HHB Radius 40
A four-stage tube voice processor that promised big-studio warmth on a project-studio budget. By the accounts that survive, it largely delivered.
Overview
The Radius 40 is a self-contained tube voice processor. It sits between a microphone or line source and the tape machine, or in practice whatever digital recorder the project studio actually owned. HHB's own documentation says it was designed for direct-to-tape recording in project and professional studio environments. The feature set is unusually complete for one box: a mic preamp and line input feeding a compressor, an expander/gate, and a four-band equalizer, all in one chassis. The company's advertising billed it as the "Tube Voice Processor" of the Radius line. The pitch was simple - the warmth and presence of a vacuum tube, made affordable to the home recordist.
The front end takes balanced XLR microphone and 1/4-inch line inputs. The back has both XLR and unbalanced line outputs, enough connectivity to slot into a small room without a patchbay. Input and output gain controls are provided. On a tube box, being able to push the input stage while trimming the output is how you actually use the thing, and the Radius 40 gives you that control rather than hiding it behind a fixed topology.
The compressor is fully variable rather than preset: threshold, ratio, gain, attack, and release are all adjustable. The whole section can be bypassed when you want the tube and EQ without the gain reduction. A four-band equalizer follows, also bypassable, with 12 dB of boost and cut per band. The band frequencies are switchable rather than fixed. The low band selects between 60 Hz, 120 Hz, 250 Hz, or 500 Hz. The low-mid selects between 250 Hz, 500 Hz, 1 kHz, or 2.2 kHz. The high-mid selects between 1.5 kHz, 2.2 kHz, 3.6 kHz, or 5 kHz. The high band selects between 2.2 kHz, 5 kHz, 8 kHz, or 12 kHz. That lets you dial the EQ to the voice in front of you rather than the other way round. The EQ can also be switched to run before or after the compressor. Pre-compressor EQ changes what the compressor reacts to. Post-compressor EQ shapes the result without altering the gain reduction.
Monitoring is handled by a backlit VU meter that can display input level, output level, or gain reduction. A meter that reads gain reduction is useful when you're learning how a compressor behaves. Two Radius 40s can be stereo-linked, so a pair can be used as a stereo bus processor. The power supply is a stabilized 150V DC design, a detail that matters to anyone who has ever chased hum in a tube box.
HHB's own advertising positioned the Radius 40 within a five-model family of professional tube processors designed and built in Britain, pitched explicitly at the project studio (EQ Magazine, December 1999, p.97). The same advertising told buyers that "nothing beats the extraordinary value for money of HHB's Radius tube processors." That is marketing copy rather than a verdict, but the price positioning was clearly the point of the line.
The broader Radius and Classic families were announced around the same period. HHB's Classic Series sat above the Radius line for more demanding applications: the Classic 60 stereo compressor, Classic 70 stereo parametric, and Classic 80 two-channel preamp. The Radius 40 was the most fully-featured single-channel voice tool in the affordable range, aimed at the person recording vocals, bass guitar, and keyboards in a small room. HHB's manual says the unit is designed to enhance "any source from vocals to bass guitar and keyboards."
The surviving documentation does not say how many were made, what they cost at retail, or how they have held up. Anyone looking for a used Radius 40 should expect the usual tube-era caveats. Valves age, and a unit of this vintage may need attention before it sounds its best. The specifics of common faults and current market prices are not documented in the sources available here. What is documented is the design intent: a flexible, fully variable tube channel strip with a switchable-order EQ and a gain-reduction meter, sold at a price that made tube processing accessible to the project studio.
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