Space Heater 500 FAQ

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I don’t have any audio passing through the Space Heater 500, what could be the problem?

Make sure to have +48V phantom power engaged on your rack, this is used to power the tube inside the Space Heater 500.

Is the Space Heater 500 compatible with API and other 500 series racks?

Yes. Like all Radial 500 modules, the Space Heater has been designed to work following API’s original specifications.

How many Space Heater modules can I use in a single 500 series rack?

Because of the power requirements of the 12AX7 tube, each Space Heater 500 requires 230mA of current to operate. This is higher than the original API specification for current draw. Combining multiple Space Heaters or using with other power hungry modules may exceed the capabilities of some rack systems. Consult your racks user guide or specifications to check the power handling requirements.

I have calculated power requirements and am not exceeding my racks capabilities, but modules are not powering up or sound thin. What is the problem?

The Space Heater 500 is equipped with a +/- power select switch next to the card-edge connector at the back of the module (only accessible out of the rack). This switches the Space Heater’s power source from the positive to the negative power rail in the rack. If you are using several modules, it is possible that the combination is exceeding the power available on one rail. By switching the rail source, you can free up un-tapped power for the Space Heater 500 or other modules that may be underperforming.

If the heat is set for the tube, how can I control the distortion?

The LEVEL and DRIVE controls allow for customization of the distorted sound. Set the HEAT for 70V and adjust the two controls as needed. Once you are happy with the sound, experiment by changing the heat setting and listen to the results.

Can I use the Space Heater 500 on microphones?

The Space Heater 500 as it is a line level device meaning that it expects a professional +4dB line level signal from a recording system or mic preamp. As a microphone produces a very low signal (typically -40dB), you will need to first go into a mic preamp to bring up the level to a +4dBu output.

Can I use the Space Heater 500 as an instrument preamp?

Yes, but only if installed in a Radial Engineering Workhorse 500 series rack. The Space Heater 500 utilizes the Workhorse’s Omniport ¼” connector as an instrument input. Plug in your bass, keys or acoustic and record directly from the +4dBu line level output.

Can I use the Space Heater 500 live?

Absolutely! A bit of tube distortion on individual tracks or on in-ear monitor mixes is a great way of warming up sterile digital tracks and making things sound more natural.

Is it possible to bypass the tube?

No, the signal will pass through the tube at all times. To minimize the effect, set the plate voltage to maximum, decrease the input drive and increase the output level.

Are there transformers inside of the Space Heater 500?

Yes, the output is coupled to an oversized Jensen transformer to reduce buzz and hum caused by ground loops, and to add some vintage character to the signal chain.

What will adjusting the ‘Heat’ voltage do to the sound?

Adjusting the Space Heater 500’s 3-position HEAT switch will greatly change the type of distortion that the tubes will produce. At its lowest setting (35V), the tube is starved for power. The tube will break up and distort quickly at low levels, making this the choice setting when you really want to mess things up! The middle setting (70V) is a great starting point as the tube will provide moderate distortion at all levels. At its highest setting (140V), the tube sees its optimal power and will produce a clean, warm sounding signal with plenty of even harmonic overtones.

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Space Heater 500 Resources

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