Aurora Audio Stinger User manual

AURORA AUDIO INTERNATIONAL
1518 North Cahuenga Boulevard
Hollywood, CA 90028
Phone: [phone] Fax: [phone]
Email: [email protected]
Website: www.auroraaudio.net
Aurora Audio Stinger Microphone and Instrument Amplifier
Page Index -
Page 2 – Introduction
Page 3 – Power Supply information
Page 4 – Aurora Stinger Block Diagram
Page 5 – Connecting To The Aurora Stinger
Page 6 – The Regular DI/Mic input and Correct Gain Structure
Page 7 – The Instrument input DI and EQ controls
Page 8 – Equalizer, Phase, and Phantom Power Controls
Page 9 – Using the Aurora Stinger
Page 10 – International dBFS Levels
Page 11– Specifications
Page 12 – Warranty details
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Introduction -
“Congratulations on your purchase of our Stinger! I am confident that you
will find that its many features and great Class A discrete vintage sound will
help you to make great recordings.
The Aurora Stinger is a portable and professional piece of equipment.
Read through this manual to familiarize yourself with the controls and
optimal operating procedures.
Please familiarize yourself with the sections dealing with metering and gain
structure when recording to digital equipment.”
-Geoff Tanner
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Power Supply information -
The Aurora Stinger has internal regulated power supplies that automatically
adjust to whatever a.c. power source you connect it to. There is no voltage
selection switch as the power supplies will automatically work between 80
and 2 5 volts a.c 50 or 0Hz.
The unit must be grounded using the supplied 3 core, 3 pin connector cable.
Do not use with any ground lifting adapter or two pin extension cable.
For the best noise performance and maximum safety, always ensure that the
Stinger is plugged into a 3 pin grounded power outlet.
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Block Diagram -
4

Connecting to the Aurora Stinger -
The Aurora Stinger has two independent audio paths, both have level controls
and XLR balanced and TRS unbalanced outputs. Both balanced outputs have
ground lift switches to eliminate ground loops when connecting to external
equipment.
At the top, the XLR female connector marked “Mic Input” can also
accommodate line inputs and has a gain range of -10dB to +80dB on the red
bar knob with additional control of +10dB to infinity via the 100mm travel
fader.
At the front are four mono jack sockets. In each pair the left sockets are
always inputs and the right is always a parallel output. Do not plug inputs
into the right hand jacks!
When a cable is plugged into the GT DI left input jack socket it will disable
the rear XLR input automatically.
The Instrument DI input is an independent circuit path
5

The Regular DI/Mic input and Correct Gain Structure -
Both the Mic and GT DI paths share the gain and
metering shown here. The meter has almost 0dB
range in 3dB steps and is calibrated on the left in
analogue VU range (the yellow LED is 0VU =
+4dBu) and digital dBFS range on the right. The
0dBFS value varies from user to user, converter to
converter, and country to country. The most common
is -18dBFS = 0VU and that is the scaling on this
meter.
To set up the correct gain for your input, set the meter
to “Post” input, the fader to 0dB, and the gain knob to
-10dB. Using whatever source you have, rotate the
gain knob clockwise until the VU is just hitting the
yellow LED. If you are using a higher dBFS setting,
ignore the color of the LEDs and adjust the gain for
whatever reference your converter needs.
Be aware that the higher the level you record at, the
less headroom you have and the red LEDs are
warning you of this issue.
The Aurora Stinger output will clip at +2 dBu =
+22VU and generally well after the A - D converter
has gone into very unpleasant sounding clipping.

The Instrument input DI and EQ controls -
The left hand front Instrument DI sockets work in
conjunction with these controls. If the FX is deselected
the path is one megohm input impedance and has
+30dB gain to the balanced output XLR.
While it is intended for use for bass guitars, with the FX
switched off the sound is clean, low distortion, and can
also work equally well with regular guitars and most
other types of sources.
The maximum input before clipping (1% THD) is
-5dBu (25dB headroom) and can accept input levels up
to +15dBu if the -20dB attenuator is switched in.
The red O/P level knob controls the output level of this
circuit path.
If the FX overdrive path is selected the gain will
increase +15dB and the blue overdrive control can be
adjusted to get whatever degree of guitar grunchiness is
required. The red output level knob can be turned back
to avoid overdriving the output while still maintaining
the overdriven sound.
Three separate outputs are available from this instrument input path :-
1. The parallel input on the front panel that could be sent to another
(guitar) amplifier.
2. The balanced XLR output on the rear panel
3. The unbalanced jack socket on the rear panel.
Either of the rear panel signals can be routed back through the mic path to
add EQ and Class A sound.
7

Equalizer, Phase, and Phantom Power Controls -
The GT Mic and DI paths both pass through the controls illustrated here.
The red bar knob, as discussed on
Page , controls the gain and the
two toggle switches to the left
switch on the 48v phantom power
for condenser microphones and
flip the phase on the balanced XLR
output path.
The three band equalizer provides
+/-1 dB boost and cut for the three
controls. The high frequency
control is 12KHz, the low
frequency control is 80Hz, and the
three mid frequency choices are
400Hz, 1 00Hz and 3,200Hz.
A high pass filter provides 18dB/octave roll-off at 80Hz.
8

