Radial Engineering Space Heater User's Guide

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Radial Engineering Ltd. 1588 Kebet Way, Port Coquitlam BC V3C 5M5 tel: 604-942-1001 • fax: 604-942-1010

www.radialeng.com

email: info@radialeng.com • web: www.radialeng.com

www.radialeng.com

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True to the Music

Radial Space Heater

Table of Contents .....................................................................................................Page

Front Panel Feature Set Overview ......................................................................................................................1

Rear Panel Feature Set Overview .......................................................................................................................2

Introduction To The Space Heater .......................................................................................................................3

Understanding The Signal Flow ..........................................................................................................................4

Features And Controls .........................................................................................................................................5

Connectivity .........................................................................................................................................................6

Master Section.....................................................................................................................................................7

Using As A Summing Mixer .................................................................................................................................8

Space Heater Applications ............................................................................................................................ 9-10

Changing the Tubes .......................................................................................................................................... 11

Speciﬁ cations and Connectors ..........................................................................................................................12

Radial Limited Warranty ..................................................................................................................... Back Cover

Congratulations on your purchase of the Radial Space Heater™ Summing Mixer and Tube Overdrive. The Space Heater is a studio-grade tube distortion unit and detailed analog mixer with personality. This manual covers the setup and operation of the Space Heater in both the studio and live sound. Please take a few minutes to read through this manual in order to familiarize yourself with the Space Heater’s features and applications. Inside you will ﬁ nd important safety features along with tips on how to get the most out of your Space Heater.

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’s FAQ section for the latest updates. If you still do not ﬁ nd what you are looking for, feel free to send us an email at info@radialeng.com.

Now lets get started warming things up… or let your destructive side shine!

Note: The Radial Space Heater is solely intended for use by audio professionals. These professionals are expected to be familiar with safety issues regarding electrical systems and sound pressure levels that could cause ear damage after extended exposure. If you are not familiar with these, please contact your local electrical and health authorities as Radial has no means to ensure products like the Space Heater are being used according to local rules and regulations.

IMPORTANT SAFETY & USER NOTICE - FOR PROFESSIONAL USE ONLY

Radial Engineering Ltd. Space Heater™ User Guide

MIX BUS LEVEL CONTROL:

Used to adjust the summing

mixer output.

MIX BUS ON: Turns

on the stereeo XLR-M

outputs.

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POWER SWITCH: Turn off to

conserve tube life and reduce

power consumption and heat.

HEADPHONE LEVEL: Built

with standard ¼” stereo output.

TUBE DRIVE ON: Routes the

audio signal to the tube drive -

may be bypassed to compare

wet versus dry.

HPF: High-pass ﬁ lter gently

rolls off low frequency

resonance below 40Hz across

both channels on the pair.

BUS: Sends the channel

set to the stereo mix bus

and headphones.

HEAT: Three position switch

changes the tube voltage for

each pair with 35,70 or 140 Volt

settings for different levels of

distortion.

LEVEL: Inner control on each

concentric pot sets the output

from the tube drive - acts like a

master volume on a tube guitar

amp.

FRONT PANEL FEATURE SET

Radial Engineering Ltd.

ON: Used to turn on (or

bypass) each of the four

channel sets.

DRIVE: Outer control on

each concentric pot sets the

level going to the tube drive

circuit.

Space Heater™ User Guide

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INPUT (1-8): Eight ¼” TRS

balanced inputs for easy

connection to the Space Heater.

14-GUAGE STEEL: Heavy duty

construction eliminates stress on

the PCB and provides excellent

shielding against magnetic ﬁ elds.

D-SUB INPUT (1-8): DB25

connector follows the Tascam/

Protools standard and is wired in

parallel to the ¼” input jacks.

SEND (1-8): Eight ¼” TRS

balanced sends feed the post tube

signal to an external processor or

may be used as additional outputs

for parallel processing.

STEREO SUM OUTPUTS:

Provide left and right summed

outputs for the most luxurious

old school analogue character.

RECV: Eight ¼” TRS balanced

receive jacks bring the signal

back to the Space Heater and

routes it to the D-Sub output or

stereo mix bus.

D-SUB OUTPUT (1-8): DB25

connector used to send all eight

+4dBu transformer isolated

channels back to the mixing

console or workstation.

