Radial has unveiled the Space Heater 500 at NAMM 2015, a single wide tube overdrive module for the Radial Workhorse and other 500 series racks. The Space Heater 500 delivers natural tube crunch to drums, adds character to voice, and natural tube compression to bass and acoustic guitar.
The design begins with a single-wide 500 series module in a fully enclosed steel enclosure. This not only protects the sensitive electronics but also helps prevent outside radiation from causing noise or from the Space Heater creating buzz due to the high voltage required by the 12AX7 tube. This, in fact, is part of the magic. A 3-position HEAT switch enables the user to choose between 35 volts, 70 volts or 140 volts for the desired level of tube distortion. Distortion is further adjusted using the combination of a drive control plus a level for make-up gain. The plate voltage is generated by an internal charge pump while the Workhorse or 500 series 16V supply provides the 12AX7 tube the 12 volts needed for the heater. A Jensen transformer is employed at the output to bring a more vintage character to the signal path while benefiting with galvanic isolation to reduce hum and buzz caused by ground loops.
To further refine the sonic response, the Space Heater 500 is equipped with both high pass and low pass filters. These allow the engineer to focus the tube effect on a particular frequency band or spread it out as needed. The EQ can also be applied to the signal path either pre or post tube for even greater tonal flexibility.
As the Space Heater 500 employs a high voltage tube circuit with a current draw of 235 milliamps, a special power allocation switch adjacent to the card edge connector is available to balance the draw for use with most 500 series racks.