Radial Engineering HEADLOAD V8 Guitar-Amp Power Soak Amp Di
About the Headload
- Combination load box and DI with speaker emulation
- Available in 4, 8, or 16 Ohms
- Can handle up to 130 watts RMS (180 peak)
- Attenuate down to 1% of total power
The Headload™ is a power attenuator that connects between your amplifier and speaker to capture the dynamics and warmth of your amp at low, neighbour-friendly volumes.
Featuring two built-in JDX amp DIs—one pre-EQ and one post-EQ—the Headload eliminates the need to use a microphone to capture the sound from your amplifier. Should you decide to combine the DI signal with a microphone, the Headload is augmented with a built-in Radial Phazer to time-align the two signals to create massive tones. The Headload uses a 6-position rotary switch to set the desired power reduction from unaltered all the way down to complete silence. When the output is completely soaked, the high-quality headphone amplifier can be used for silent 3:00AM practicing.
The blue-enamelled steel case is vented high up on all four sides and at the back edge of the top plate, which implies that heat is going to be generated in the Headload’s upper reaches. Whipping off the top cover reveals a phalanx of cement-encased resistors that can attenuate a maximum of 120W RMS of valve amplification. Achieving this means dissipating up to a peak of 180 Watts as heat, and a temperature-controlled fan is strategically positioned to drive airflow across the resistor board. The front-panel controls are divided into four functional areas, the leftmost of which contains the five-position attenuation level selector switch, which reduces the amplifier output level leaving the Headload from 100 percent down to zero in increments of 20. At the 20 percent position, a trim control (which has the feel of a wire-wound variable resistor) comes into play, allowing you to reduce the amplifier output anywhere from 20 down to one percent. Associated with the attenuation level selector are the separate Hi and Lo Resonance on/off switches. These act in much the same way as the loudness control on a stereo system, by compensating for the vagaries of the human hearing at low volume levels, boosting 6.5kHz and 60Hz respectively by +3dB at 20 percent reduction, rising in +3dB steps to a +12dB boost at 80 percent reduction. The central area carries the controls for the JDX Reactor outputs. The JDX input is taken pre-attenuation and passes straight to a transformer, which effectively sits in parallel with the loudspeaker. The transformer and loudspeaker act together to form a reactive load which is not only designed to capture the amplifier’s output and the effect of the back-EMF (electro-motive force) generated by the loudspeaker’s voice coil as it moves within the loudspeaker magnet’s magnetic field, but also to provide a realistic playing experience for the guitarist. From there, the signal passes into an active, multi-stage band-pass filter, which is designed to replicate the sound you’d get from a Shure SM57 sitting a couple of inches away from one of the loudspeakers in a Marshall 4x12 cabinet. At that point, the signal splits in two, one part passing via a balancing transformer and polarity-invert switch to the pre-EQ XLR output, and the other through a voicing section that adds five cabinet emulations and offers a two-band EQ for further tonal fine-tuning. From here, the signal is split to feed three outputs: the front-panel headphone jack, an unbalanced, line-level, post-EQ, post-JDX jack and, via an active balanced driver and polarity-invert switch, a second, post-EQ balanced XLR output.