GROUND LIFT: Recessed

switch lifts pin-1 on the two

XLR outputs to help reduce

hum and buzz caused by

ground loops.

REAR PANEL FEATURE SET

Radial Engineering Ltd. Space Heater™ User Guide

LINK: Stereo ¼” TRS link used

to combine two or more Space

Heaters together for 16x2, 24x2

or 32x2 tube summing.

POWER: 5-pin locking XLR

connection for external

power supply.

INTRODUCTION

The Space Heater is a combination 8x2 summing mixer and a badass 8-channel harmonic distortion device that lets you add a little, more, or a lot of distortion to your signal path. In some situations you may ﬁ nd that adding just a bit of bite to a vocal track can bring out subtleties without adding a compressor or increasing level. On acoustic guitar, the natural compression of a distorted tube circuit can enhance harmonics that may otherwise be lost. On bass, a medium distortion will bring back the vintage tone and feel as if connected to an old SVT or Marshall bass amp. And with drums, you can add crunch to expand the size of the drums without overprocessing.

Because the Space Heater can be used in a number of ways, it is important to understand its architecture and signal ﬂ ow. It is equipped with four 12AX7 tube drive circuits wired in stereo. While you do have separate DRIVE and LEVEL controls on each channel, certain functions are shared across both sides of the tube. Lets get started...

POWER

The Space Heater employs a universal power supply that accepts all voltages from 100V to 240V. This in-line power supply is equipped with a standard IEC/EIN power input so that you only need to change the cable to suit the local power connector types. A locking 5-pin XLR connects the external power supply to the Space Heater.

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Channel 1 Channel 1

Channel 2

EXTERNAL POWER SUPPLY

Channel 2

At the far right hand side of the front panel is a power switch. We recommend that you keep the Space Heater turned off when not in use to prolong tube life and save power. Turn the Space Heater on at least 15 minutes before use to allow the tubes to achieve thermal stability and maximum performance.

SIGNAL LEVELS

Before making connections, always reduce signal levels or turn off audio equipment. This helps prevent turn on and connection transients from damaging more sensitive components such as tweeters. All controls on the Space Heater should be turned fully counter-clockwise and all channels and tube drive circuits should be turned off (ON switch in out position) before using for the ﬁ rst time.

NOTE: Changing the HEAT voltage setting will change signal levels slightly. Be prepared to reduce the level when changing the HEAT switch to higher voltages.

INSTALLING THE SPACE HEATER

The Space Heater can be mounted in a standard 19-inch rack system or placed on the desktop using the included adhesivebacked feet. As it is a tube device, the Space Heater generates quite a bit of heat. Passive ventilation on the top and sides of its enclosure are provided to help dissipate heat build-up. When rack mounting, we recommend leaving at least one space open above the Space Heater for ventilation. Keep other sensitive equipment away from the Space Heater if temperature is a concern and always power the unit OFF when not in use to prolong tube life.

9”

11”

The Space Heater is 19” (48.3cm) wide, 7” (17.7cm) deep, and one standard vertical rack space (1.75”/4.5cm) tall. The total rack depth required for installation is 11” (28cm) to accommodate rear panel cable connectors. It is a good idea to provide some means of support and strain relief for the cable bundle connecting to the rear panel.

Radial Engineering Ltd.

Space Heater™ User Guide

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UNDERSTANDING THE SIGNAL FLOW

CHANNEL:

FROM INPUT DB25

INPUT

MASTER SECTION:

BUSS ODD

LINK

INPUT

TO EVEN BUSS

“HEAT” SWITCH

150V

75V 35V

TO OUTPUT DSUB

VIRTUAL

EARTH MIXER

TUBE ON

HIGH

IMPEDANCE

LINK

OUTPUT

BUFFER

UNBAL TO BAL

CONVERTER

HEADPHONES

BUSS OUT ODD

DRIVE

CHANNEL

PAIR ON

HEADPHONE

AMPLIFIER

HIGH

GAIN

PASS

FILTER

EXPLAINING THE SIGNAL FLOW:

The routing of the Space Heater is quite complex, so it is important to study this block diagram to understand how audio is passed. First,

signal enters the Space Heater at the channel input (1). Next, the on switch (2) either turns on the circuit or bypasses it completely, routing the signal directly to the output without processing. The Drive control (3) sets the level of signal entering the tube (4), which also has its own On switch (5) to bypass the 12AX7 as well as a Heat switch (6) to modify the voltage applied. A ﬁ xed-frequency high pass ﬁ lter (7) is next in line, before the signal passes through the output Level control (8). Finally the signal passes through an output transformer (9) followed by balanced insert points (10).

