BLUE SKY SUB 15 UNIVERSAL Owner'S Manual Download

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Page 7

6. Expanded Calibration

Guide

nstructions for electroacoustic calibration of a 2.1 audio system using

a SPL meter and Blue Sky’s test files.

Before starting this procedure you will need to download BlueSkyTestFiles.zip
(an 18 MB zip file) by going to www.abluesky.com/calibration. To download
the test file, “Right Click” and select “Save Target As”. The file will begin
downloading once a location has been selected.

Once downloaded, either burn the test files to a CD or import them into your
DAW and follow the instructions below.

ADDITIONAL REQUIRED ITEMS

2.1 Monitoring System

SPL Meter - such as the SPL meter sold by RadioShack

in the U.S.

BlueSkyTestFiles.zip Includes 4 files:

•

1000Hz SINEWAVE -20dBFS.wav – a 1kHz file recorded at -
20dBFS for electrical calibration

•

40-80Hz PINK NOISE -20dBFS.wav – a 40Hz to 80Hz bandwidth
limited pink-noise file recorded at -20dBFS

•

500-2.5kHz PINK NOISE -20dBFS.wav – a 500Hz to 2.5Hz
bandwidth limited pink-noise file recorded at 20dBFS

•

Pink Noise full bw -20dBFS.wav – a full-bandwidth pink-noise file
recorded at - 20dBFS

These test files are all mono files. Please make sure you hard assign
them to the left and then the right, not both channels at the same time.
If you are using a CD player use only one channel of the CD player.

THEORY

The purpose of calibration is to adjust the overall electroacoustics system gain
so that 0dBVU of electrical signal level equals a certain acoustic level at the
listening position. Since most recording media is now digital, the reference
electrical signal level is usually –20dBFS with 20dB of headroom. The reference
SPL level however can vary based on the delivery media and speaker type.

Please note that the bandwidth limited signals that have been provided, limit
many of the room interaction affects often associated with measuring SPL and
broadband pink noise.

All test signals are recorded at –20dBFS including the 1 kHz sine wave tone.
The sine wave tone is used to set the electrical output level throughout the
signal path, right up to the point you get to the speakers, while the various pink
noise signals are used for acoustic measurements and calibration.

The following procedure assumes you are calibrating the system to 85dBC
SPL.

Step 1

TURN OFF THE MONITORING SYSTEM (until step 4)

Step 2

Remove  all  eq  and  dynamics  from  the  signal  path  and  set  all
controls to zero / unity gain.  Play the 1kHz Sine Wave, hard assign
it to the left channel only, and adjust the output fader so the output
meter reads -20dBFS. If you are using an analog console, set the
output level to 0 VU.  Then hard pan the signal to the right channel
output and repeat for the right channel.

Once calibrated do not

move the output faders.

Step 3

Mute everything and make sure the 1kHz tone is OFF .

Step 4

Now that the system has been electrically calibrated

turn ON your 2.1 System (SUB 15 Uni monitors).

Step 5

Assign  the  500-2.5kHz  pink  noise  signal  to  the  left  channel  only.
Make sure there is nothing coming from the right channel (or any
other  channels).    Because  this  signal  is  bandwidth  limited,  you
don’t  have  to  worry  about  turning  the  sub  off.  There  are  two
methods of setting the levels.

A. If you have a master monitor level control, you can set the sat
gain control at reference and then adjust the monitor gain control
for 85 dBC. Then mark the monitor level as your reference position.

B. The other method is to set master monitor level to the position
you  want  as  a  reference  level  and  then  use  the  volume  controls
to set 85 dBC.  If you use this method you should mark the knob
position  with  a  grease  pencil  so  you  can  always  go  back  to
reference level if the knob gets moved.

For either method:

SPL should be measured at the mix position, with the SPL meter
at arms length, with the microphone at seated ear height, angled
at approximately 45 degrees, and pointed at the center point
between the left and right speakers.

Once the left channel is set to 85dBC, repeat this step for the right
channel

Step 6

Feed 40-80Hz pink noise signal to the left channel only. Adjust the
subwoofer level

control until the subwoofer reads 85dBC (slow)

at the mix position. The meter will bounce around a little, so you
will need to do a mental average (I tend to filter out the peaks in
my mind, so I don’t set the sub too hot). The right channel should
measure about the same and no additional adjustments need to be
made.

Step 7

You can play the full-bandwidth pink noise, assigning it to the left
and then the right channel (not at the same time). You should
measure about 85dBc. It may be a little higher, because below
30Hz the room may have a little extra gain. No adjustments should
be made with Full Bandwidth pink noise, unless you have an RTA
(real time analyzer).

Step 8 You are finished and the calibration process has been completed

– enjoy!

A note about the LF EXTENSION and PHASE switches:

One of the SUB 15 Universal’s unique features is a switchable
low frequency response characteristic, of either 30Hz to 200Hz
+/-3dB  or,  in  “extended  LF  mode”,  20Hz  to  200Hz  +/-3dB
(anechoic), marked 30Hz and 20Hz respectively. The extended
mode is ideal for large rooms that don’t exhibit the room gain
phenomenon of smaller sealed spaces.  The only way to be absolutely sure
of which setting is appropriate for your studio is to use an acoustic analyzer.
Using the 20Hz in a sealed space, such as a small to medium size studio, can
result in a rising LF response characteristic below 30Hz.

