®
True to the Music
Space Heater
500 Series Module
Tube Drive
500
™
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam, British Columbia, Canada, V3C 5M5
Tel: 604-942-1001 • Fax: 604-942-1010 • Email: info@radialeng.com
www.radialeng.com
User Guide
Radial® Space Heater 500™ User Guide
Table of Contents Page
Warning .......................................................................... 1
Feature set ..................................................................... 2
Overview ........................................................................ 3
Making connections ....................................................... 4
The control panel ........................................................... 5
Using the lters .............................................................. 6
Using the Space Heater 500 .......................................... 7
Applications .................................................................... 8
Block diagram and specications ................................... 9
Warranty ............................................................Back cover
Congratulations… Thank you for joining the growing
number of Radial 500 series module users. The Space
Heater 500™ will be a truly unique and useful addition
to your recording studio setup. Although its standard
operation and connections are no different than any
other 500 series module, we recommend that you take a
few minutes to read through this manual and familiarize
yourself with the design and controls.
Should you have any questions on an application not
covered in this manual, we invite you to log onto the Radial
Engineering website at radialeng.com to check the Space
Heater 500’s FAQ section for the latest updates. If you still
do not nd what you are looking for, feel free to send us an
email at info@radialeng.com.
Now lets warm things up and embrace the distortion!
True to the Music
!
The Space Heater 500™ is a high-voltage tube device designed for professional
use only. Although preventative safety measures have been designed into Radial
500 series products, we strictly advise against hot-swapping modules or plugging
and unplugging them while your Workhorse or other 500 series rack is powered.
Hot-swapping can cause connection shorts at the card-edge connector that could
damage other equipment. This also greatly reduces the life span of the contacts.
Damage due to hot-swapping is not covered under warranty.
The 12AX7 tube inside the Space Heater 500™ can be removed and replaced as
required. Opening the unit should only be performed by a qualied technician familiar
with 500 Series modules or by those experienced with replacing tubes.
Warning Notice to User!
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Radial Engineering Ltd.
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Space Heater 500™ Module
®
FEATURE SET
1. DRIVE: Controls the input level of the tube circuit.
Increase the drive to allow more signal to enter the
tube adding saturation and warmth.
2. HEAT: 3-position switch selects between 35, 70 and
140 volts at the tube. At 35V the tube is starved for
voltage creating more distortion.
3. LEVEL: Controls overall output level. Depending on
the amount of drive added, the level control can be
adjusted to achieve an optimal signal level.
4. HI-CUT: The low-pass lter is used to tame
excessive harmonics when using heavy distortion.
5. EQ: Assigns the lters pre or post tube circuit, or
turns them off completely.
6. LOW-CUT: Variable high-pass lter from 5Hz to
500Hz used for reducing unwanted low frequencies.
7. ON: Engage or bypass the circuit completely.
8. OMNIPORT: Available when used with the
Radial Workhorse, the Omniport accesses a hi-Z
instrument input.
9. POWER ASSIGN SWITCH: Lets you toggle the
input supply from the positive or negative rail. This
enables multiple Space Heaters to be used together
without power sag.
10. 12AX7 TUBE: The Space Heater 500 employs a
select low-noise 12AX7 tube with a non-radiating
140V charge pump to deliver the performance of a
high voltage tube preamp.
True to the Music
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Radial Engineering Ltd.
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Space Heater 500™ Module
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True to the Music
INPUT
OMNIPORT
FEED
LINK
123456
OFF
OFF
CARD SLOT 1CARD SLOT 3CARD SLOT 5CARD SLOT 7 CARD SLOT 2CARD SLOT 4CARD SLOT 6CARD SLOT 8
OUTPUT
INPUT
ON
ON
MONO
Made in Canada
MAIN
MON
48V PHANTOM
+16V / -16V
OVERVIEW
The Space Heater 500 is a studio-grade tube overdrive and distortion unit in a 500 series.
Think of it as a 12AX7 tube distortion pedal designed for professional recording. It’s versatile
controls and high-grade signal path make it useable in a variety of ways.