Using the Aurora Stinger -
The Aurora Stinger has been designed to provide the user with an amazing
number of configurations. I have listed several options below.
1. Simultaneous mic preamplifier/EQ with separate guitar accompaniment
via the instrument input.
2. Two separate guitar inputs using both DI inputs
3. Unity-gain Class A sweetening of a pre-recorded source via the mic
preamplifier path while using the instrument DI for accompaniment.
4. The instrument DI can have the parallel input sent to a guitar amplifier.
The guitar amplifier can be mic'd up and that signal sent through the
mic pre path, eq'd if necessary, and then you have two (four if you
include unbalanced outputs) separate outputs that you can send to your
work station and monitoring, or whatever.
5. The instrument input can have either the balanced or unbalanced
outputs looped back through the mic pre/EQ circuitry to add EQ and
class A sweetening.
. As both the instrument DI input and the mic/DI input have two outputs,
balanced and unbalanced, this acts like a splitter and the outputs can be
sent to two destinations.
7. While it is best, in normal circumstances, to keep the mic/DI path fader
as close to the 0dB point for best headroom, there is nothing stopping
one pulling that fader back and increasing the gain on the red bar knob
to deliberately overdrive the preamplifier to get nice Class A grunginess
from the GT DI path.
9

International dBFS Levels -
On a technical note, 0dBm (an old telephone and early broadcast system of
reference) is the voltage required to dissipate 1mW into 00 ohms = 0.775v
ac. 0dBu (also 0.775v ac) just means that the impedance of the circuit is not
specified. These, set in granite actual voltage levels, rather go out of the
window when referred to dBFS figures associated with digital converters!
(dBFS = deciBels Relative to Full Scale... i.e the clipping point of the
system)
There is no single standard for setting where the 0dBFS point is...!!!
For example...
1. EBU R 8 is used in most European countries, specifying +18 dBu at 0
dBFS
2. In Europe, the EBU recommend that -18 dBFS equates to the
Alignment Level
3. European & UK calibration for Post & Film is −18 dBFS = 0 VU
4. UK broadcasters, Alignment Level is taken as 0 dBu (PPM4 or -4VU)
5. US installations use +24 dBu for 0 dBFS
. The American SMPTE standard defines -20 dBFS as the Alignment
Level
7. In Japan, France and some other countries, converters may be
calibrated for +22 dBu at 0 dBFS.
8. BBC spec: −18 dBFS = PPM "4" = 0 dBu
9. German ARD & studio PPM + dBu = −10 (−9) dBFS. +1 (+15)dBu
= 0 dBFS. No VU.
10. Belgium VRT: 0dB (VRT Ref.) = + dBu ; -9dBFS = 0dB (VRT
Ref.) ; 0dBFS = +15dBu.
0VU on the Aurora Stinger VU meter (the yellow LED) is +4dBu (1.228v ac)
and normally -18dBFS on the meters of most digital converters. Any other
digital reference could be used but the higher above -18dBFS you go, the
headroom, both analogue and digital, drops by the same amount! Not good!
10

Specifications -
Mic / DI Path
Gain :- -10dB to +80dB on the input sensitivity switch plus
another 10dB in the fader.
Input Impedance :- 1.2Kohm (XLR I/P), 10Mohm (DI I/P)
Output Impedance :- < 50 ohms balanced
VU Meter range :- VU points from -33VU to +24VU in 3dB steps
where 0VU = +4dBu = 1.228 vac.
Front panel trimpot to align the 0VU point.
Input headroom :- 2 dB
Frequency response :-< +/- 1dB at 20Hz and 20KHz ref. 0dBu @ 1KHz
Noise :- +80dB gain = -45dB (EIN = -125dB)
0dB gain = -85dB
Headroom :- Maximum output > +2 dBu
Distortion :- < 0.075% @ 1KHz
Instrument DI Path
Gain :- +30dB (+10dB with -20dB attenuator selected)
Input Impedance :- 1 Mohm
Output Impedance :- <50 ohms
Distortion (FX off) :- <0.075% (FX on and fully driven = > 18%)
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Warranty ONE YEAR PARTS AND LABOR LIMITED WARRANTY
Aurora Audio International warrants this Aurora Stinger unit against defects in
workmanship for a period of one year and parts for a period of one year from receipt by
the original end user. This warranty shall not apply to damage resulting from misuse
including water damage, in-transit damage, fire damage, improper maintenance,
dropping the unit and operation or storage outside the environmental specification for
the product.
Only skilled technicians should repair the Aurora Stinger. Please contact Aurora Audio
for technical advice. Aurora Audio is committed to helping you get best use out of the
Aurora Stinger.
ROHS Directives
The RoHS Directive stands for "the restriction of the use of certain
hazardous substances in electrical and electronic equipment". This
Directive bans the placing on the EU market of new electrical and
electronic equipment containing more than agreed levels of lead,
cadmium, mercury, hexavalent chromium, polybrominated biphenyl
(PBB) and polybrominated diphenyl ether (PBDE) flame retardants.
The restrictions took effect in the E.U from 1st July 200 .
It is very important that the owner of any piece of equipment that contains even
microscopic amounts of the listed hazardous substances (in relation to the weight of
the unit) realize that the responsibility of its disposal rests with them. The unit
should not just be thrown away at the end of its lifetime, whether that's 10, 20 or 30
years hence.
Please contact us at the address below and Aurora Audio will provide the necessary
information for proper disposal.
Aurora Audio International
1518 North Cahuenga Boulevard
Hollywood, CA 90028
Phone [phone]
Fax [phone]
Email [email protected]
Website www.auroraaudio.net
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