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Copyright© 2011 Octet Matrix Audio
Advanced Test Procedures
Determination of highest output source
1)
You should have a voltmeter or a computer with a soundcard* in order to determine
which source has the highest output level for a given input signal. You do not need a
calibrated measurement system because you only need to determine the
relative
output
of each source with a known signal (the Octet Matrix Audio 0 dBFS test tone). If you have
a voltmeter, play track 5 through each source and measure the voltage at the source
output. The source output that registers the highest voltage is the source you should use
for the dynamic range optimization setup. If you do not have a voltmeter, you can
download one of the audio level meters in the Resources section to a computer with a
soundcard (preferably a laptop) and connect the source outputs to the soundcard input to
determine the highest analog output.
2)
If you want to skip the technical nonsense and trust your ears, make a copy of the Octet
Matrix Audio Test CD and play Track 5 in two sources at the same time. Set the Main
System Volume to ¼ volume and switch the source selector from one source to the other
to determine which source sounds louder for a given Main System Volume setting. The
source with the highest output should be used for Dynamic Range Optimization.
*
Any AC voltmeter or PC soundcard will do. You will be measuring sine waves and are interested in relative levels, so it
doesn’t matter if your meter is an RMS responding meter or an average responding meter, or even if it’s out of calibration. If
none of this makes sense to you, don’t worry. The relative values you measure with anything other than a truly broken
meter or soundcard will give you the results you need.
Resources
Free and low cost audio software
Audacity – easy to use and powerful open source audio recording and editing software. You
need this software if you do anything with audio on a computer. Use this to normalize any
song to set DWT4416 levels.
http://audacity.sourceforge.net/
BIP Oscilloscope – Turns your soundcard into a 2 channel oscilloscope.
http://www.electronics-lab.com/downloads/pc/002/index.html
Darkwood Designs – Audio Level Meters by Paul Mitchell – various audio level meters & tools
http://www.darkwood.demon.co.uk/PC/meter.html
ARTA - Audio Measurement and Analysis Software – free to use without saving results. Low
cost, high feature acoustic analysis software.
http://www.fesb.hr/~mateljan/arta/index.htm