The signal path begins at the 12AX7 tube. A HEAT switch allows you to select between
three different tube voltage levels. An adjustable DRIVE control sets the input level to the
tube while a LEVEL control acts as a master output fader. Adjusting the balance between
DRIVE and LEVEL allows you to tailor the sound from subtle analog warmth to over the top
distortion. All of this is coupled with an oversized output transformer, bringing more vintage
character and warmth to the signal path.
®
BALANCED
INPUT
OMNIPORT
INSTRUMENT
INPUT
FILTER
ASSIGN
PRE TUBE
FILTER
SWITCH
HIGH
PASS
FILTER
12AX7
LOW
PASS
FILTER
FILTER
ASSIGN
POST TUBE
FILTER
SWITCH
JENSEN
TRANSFORMER
The Space Heater 500 also features variable high-pass (5Hz to 500Hz) and low-pass lters
(500Hz to 20kHz). These lters can be assigned pre or post tube, allowing you to drive the
circuit in different ways. Rolling off high or low frequencies before passing through a tube will
cause it to produce a different distortion. Sometimes you want the tube to break up normally
and roll off the unwanted frequencies later. And if you don’t want the lters in the path at all,
they can be bypassed.
When used with Radial’s Workhorse™ 500 series racks, the Space Heater 500 supports
Omniport functionality by becoming a hi-Z instrument input. Simply plug the instrument of
your choice into the Omniport using an unbalanced ¼” cable and adjust the Level and Drive
controls to suit. This effectively turns the Space Heater 500 into an instrument preamp with a
+4dBu line level output, suitable for driving power amps or for direct recording.
OUTPUT
Radial Engineering Ltd.
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Omniport
In
Instrument level
Space Heater 500™ Module
®
INPUT
INPUT
OMNIPORT
FEED
LINK
123456
OFF
OFF
CARD SLOT 1CARD SLOT 3CARD SLOT 5CARD SLOT 7 CARD SLOT 2CARD SLOT 4CARD SLOT 6CARD SLOT 8
OUTPUT
INPUT
ON
ON
MONO
Made in Canada
MAIN
MON
48V PHANTOM
+16V / -16V
True to the Music
MAKING CONNECTIONS
Before making any connections, power down your 500 series rack and loudspeakers. Turn
all level controls on your Space Heater 500 down to their lowest positions. This helps protect
equipment (and your ears!) from damaging volume spikes during setup. Carefully plug the
Space Heater 500 into your 500 series rack to avoid stress on the card-edge connector.
Once properly seated, screw the module in place to ensure it does not become accidentally
dislodged. Engage +48V phantom power on your 500 series rack so that the tube inside your
Space Heater 500 will power up.
Connections between the Space Heater 500 and your recording system are made via the
rear panel on your 500 series rack. Most 500 series racks are equipped with XLR connectors,
but may also include D-Sub or ¼” TRS connectors. When you plug the Space Heater 500
into a 500 series rack, it will automatically route the input and output to the module.
The Space Heater 500 is a professional line level device that is designed for use with
balanced +4dBu line level signals. To ensure proper performance, ensure that your recording
system or audio interface is set up for professional line level inputs and outputs.
Input
Input
+4dBu line level
Output
REAR PANEL INPUT
(500 SERIES RACK)
MANAGING POWER
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 tube’s
REAR PANEL INPUT
(WORKHORSE)
heater voltage from the positive to the negative power rail in the rack. If you are using several
modules, it is possible that the combination can exceed 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.
Switch Located Here
Radial Engineering Ltd.
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Space Heater 500™ Module
True to the Music
THE CONTROL PANEL
Once signal is running through the Space Heater 500, it is time to start having fun! The
Space Heater 500 can be used for anything from slight analog warmth to full-out distortion
reminiscent of a high-gain guitar amplier. How you set the controls will greatly alter the
output, so it is important to understand how each control effects the signal path.
DRIVE
The DRIVE control sets the input level to the tube section.
As you increase the DRIVE, more signal is allowed to enter
the tube. More signal will drive the tube harder, pushing
it into saturation and creating more distortion. Subtle
harmonic saturation that we perceive as analog ‘warmth’
can be achieved by setting the Drive level very low. This has
a result similar to compression, where the signal becomes
more present in the mix but dynamics are retained. The
opposite is to turn the DRIVE control all the way up,
forcing lots of signal through the tube. This will allow the
tube to behave like a traditional overdrive with a shredding
distortion that can be fun to apply on any instrument. You
will quickly nd that even small adjustments to the DRIVE
control will greatly change the output of the Space Heater
500, allowing for innite tone shaping.
