Inter-m PX-1650 Operating Manual page 27

※ USING THE GRAPHIC EQUALIZER
The PX-1650 built-in graphic equalizer (GEQ) has two main uses: compensation for acoustic deficiencies in
the listening area, and feedback control. Like the channel equalizers, the GEQ should not be used unless it
is absolutely necessary. The more equalization you use, the more phase deviation you introduce into the
program signal-and the greater the chance that the phase deviation can result in an unnatural, distorted
sound.
There are many instances, however, in which the acoustic characteristics of the listening area cause
response anomalies. Large areas of uncovered glass or tiled floors, for example, are extremely effective
reflectors of high-frequency sound. Amplified sound produced in such environments can seem painfully
sharp, in which case some reduction in the high-frequency rang may be called for.
Smaller symmetrical rooms (a square room being the worst case) can actually have resonant frequencies
within the audible low-frequency range. In such rooms, a slight reduction in the low frequencies can help to
clarify the sound. Please note that in almost all cases, good equalization demands a cut in the offending
frequency range rather than a boost in ranges where response is lacking.
The GEQ can also be used-although to a limited degree-to control feedback. Proper microphone placement
is the primary means of preventing feedback, but this can be extremely difficult if you're working in a tight
stage area. To get around this problem, try cutting response in the frequency range where the feedback is
occurring (You may have to experiment a bit to find this range.). This solution will compromise the overall
frequency response of the program, but it is better than running the risk of squealing feedback in the mid-
dle of an important performance.
※ CONNECTING SPEAKERS
The PX-1650 Powered Mixer has two 1/4" phone jack and two speaker connect jack speaker outputs per
channel. The outputs for each channel are connected in parallel internally. This places some restrictions on
their use, as described below;
- If you connect speakers to only one of the output jacks (SPEAKER 1 or SPEAKER 2), on either channel (R
or L), the total impedance of the speaker system connected to that channel may be no less than 4Ω.
- If you plug speakers to both the SPEAKER 1 and SPEAKER 2 or SPEAKER 3 and SPEAKER 4 jacks of
either channel (R or L), the total load impedance of the speaker systems connected to each output of that
channel must be no less than 8Ω (Note that two 8Ω speaker systems connected in parallel from a 4Ω
load).
- The maximum total impedance of speakers connected to the speaker outputs of each channel should be
16Ω.
- The maximum speakers allowable per channel are: one 4Ω speaker, two 8Ω speakers, or four 16Ω
speakers.
Although a higher total load impedance than the recommended 16Ω will only result in a loss of power out-
put, a total load impedance that is too low can actually damage the PX-1650 Series.
- PX-1650 maximum output power
250 watt per channel with a total load impedance of 4Ω or 330 watt per channel with a total load
impedance of 8Ω.
- Never connect or disconnect speakers while the mixer's power supply is turned on!
- Solid phone plugs can overheat when inserted in the rear-panel SPEAKER jacks of the PX-1650, causing
a potential fire hazard. Make a habit of checking the metal tips of your speaker plugs, and cleaning
them if necessary, before connecting them to the PX-1650.
STEREO BUILT IN X-OVER
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PX-1650