Phantom Power

[Eboy87]

So I know they make stand-alone phantom power supplies for mics, but do they make the opposite? I'm looking into getting a Cascade Fat Head, but my concern is running into situations with a broken snake leaking phantom power onto all channels. I don't really want my ribbon mic becoming a speaker for a very short period of time. Do they make a phantom power blocking device?

Or in this case, since I can order one with a transformer, do I not need to worry about phantom? Everyone I've spoken with (since I don't have first hand experience with ribbons) says ribbon + phantom = no more ribbon.

Thoughts?

 

[mbenonis]

If there is a transformer between your microphone and the console, phantom power will be blocked. Short of adding a transformer, you could also put two capacitors in line (one on the + and one on the - leg), but a transformer would be a much nicer solution. You'll want a transformer with a 1:1 windings ratio so as not to change the impedance that the microphone sees.

It's worth noting that GOOD transformers are fairly costly...expect to pay in the neighborhood of $100 for a Jensen transformer box. That said, if you are investing in a good ribbon microphone, this figure shouldn't make you blink too much.

EDIT: Some links:
http://www.jensen-transformers.com/ (Jensen Transformers; lots of good info here)
http://www.radialeng.com/di-twiniso.htm (Dual-Channel Jensen-Xfmr-based isolator)

 

[museav]

Ian, you might want to look at Cascade's site, they state that all Cascade ribbon mics are now phantom power safe, http://www.cascademicrophones.com/cascade_PhantomPower.html. I also believe that the Fat Head has an integral transformer with options for CineMag or Lundahl transformers.

 

[Eboy87]

Thanks Muse, somehow I missed that. And yes, they do have a transformer in them; I have the option to order the standard or the Lundahl. I should think the standard suits my needs just fine.

 

[FMEng]

So I know they make stand-alone phantom power supplies for mics, but do they make the opposite? I'm looking into getting a Cascade Fat Head, but my concern is running into situations with a broken snake leaking phantom power onto all channels. I don't really want my ribbon mic becoming a speaker for a very short period of time. Do they make a phantom power blocking device?

Or in this case, since I can order one with a transformer, do I not need to worry about phantom? Everyone I've spoken with (since I don't have first hand experience with ribbons) says ribbon + phantom = no more ribbon.

Thoughts?

Your premise is a little shaky. A broken snake isn't likely to "leak phantom power onto all channels." Maybe that'll happen if you squish it by driving a big truck over it, (flattening/shredding the cable) but otherwise the most common failure is simply an open wire on one pin of a channel.

Phantom power is only a concern with some models of VINTAGE ribbon mics because they had a grounded center tap on the internal matching transformer. And then, it is only a concern while plugging things together. Basically, unless you are using a 40+ year old RCA, don't lose any sleep over it.