Phonic i7600, User Manual

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below the viewable range. Try lowering the
range to resolve the problem.
On the other hand, if you see the top LEDs in
most of the bands are often lit, you probably
have set a range that is too low. Try raising the
range to see whether the problem is resolved.
If the problem continues even when the highest
range is selected, try to lower the gain setting in
the EQ Module (if the measurement is post-EQ)
or the output level of the source device (if the
measurement is pre-EQ).
Response Time
This function determines the length of the
time span within which measurements are
averaged. The average value of each interval
is represented by the height of the lit LED in a
column. In effect, the value you choose for the
response time will determine how fast the LEDs
respond to the changes in sound intensity.
Different types of sound have different rates
of change in intensity. In order to see a faithful
representation of the sound on the LED display,
you need to adjust the response time according
to the type of sound that is being measured.
Choose, for example, a short response time
for a fast-attack and fast-decay sound, such as
snare-drum beats; but opt for a longer response
time for the long-sustaining sound of a typical
wind instrument.
Options for the response time are: 35 ms,
125 ms, 250 ms, 500 ms, 1 second, and
2 seconds.
Weighting Type
The human ear responds differently to sounds
at different frequencies. Even when the
sound pressure level (SPL) is identical at all
frequencies, an average person tends to hear
a louder midrange sound as compared to the
bass or high-frequency sounds. However, as
the SPL is increased equally at all frequencies,
the perceived loudness difference between
the midrange and bass sounds becomes less
predominant, and the difference between the
midrange and high-frequency sounds becomes
more apparent.
Because of this effect, the scale of a
sound-level meter must be "weighted" in order
to better represent the loudness as perceived
by an average person. The i7600 offers two
types of weighting: The A weighting is designed
to represent human hearing for low-level
sounds, at 40 phons (40 dB SPL at 1 kHz);
whereas the C weighting mimics the hearing
for high-level sounds, at 100 phons (100 dB
SPL at 1 kHz). When you want to measure the
straightforward SPL of the signal, remember to
set the Weighting type to F (Flat) for the un-
weighted scale.
Unit of Measurement (dBu/dBV)
This function lets you choose the unit of
measurement for the signal level. The unit
dBu is referenced to 0.775 volts RMS
(0 dBu = 0.775 V), whereas the unit dBV is
referenced to 1 volt RMS (0 dBV = 1 V).
Peak Hold
When this function is set to ON , the highest
level reached in each band is indicated by an
LED that stays lit in the corresponding column
in the Band Level Display. This lit LED will hold
its position in the column until it is "pushed up"
by a higher-level signal in the band.
Signal Source (Pre EQ/Post EQ)
This function lets you choose which signal is
to be measured. Set to Pre EQ if you want
to measure the input signal in its original,
unprocessed form. On the other hand, if the
processed (equalized) sound is what you want
to measure, then Post EQ is the choice.
Pink Noise
The i7600 can generate a continuous stream
of pink noise to help you calibrate your
system. Turn on this function to send out the
signal stream through the PINK NOISE OUT
connector in the back of the unit.
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