Phonic i7600 User Manual page 12

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: 5 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.
8
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 0 phons (0 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.
125 ms,
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.
i7600