A stereo miniplug is UNbalanced, while phantom powering is for balanced microphones. You're not just wiring a mechanical adapter (like the difference between the two well-known types of stereo headphone plug, both of which have the same number of contacts but are different-sized). You're also converting the audio signals themselves from one format (two leads whose voltage is related only to one another, enclosed by a shield that's independent of either lead) to another format that works on a different principle (a single lead carrying a voltage that is referenced only to the shield that encloses it).
Different microphones have different types of balanced output circuits with different (in some cases diametrically opposite) requirements for how unbalancing has to be done. There is no standard for this, since standards are either professional or consumer, and professional standards are generally all balanced all the time, while consumer standards are all unbalanced all the time--so the translation between the two realms is like a blind spot in the standards. The approach you need to use depends on the output stage design in your particular microphones. Thus anyone who tries to tell you how this type of adapter should be wired (or to sell you one) without knowing the specifics of the microphones you'll be using it with, is basically proving that he doesn't know enough about the subject to be giving you advice on this topic.
The only "universal" method that will allow any and all known balanced microphones to drive unbalanced inputs is to use a suitable transformer at the unbalanced input. That effectively makes the input balanced as far as the microphone and the phantom power supply are concerned, so the problem basically goes away. Unfortunately, good audio transformers are neither cheap nor tiny. Other than that, you'd have to get advice from the manufacturer of your particular microphones, or see whether the manual for your microphones covers this situation (as Neumann's and Schoeps' manuals do).
There are four different possible hookups for balanced-to-unbalanced conversion without a transformer, and three of the possible four are needed by different microphones that people here often mention using. No matter which of these ways you wire the plugs coming out of the PS-2, it will simply not work correctly, or will not work at all, for many types of microphones. That's just the way things are; I'm sorry.
I wouldn't even go by someone else's word that they tried a certain wiring arrangement with your type of microphone and that it seemed to work, because there are numerous cases in which you will get a signal, but the microphone will have considerably lower headroom (ability to handle loud sound without distorting) than it would have if you wired things the right way. Check with the manufacturer and follow their instructions. Don't accept folklore as a substitute, even when it's coming from a friendly place such as the nice people on this board.
--best regards
P.S.: To be specific, the four ways are:
[1] Tie pin 3 of the mike to pin 1, use pin 1 as the ground and pin 2 as the hot lead.
[2] Tie pin 2 of the mike to pin 1, use pin 1 as the ground and pin 3 as the hot lead.
[3] Leave pin 2 unconnected completely, use pin 1 as the ground and pin 3 as the hot lead.
[4] Leave pin 3 unconnected completely, use pin 1 as the ground and pin 2 as the hot lead.
For example, a (transformerless) Schoeps phantom-powered microphone should use method [4] (it will distort if you use [1] or [2], and will have inverted signal polarity if you use [3]) while a Neumann KM 184 should use method [1] (it will produce no signal apart from a very small, noisy crosstalk voltage if you use another method) and a Neumann KM 140 should use method [2] (same remark, though unfortunately method [2] produces inverted signal polarity, which can't be avoided given this output stage design).
Note that the Neumann KM 140 and KM 184 are essentially the same microphone sonically, but one series is modular while the other isn't, and their output circuits are different enough that you can't unbalance their signals the same way. It's individual to that degree, depending on the particular model of microphone--it's not even necessarily consistent within the same brand of microphone.
Topic: Modify a PS2 : XLR out to mini plug (Read 6747 times)