Phantom power block?

  • Thread starter Thread starter dgatwood
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dgatwood

dgatwood

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I'm curious why no one seems to sell an inline phantom power block. For those of us who are paranoid about protecting our ribbon mics (or the transformers in our dynamics if you have a miswired cable), this seems like a useful tool to have lying around. You'd basically build it with a metal tube that contains an XLRM on one end and an XLRF on the other end just like the inline line this:

http://www.bhphotovideo.com/bnh/con...kw=PRMAX30&is=REG&Q=&O=productlist&sku=135094

But instead of having a voltage divider (two resistors) for each wire, you'd have a high quality capacitor inline.

Does anybody know of such a beast available commercially? Anybody know how to do metalwork? I guess somebody could start with:

http://www.markertek.com/Search.asp?search=35-465

For a cheap starting point, then add the caps and resell them. Anybody interested in such a project? MsHilarious? :)
 
You need more than caps, the caps can pass a pulse before they are fully charged, and of course they can pass AC. I have a Schottky limiter as well as a few resistors to drop incoming voltage. The resistors aren't strictly necessary, but it's easier to fit lower voltage rated caps. I have done all sorts of horrible tests, and the blocker has never passed more than 250mV, which for most ribbons is equivalent to 140dBSPL or less. If you wanted to keep it even lower, a couple of 220 ohm resistors between the transformer secondary and diode limiter will cut that voltage in half, at the cost of a couple of dB of signal.
 
Should have thought to search MsHilarious's website first. That'll teach me to Google for something obscure.
 
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