SEND RECEIVE

LOOP

JACKS

BYPASS

RELAY

OUTPUT

BUSS ON

ODD CHANNELS TO LEFT OUT EVEN CHANNELS TO RIGHT OUT

HOW 12AX7 TUBES WORKS

The 12AX7 is a dual-triode tube, which essentially means that it has two tubes in one. This allows it to be wired in a 2-channel/stereo conﬁ guration, which means that the Space Heater requires only four tubes to cover eight channels.

VOLTAGE AND DISTORTION

Tubes produce a rich, even order harmonic distortion that is warm and pleasing to the ears. Unlike solid-state circuits that go from no distortion to 100%, tubes distort in a more gradual fashion. Tubes work best when provided optimal voltage, as they will have plenty of headroom before distorting. Starving the tube with a lower voltage causes the tube to prematurely distort. The Space Heater’s adjustable B+ voltage (HEAT) allows you to choose how you want to drive the circuit.

When the Bus switch (11) is engaged, signal is passed to the master section. The Link input (12) and output allows the user to patch another Space Heater in and out of the virtual earth mixer (13), combining the stereo outputs of multiple units. The built-in headphone ampliﬁ er (14) takes its signal directly from the mixer output and is always on with a dedicated volume control. The master bus output can be turned on and off (15) and is equipped with its own volume control.

Cathode

Plate

Grid

Filament 1 (CH 1)

Filament 2 (CH 2)

12 3

Radial Engineering Ltd. Space Heater™ User Guide

FEA TURES AND CONTROLS

UNDERSTANDING THE CONTROLS

The Space Heater is an 8-channel device with stereo summing. The eight channels pass through four 12AX7 tubes, each of which is wired in stereo. All eight outputs are transformer coupled for isolation and analog character. While individual LEVEL and DRIVE controls can be found on each channel, other features are shared across both channels of the tube. It is important to understand these features before connecting your Space Heater for the ﬁ rst time.

DRIVE AND LEVEL

No matter how you decide to use your Space Heater, everything revolves around the DRIVE and LEVEL controls. The DRIVE sets the amount of signal going into the tube. The more you turn up the drive, the more the tube will distort. The LEVEL acts like an output fader, controlling the output of the channel.

BE CAREFUL! Turn down the DRIVE control before turning the tube drive on. As you turn up the DRIVE, you will need to compensate by turning down the LEVEL control. Engaging the tube drive with both controls turned up could get loud… quickly!

DRIVE LEVEL

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High Pass Filter Response

-5

-10

20 50 100 200 500

TUBE SECTION

The tube drive circuit can be turned on or off on each channel pair. When the tube section is switched ON, the signal will pass through the 12AX7 based on the level of the DRIVE control. When the tube section is switched OFF, it is effectively bypassed and the signal will only pass through the LEVEL control and output transformer.

HEAT SWITCH

The HEAT switch allows the user to adjust the plate voltage of each 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 ampliﬁ er.

HIGH-PASS FILTER

Each channel pair on the Space Heater is equipped with a high-pass ﬁ lter. This ﬁ lter starts at 40Hz and has a very gentle 6dB/octave roll-off. It is intended to subtly reduce low frequency rumble and resonance. This gradual slope makes it very useful on kick drums and bass guitar when retaining most of the low frequency content is desirable.

TRANSFORMER COUPLED OUTPUT

The Space Heater is equipped with output transformers on each of the eight channels. These oversized transformers were selected to deliver deep bass and add a vintage character reminiscent of a classic analog mixing console. They also help eliminate buzz, hum and other DC noise issues that can occur when connecting equipment in a studio. Because the tube drive can be bypassed on each channel pair, the transformers can be used to add character all on their own. Simply run your signal through the channel and adjust the level accordingly.

Radial Engineering Ltd.

Space Heater™ User Guide

True to the Music

INPUT

234

INPUT

234

INPUT

234

INPUT

234

INPUT

234

INPUT

234

INPUT

234

INPUT

234

CONNECTIVITY

CHANNEL INPUTS - ¼” TRS

The Space Heater is equipped with balanced ¼” TRS (Tip-RingSleeve) input jacks for all eight channels. These inputs are set to +4dBu nominal line level for optimal performance. We recommend that +4dBu balanced signals be maintained throughout the system.

