PARK AUDIO GS Series User manual
TWO-CHANNEL
PROFESSIONAL
POWER AMPLIFIERS
GS4
GS5
GS6
GS7
GS8
GS series
Owner’s Manual
Park Audio
SUPPLY KIT
Power Amplifier 1 pc.
Power Cable 1 pc.
Spare air filter 2 pcs.
Warranty 1 pc.
TABLE OF CONTENTS
Page
Safety Precautions .......................................................................................................................2
General.............................................................................................................................................3
Unpacking .......................................................................................................................................3
Design Features............................................................................................................................4
Functional Features .....................................................................................................................6
Amplifier Block Diagram .............................................................................................................8
Front Panel......................................................................................................................................9
Rear Panel.......................................................................................................................................10
Input and Output Connectors....................................................................................................12
Cabel Requirements ..................................................................................................................14
AC Power Requirements............................................................................................................15
Rack-Mounting Requirements................................................................................................16
Operating Modes .........................................................................................................................17
Maintenance...................................................................................................................................18
Specifications.................................................................................................................................19
Operating Conditions ..................................................................................................................20
Dimensions .....................................................................................................................................21
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
AVIS
RISQUE DE CHOC ELECTRIQUE
NE PAS OUVRIR
CAUTION! The GS4, GS5, GS6, GS7,GS8 amplifiers run on 230VAC voltage. Removing
the cover will expose you to a potentially dangerous voltage!
Do not use the unit if the electrical power cord is frayed or broken.
Power is supplied from 230VAC single-phase grounded 50/60 Hz source.
CAUTION! The GS4, GS5, GS6, GS7, GS8 amplifiers can yield dangerous output voltage!
Do not touch the non-insulated cable parts connected to outputs of the unit in operation!
CAUTION! The high sound pressure caused by the high output signal applied to speaker
systems, may endanger your hearing. Please, take care to observe the required safety
precautions.
WARNING SIGNS
Important information! Intended to warn the user about any
important information contained in this Owner’s Manual.
Hazardous voltage inside! Intended to warn the user about electric
shock hazard due to high voltage inside the product.
This sign next to the output terminals warns about dangerous voltage
while in operation.
2
GENERAL
The GS4, GS5, GS6, GS7, GS8 power amplifiers (GS - Series) are designed for sound
signal high-fidelity amplification within professional sound reproduction systems.
The amplifier’s schematics provides for high sound quality whether under low signal
conditions or overload.
WARNING!
Make sure to take all precautions where required.
Please, follow all instructions and guidelines.
To avoid any risk of electrical shock and/or fire hazard, please, do not expose this unit
to rain or moisture. Do not use this unit near open water.
Use dry cloth to clean the unit.
Do not block fan vents.
Do not place the unit near heating radiators, furnaces or other heat-emitting devices.
Do not connect this unit to an ungrounded power supply line.
Protect the power cord against damage.
Disconnect the unit from power supply in case of thunder or during downtime.
In case of malfunctioning, caused by water or any other foreign matter inside or when
the unit has been dropped, or the power cord has been damaged, or the unit has been found
faulty, please, consult qualified personnel.
ATTENTION!
The GS4, GS5, GS6, GS7, GS8 amplifiers have the same design and functional
features and differ only in the schematics elements, output power and weight. Unless
specified otherwise, the word “amplifier” hereinafter applies to any of the above models.
UNPACKING
The manufacturer’s quality control system provides for careful examination of each
product before it leaves the factory to ensure its flawless appearance. After unpacking,
please, check the unit for any physical damage. In case of damage, please, contact your
local dealer. Keep the shipping carton and all packing material, as you may require them for
reshipment of the unit.
3
4
DESIGN FEATURES
Physical Design
The amplifier is enclosed in a metal (steel) case of 2U height. The amplifier is
designed to be installed into a standard 19" rack.
Power Supply Source
Switchable. Individual for each channel.
Cooling System
Forced, cooling rate smooth adjustable system.
Four fans, two per each channel. Backward air flow direction.
Dust Filter
Front panel filter easily removable/replaceable for periodic maintenance.
Power Amplifier Unit
Based on TD Class schematics.
TD Class power amplifier combines the best features of both Class D and analogue
amplifiers. The amplifier boasts the efficiency comparable to Class D amplifiers and
sound quality typical of analogue amplifiers.
Balanced inputs
The use of balanced inputs provides for an essential reduction of the environment-
induced hum and noise interference with long input connecting cables.
Input level Attenuators
Precision ALPS 31-step control knobs, individual for each channel.
Sensitivity slide switches
3 positions: 0.775V, 1.4V or 32dB fixed gain. Individual for each channel.
Mode switch
3-position slide switch.
Operating modes available:
– STEREO – two channels drive two separate loads from two separate signal
sources;
– MONO – two channels drive two separate loads from a single input signal source;
– BRIDGE – two channels drive a common load from a single signal source.
Input filter
Third-order filter individual for each channel.
Two pre-set cutoff frequency points (35Hz and 45Hz ) plus a disable position.
Recommended by world leading manufacturers of loudspeakers.
This filter cuts off any signals below 35Hz or 45 Hz which generally cannot be
reproduced by most professional loudspeakers.
