Radial Engineering Space Heater Summing Mixer, 8-Channel with 12Ax7 Tubes and Transformer Isolation

The Space Heater is an 8-channel tube overdrive that functions as either an analog summing mixer or a multi-channel studio effects device. Its tube circuitry gives a range of effects on its own from subtle warmth and grit to full harmonic distortion.

Set up as four stereo pairs, the Space Heater design begins with a choice of 1/4" TRS or D-sub inputs for quick connection to a workstation. Each channel pair is 100% discrete enabling 4 stereo sets to be used independently or be sent to a stereo mix bus with left and right outputs.

To control the effect on the tube, each channel set is equipped with a separate drive control to increase or decrease the signal being sent to the 12AX7 tube and a level control to set the output. A unique Heat switch lets the user apply 25, 50 or 100 volts on the tube depending on the fidelity needed. Lower voltages starve the tube causing more distortion. On the other hand, higher voltages produce a cleaner signal. Each stereo set is also equipped with a handy high-pass filter to help eliminate resonance and clutter. This is extremely useful for cleaning up a mix.

To expand patching options, all 8 channels are equipped with separate send and receive insert jacks. The send jack works double duty as a second output with the D-Sub for parallel processing. The master section features a simple level control, headphone amp and choice of XLR or TRS outputs. Everything is housed in a 1 RU 19" rack frame and as with all Radial product, it is made from 14 gauge steel for greater rigidity and maximum shielding. An external power brick works globally by accepting anything from 100 to 240 volts.

Features

• 12AX7 vacuum tube overdrive and summing mixer
• Heat switch adjust voltage applied to each tube
• Individual outputs to use as an 8-channel effects insert
• Transformer-coupled outputs for vintage tone

Specifications

• Audio Circuit Type: Class-A tube gain stage with IC buffers
• # of Channels: 8
• Frequency Response: 20 Hz to 20 kHz, +0/-3 dB
• Dynamic Range: 96 dB
• Gain:
  • +33 dB @ 140V
  • +29 dB @ 70V
  • +27 dB @ 35V
• Clip Level: +26 dBu
• Input Connectors: 1/4" TRS, D-sub
  • Input Impedance:
    • Bypasses: 50 kΩ in parallel with your load device
    • Active: 100 kΩ
  • Equivalent Input Noise: 103 dBu
  • Noise:
    • -64 dBu @ 140V
    • -66 dBu @ 70V
    • -70 dBu @ 35V
  • Maximum Input: +22 dBu
• Output Connectors: XLR, 1/4" TRS, D-sub
• Features: LPF
• Construction: 14-gauge steel chassis and outer shell
• Power: External switching type 100V-240V AC, 1600 mA output with 5-pin XLR
• Conditions: For use in dry locations only, 5-40°C
• Dimensions (H x W x D): 1.75" x 17.5" x 6"
• Weight: 8.5 lbs (3.8 kg)