HeadRush | VX5 AutoTune - Why is there a hiss/hum/buzz coming from my VX5?

There are a few reasons why you could hear a higher-than-expected level of hiss/hum/buzz coming from the VX5 and all of them are simple to check and fix.

TABLE OF CONTENTS

• Check that the ground switch is in the right position
• Check that the VX5 is connected to a line-level input on your mixer, interface, or speaker system
• Check the signal flow balance between your microphone, VX5, and mixer, interface, or speaker system (Gain Staging)
• Check your cables

Check that the ground switch is in the right position:

The "right" position depends on the other devices in your setup, but the easy test here is to simply flip the GND/LIFT switch on the back of the VX5 between the settings. If the buzz or hum goes away in the LIFT position, this means there is electrical ground noise bleeding into your audio signal, and the switch is now doing its job to filter this out. The dependence on this switch may change from one location to the next, or the devices connected to the VX5.

Check that the VX5 is connected to a line-level input on your mixer, interface, or speaker system:

Without the VX5, you may be connecting your microphone directly into a microphone preamp (mic input) on your mixer, interface, speaker system, etc. To simplify it, this is necessary because a microphone output level is very small and requires special amplification from a microphone preamp in order to reach a suitable level (line-level) to use with a mixer, speaker system, software, etc.

The VX5 microphone input is built with this microphone pre-amplification, so the output of the VX5 is already at line-level. This means that you will need to connect the VX5 to a line-level input on your interface, mixer, speaker system, etc. Running the output of the VX5 into another microphone pre-amp may result in a high level of noise and distortion because the signal may receive too much amplification.

Line-level inputs on your mixer/interface/speaker system can come in many forms and will be different depending on the device. For instance, a mixer may have a dedicated line-level TRS (1/4"/6.35mm) input for each channel, a button or switch to choose the input level for the channel, or it may have entirely separate line-level channels. Other inputs may accept both mic and line-levels and provide enough gain range to handle both, in which case you may not even notice unless you apply too much gain (see next section). To know for sure, please consult documentation or the manufacturer of your mixer, interface, or speaker system.

Check the signal flow balance between your microphone, VX5, and mixer, interface, or speaker system (Gain Staging):

Gain staging is the process of balancing input and output signal levels across your signal chain (i.e. Microphone > VX5 > Mixer/Interface/Speaker System) so no one input gain or output volume control is overcompensating for a low signal level earlier in the signal chain. For example, noise may occur if the input on the VX5 is set too low, and your speaker volume is set higher to compensate for that low signal. This noise (usually a hiss, hum, or buzz) is what's called the "noise floor" and it is always present in an audio signal, albeit extremely low and inaudible. If your microphone does not receive enough gain from the microphone preamp, the microphone signal will be closer to the noise-floor. Therefore, when you increase the output volume of your VX5 or speaker to bring the signal up to an appropriate level, you are also increasing the level of the noise floor.

Gain staging is actually very simple and really only means utilizing the signal/limit LEDs on your device inputs. Here's an example of gain staging between a microphone, the VX5, and a loudspeaker:

1. Start with the loudspeaker turned off (power or input level) or set to a low-level.
2. With your microphone connected and the VX5 turned on, start speaking/singing into the microphone at a decent level - you want to predict the maximum volume your voice will reach and use that to set your input level. This will prevent a loud moment later on from clipping your input and distorting.
3. While speaking/singing, increase the input gain on the VX5 until you see the PEAK light turn red, then reduce the input gain just enough so the PEAK light no longer blinks red. Don't worry, there is a good amount of range to set your level without clipping and without increasing noise, so setting your levels a little lower is probably fine and good practice to prevent unwanted distortion.
4. While still speaking/singing, do the same with the signal limit/clip/peak LED on your loudspeaker and the output Volume knob on the VX5 - increase the output Volume level on the VX5 until the signal limit/clip/peak LED on your loudspeaker blinks red, then turn the volume down just enough until the LED stops blinking red. You may want to refer to the loudspeaker documentation for that model on how exactly to interpret the input and LED behavior. Note - if your loudspeaker or receiving device does not have a signal limit/clip/peak LED, you'll need to listen for distortion in the signal to determine when the signal is too high and should be turned down.
5. At this point, you should be able to increase the level on your loudspeaker, and you will have a clear, noise-free signal from your VX5.

This is a simple example, but if you can understand the importance of the practice, it can be easy to apply to different devices or larger signal chains. If you are having trouble doing this with a larger, more complex signal chain, consider removing devices in the chain and adding them back one-by-one, or learning more about gain staging and other factors, such as impedance.

Check your cables:

This is usually obvious, but it's important to check your cables as well. The best way to test a cable is to simply swap it with another or use it in a completely different setup. If using longer cables, make sure they are shielded/balanced and avoid running these directly parallel to any extension cables or long power cords because this can create noise in the cables signal.

You will also want to check or eliminate any adapters in your signal chain. Adapters aren't necessarily a problem, but they are an extra link in the chain and therefore an added point of failure.