One of the BIGGEST myths in audio…

If you’ve ever worked with wireless microphone kits before, you may already know where I’m going with this.

This myth is so prevalent that I’ve met more technicians who believe it than those who don’t.

But if you actually research what the correct approach to gain staging digital wireless kits is, you’ll realize this belief is just plain wrong.

Here’s one of the biggest audio myths:

“You should always set wireless gain to 0dB”.

I’m not sure how this myth started.

Maybe it’s because 0dB is a good target SNR for your input and output fader levels (ie unity gain).

Maybe it’s because people think the preamp of the receiver isn’t as good as their mixer preamps.

Maybe it’s because analog wireless relied on companders that degraded audio quality especially over greater distances.

Regardless, here are some facts for you:

• Proper gain staging starts with the transmitter.

• Most digital wireless kits manage transmitter gain via the gain increase/decrease buttons on the front of the receiver. This is what your receiver’s audio meter is indicating.

• There is no magic, one size fits all dB value.

• The goal is to acquire a healthy audio signal level from your transmitter BEFORE it gets RF Modulated or digitized and sent to your mixer.

• Otherwise, you’re compensating with your mixer preamp, resulting in a noisy signal and RF Hiss.

• In digital wireless systems, the transmitter gain dictates the dynamic range of your analog to digital converter. So if set too low, you lose dynamic range.

• If you’re barely seeing signal in the receiver’s audio meter, your transmitter gain is too low.

• Your wireless receiver channels should be set to line level to reduce noise as well.

• Your mic offset should initially be set to 0dB. You can utilize this feature later if you need to and can adjust overall transmitter gain on the receiver to keep signal healthy for both mic types. This is just good general practice - only use mic offset if you need it.

• If you do this, your mixer should still see a signal that requires amplification.

• You can then use your mixer’s channel preamps to bring each transmitter up to an appropriate level with faders at unity, adjust speaker amplifier levels for volume, and use faders for fine tuning the mix.

• Your mixer’s preamp should just be flavouring the sound and bringing it into an audible range, not compensating for improper initial gain staging where the SNR is too low.

• It’s okay and in fact, normal for you to need to adjust transmitter gain levels a few times because the dynamic range of each presenter/performer is going to vary.

• If the dynamic range is too large for a given presenter/performer, you can use a subtle compressor to reduce the variance in gain levels, rather than constantly adjusting the transmitter gain. Just make sure the transmitter isn’t clipping.

• Avoid make up gain as a volume tool. Bypassing the compressor shouldn’t result in a big difference in average volume. Dynamics tools are meant to adjust extremes not necessarily averages.

• Shure Digital Wireless Kits have excellent preamps. There isn’t a clear advantage to relying solely on your digital mixer’s preamps and this approach can actually cause problems.

  
  

So, no, you should not always set your transmitter’s gain to 0dB.

This should be obvious as you’re perfectly comfortable using mic offset to normalize inherent signal differences between handhelds and lavs.

When you do that, your lav’s transmitter gain is no longer 0dB, even if the audio meter on the receiver says 0dB.

Yet, for some reason this is still a controversial issue.

It’s important to challenge any and all beliefs, especially if there are good reasons to doubt them, and I encourage discussion and debate on this.

Feel free to ask questions or post comments!