Something weird is happening with phantom power and Dynamics on my Firepod

[AndrewClaycomb]

I use 2 Firepods chained together and this problem only happens on Channel 3 of one of the Firepods. When I have a microphone requiring phantom power hooked up like a LDC I don't have any problems. But if a Dynamic is plugged in like an SM57 or a Beta57a, I'm getting a loud buzz. It also doesn't happen with a phantom powered dynamic like my Blue kickball.

My question is what can I do to fix this? The Firepods will only apply phantom power to 4 preamps at a time, so I can't simply turn off phantom power all the time. Luckily today when I was tracking drums I was able to just throw the mic to the unused section (group of 4) of my second firepod and I could keep going but if I'm doing a "live in the studio" type of recording I won't necessarily always be able to do that... I've got some "live" stuff coming up next month.


EDIT: I meant to post this in The Rack, sorry.

[mattr]

Have you checked the cable you were using with a cable-tester? Unbalanced or cables with shorting connections can cause problems with phantom power.

[AndrewClaycomb]

I checked it on 3 different cables both through my snake and bypassing my snake. All the cables work fine in other channels with the same mics.

It's definitely the one preamp. I don't know if it's really a problem though because phantom works fine with mics requiring phantom power. And everything works as it should when power is disengaged. It seems that all mic manufacturers say not to use phantom power unless required to cover their asses anyways, so I don't know if it's worth sending in just to have Presonus tell me the same thing.

[mshilarious]

Originally Posted by AndrewClaycomb

so I don't know if it's worth sending in just to have Presonus tell me the same thing.

That channel is clearly defective, so they should not say that at all. I would send it for repair.

[antichef]

I've got an Inspire 1394, and recently when I turn on phantom (on either of the two channels that support it) I get a loud rapid thumping hum -- I'd call it "motorboating" if I hadn't seen that term used for what might be something else. Anyway, it's unusable with phantom on, whether there's a dynamic or a condenser plugged in. It seems like the progression to this state was gradual, but I've only used it intermittently over the last couple of years, so it's hard to say.

[reklus]

Originally Posted by AndrewClaycomb

I checked it on 3 different cables both through my snake and bypassing my snake. All the cables work fine in other channels with the same mics.

Do you have any other preamps you could use instead? Going through the pre, down to a TRS cable might fix the issue.