®
HEAT
The HEAT switch allows the user to adjust the B+ voltage of the tube. There are three
selectable voltages: 35V, 70V and 140V. At 35 volts, the tube is starved for voltage. This will
cause it to break up at very low levels, which makes it ideal when heavy, crushing distortion
is desirable. 70 volts allows for more headroom before the tube starts to distort and provides
moderate distortion as you apply more drive. At 140 volts, the tube will accept a lot more
signal before breaking up. This allows you to warm things up slightly at low drive settings, or
ramp it up to drive the tube with plenty of voltage, reminiscent of your favorite high-gain guitar
amplier. When rst using the Space Heater 500, begin with the HEAT switch set at 70V. This
medium setting makes it very easy to dial in the sound you are looking for and allows you to
quickly audition the 35V and 150V settings.
LEVEL
The LEVEL control adjusts the overall output of the Space Heater 500. Depending on how
you have the DRIVE control set, increasing or decreasing the LEVEL may be required for
optimal signal levels. Adjusting the balance between these two controls is the quickest way
to achieve your desired amount of distortion. All other controls can then be used to ne-tune
the result.
IN / BYPASS
The Space Heater 500 is able to be completely bypassed when not needed. This removes
the entire circuit from the signal chain.
Radial Engineering Ltd.
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Space Heater 500™ Module
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USING THE FILTERS
EQ SELECTION
A 3-position EQ switch allows you to place the lter
section before or after the tube, or turn it off completely.
This allows the user to create frequency-specic
distortion by applying the lters before the tube, causing
it to break up differently. Inserting the lters after the tube
section lets you create full-bandwidth distortion, then roll
off what you don’t want afterwards. Play around with the
positioning to hear the difference in tone!
HI-CUT
The variable low-pass lter is active from 20kHz down
to 500Hz. This lter can be very helpful in reducing high
frequencies caused by heavy distortion.
LO-CUT
The variable high-pass lter is active from 5Hz to 500Hz.
This is useful for rolling off unwanted low frequency
resonance and cleaning up the bottom end.
HI-CUT
500Hz 20kHz
EQ
5Hz 500Hz
LO-CUT
SPACE
True to the Music
LPF
PRE TUBE
EQ OFF
POST TUBE
HPF
IN
Radial
HEATER
Made in Canada
MIN MAX
140V
70V
35V
HEAT DRIVE
LEVEL
MIN MAX
HI-CUT
500Hz 20kHz
PRE TUBE
EQ OFF
EQ
POST TUBE
5Hz 500Hz
LO-CUT
IN
Radial
SPACE
Radial Engineering Ltd.
HEATER
GETTING STARTED
The Space Heater 500 can be used on any source where analog
warmth or harmonic distortion is desired. Like an analog EQ or
compressor, the Space Heater 500 can be patched into your system
as a hardware insert or used in-line with other hardware.
Start by setting up the Space Heater 500 controls as follows:
1 – DRIVE: set to the 12 o’clock position.
OMNIPORT: UNBALANCED HI-Z INPUT
2 – HEAT: set to 70V (middle position).
3 – LEVEL: set to the 12 o’clock position.
4 – HI-CUT: set fully clockwise (20kHz).
LPF
5 – EQ: Set to OFF (middle position).
6 – LO-CUT: set fully counter-clockwise (5Hz).
7 – IN: push in to activate the circuit.
HPF
You should now be able to hear a subtle distortion when audio
passes through the Space Heater 500. For optimal signal to noise
performance, it is recommended that you adjust the LEVEL control to
match the output of the dry signal. This can be quickly accomplished
with the IN button. Press to activate, depress to bypass.
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Space Heater 500™ Module
True to the Music
USING THE SPACE HEATER 500
DRUMS
The Space Heater 500 is a fantastic piece to add excitement and punch to a drum kit by
inserting it on individual channels. Slowly bring up the distortion by increasing the DRIVE
control, the audio will compress and become more present in the mix. Adding subtle distortion
to a kick or heavy distortion to a snare is particularly effective as it is often difcult to increase
the presence of these instruments without drastically increasing their level.