FROM MIXER OR DAW

CHANNEL INPUTS - DB25

The Space Heater is also equipped with a DB25 input that is connected in parallel to the ¼” TRS input Jacks. This allows for easy connection to many audio interfaces such as Avid’s HD I/O.

INSERT POINTS - WHAT TO CONNECT:

The Space Heater is equipped with both send and receive +4dBu balanced insert jacks. This makes it suitable for connection to a wide array of professional audio equipment that would traditionally be used with an analog recording console or live sound mixer. The Space Heater’s insert points are the last step in each channel’s signal ﬂ ow diagram (after the level control and output transformer). This makes them particularly well suited for connection to equalizers or compressors when using the Space Heater for summing during mix down, but they can also be used with other stand alone processors or effects units.

Transformer

Insert

Send/Receive

Bus

OFF

Output

PROTOOLS INTERFACE

OUTPUTS

CHANNEL OUTPUTS - DB25

Individual channel outputs are routed to a DB25 connector. A standard 8 CH DB25 to TRS or DB25b cable is used to interface with different studio setups.

TO MIXER OR DAW

SEND USED FOR OUTPUT

PROTOOLS

INPUT

INTERFACE

When using the Space Heater as an effect on individual channels, the insert jacks can be used as a patch bay. This can be convenient for connecting other pieces of equipment to your signal chain while already in the analog domain, or to simply use the insert “SEND” jack as a parallel output for recording or processing elsewhere. Keep in mind that the insert jacks are still the last step in the Space Heater’s signal path, so any equipment inserted will be processing the wet sound.

PROTOOLS

Q3EQKOMIT

COMPRESSOR

INTERFACE

OUTPUTS

CHANNEL OUTPUTS - ¼” TRS

While there are no dedicated ¼” connectors for the individual channel outputs, the INSERT SEND jacks can be used for this purpose. The signal is tapped just after the output transformer on each channel, making it identical to the DB25 channel output connector.

Radial Engineering Ltd. Space Heater™ User Guide

MASTER SECTION

The heart of the Space Heater lies within its 2-channel master section. All channels may be assigned to the stereo bus in a leftright conﬁ guration and mixed down to a stereo pair at the main output. This allows the Space Heater to be used as a mixer for analog summing ‘out of the box’ when working in the digital domain. When used alongside the individual channel outputs and balanced insert points, the master section also allows for some unique parallel processing opportunities.

BUS SWITCH

The BUS switch (found on each channel pair) routes the channel to the stereo bus. Odd channels will be routed to the LEFT output, even channels to the RIGHT output. Individual channel outputs remain active, so it is possible to use both the stereo output and the channel outputs at the same time.

CH 1

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HEADPHONE AMPLIFIER

The Space Heater features a built-in headphone ampliﬁ er. The headphone output takes a feed off the main stereo bus, with its own level control to monitor the stereo output when using the Space Heater as a summing mixer. It can also be used to audition channels when using the Space Heater as a hardware insert. Simply engage the BUS switch on any stereo pair to monitor those channels in the headphones.

As with all products capable of producing high Sound Pressure Levels (SPL) users must be very careful to avoid the hearing damage that may occur from prolonged exposure. This is particularly important as it applies to headphones. Prolonged listening at high SPLs will eventually cause tinnitus and can lead to partial or complete loss of hearing. Please be aware of the recommended exposure limits within your legal jurisdiction and follow them very closely. The user agrees that Radial Engineering Ltd. remains harmless from any health effects resulting from the use of this product and the user clearly understands that he or she is entirely responsible for the safe and proper use of this product. Please consult the Radial Limited Warranty for further details.

USING THE LINK TO SUM MORE CHANNELS

The Space Heater is equipped with a LINK IN and LINK OUT jack on the back panel. This unbalanced stereo connector provides a way of expanding the Space Heater’s summing mixer capabilities to 16, 24 or even 32 channels by cascading several Space Heaters together. Connections are made using balanced ¼” TRS cables. The jacks are wired in stereo to retain the left-right conﬁ guration. Simply connect the LINK OUT from the ﬁ rst Space Heater to the LINK IN on the second unit. Continue linking until all Space Heaters are connected. The ﬁ nal unit in the chain will become the master, and the summed stereo bus of all units will combine at its output.

