Headload™ Specifications

The Headload is a device that is intended to simulate the sound of a guitar cabinet and allow the user to compensate for the sound depending on the level that is being produced. That said, the following specifications do not provide any truly significant information as it is completely dependent on the amplifier and speaker cabinet in use. As such, we ask you to please review with the awareness that these measurements are truly subjective in nature. The Radial Headload is quite likely the most useful load box ever made.

Headload Block Diagram
Headload Frequency Response
Click to enlarge
Audio Circuit Type:  Passive attenuation circuit with active equalization
Frequency Response: 90Hz at -3dB to 4KHz at -6dB
Low EQ: +/- 9dB @ 80Hz
High EQ: +/- 9dB @ 6Khz
Low & high resonance: 60Hz & 6.5KHz, shelving filter 6dB/octave slope
+12dB at 20% load setting
+9dB at 40% load setting
+6dB at 60% load setting
+3dB at 80% load setting
None at 100% load setting
Headphone output power:  400mW into 32 Ω
Headphones impedance:  32 Ω or higher recommended
Gain:  -40dB typical
Intermodulation distortion:  <0.05%
Noise:  -104dbu Unweighted
Input impedance:  8 Ω
Output impedance:  250 Ω
Total harmonic distortion:  <0.05%
Gain reduction: Variable from 100% to 0%
Equalization:  Low & high frequency shelving
Load:  Available in 4 Ω, 8 Ω, and 16 Ω
Power:  Radial +/-15V 4-Pin 500mA power supply
Construction:  14 gauge steel chassis & outer shell
Finish: Durable powder coat
Size: (L x W x D) 6.05" x 12" x 3.45" (154mm x 305mm x 87.6mm)
Weight:  8lbs. (3.63kg)
Shipping size: (L x W x D) 8" x 14" x 5" (203mm x 365mm x 127mm)
Shipping weight: 10lbs. (4.5kg)
Conditions: For use in dry locations only between 5°C and 40°C
Warranty:  Radial 3-year, transferable
Specifications are subject to change without notice.