I have a few questions regarding the usage of radio mics and their input level into an SQN mixer;

Does the radio transmitter/receiver for the mic transmit/receive "mic level" or "line level" audio, and what setting should the input selection be on the SQN channel? (i.e. 48v, 12v, line, dynamic, 12vt etc)

Does selecting one input over the other reduce the pre amp noise floor?

Many thanks

2 Answers 2


Depends on the radio RX.

Lectrosonics, Micron and Zaxcom can output at mic or line level,

Audio 2040s and the G2 range are mic level. The mixer doesn't make a difference long as it can take line or mic in.

Dynamic is mic level without power, so depending on your RX it would be line or dynamic (mic) level

The inputs make no odds. SQN are noisy preamps, but that is a good reason to use line level radio mics to reduce the gain structure :)

  • Thanks for that :) @user8233 I'm planning on using Micron Explorer SDR550 RX, but cannot see where mic/line can be selected? There is only an rf gain dial……Although, there is a gain setting on the TX700B (Micron Exporer) 0-9 currently just keeping at 0. I'm guessing that therefore this particular RX only outputs mic level? And therefore dynamic 200 ohm input selector would suffice?
    – user8231
    May 18, 2014 at 20:03
  • 1
    Off topic: I don't consider the sqn preamps noisy. Yes they are old, and the heaphone preamp is noisy, but combine the sqn with a set of mkh mics and you have a very good ENG/docu set... Unless the newer models have gotten worse performance. On topic: can't you test the setup with different settings? May 19, 2014 at 7:52

With a wireless mic, the microphone takes in a signal on the transmitter. Depending on the transmitter, it may accept line level, mic level or both.

The transmitter then either translates that in to radio waves or digitizes it and transmits the digital audio. The exact means is defined by the particular microphone system and is basically irrelevant to your purposes. The important part is that the receiver knows how to read that signal and translate it back in to an analog audio signal that is produced by the receiver.

Similar to the transmitter, the level of signal that the receiver produces is dependent on the receiver and doesn't necessarily match with what went in to the transmitter. You should not need to (nor should you) send any phantom power (+##V) to the receiver as the receiver uses its own power. It is most likely giving a line level output, but that isn't a guarantee.

If your transmitter supports both line and mic level, you should choose whatever level your input actually produces to ensure the least noise. This selection determines how the signal is translated to radio waves and generally, this processing and transmission is the easiest time for it to pick up noise. Using incorrect settings will result in a too loud signal that clips or a too soft signal that gets excess noise.

  • Thanks for the detailed response :) furthermore to my query, the Micron Explorers I am using transmit/receive mic level, but selecting "dynamic mic level" produces far more noise (and "hotter level") than selecting 48v on the SQN input. Can you perhaps offer a suggestion on why this is? Or is this possibly a gain staging problem? I am just trying to figure out why these radio mics are causing a little more background hiss than I'd like
    – user8231
    May 25, 2014 at 7:21
  • 48v isn't going to be related to the level. Most likely dynamic level means it tries to maintain a constant output level and may result in excess gain being applied. If the preamp in the device isn't very good that could produce more noise than handling the gain later potentially.
    – AJ Henderson
    May 25, 2014 at 13:32

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