Space Heater 1

Headphone Safety Warning

Caution: Very Loud Ampliﬁ er

Slave

Space Heater 2

Master

BUS

CH 2

ODD CHANNELS

EVEN CHANNELS

Space Heater 3 Slave

Space Heater 2 Slave

Radial Engineering Ltd.

Space Heater 1 Master

Space Heater™ User Guide

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INPUT

USING THE SPACE HEATER AS A SUMMING MIXER

When mixing in a digital audio workstation (DAW) or even with some digital mixers, folks often complain that something is lost. There are lots of theories as to why or even if this actually occurs, but most agree that something magical happens when audio tracks are combined in the analog domain. The Space Heater handles this task with ease. Not only is it an extremely high quality, transformer coupled analog mixer; it also offers a tube circuit for endless personality!

Because the tube drive section may be turned on or off for each channel pair, the Space Heater can be used when clean analog summing with slight vintage character is preferred. In this case, the signal will only pass through the level control and output transformer on each channel.

1. Make sure all LEVEL and DRIVE controls are turned off (fully counter-clockwise) to prevent accidental volume spikes.

2. Connect your DAW outputs to the Space Heater’s eight individual channel inputs via ¼” TRS or DB25.

3. Connect Left and Right XLR outputs of the Space Heater to your recorder. Try routing the ﬁ nal stereo mix back to new channels on your DAW for recording and monitoring or if you prefer, connect to a dedicated 2-channel tape machine.

STEM MIXES IN YOUR DAW

A common method for using the Space Heater as an analog summing mixer alongside a DAW is to work with stereo stem mixes. This means that you mix similar instruments to separate stereo outputs. All panning is handled by the workstation so the Space Heater is only performing the ﬁ nal stereo mix from these groups. When you engage the BUS switch on the front panel, odd channels are automatically routed to the LEFT bus and even channels routed to the RIGHT bus.

TYPICAL STEM MIX ROUTING

DRUMS (LEFT) .......................................CH 1

DRUMS (RIGHT) ......................................CH 2

BASS (LEFT) ............................................CH 3

BASS (RIGHT) .........................................CH 4

GUITAR (LEFT) ........................................CH 5

GUITAR (RIGHT) .....................................CH 6

4. Turn each channel pair of the Space Heater ON and engage the BUS switch to assign outputs to the stereo mix.

5. Turn the TUBE DRIVE ON for each channel pair where desired. Leave off if simple resistive analog summing through transformers is desired.

6. Setup DAW or recorder to play back 4-stereo recordings assigned to the outputs connected in step 2.

7. Turn MIX BUS ON and adjust level control. If sending the stereo mix back to your recorder, set the output level between 12 o’clock and 3’o’clock. If connected directly to studio monitors, set at a lower level until playback begins.

8. Begin playback. Slowly increase the LEVEL and DRIVE controls on any one channel (only LEVEL control is necessary if tube is not engaged).

9. Adjust balance between LEVEL and DRIVE on all eight channels. Increasing the level will result in a cleaner sound while increasing the drive will introduce more distortion.

10. Adjust the HEAT switch between the three different voltages. Lower voltages will starve the tube and result in a grittier distortion while higher voltages will produce a warmer overdrive.

VOX (LEFT) ..............................................CH 7

VOX (RIGHT) ...........................................CH 8

PROTOOLS INTERFACE

OUTPUTS

Radial Engineering Ltd. Space Heater™ User Guide

USING THE SPACE HEA TER AS AN INSERT ON INDIVIDUAL TRACKS

One of our favorite ways to use the Space Heater is as an effect on individual channels. Whether applying heavy distortion on a single instrument to completely change its character, or simply adding subtle warmth to a sterile recording, the Space Heater will add all kinds of analog mojo to the music.

HARDWARE INSERT Most hardware mixing boards are equipped with insert jacks on every channel. These allow the Space Heater to be inserted before the fader on an individual channel. Sometimes the option to be pre or post EQ on the consoles channel strip is also possible.

