The Space Heater 8-Channel Tube Drive Summing Mixer by Radial Engineering is a 1U rack-mountable summing mixer designed to warm up tracks in digital recording applications and to add character, headroom and quality of analog sound to digital mixing. The unit has four 12AX7 dual-cathode tubes wired as stereo pairs to drive the eight channels. Each channel features a unique Heat switch that lets you set the B+ tube voltage from 37, 75 and 150 volts to produce the desired amount of harmonic content or distortion. Setting the Space Heater to the highest voltage optimizes the tube performance for natural tube warmth. Reducing the voltage delivers a creamy and smooth distortion. 

Each of the eight channels is transformer coupled for added character while providing greater immunity against hum and buzz caused by ground loops. For recordings where you may prefer the sound of a vintage resistive summing mixer, the tube drive on each channel may be bypassed. A master left-right bus enables all eight channels to be mixed to stereo and auditioned via the built-in headphone amplifier. Eight balanced 1/4" TRS inputs, with individual sends and returns are coupled with two 25-pin D-Sub connectors to provide plenty of connectivity. And with a stereo LINK, you can easily expand to 16, 24 or even 32 channels for more possibilities.

This Space Heater is ideal for warming up vocals, adding grit to bass, and producing crushing drum tracks. Used live, it delivers a more natural sound to in-ear monitors without having to revert to lackluster compression.