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Appendix D
This appendix will provide information about the methods
and settings used during the spectrum and level analysis of
the GT-3/5 which has revealed so much technical
information.
Much of the information presented in this document has
been obtained through careful, and lengthy analysis of a
GT-3. So that these findings may be understood, and the
analysis repeated, I have detailed the methods and settings
for analysis below.
Equipment Set-up & Connections
The set-up is not overly complex, but is flexible enough to
suit all needs.
PC Out- RQ200 Mixer - Mixer Monitor Out - GT-3 In -
GT-3 Out - MX2004A Mixer – Mixer Main Out - PC In
This method of connection was used for much of the
analysis with the left channel being the primary channel.
Both channels of the GT-3 were tested and yielded identical
results during frequency analysis; therefore only the left
channel is shown in the resultant analysis as this allows a
greater display resolution.
At times, a second routing was added. The right channel
input on the mixing desk was replaced, so that instead of
coming from the GT-3 it was split from the same Monitor
Out signal and routed DIRECT to the R in of the
MX2004A.
These two connections provide the following scenarios
(respectively)
1. GT-3 analysis
2. GT-3 vs. Direct signal comparison
This second method is particularly useful where a
comparison between the GT-3 and the original signal were
required.
GT-3 Patch used
The GT-3 was programmed with a completely empty patch.
NOTHING was turned on, not even the FV or NS. Neither
were any control assigns were used. The '[Master] Level'
was set to 20 to avoid overloading the GT-3 output when
checking EQ 20dB.
Spectrum Analysis
The spectrum analysis was conducted using the first
configuration described above and a piece of software
called SpectraLAB 4.32.14, which may be found here...
http:// www.SoundTechnology.com
© Copyright 2000-2002 Barry S. Pearce et al.
Analysis Methods
Spectrum analysis was used to determine the various
frequency characteristics of the GT-3.
SpectraLAB was configured using the following settings.
Frequency & Range Resolution
Sample Rate (Hz)
Decimation Ratio
FFT size (samples)
Spectral Line Resolution
Frequency Limit
Sampling Format
Bit Depth
Smoothing Window
Window Type
The Hanning smoothing window algorithm was chosen
because although its frequency resolution is not the best
possible, it does have excellent amplitude resolution and
leakage suppression. This means the resultant analysis is far
more accurate than with any other type of window.
Averaging Settings
Block Size
Style
Scaling Control
Amplitude Axis
Frequency Axis
Standard Freq. Weighting
Mic Compensation
In order to prove the analysis bed was accurate, four tests
were performed:
1. PC out-PC In direct connection
This proves the PC soundcard is not affecting the
results.
2. PC-Out -> Mixers -> PC In
This proves the mixers are not affecting the results.
3. Full Set-up thru GT-3 with the GT-3 in BYPASS
mode.
This profiles the GT-3 bypass mode.
4. Full set-up thru GT-3 with the GT-3 running the
analysis patch.
This profiles the GT-3 analysis patch vs. the 3
other tests.
The above results are all shown in the image file called
'GTx-Reference.gif', which may be found at:
http://www.breakingtaboo.com/gear/boss_gt-x/GTx-
Reference.gif
Or
96kHz
1
65536
1.465Hz
48000.000Hz
16bit
Hanning
1
Exponential
Logarithmic
Narrowband:Logarithmic
Flat(none)
None
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