Radial Headload Guitar Amp Load Box | Vintage Guitar® magazine

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As low-power amps gain in popularity, one wonders what will happen to all the 50- and 100-watt amps starting to gather dust in storerooms. Radial Engineering’s Headload attenuator/load box to the rescue! Jitter Attenuator

Radial Headload Guitar Amp Load Box | Vintage Guitar® magazine

The Headload’s attenuator section gives the player the option of dialing up 1% to 100% of the amp’s output (120 watts max) to his or her favorite guitar cab. The Headload is available in 4-, 8-, and 16-ohm versions (the tester was an 8-ohm version).

The attenuator’s controls are simple. A Load knob notches at 100, 80, 60, 40, and 20%, and if your roommate is asleep and you need to really drop the output, the Range knob sweeps from 20% down to a miniscule 1% of output. There’s also an Off detent that cuts signal to the speaker cab for silent recording (warnings in the manual and on the unit itself advise to always have a the unit plugged into a speaker/cab). Along with the attenuation controls in this section, there are two Resonance switches (Lo and Hi) to compensate for the ear’s perceived need for more lows and highs at lower volumes (for you sound geeks, this phenomenon is described by the Fletcher-Munson curve). These switches work much like the “Loudness” button on your ’70s-era stereo.

Working with basic/no-frills 60-watt amp that had never seen its Volume turned past 8, the Headload easily managed the volume drop at each indent. At 40%, the tone was creamy and still loud enough for small club work. At 20%, we turned on the Lo Resonance switch to beef up the sound a bit and, using the Range knob, dialed down to 1%, activating the Hi Resonance switch at about the midway point. Even at 1%, the tone was pleasant (and quiet). More importantly, it had the sustain and feel of an amp at full stage volume. It’s not a stretch to say this particular amp, always too loud and crass to use without the help of pedals, never sounded so good. Adjusting the amp’s preamp volume down to 4 reduced the amount of natural overdrive, leaving a clean-but-round tone with a nice sustain.

The Headload also features a Radial JDX DI with Pre- and Post-EQ balanced mic outputs. In a live setting, the Pre-EQ output would be sent to the house mixing console; the Post-EQ output would be used for a monitor send to the stage. We ran the post signal through a mixer to a powered 1×12 two-way PA speaker to simulate a stage monitor. The headload offered plenty of control to dial in good, usable tones, and the five cab simulations in the Post-EQ section did a pretty good job replicating open and closed cabinets of different sizes (think mid-boost and cut). Combining them with the Low and High EQ controls, one could come close to replicating favorite live speaker outputs even through a PA speaker.

Last but not least, the Headload’s Phazer circuit aligns the JDX output with the speaker output, making up for the slight phase shift caused by the distance between the mic and speaker compared to the direct signal. One might think this minute difference wouldn’t matter, but setting the switch to 180 degrees and rotating the Shift knob even a little produced noticeable changes in sound. Switch to 360 degrees for infinite control. This is not only a real tool to fix a real problem (phase shift), it’s also fun for dialing up weird stereo imaging.

In all, seven different outputs (including a set of pre and post unbalanced ¼″ outputs with a level control) make the Headlong ideal for gigging musicians who need to split a signal and keep the volume down. Packed with cool usable features and its ability to bring a high-wattage amp back into play or revitalize a tired old soldier, the Headload is a worthy investment.

Radial Headload Guitar Amp Load Box | Vintage Guitar® magazine

Diy Amp Attenuator This article originally appeared in VG May 2016 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.