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Receive Send

12345678

SPACE HEATER

MIXER

USING THE SPACE HEATER AS A SOFTWARE INSERT

Most multi channel recording software programs provide a method of setting up hardware inserts within the program. These utilize different inputs and outputs on your audio interface, and allow them to behave as an insert point within your software. This is the most popular method of connecting the Space Heater when using it as an effect.

INTERFACECOMPUTER

SPACE HEATER

USING THE SPACE HEATER IN-LINE The Space Heater is a professional +4dBu line level device. It can be used ‘In Line’ (connected in series) with other analog hardware. Try connecting the output from a microphone preamp directly into the Space Heater input when tracking, or as the last device in a recording chain.

MIC PRE

EQ COMP

SPACE HEATER

Radial Engineering Ltd.

POWER

PRE

KOMIT

LITTLE

COMP

DEVIL

Space Heater™ User Guide

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SAMPLE APPLICA TIONS

DRUMS

The Space Heater is a fantastic piece to add some excitement and punch to a drum kit. As you 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 difﬁ cult to increase the presence of these instruments without drastically increasing their level. A slight amount of distortion on a stem mix of the entire kit can really make a drum mix pop!

TIP: Try assigning the output of the Space Heater 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!

IN EAR MONITORS

In-ear monitor systems often sound sterile and out of place. Closemic’d instruments and direct box signals passing through a digital console and into a pair of ear buds will not create the same sound as what is coming out of the PA system, where the speakers are actually moving air. Some musicians can never get used to them, while others simply put up with the sound. The Space Heater quickly brings back the natural feel and tone that has been missing. Applying distortion to individual instrument tracks or even the stereo bus slightly compresses the signal without a loss of dynamic range. Less EQ and compression are required overall, and the added grit makes you feel like you are standing in front of a speaker instead of listening to tiny little buds!

Radial Workhorse

PAN

2341

MAIN

LEVEL

CLIP

MON

48V PHANTOM

PAN PANPANPAN

+16V / -16V

LEVEL

LEVELONLEVEL

LEVEL

CLIP

CLIPON

MONO

Made in Canada

BASS

Bass guitar is an instrument that can deﬁ nitely beneﬁ t from some grit. First, it can limit 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 deﬁ ne bass frequencies in small speakers or headphones. Try applying a small amount of

ELECTRONIC MUSIC

Keyboards, synths and various tone generators will all react differently when applying distortion. Experiment by running different signals and instruments through a channel on the Space Heater and listen to the results. Try running a ﬁ xed frequency tone through the Space Heater 500 and listen to the results - The possibilities are

endless! distortion with the Space Heater while listening with headphones. Even if the change is inaudible in larger speakers, it can make all the difference when listening on small speakers.

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

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. The guitar distortion tends to live in the

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. same frequency space as the vocal, so turning up one will quickly mask the other. Using the Space Heater to apply a small amount of distortion to the vocal can help the track move into a different frequency space, bringing clarity and deﬁ nition without resorting to heavy-handed compression or drastic EQ.

Radial Engineering Ltd. Space Heater™ User Guide

CHANGING THE TUBES

The Space Heater is equipped with four 12AX7 tubes. Although the Space Heater is intended to provide many years of problem free service, the tubes are designed to be user replaceable when required.

ONLY use 12AX7 tubes in the Space Heater. Other tubes such as the 12AT7 and 12AU7 are not suitable, as they operate at different voltages.

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 REDUCE THE CHANCE OF ELECTRIC SHOCK BY GIVING THE SPACE HEATER’S INTERNAL CAPACITORS TIME TO DISCHARGE.

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STEP 1

Step 1: Remove the top cover of the Space Heater. There are seven hex-style screws on the sides and back of the chassis, and two Phillips screws on the top panel.

STEP 3

STEP 2

Step 2: Carefully wiggle each tube out of their socket. Be sure to apply even pressure to the base of the tube as you pull the tube out of its socket.

STEP 4

Step 3: Replace each 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.

Radial Engineering Ltd.

Step 4: Re-install and fasten top cover.

