Microphone Mod/Repair...

  • Thread starter Thread starter peritus
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peritus

peritus

The not fountain head
I found this 70's looking Realistic brand dynamic cardioid mike at a thrift store for 50 cents... While I am quite aware that it isn't a Shure SM-Anything, I'd like to repair it and learn something in the process... So if you can help me, here are my problems:

1) I've taken cheap microphones apart before. This one appears to have some sort of transformer inside (that's a guess). It is shielded with foil. What is this? Does this suggest a need for phantom power? Is this what makes it dynamic (as opposed to electret condenser)?

2) There were REALLY tight knots in the cable (the plug is not on the mic itself). Also, the TS plug was bent and falling apart. Should I trim the cable really short and solder on a female XLR? Does my thinking make sense?

3) There are two wires and a metal jacket in the cable... Does the following picture properly desribe the wiring sequence?

bulkmicdgrm.gif


4) The microphone itself has a label that reads 600 OHMs / 20K OHMs... Can anyone the meaning of this in english? I understand the concept of resistance. Is this describing the microphones capable range?

5) If it's carioid, it's directional. How can I define which direction is which?

100px-Cardioidpattern.svg.png


Thanks for your help in advance!
 
1)No, dynamics don't need phantom power. Condesers are the ones that need phantom power. It usually won't hurt to send phantom power down a balanced line into a dynamic, though.

2)Why not try it? For $0.50, it can't hurt. Makes sense to me, as long as you get the wiring correct.

5)Usually, cardiod on a hand-held dynamic mic has the null spot directly towards the body of the mic. (Yeah, akward, I know, but its easier to show you than to tell) So in your picture, the mic would be facing upwards, with the capsule at the top, and the body and cord heading down. Do you get what I mean?
 
The transformer and the dual ohm rating suggests that your mic can be wired as a balanced low-impedance mic (XLR connector) or unbalanced high-impedance mic (1/4" TS connector), as does the two conductors and separate shield in the existing cable.

If the cable is detachable, I'd pitch it and go with a balanced XLR-F to XLR-M mic cable, unless you need to run it unbalanced.

Since you received it with a 1/4" plug on it, I'd say it's wired as a high-impedance mic; I'm also guessing that the two main conductors in the mic cable were wired to the tip, and the shield was wired to the sleeve.
 
Wow... Thanks guys... I'll let you know what I come up with...
 
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