Q: I liked the review you did on the Focusrite iTrack Solo, but have a question about results you got with the SM58 mic.  I have purchased the iTrack and have had mixed results with vocal recording and the SM58.

Did you use the phantom power when recording with the SM58? The connector on my mic cable required that I record through the guitar channel.  I got decent sound from it, but I had to practically eat the mic to get volume high enough to move the meter in GarageBand.  In the end, the sound is a bit muffled. I will be trying the mic channel with some new cable, but thought I would ask your opinion.

– Paul

A: Like almost all professional microphones, the SM58 is a low-impedance microphone, and therefore needs to be connected to a low-impedance input, such as the first channel on the Focusrite iTrack Solo or the IK Multimedia iRig PRE. Both of these require an XLR connector, which are normally the standard cables with most professional microphones, although XLR to 1/4” connector cables are also sometimes used with certain mixing boards and other audio equipment.

By contrast, guitar jacks are high-impedance inputs, designed for connecting guitars as well as other professional audio equipment such as preamps and effects processors. Connecting a low-impedance audio source, such as a professional dynamic or condenser microphone, will yield exactly the results that you are experiencing—low volume levels and muffled sound.

Note that you don’t need to use phantom power with the SM58 or other dynamic mics; simply pick up an XLR cable and plug into the mic input and you should get proper results. Alternatively, you could also purchase a high impedance transformer for the SM58, but that would be far less practical both in terms of price and complexity than simply getting a new cable, since the iTrack Solo already handles the low-impedance mic input on the first channel.