Radial Stagebug User Guide
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Speaker Cable Chart

Speaker Cable Chart Guide

Using The Headload™

The following page describes the basic hook-up and functionality when using a Headload. For complete details, feel free to click on the icon at left to download the full manual.

Connecting speaker and amps

To use the power attenuator, you connect the output of your amplifier to the FROM AMP jack on the Headload and connect your speaker cabinet to the TO SPEAKERS jack. The impedance of your amplifier and speaker cabinet must match the impedance of the Headload. For instance, if you purchased an eight Ohm Headload, you should only connect it to a matching eight Ohm amp and speaker cab.

For the best power transfer it is important to use heavy gauge speaker cable with the shortest possible length. Refer to the speaker cable chart or the Users Guide for more information.

Connecting two speaker cabs

The Headload is equipped with two parallel TO SPEAKERS jacks that make connecting more than one cabinet easy. However it is important that the combined impedance of both cabinets match the impedance of the Headload. For instance, two 8 Ohms cabinets equal a 4 Ohm load. Therefore you would need the 4 Ohm version of the Headload to connect two 8 ohm cabs.

Before activating your amplifier, make sure the volume controls are turned off. This precaution will reduce opportunity for damage should a connection or cable be faulty. Always test at low volumes. Plug the power supply into the Headload. There is no power switch. As soon as you plug it in, the power on LED on the front panel will illuminate to let you know the Headload is ready to be used.

Using the power attenuator

The power attentuator lets you drive your amp hard while keeping the speaker volume low. This lets you optimize the tone from your guitar amplifier without having to perform at ear-blistering levels. You can shave off a little to bring down the volume on stage or cut the speaker level way down for recordig and rehersing at home.

The LOAD control adjusts the speaker volume from 100% (no attenuation) down to 20%. When the 20% setting is selected, the RANGE control can be used to continuously adjust the speaker volume down to 1% of the original. This is particularly beneficial in the studio or on very quiet stages.

After you have adjusted the attenuation, try testing the RESONANCE switches to hear their effect on the tone. These are used to boost low or high frequencies to your speaker cabinet and compensate for the way the human ear responds to music when listening at low volume levels.

Using the loadbox

You can mute the Headload’s speaker outputs by selecting the OFF position. This enables silent performance, recording, or practicing via the built-in headphone amp. The safest way to use the Headload is to always have a speaker cab connected, however it is possible to use the Headload without a speaker when the LOAD switch is set to OFF. Please observe the following user warning before operating the Headload without a speaker cabinet:

The danger is the LOAD switch could be bumped or moved and potentially put the Headload and/or amplifier at risk of damage. For this reason we recommend the Headload be connected to a speaker at all times. If you choose to ignore this warning, you should check the position of the LOAD switch before each use to minimize the risk.

Using the JDX direct box

The Headload is equipped with a built-in Radial JDX direct box. The JDX is designed to capture the sound of your amp/speaker and feed a balanced line to a mixing console or recorder without having to necessarily use a microphone. The benefits of using the JDX are lower sound pressure levels on stage, a consistent guitar tone night after night and of course, quiet recording for those late night sessions.

The JDX features two balanced XLR outputs. The Pre-EQ output produces the classic JDX signal and is intended to feed a clean stable signal to the FOH PA system. The Post-EQ output offers more control over the tone by adding a two-band EQ and five additional speaker emulation voicings to the JDX. The POST-EQ output is intended to feed the monitor system. Connected this way you are able to hear the effects of the JDX equalizer and VOICING switch in your monitors or in-ear system and fine tune it to your liking.

NOTE: You can also audition the JDX equalizer by connecting a set of headphones to the Headload. This way, you can mute the speakers by setting the LOAD switch to OFF and quietly go about testing the JDX EQ and VOICING controls.

The JDX features a two-band EQ and six speaker emulation filters. While listening to the Post-EQ output (or headphones), test the SPEAKER CAB VOICING switch. Setting-A is the classic JDX sound and the other five settings emulate the character of different types of speaker cabinets. Choose a setting that works best with your system.

The two-band EQ boosts or cuts the low and high frequencies and is used to make fine adjustments to the tone. You can use the HIGH EQ to add presence to a dull sounding amp or tame an overtly bright one. The LOW EQ can boost a weak bass response or clean up a muddy sounding amp by rolling off bass.

Using the Phazer

In order to get the most natural tone from a guitar or bass amp, many engineers will opt to combine the sound of a microphone with a direct feed. Because the microphone is distanced away from the loudspeaker, a slight time delay is introduced when compared to the direct electrical signal produced by the Headload's JDX 'hard' electrical output connection.

To compensate, the Headload is equipped with a Radial Phazer that essentially delays the JDX output so that it can be phase aligned with the microphone. The Phazer is completely analog and will only shift the sound to 360 degrees. It is not a digital delay.

Place a mic in front of your speaker cabinet and patch it into the first channel of your mixer. Next, take the JDX XLR output from the rear of the Headload and connect it to the second channel of your mixer. Note there are two JDX outputs: the first is dry (pre-EQ) and the second is wet (post-EQ). Turn up the mic channel to make sure it is working. Now test the direct JDX output. Set both channels to the same volume and listen. Activate the Phazer and slowly rotate clockwise. For fun, depress the 360° switch to set the phase adjustment range from 180 degrees to 360 and experiment. You will be amazed at how wide a tonal landscape you can create.

Its purpose is to shape the sound by shifting the phase of the JDX signal from the Headload in relation to a microphone signal allowing you to tune the overall phase-response of the combined signals. The diagrams below show the phase offset created by the JDX and microphone signals. The Phazer is used to shift the JDX signal and align the fundamental waveforms. You simply dial in the amount of phase shift that sounds best to your ears.