Sennheiser G4 Manual

What is wireless audio

A wireless audio system consists of a mic, a small radio transmitter (Tx), and a small radio receiver (Rx). When the mic's plugged into the transmitter, and the transmitter and receiver are both tuned to the same frequency, we can mic up something much further away than it would be practical to run an XLR cable. With clear line of sight this can be a couple hundred feet–or substantially less if there are obstacles such as walls or foliage.
Our wireless audio equipment is Sennheiser G4. We have some configured for use in the field, and some for use in the studios. Field production wireless kits can be checked out from the Production Office. Our studio wireless equipment is built into two rolling cases, one assigned to Studio A and the other to Studio B.

In the field production kits, the body-pack transmitter (SK 500) and the camera-mount receiver (EK 500) appear very similar. A closer look reveals that the body-pack transmitter has one plug on top--an input, for lavalier mic--while the receiver has two plugs on top--AF OUT, that sends mic level signal to a recording device, and a headphone plug.

We use the same SK 500 bodypack transmitters and lavalier mics in all kits: field and studio. Field kits 9-12 are EW100 with two transmitters. The second transmitter, called a plug-on transmitter, turns a Røde NTG-2, a Sennheiser K6+ME66, or any dynamic microphone into a wireless mic. These plug-on transmitters don't provide phantom power, so you'll need to make sure there's a fresh battery in your mic.

We use receivers that perform the same function in different physical packages: the camera-mount receivers in field kits and rack-mount receivers mounted in the studio carts.

Some important things:

1. A receiver can pick up signal properly from only one transmitter at a time.
2. How much power? In the U.S. wireless audio equipment can be operated at a maximum of 50 milliwatts (mW).
3. At what frequencies? Around the world, wireless audio equipment can be operated only on certain frequencies. Some frequencies are already occupied by existing license-holders: mostly television broadcasters and emergency services.
4. Already-occupied frequencies are different depending on where you are geographically. Densely-populated areas have more frequencies already in use.
5. Wireless audio is always the lowest priority use of any given frequency. If another type of device is on the same frequency we are, it has more right to the frequency than we do and we need to find another frequency. This is as true for major motion pictures as it is for student productions.
6. Fewer frequencies are available for wireless audio than there used to be, and the spectrum^[1] is getting more crowded than ever. This trend is continuing, so a frequency available today in a given place might not be available tomorrow.
7. Monitor wireless audio closely at all times for interference and loss of signal.
   Someone could turn on a device near you that wasn't on when you started the set-up.
8. How long a mic cable do you have in case you can't find any open frequencies? Unlikely but entirely possible.
9. Watch battery levels closely and bring fresh spare batteries.

1. The electromagnetic spectrum is a broad range of frequencies: VHF, UHF, microwaves, infrared, visible, and ultraviolet light, x-rays, and deadly gamma rays. Parts of the VHF band (30–300 MHz) and UHF band (300 MHz–3 GHz) are used for public safety, air traffic control, marine band radios, broadcast television and radio, Wi-Fi, Bluetooth, cordless phones, two-way radios, and wireless audio. In the United States, the Federal Communications Commission regulates what devices can use which parts of the electromagnetic spectrum.

What frequencies does our gear operate on

Our wireless audio equipment (field and studio) operates on one of three bands, which Sennheiser calls AW+, A, and GW1:

As of this writing, it's legal to use our gear at full power (50 mW) anywhere in the United States on any unused frequency in these ranges.

Finding an unused frequency

The good news is that our equipment can scan what frequencies are free or in use wherever you are at the moment and pick the best one. Here's how to do that with our field equipment:

1. Make sure you have the receiver in hand, not the transmitter, and all other wireless equipment is turned off.
2. Open the door on the front of the receiver you want to tune and press the ON/OFF button. The blue screen will light up and show you a control panel.
3. Press SET, then use the up or down arrow to find Easy Setup. Use the SET button again to select Easy Setup.
   
4. Under Easy Setup use the up or down arrow to find Scan New List, then use the SET button again to select Scan New List. The receiver takes about a minute to work across its range, identifying frequencies that would give you poor results and temporarily programming them out of the frequencies available. This is a seriously useful feature.
   
5. Scroll to Current List and press SET again.
   
6. The receiver groups currently available frequencies into banks. Scroll up and down through the 20 banks on this receiver and choose one. The receiver will choose the first available frequency in that bank for you.
7. Now turn on the wireless transmitter you want to tune to this receiver.
8. On the receiver, use the SET button and up or down arrow button to navigate to the menu item called SYNC and press to select it. The display will show "SYNC" with a large target icon next to it.
   
