Inter-m PA-920 User manual

PA-920/PA-935
Mixer/Amplifier
Copyright 2004 Inter-M Corporation

PA-920/PA-935 Mixer/Amplifier
Contents
Welcome ..................................................................................................................................... 3
Unpacking ............................................................................................................................... 3
Warnings .................................................................................................................................. 3
Operation................................................................................................................................. 5
Features ....................................................................................................................................... 6
Front Panel Controls.................................................................................................................... 7
Rear Panel Controls .................................................................................................................... 8
Connecting Speakers............................................................................................................... 10
Connections.............................................................................................................................. 11
Schematic Diagram (PA-920).................................................................................................. 12
Schematic Diagram (PA-935).................................................................................................. 13
Specifications............................................................................................................................ 14
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PA-920/PA-935 Mixer/Amplifier
Welcome
A personal welcome to you from the management and employees of Inter-M
Thank you for purchasing this fine Inter-M product. All of us here at Inter-M are dedicated
to providing you with the highest quality products and the best value.
We sincerely trust this product will provide you with years of satisfactory service, but if
anything is not to your complete satisfaction, we will endeavor to make things right.
Welcome to Inter-M, and thank you for becoming a part of our worldwide extended
family!
Unpacking
Although your PA-920/PA-935 is neither complicated nor difficult to operate, we
recommend you take a few minutes to read this brief manual and familiarize yourself
with the important information regarding product features, setup and operation.
As with most electronic devices, we strongly recommend you retain the original
packaging. In the unlikely event the product must be returned for servicing, the original
packaging (or reasonable equivalent) is required.
Warnings
Environment
Never place this product in an environment that could alter its performance or reduce its
service life. Such environments are usually characterized by high levels of heat, dust,
moisture, or vibration.
Safety
1. Read these instructions carefully.
2. Follow all instructions.
3. Keep all warnings.
4. Do not operate this apparatus near water.
5. Clean only with a damp cloth.
6. Do not block any of the ventilation openings.
7. Install only in accordance with the instructions in this manual.
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PA-920/PA-935 Mixer/Amplifier
8. Do not install near any heat sources such as radiators, heat registers, stoves, or other
devices (including amplifiers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding type plug. A polarized
plug has two blades, with one wider than the other. A grounding type plug has two
blades and a third grounding prong. The wide blade or the third prong is provided for
your safety. If the provided plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.
10. Protect the power cord from being walked on or pinched, particularly at plugs,
convenience receptacles, and the point where it is attached to the apparatus.
11. Use only the attachments/accessories specified.
12. Use only with a cart, stand, tripod, bracket, or table specified, or sold with the
apparatus. When a cart is used, use caution when moving the cart/apparatus
combination to avoid overturning.
13. Unplug this apparatus during lightning storms or when unused for long periods of
time.
14. Refer all servicing to qualified service personnel. Servicing is required when the
apparatus has been damaged in any way, such as power supply cord or plug is
damaged, liquid has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or
has been dropped.
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PA-920/PA-935 Mixer/Amplifier
Operation
Make certain that speakers and input sources are properly connected before switching
on.
Keep volume levels at minimum gain before switching on.
NOTE: The system’s operation is delayed by approximately three seconds after pressing
the AC Mains power switch. This is due to the built-in protection circuitry, designed to
protect speakers and other system components.
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PA-920/PA-935 Mixer/Amplifier
PA-920/PA-935
Mixer/Amplifier
Features
High Power, Low Distortion
• 20W (PA-920) or 35W (PA-935) of RMS power, with less than 5% THD.
Versatile and Convenient
• Three mixable inputs: Mic 1, Mic2/Aux1, Mic3/Aux2.
Configurable
• Mic2/Aux1 and Mic3/Aux2 are individually selectable.
Telephone Paging Input
• Telephone input for connection with telephone system.
Priority Muting
• Mic 2/Aux 1 and Mic 3/Aux 2 inputs mute when telephone paging and/or Mic 1 in
use.
Tone Control
• Separate Bass and Treble controls to tailor your sound.
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PA-920/PA-935 Mixer/Amplifier
Front Panel Controls
1. Power Switch
Pressing this switch switches the unit on, as indicated by the Power LED (2) above
the switch. Pressing it again switches the unit off.
2. Power LED
When the unit is switched on, the Power LED will glow steadily.
3. Treble Control
This knob controls the high frequency response, by adding up to 12dB of cut
(decrease) or boost (increase).
4. Bass Control
This knob controls the low frequency response, by adding up to 12dB of cut
(decrease) or boost (increase).
5. Mic Volumes 1-3
These knobs control the volume of Mic Inputs 1-3.
6. Aux Volume 1-2
These knobs control the volume of Aux Inputs 1 and 2.
7. Master Volume
This knob controls the overall volume of the PA-920/935 output.
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PA-920/PA-935 Mixer/Amplifier
Rear Panel Controls
1. AC Power Cable
Connect this cable to your AC outlet.
2. Fuse Holder
This holder contains the AC overload protection fuse. If the fuse has blown out,
replace it with a fuse of the same type and rating, as shown below.
If the fuse continues to blow, refer servicing to a qualified service technician.
AC Fuse Ratings
Model 100VAC – 120 VAC 220VAC-240VAC
PA-920 1A / 250V .5A / 250V
PA-935 2A / 250V 1A / 250V
3. Speaker Output Terminal
These terminals are used to connect speakers to the unit. You may select either
4or 8conventional operation, or High Impedance operation at either 70V or
100V.
4. GND Terminal
This grounding terminal is provided for connecting with the chassis of a turntable
or other input device to reduce hum and other ground loop noise. It may also be
connected to a true earth ground, such as an AC third-pin ground or water pipe,
to further reduce ground loop noise.
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PA-920/PA-935 Mixer/Amplifier
5. Mic 1,2,3 Inputs
These 1/4" phone jacks accept a standard mic-level or line-level input. Mic inputs
2 and 3 may be set to line-level with the use of their associated Mic/Aux switches
(see 7-8 below).
6. Mute Controls
When signal is present at Mic 1 or Telephone input, all other inputs are muted.
These controls adjust the level of Mic 1 and Telephone output when muting is in
use.
7. Mic 2/Aux 1 Selector Switch
This switch is used to select between mic level and line level for Mic 2/Aux 1 input.
8. Mic 3/Aux 2 Selector Switch
This switch is used to select between mic level and line level for Mic 3/Aux 2 input.
9. Telephone In Terminal
These terminals are used to connect to a telephone exchange system for paging
purposes.
NOTE: When signal is present on the Telephone Input terminal, all other input
signals (except Mic 1) are muted.
10. Aux Inputs
These inputs are used for connecting line-level sources, such as CD or cassette
deck. When using these inputs, the respective Mic/Aux switches must be set to
their Aux settings.
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PA-920/PA-935 Mixer/Amplifier
Connecting Speakers
Before connecting speakers to your PA-920/PA-935 unit, be sure to disconnect the AC
power cable. Make certain that the total impedance is not less than the rated
impedance indicated.
For 4speakers, connect in parallel, with the negative (-) connectors to the 4terminal
and the positive (+) connectors to the COM terminal. See Figure 2-1 below.
For 8speakers, connect in parallel, with the negative (-) connectors to the 8terminal
and the positive (+) connectors to the COM terminal. See Figure 2-2 below.
For high-voltage distributed systems, connect with matching transformer as per Figures 2-
3 and 2-4 below. Be certain that the total impedance does not equal less than the rated
impedance.
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