TIP: Try assigning the output of the Space Heater 500 to a different channel on your recorder.
This will allow you to bring up the distorted track separately from the original clean track.
Playing back the two channels in parallel will allow you to adjust the blend between the two,
which will allow you to dial in your sound even more quickly!
Original Signal
Made in Canada
MIN MAX
140V
70V
35V
HEAT DRIVE
OMNIPORT: UNBALANCED HI-Z INPUT
LEVEL
MIN MAX
LPF
HI-CUT
500Hz 20kHz
PRE TUBE
EQ OFF
EQ
POST TUBE
HPF
5Hz 500Hz
LO-CUT
IN
Radial
SPACE
HEATER
®
BASS
Bass guitar is an instrument that can denitely benet from some grit. First, the Space Heater
500 can reduce the amount of compression needed as the distortion will add harmonics to the
bass sound, effectively allowing it to live in a different frequency space that is not competing
so closely with other instruments. Distortion can also help dene bass frequencies in small
speakers or headphones. Try applying a small amount of distortion with the Space Heater
500 while listening with headphones. Even if the change is inaudible in larger speakers, it can
make all the difference when listening on small speakers.
Made in Canada
MIN MAX
140V
70V
35V
HEAT DRIVE
OMNIPORT: UNBALANCED HI-Z INPUT
LEVEL
MIN MAX
LPF
HI-CUT
500Hz 20kHz
PRE TUBE
EQ OFF
EQ
POST TUBE
HPF
5Hz 500Hz
LO-CUT
IN
Radial
SPACE
HEATER
Radial Engineering Ltd.
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Space Heater 500™ Module
®
True to the Music
VOCALS
It is always a challenge to maintain a lead vocals presence in a mix, particularly in rock music
where they are competing for space with distorted guitars. Guitar distortion tends to live in the
same frequency space as the vocal, so turning up one will quickly mask the other. Using the
Space Heater 500 to apply a small amount of distortion to the vocal can help the track move
into a different frequency space, bringing clarity and denition without resorting to heavy-
handed compression or drastic EQ.
ELECTRONIC MUSIC
Keyboards, synths and various tone generators will react differently when applying distortion.
Experiment by running different signals and instruments through a channel on the Space
Heater 500 and listen to the results. Try running a xed frequency tone through the Space
Heater 500 and listen to the results - The possibilities are endless!
GUITAR
Direct recorded electric guitars can often be too clean or shrill. Applying a slight distortion
can make them sound more like they are coming out of a clean amp rather than a direct box.
Turning up the distortion can make you quickly forget that the guitar was ever clean in the rst
place and leave others thinking that you recorded a tube powered half-stack!
DISTORTED DELAY OR REVERB
A bit of distortion on an EFX return can make your delays or reverbs sound quite a bit different
than the dry recording. This makes the effect much more present in the mix, and can add a
vintage character to your digital delay or reverb. Light distortion can mimic famous vintage
analog gear, while a heavy distortion can transform a delay into a completely different effect.
REPLACING THE TUBE
Step 1: Remove the top cover of the Space Heater. There are
four Hex screws on the cover.
Step 2: Carefully wiggle the tube out of its socket. Be sure to
apply even pressure to the base of the tube as you pull the tube
out of its socket.
Step 3: Replace the tube by aligning the pins up with the socket.
Tubes are ‘keyed’ so that they can only be installed in one
position. Once aligned, carefully push the tube in by applying
even pressure across the top of the tube.
Step 4: Re-install and fasten top cover.
CAUTION: THE SPACE HEATER IS A HIGH VOLTAGE DEVICE. TURN OFF THE UNIT AND DISCONNECT
THE POWER SUPPLY FOR 10-15 MINUTES BEFORE ATTEMPTING TO CHANGE THE TUBES. THIS
WILL ALLOW THEM TIME, TO COOL AND WILL REDUCE THE CHANCE OF ELECTRIC SHOCK BY
GIVING THE SPACE HEATERS INTERNAL CAPACITORS TIME TO DISCHARGE.
Radial Engineering Ltd.
