Phantom Power

[Si600]

If this is in the wrong section then please move it, it's part of the backline/monitoring world though

When to use the phantom power option on my mixer? My mics are Behringer SM58 clones (I think) plus a drum mic. The vocalist has a real SM58. Do I need to use the PP for these?

If I do, and that's fine, can I then run an XLR cable from my amp and the guitarists amp to the mixer for monitoring/recording purposes without damaging anything, would it be better to get an active DI box for both of the amps to isolate them from electrical death?

Edited September 29, 2017 by Si600

[Jus Lukin]

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Edited February 25, 2022 by Jus Lukin

[Bill Fitzmaurice]

You use phantom power with mics that need it, typically condenser mics. SM58s aren't condenser mics. Most DIs aren't bothered being hooked up to phantom power anyway, since it's assumed that will be the case in many instances. The DI owners manual will say. BTW, I can't imagine using a DI on a guitar amp, and I don't recommend them for bass either. DIs don't capture the sound of the speaker.

Edited September 29, 2017 by Bill Fitzmaurice

[Wiggybass]

I'm guessing that your mixing console has a single phantom power on / off button which will switch the +48v supply on to all the channels fitted with XLR inputs when activated. Unless you are using a condenser microphone or a professional-spec DI box then leave the phantom off as it will serve no purpose.

If you do connect something that needs phantom power to operate (and this will be made clear in the spec and packaging) then you will have to turn the phantom on at the desk for it to work. If this is the case then you need to be sure that anything else you connect to one of the inputs is phantom-tolerant. Most things will not be affected at all but some cheap dynamic mics might not like it. Depending on the quality of your guitar amp, its DI output may also not like seeing +48v.

Typically guitarists don't use only a DI feed from an amp to record as it will be very dry and sterile, but it's not uncommon to use a DI feed along with a mic (or mics) in front of the cabinet then mix to taste. Bass guitars are easier to DI (both for live and recording) because of the frequency range they produce but again you'll probably need to mic the cab as well to get a true representation of your bass sound.

[Dan Dare]

[quote name='Bill Fitzmaurice' timestamp='1506696630' post='3380515']
You use phantom power with mics that need it, typically condenser mics. SM58s aren't condenser mics. Most DIs aren't bothered being hooked up to phantom power anyway, since it's assumed that will be the case in many instances. The DI owners manual will say. BTW, I can't imagine using a DI on a guitar amp, and I don't recommend them for bass either. DIs don't capture the sound of the speaker.
[/quote]

Bill's right about DI for bass not capturing the tone of your rig. However, I find it can be handy to add a little bass to the PA via the DI. It fattens the sound out front and gives a bit more weight to the sound from your rig on the stage. In larger venues and with a bigger PA, just mic up the cab.

[bazzbass]

generally an active DI and condensor mics want PP , if you have them , turn on PP, it won't harm the SM58s or most other dynamics