A stupid question I should know the answer to, but I always set the recorders for 24 volts. No reason, I've just always done it.
On the mics that are designed for it, does 48 volts give better performance?
I'm using MXL FR 300 mics which use 9-52 volts.
It depends on the circuitry inside the mic. Some mics reduce the external 9-52 V to something around 9 V internally, in which case it doesn't matter what voltage you supply. Your MXL probably falls into that category.
Some mics charge the back plate directly from the external voltage, in which case a higher voltage will increase the sensitivity of the mic and support higher sound pressure levels before distortion, effectively increasing the dynamic range. Mics in this category usually don't accept such a wide range as 9-52 V.
My mics can work either with an internal (low voltage) battery or with +48v through the XLR connection. According to the spec sheet, at +48v the mic has greater dynamic range. Off the top of my head, I do not remember the specific increase in dynamic range but the spec gives a definite advantage to the +48v option.
+48v phantom powering means low voltage: it is effectively only approx. 4V. +48v is kind of professional standard, but before you turn it on, it is very important to know how reliable is phantom power supply of your recording device or whatever you use on the other side of your XLR cables. Read about IEC 61938 and you will find all the answers you need.
Electret condenser mics will drop the voltage down to around 1.5-9v for the impedance converting FET biasing. The capsules on these types are not voltage biased. True condenser mics will run anywhere from 48v to 120v for the capsule biasing and can be anywhere from 3-20v for the FET biasing. Each mic is different and each will react slightly differently when given drastically different phantom voltages. Usually though, unless the mic has internal power regulation, higher phantom voltages will mean higher mic headroom. This doesn't necessarily mean much as the preamp of the recording device will likely have a lesser headroom and thus a lower DR.
It looks like you're new here. If you want to get involved, click one of these buttons!