Topic started by: caymanreview on April 23, 2005, 08:32:27 AM
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not real sure on this issue. is it allright to run phantom into something that has a 5pin xlr?
it would be V3 > 3pin xlrs to 5pin xlr cable > bodies
not really the bodies in there, just the electronics out of the bodies. im just workin on some plans for a little project ive been dreaming of for awhile and using two 5pin xlr's would be alot better than 4 3pin xlrs to keep it small
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hmmmmm. i can't remember where in the xlr cable scheme the "phantom" 48volts travels. I think it is pin 2 as that is positive and i've always seen phantom power labeled as "48+". But i can't remember if and how it travels back down the cable.
I'd say as long as you have your pin assignments correct, you should be able to work something out. I'm not positive though. I'm not as good on the electrical engineering side of the business. Still learning lots there. There's so much!
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Pin Assignment with
XLR-5M Plugs:
Pin 1: GND
Pin 2: +phase channel I
Pin 3: –phase channel I
Pin 4: +phase channel II
Pin 5: –phase channel II
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ok, so if my memory is working correctly here at 830am then you'll probably need 3pin xlr breakout cables to provide phantom down both pins 2 and 4. pin 2 from one 3pin going to pin 2 of the 5pin and pin 2 of the other 3pin to pin 4 of the pin.
seems logical to me. although i'd wait for somebody smarter about this stuff than I to further assist you ;)
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it will be 3 pin xlrs out of the v3 providing the phantom, and those combine into the 5pin xlr on the other end when they enter the project box. which where it will enter is theoretically the bodies
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oh this idea again? i was liking the cylindrical t00b idea myself.
i hope you know what you are doing ;)
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im not really going to be doing anything to the electronics except changing thier housing and hooking up the inputs/outputs to really small interconnects inside
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i know, i'm just messin'. can't wait to see it if you can bring to fruition! It'll be like building your own jklabs box :)
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its basically the same "idea" as his dvc box without the internal pre...
i want something i can slide in a small pocket of the 722 portabrace and not worry about scratching up and shit
il still be able to return the electronics to the bodies if i ever needed to
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bump, anyone have a definant answer?
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bump, anyone have a definant answer?
d;
the 5pin in the chain will not affect P48. as long as you follow the correct pin assignments, you're fine.
marc
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A cable is a cable regardless of what connectors you have. As long as the connectors are going through you might use any connector you wish.
So simply connect them through and be happy. The scheme given above is the standard version. This might help if you ever come across other equipment.
You are allowed, generally, to combine the two GND signals into one in order to save one pin. They start at the same point in the preamp anyway. It might be a good idea if you make a "Y-cable" to connect only to one of the grounds in the 5pin in order to avoid a ground loop.
Theory behind phantom power is very simple:
- take a 48 V well regulated supply
- take two resistors, 6.8 kOhm.
- connect each resistor from 48V to the two signal lines (cold and hot)
- ground of course to GND.
- power (a current) now flows from the 48V source, through the resistors, equally over the two signal lines, through the mic elecronics and back through ground.
- the signal is created by the mic electronics by at the same time pulling a little more current from the hot and a little less from the cold. This of course changes with every change in the signal so a short while later it is less from hot and more from cold.
- the mic pre registers the difference between the hot and cold signal lines and disregards any "common" signals. The largest common signal of course is the 48V phantom power if you measure towards ground which is one way to make a mic pre. (You might measure the difference directly instead if that pleases you). Another common signal might be induced hum from a power cable. This tends to be induced as much in both signal lines, and is hence removed by the mic pre.
- 48V phantom power is a very clever solution on a lot of problmes. As any engineering solution it has some drawbacks, but for just about any sound recording usage it works really well. One drawback is that the mic preamp has to create 48V somehow. This used to be a problem in portable equipment, but with todays IC circuits it is both cheap and easy. Another drawback is that phantom power delivers a little too little energy to efficiently power a tube amplifier. This is the main reason why almost all tube microphones has a dedicated power supply. And, on it goes, all in all though, phantom power is very good.
G.
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nice write up! +tee
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Dustin - are you thinking of physically separating the diaphragms from the electronics?
That's not easily done well...the raw signals are very, very low and simply adding some distance of cable between the two should be enough to mess things up good. I believe that a true 'active' setup puts an impedance converter close to the diaphragm so the signal can safely make the journey thru the cable to the bodies.
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eh what?
i was just thinking of taking the guts out of the bodies and putting them into a jk labs style box
http://taperssection.com/index.php?topic=5086.0
very similar to that, but without the internal pre
this project is officially scrapped
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what? you don't want to try this with the neumanns ???
;)
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yeah right. neumann was smart enough to not make the actual bodies 18 fucking inches long ;)
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yeah right. neumann was smart enough to not make the actual bodies 18 fucking inches long ;)
lol.....no doubt ;D