Space Heater™ User Guide

True to the Music

OUTPUT D-SUB CONNECTORINPUT D-SUB CONNECTOR

Pin # 1 Channel 8 Hot 2 Channel 8 Ground 3 Channel 7 Cold 4 Channel 6 Hot 5 Channel 6 Ground 6 Channel 5 Cold 7 Channel 4 Hot 8 Channel 4 Ground 9 Channel 3 Cold 10 Channel 2 Hot 11 Channel 2 Ground 12 Channel 1 Cold 13 Not Used

Pin # 14 Channel 8 Cold 15 Channel 7 Hot 16 Channel 7 Ground 17 Channel 6 Cold 18 Channel 5 Hot 19 Channel 5 Ground 20 Channel 4 Cold 21 Channel 3 Hot 22 Channel 3 Ground 23 Channel 2 Cold 24 Channel 1 Hot 25 Channel 1 Ground

Pin # 1 Channel 8 Hot 2 Channel 8 Ground 3 Channel 7 Ground 4 Channel 6 Hot 5 Channel 6 Ground 6 Channel 5 Ground 7 Channel 4 Hot 8 Channel 4 Ground 9 Channel 3 Ground 10 Channel 2 Hot 11 Channel 2 Ground 12 Channel 1 Ground 13 Not Used

SPECIFICATIONS

Circuit Type: Class A tube gain stage with

IC buffers

Frequency response: 20Hz – 20Khz, +0/-3dB

Total Harmonic Distortion:

Variable

(THD+N)

Dynamic range: 96dB

Input impedance – Bypassed: 50kΩ in parallel with your load

device

Input impedance – Active: 100kΩ

Maximum input: +22dBu

Gain: +33dB@140V, +29db@70V,

+27dB@35V

Gain - Mix Bus: 6dB above individual channel

output

Bypass: Full Bypass

Clip Level – Output: +26dBu

Output impedance - Balanced

180 Ohms

Outputs:

Output Impedance -

15 ohms

Headphone Out:

Output Impedance - Mix Bus

100 Ohms

Out:

Common Mode Rejection -70dBu @ 55Hz

Equivalent input noise: -103dBu

Noise ﬂ oor - Maximum Gain: -64dBu@140V, -66dBu@70V,

-70dBu@35V

Noise ﬂ oor - Controls at 50%: -70dBu@140Hz, -72dBu@70V,

-76dBu@35V

Intermodulation distortion: Variable

Unity Gain Control Setting: Drive and Gain at “11 o’clock”

GG G G

GGGG

Pin # 14 Channel 8 Ground 15 Channel 7 Hot 16 Channel 7 Ground 17 Channel 6 Ground 18 Channel 5 Hot 19 Channel 5 Ground 20 Channel 4 Ground 21 Channel 3 Hot 22 Channel 3 Ground 23 Channel 2 Ground 24 Channel 1 Hot 25 Channel 1 Ground

Features:

Number of channels: Eight channels

Input Connectors: ¼” TRS, DB-25

Output Connectors: DB-25

Insert Connectors: 8 x ¼” TRS Send, 8 x ¼”

Mix bus output XLR

Low pass ﬁ lter -5dB @ 40Hz, 6dB/Octave

XLR conﬁ guration: Pin 2 +, Pin 3 -, Pin 1 GND

General:

Power Supply (Included) External switching type 100V –

Construction: 14 gauge steel chassis and

Finish: Powder coat

Construction: 14 gauge steel chassis and

Size: 17.5” x 6” x 1.75” (44.5 x15.25

Weight: 8.5 lbs (3.8kg)

Conditions: For use in dry locations only

Warranty: Radial 3-year, transferable

CONNECTOR WIRING

XLR Connector

GGG

GROUND

TRS ¼” Phone Connector

5-Pin XLR Power Connector

GROUND

COM

+48VDC

COLD (-)

234

-16VDC

HOT (+)

COLD (-)

HOT (+)

+16VDC

COM

Receive

slope

240V AC, 1600mA output with 5 pin XLR

outer shell

x 1.75cm)

between 5°C and 40°C

Radial Engineering Ltd. Space Heater™ User Guide

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 ﬁ 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 an 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 center 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 modiﬁ cation by any other than an authorized Radial repair center.

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.

www.radialeng.com

Radial Engineering Ltd. 1588 Kebet Way, Port Coquitlam BC V3C 5M5 tel: 604-942-1001 • fax: 604-942-1010 email: info@radialeng.com • web: www.radialeng.com

Radial Space Heater™ User Guide - Part #R870 1002 00 Speciﬁ cations and appearance are subject to change without notice.

Radial Engineering Space Heater User's Guide

Specifications and Main Features

Frequently Asked Questions

User Manual