Blocking Phantom Power

[Jazznoise]

Hey guys, this probably appeals less to some than others but I'm interested in building a box that will allow me to use a desk with universal phantom and not have to worry about phantom getting on any Ribbon mics.

My 2 modes of thought so far is high voltage DC caps on pins 2 and 3..but I'm aware this will suck some of the current which I'm trying to avoid. It'll also mess with CMR if the cap values start to get too different. The 2nd idea is a 1:1 transformer across pins 2+3, but this is expensive. However this box could have other uses, too! (Screw those transformer saturation plug ins!  )

I was wondering if anyone had tried either or had any input on the issue? I'm aware that unless you hot patch a mic or there's a faulty cable that phantom is generaly not something you've to worry about, but I can never gaurantee neither is going to happen  - so this is my solution at this point and time. I'll probably have 4 ins and outs, and maybe 2 of them will have an unbal in and out so I can drive it with something if I go with the transformer option.

Ideas? Queries? Comments? Criticism?

[therecordingart]

Are these high dollar ribbon mics that can't be replaced? I own quite a few ribbon mics, and I do two things:

-Set aside specific cables that you know are in good working order
-At our facility we have a patchbay for patching different mics to different pres...bypass it when using ribbons!

[Jazznoise]

Hey! Thanks for the reply.

They aren't, no. They're the T-Bone RM700's, 80 Euro Ribbon Mics! I've heard a few recordings and they're great value for the money. I'm not quite at the Royer stage yet 

I'm aware simple precautions can be more than sufficent but since my desk has global phantom, cables can go on a whim and there's always people. People have this huge capacity to create dozens of new problems in seconds without even really understanding how they're even doing it. So I've found this isolating transformer box that I'm going to use for it, about 50 euro for 2 channels of isolation but I'll have it forever I suppose!

[TimWaldvogel]

I personally use a 30$ active behringer direct box that sounds amazing. It runs off phantom power and it doesn't transfer it to the input.
It doesn't color my tone. And my church had been beating up the same ones for over 4-5 years now with a defective one yet. And they've been dropped !!
It's better than my radial passive DI !

[Jazznoise]

I considered using an active or passive DI to buffer it, but even despite the A/B thread I did earlier I was still afraid of the tonal changes the impedance change might give (Different strokes for different loads!). But luckily API do a Dual Transformer Isolator for 50 Euro, which is two 1:1 isolating transformers in a box with TRS and XLR inputs and outs. Can't really say I'd build one for cheaper, so I'm ordering that instead!

[a soBer Newt]

what about designing and building something similar to a fet head

[Processaurus]

http://recordinghacks.com/2008/04/02/phantom-power-kills-ribbon-microphones-truth-vs-fiction/

If it was still worrisome, you could use appropriately rated coupling caps, and on the mic side, some 1n4001 power diodes or similar to shunt the 48v transient that would sneak through the caps momentarily to ground, I don't think the average mic signal would ever be high enough to turn the diodes on and clip.