The filter significantly reduces the displacement of the LF speaker cone below the
loudspeaker frequency cut-off point which makes it possible to increase the power applied to
the LF speaker (the power being not wasted for the cone “flapping”) and thus to raise the
sound pressure created by the loudspeaker without any danger of overheating the LF drivers
. When it is necessary to achieve a linear frequency response to drive full-range
loudspeakers generally used in studios or in cinema theaters, the input filter can be disabled
(bypassed for each channel individually) with the slide switches located on the amplifier rear
panel.
See below the amplifier low frequency response diagrams.
Optoelectronic Clip-Limiter
Independent for each channel.
Reduces the level of the input signal and eliminates the distortion, caused by hard clipping.
Removable Power Cord
A powerCON 20A NEUTRIK connector for GS4, GS5 and a powerCON 32A
NEUTRIK connector for GS6, GS7, GS8.
This feature is provided for convenience of transportation and rack mounting.
20Hz 50Hz 100Hz 200Hz 900Hz
-10
-5
0
5
10
«45 Гц»
20Hz 50Hz 100Hz 200Hz 900Hz
-10
-5
0
5
10
«OFF»
20Hz 50Hz 100Hz 200Hz 900Hz
-10
-5
0
5
10
«35 Гц»
5
6
FUNCTIONAL FEATURES
Output Short-Circuit Protection
Individual per each channel. Protects the output stage of the power amplifier against
short-circuiting, as well as limits the output current when a maximum-level sine signal is
applied continuously to 2-Ohms loudspeaker.
Overload Protection
The double-stage overload protection system, independent for each channel, protects
the output stage and optimizes the quality sound under overload.
In the event of short overloads (for example, caused by a sharp decrease in the
complex load resistance), only the current protection of the output stage is activated. It
limits the output transistors current to safe level. Protect threshold allows to give full
output power shortly, even on case of very low load.
In case of a more continuous overload, the protection system activates the built-in
Clip-limiter, which reduces the level of the input signal.
DC Output Protection
Independent for each channel. Prevents DC damage to loudspeakers.
The amplifier’s schematics precludes transit of any clicks or noise during the
power-on/off transition process.
Protection of loudspeakers against DC damage is ensured for each channel by
individual power supply units which are disabled in the event of output DC voltage or
any powerful LF fluctuations. In case the protection system becomes active on both
channels and both power supply units become disabled, all indicators go off.
The amplifier can be restarted with the POWER toggle switch, by way of turning
the amplifier off and turning it on, about 2 minutes later again.
High Frequency Protection
Independent for each channel. Prevents any damage to HF drivers as might be caused
by non-musical signals of powerful high frequency spectrum.
Should any powerful high frequency fluctuations occur on the output either as a
result of poor contact in the input cable connectors, or being send to the amplifier’s
input by any other device (such as a crossover or mixing console), the protection
system activates the built-in optoelectronic Clip-limiter to reduce the input signal level.
Thus the protection system effectively prevents any damage to tweeters as might be
caused by non-musical signals of powerful high frequency spectrum.
Thermal Protection
Independent for each channel. Protects the amplifier’s output stage against
overheating.
The amplifier may stop functioning only in case of the fan breakdown or blocked
air flow. In this case upon reaching 85°С, the independent protection system disables
the respective channel of the amplifier. The CLIP LED goes on and the SIGNAL LED of
the affected channel goes off. The amplifier resumes its operation in the reverse order.
As soon as the amplifier cools down, the affected channels gradually regain their
amplification level up to the set value.
7
Soft Start
Reduces the power-on inrush current.
The soft start system is provided to reduce inrush current to the amplifier and
to minimize the noise contributed by the amplifier to the power mains during the
power-on process.
Soft Signal Start
Ensures smooth power-on sound signal rise.
During the power-on process, this feature ensures smooth gain from zero to
the maximum level to provide for a smooth rise of the sound level emitted from the
loudspeakers.
Overvoltage Protection System
Relay system. Used to protect the amplifier against overvoltage in the mains.
In case of accidental connection of the amplifier to incorrect-wired mains, the
inter-phase voltage of 400V may be applied to the amplifier. In this case the
protection system will block the mains connection to the power supply. Only the
protection system stand-by power supply unit remains in operation. The system
activates, whenever the mains voltage exceeds ~265V. The amplifier automatically
resumes operation after the mains voltage goes down to ~260V.
8
AMPLIFIER BLOCK DIAGRAM
1+
2+
CH 1
INPUT
THRU
1+
2+
OUTPUT
CH 1, CH 2,
BRIDGE
+U
OUTPUT
CH 2
CH 2
INPUT
THRU
Power
amplifier
Power
amplifier
Class D
Class D
_U
+U
_U
Class D
Class D
MONO
MODE
LEVEL
Clip
Limiter
0.775V
GAIN
45 Hz
HI PASS
FILTER
35Hz
45Hz
35 Hz
OFF
1.4V
32 dB
45Hz
LEVEL
0.775V
GAIN
45 Hz
HI PASS
FILTER
35Hz
45Hz
35 Hz
OFF
1.4V
32 dB
45Hz
STEREO
BRIDGE
Clip
Limiter
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