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Space Heater 500™ Module
True to the Music
BLOCK DIAGRAM*
SPACE HEATER 500 MODULE SPECIFICATIONS*
Audio circuit type: .................................... Thermionic gain stage with solid state input and output buffers
Frequency response: ................................................................................................. 20Hz - 20KHz ± 1dB
Total Harmonic Distortion: (THD+N) .................................................... Varies with drive and level settings
Dynamic range: ..................................................................................................................................92dB
Input impedance: .................................................................................................................................50K
Input impedance: Instrument ................................................................................................................. 1M
Maximum input: ..............................................................................................................................+20dBu
Maximum gain: ......................................................................32dB @ 140V / 27dB @ 70V / 13dB @ 35V
Clip Level - Output ..........................................................................................................................+22dBu
Output impedance: .................................................................................................................... 100 Ohms
Equivalent input noise: ................................................................................................................. -102dBu
Noise oor: ..................................................................................................................................... -70dBu
Intermodulation distortion: ................................................................... Varies with drive and level settings
Common Mode Rejection Ratio........................................................................................................ -60dB
Omniport: ..................................................................................................... Unbalanced instrument input
Power requirement: ...........................................................................................................................80mA
Weight: .................................................................................................................................1.5lbs (0.7Kg)
Size:..............................................................................................................................9 x 6.5 x 2 (inches)
Warranty: ...................................................................................................................3 Years, transferable
* Subject to change without notice.
®
CONNECTOR WIRING
XLR Connector
GROUND
Radial Engineering Ltd.
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1
3
HOT (+)
COLD (-)
TS ¼” Phone Connector
GROUND
HOT (+)
9
TRS ¼” Phone Connector
COLD (-)
GROUND
HOT (+)
Space Heater 500™ Module
THREE YEAR TRANSFERABLE LIMITED WARRANTY
RADIAL ENGINEERING LTD. (“Radial”) warrants this product to be free from defects in material and
workmanship and will remedy any such defects free of charge according to the terms of this warranty.
Radial will repair or replace (at its option) any defective component(s) of this product (excluding nish
and wear and tear on components under normal use) for a period of three (3) years from the original
date of purchase. In the event that a particular product is no longer available, Radial reserves the
right to replace the product with a similar product of equal or greater value. In the unlikely event that
a defect is uncovered, please call 604-942-1001 or email service@radialeng.com to obtain a RA
number (Return Authorization number) before the 3 year warranty period expires. The product must be
returned prepaid in the original shipping container (or equivalent) to Radial or to an authorized Radial
repair centre and you must assume the risk of loss or damage. A copy of the original invoice showing
date of purchase and the dealer name must accompany any request for work to be performed under
this limited and transferable warranty. This warranty shall not apply if the product has been damaged
due to abuse, misuse, misapplication, accident or as a result of service or modication by any other
than an authorized Radial repair centre.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE FACE HEREOF
AND DESCRIBED ABOVE. NO WARRANTIES WHETHER EXPRESSED OR IMPLIED, INCLUDING
BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE SHALL EXTEND BEYOND THE RESPECTIVE WARRANTY PERIOD
DESCRIBED ABOVE OF THREE YEARS. RADIAL SHALL NOT BE RESPONSIBLE OR LIABLE
FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSS ARISING FROM
THE USE OF THIS PRODUCT. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND
YOU MAY ALSO HAVE OTHER RIGHTS, WHICH MAY VARY DEPENDING ON WHERE YOU LIVE
AND WHERE THE PRODUCT WAS PURCHASED.
To meet the requirements of California Proposition 65, it is our responsibility to inform you of the following:
WARNING: This product contains chemicals known to the State of California to cause
cancer, birth defects or other reproductive harm.
Please take proper care when handling and consult local government regulations before discarding.
This product is intended for professional use only.
The user should be familiar and experienced with
!
the 500 series rack and module format
®
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5
tel: 604-942-1001 • fax: 604-942-1010
info@radialeng.com • www.radialeng.com
Radial® Space Heater 500™ Module User Guide - Part #: R870 1255 00 / 11-2016
Copyright 2015 Radial Engineering Ltd. All rights reserved.
Specications and appearances subject to change without notice.
www.radialeng.com
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