The PHASE setting on the SUB 15 Universal should typically be set to 0,
especially when the SUB 15 Universal is used with Blue Sky SATs. However,
there may be times, depending on the speakers used with the SUB 15 Universal
or because of certain acoustic conditions, that the phase setting needs to be
set to 180, so as to get proper summation between SAT and SUB. The only way
to be absolutely sure which setting is appropriate for your studio is to use an
acoustic analyzer.

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Summary of Contents for SUB 15 UNIVERSAL

Page 1: ...Blue Sky International 70 Sea Lane Farmingdale NY 11735 www abluesky com Owner s Manual Version 1 9R January 18 2005 Blue Sky SUB 15 Universal 1000 Watt subwoofer with adaptive x over ...

Page 2: ...up with filter setting instructions _ _ Page 5 5 System Signal Connections _ __ __ __ __ __ __ _ Page 6 6 Expanded Calibration Guide _ __ __ __ __ __ _ Page 7 7 A Tour of the Amplifier and I O _ __ __ __ __ _ Page 8 8 Subwoofer Placement Guide _ __ __ __ __ __ _Page 10 9 Technical Information _ __ __ __ __ __ __ __ __ _Page 11 10 SUB 15 Universal Cabinet Dimensions _ __ __ _Page 12 11 Factory Serv...

Page 3: ... lightning and power line surges 10 OVERLOADING Do not overload wall outlets or extension cords as this can result in a risk of fire or electric shock 11 LIQUID ENTRY Never spill any liquid of any kind on the product 12 SERVICING Do not attempt to service this product yourself Opening or removing covers including any over bottom or side speaker drivers may expose you to dangerous voltage or other ...

Page 4: ...ubwoofer brings you years of accurate and problem free operation We ask that you take the time to read this manual register the product and visit our website for any updated information regarding this product If you have any questions please don t hesitate to contact us www abluesky com Thank you for choosing Blue Sky 2 Important notes about the SUB 15 Universal and this Owner s Manual Voltage Sel...

Page 5: ...ring system 10 It is now time to set the Variable Cutoff Frequency on the back of the SUB 15 Universal to best match your monitoring system if you are using the SUB 15 Universal with Blue Sky monitors set the Filter Selector Switch to BLUE SKY and skip to item 11 To determine the proper filter setting on the SUB 15 Universal you first need to know the cutoff frequency of your monitors This can typ...

Page 6: ...INPUTS ELECTRONICALLY BALANCED Figure 2 The SUB 15 Universal s XLR inputs can handle up to 24dBu of signal level at the input and are compatible with most if not all professional gear Additional adaptor cables can be purchased from most professional audio dealers so that the SUB 15 Universal can be used with other output types TRS RCA etc Figure 3 FLAT POSITION IS ALL SWITCHES DOWN FLAT POSITION I...

Page 7: ...5 Universal monitors Step 5 Assign the 500 2 5kHz pink noise signal to the left channel only Make sure there is nothing coming from the right channel or any other channels Because this signal is bandwidth limited you don t have to worry about turning the sub off There are two methods of setting the levels A If you have a master monitor level control you can set the sat gain control at reference an...

Page 8: ...Page 8 7 A Tour of the SUB 15 Universal Amplifier and I O ...

Page 9: ...TSINK The heatsink provides essential cooling to the amplifier inside the SUB 15 Universal Please ensure that proper air circulation is available for proper cooling 9 SUB GAIN This knob controls the input sensitivity of the subwoofer amplifier only When set to the reference position a 100mV signal at the input equals 90dB output at a meter 10 LF Extension One of the SUB 15 Universal s unique featu...

Page 10: ...and definition You are not just listening for the most boom but rather where the bass is most accurate and natural sounding Remember because the subwoofer is basically omni directional the best spot for the subwoofer can be next to or even behind the main monitoring area After finding the spot where the subwoofer has the best response in the room place the subwoofer in that location Now listen fro...

Page 11: ...ltage 115 230 VAC 50 60Hz switchable Wattage 1600 Watts Fuse 115VAC 8A 250 V 5x20mm Time Delay or Slo Blo 230VAC 15A 250 V 5x20mm Time Delay or Slo Blo Amplifier Class D design 1000 Watts RMS into 4 Ohm 1 THD noise at rated power 1kHz XLR balanced input Adjustable gain control Voltage Sensitivity 100mv 90dB SPL 1m Switchable low frequency response characteristic Frequency Resp 30Hz mode 3dB 30Hz t...

Page 12: ...Page 12 10 SUB 15 Universal Cabinet Dimensions ...

Page 13: ...e that occurs due to non factory packaging 4 Include a legible note stating your name shipping address no P O boxes daytime phone number RA number and a detailed description of the problem including how it can be duplicated 5 Write the RA number on the top of the carton 6 Ship the product to the address below We recommend United Parcel Service UPS Please insure the product regardless of shipping m...

Page 14: ......

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Page 16: ...Blue Sky International 70 Sea Lane Farmingdale NY 11735 www abluesky com ...

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