9. Pick up the transmitter and receiver. Look for two clear circles next to the on/off button--these are each unit's infrared sensors. Point the transmitter and receiver's infrared sensors at each other about four inches apart.
10. Three things will indicate when the receiver has tuned the transmitter to its frequency: the target icon next to "SYNC" will briefly turn to a check mark, the receiver's RF sensor light will turn from off to green, and there will be a tiny tick mark in the transmitter's display next to the frequency. Use the up- or down-arrow on the receiver to scroll to Exit and press SET to exit.
11. If the receiver displays an X, it couldn't tune the transmitter. Try the sync procedure again, holding the units closer together. Alternately, go back to Easy Setup on the receiver, choose Current List, and choose a different bank and channel, then go to the transmitter menu, choose Frequency Preset, and use the up and down arrow buttons and Set button to choose that frequency.

How do I tune a transmitter to a rack-mounted receiver in the studio cart

The procedure to tune a transmitter to a receiver is exactly the same, just the physical interface is slightly different. Pushing the big knob on the front panel of the rack-mounted receiver is equivalent to pressing the set button on the camera-mounted receiver, turning the knob clockwise or counter-clockwise is equivalent to using the up or down arrow button, and the Sync function has its own button on the front panel of the rack-mounted receiver.

What if I'm working with more than one transmitter-receiver pair?
It's good practice to choose a different bank for each transmitter-receiver pair.

Battery levels

According to Sennheiser, this is what its G4 wireless battery indicators mean:

Actual performance varies. Batteries don't last as long when they're cold as when they're at room temperature. The gear draws a tiny amount of current even when switched off.

Setting levels in the field

The wireless audio receiver and transmitter each has its own audio level you need to check and set, in addition to the record level on your camera or outboard audio recorder, so that 0 db on the transmitter and receiver are as close as possible to 0 db on the camera.

1. If your recording device is a camera, mount the receiver to the slot on top of camera called a shoe.
2. Use the ⅛"-to-XLR cable provided in the kit to connect the receiver's AF OUT to the recording device's XLR input.
3. Set the recording device to Mic level input. Leave phantom power (+48V) off.
4. Set the recording device's record level to the middle of its range (5 on a scale from 1 to 10).
5. On the wireless audio receiver, use the SET button, and up and down arrow buttons, to choose AF Out. Check that it's set to 0 dB.
6. On the transmitter, use the SET button and up and down arrow buttons and select Sensitivity to control the microphone's level. For dialogue, -21 dB is a good starting place.
7. Sound check the person (or other source of sound) you're miking up and adjust transmitter sensitivity so levels on the transmitter never reach 0 dB.
8. Set the recording device's input so record levels don't exceed -12 dB.
9. Always monitor what the recording device is actually recording. For troubleshooting it's helpful to plug your headphones into the PHONES jack on the receiver and give a listen.

Setting levels in studio

Each receiver, 1 through 4, in a studio cart is already internally wired to a mixer channel, 1 through 4. The headphone jacks on receivers and mixer are ¼" instead of ⅛".

1. Set the board's gain to half on each channel, 1 through 4.
2. Set each channels fader, as well the MAIN MIX fader, to zero.
3. Make sure the front panel of each receiver indicates that it's set to AF Out +6 dB. (If not, push in the big knob once and rotate to AF Out, push the big knob in again and rotate to select +6 dB, then push the big knob again to store +6 dB as the AF Out level.)
4. On the transmitter, start with sensitivity at -21 dB, sound check the person, and adjust so the transmitter's levels never reach 0 dB, just as in the field.
5. Adjust each channel's level up or down as needed to create record levels that don't exceed -12 dB.

What is squelch

Squelch takes the quiet parts and makes them quieter. Squelch can't distinguish noise from signal. When audio level falls below a certain threshold, all squelch does is turn it down some more. So, while squelch can reduce background noise, it can also create artifacts in the sounds you want to record.

1. On the receiver's home screen, press SET to open the menu.
2. Press the UP or DOWN button until you find SQUELCH.
3. Press the SET button to open the squelch settings.
4. Choose a very low setting such as 5 dB.
5. Press the SET button again to save your changes.

Travelling overseas

Just as the Federal Communications Commission regulates use of the electromagnetic spectrum in the United States, similar governmental agencies do so in other countries.
Wherever you go, you're responsible for knowing on what frequency it's legal to operate wireless audio gear at what power level. The Association of Professional Wireless Production Technology (APWPT) lists legal frequency ranges for some countries at www.apwpt.org. It's up to you to research what's legal to operate where you're going. Please contact the Technical Director as you begin planning any part of a production outside the U.S. around wireless audio.