LD Systems PRE ST 1 4-Channel Stereo Mixer Preamplifier Ldprest1 User Manual

June 6, 2024
LD Systems

USER´S MANUAL
LD Systems PRE ST 1 4 Channel Stereo Mixer Preamplifier
Ldprest1

View the complete user manual online
including more languages at: ld-systems.com/PREST1-downloads
PRE ST 1
4-CHANNEL STEREO MIXER PREAMPLIFIER
LDPREST1

COMPLETE USER MANUAL

PRE ST 1 USER MANUAL ONLINE
Scan this QR Code to get to the download section of PREST 1.
Here you can get the complete User manual in the following languages: EN, DE, FR, ES, PL, IT, RUS
www.ld-systems.com/PREST1-downloads

YOU‘VE MADE THE RIGHT CHOICE!
We have designed this product to operate reliably over many years. LD Systems stands for this with its name and many years of experience as
a manufacturer of high-quality audio products. Please read this User‘s Manual carefully, so that you can begin making optimum use of your LD
Systems product quickly.
You can find more information about LD-SYSTEMS at our Internet site WWW.LD- SYSTEMS.COM

INTENDED USE

This product is a device for professional audio installation!
The product has been developed for professional use in audio installations and is not suitable for use in private homes!
In addition, this product must only be used by qualified persons with technical knowledge of audio installations!
The product must not be used outside the specified technical data and operating conditions!
Any liability for damage and third-party damage to persons and property is excluded if the product is not used as intended!
The product is not suitable for:
• Persons (including children) with limited physical, sensory or mental capabilities or lack of experience and knowledge.
• Children (children must be instructed not to play with the device).

SAFETY INFORMATION

  1. Please read these instructions carefully.

  2. Keep all information and instructions in a safe place.

  3.  Follow the instructions.

  4. Observe all safety warnings. Never remove safety warnings or other information from the equipment.

  5. Use the equipment only in the intended manner and for the intended purpose.

  6.  Use only sufficiently stable and compatible stands and/or mounts (for fixed installations). Make certain that wall mounts are properly installed and secured. Make certain that the equipment is installed securely and cannot fall down.

  7. During installation, observe the applicable safety regulations for your country.

  8. Never install and operate the equipment near radiators, heat registers, ovens or other sources of heat. Make certain that the equipment is always installed so that is cooled sufficiently and cannot overheat.

  9. Never place sources of ignition, e.g., burning candles, on the equipment.

  10. Ventilation slits must not be blocked.

  11. Keep a minimum distance of 20 cm around and above the device.

  12. Do not use this equipment in the immediate vicinity of water (does not apply to special outdoor equipment – in this case, observe the special instructions noted below. Do not expose this equipment to flammable materials, fluids or gases. Avoid direct sunlight!

  13. Make certain that dripping or splashed water cannot enter the equipment. Do not place containers filled with liquids, such as vases or drinking vessels, on the equipment.

  14. Make certain that objects cannot fall into the device.

  15. Use this equipment only with the accessories recommended and intended by the manufacturer.

  16. Do not open or modify this equipment.

  17. After connecting the equipment, check all cables in order to prevent damage or accidents, e.g., due to tripping hazards.

  18. During transport, make certain that the equipment cannot fall down and possibly cause property damage and personal injuries.

  19. If your equipment is no longer functioning properly, if fluids or objects have gotten inside the equipment or if it has been damaged in anot her way, switch it off immediately and unplug it from the mains outlet (if it is a powered device). This equipment may only be repaired by authorized, qualified personnel.

  20. Clean the equipment using a dry cloth.

  21. Comply with all applicable disposal laws in your country. During disposal of packaging, please separate plastic and paper/cardboard.

  22.  Plastic bags must be kept out of reach of children.

  23. Please note that changes or modifications not expressly approved by the party responsible for compliance could void the user´s authority to operate the equipment.
    FOR EQUIPMENT THAT CONNECTS TO THE POWER MAINS

  24. CAUTION : If the power cord of the device is equipped with earthing contact, then it must be connected to an outlet with a protective ground. Never deactivate the protective ground of a power cord.

  25.  If the equipment has been exposed to strong fluctuations in temperature (for example, after transport), do not switch it on immediately. Moisture and condensation could damage the equipment. Do not switch on the equipment until it has reached room temperature.

  26. Before connecting the equipment to the power outlet, first verify that the mains voltage and frequency match the values specified on the equipment. If the equipment has a voltage selection switch, connect the equipment to the power outlet only if the equipment values and the mains power values match. If the included power cord or the power adapter does not fit in your wall outlet, contact your electrician.

  27. Do not step on the power cord. Make certain that the power cable does not become kinked, especially at the main outlet and/or power adapter and the equipment connector.

  28.  When connecting the equipment, make certain that the power cord or power adapter is always freely accessible. Always disconnect the equipment from the power supply if the equipment is not in use or if you want to clean the equipment. Always unplug the power cord and power adapter from the power outlet at the plug or adapter and not by pulling on the cord. Never touch the power cord and power adapter with wet hands.

  29.  Whenever possible, avoid switching the equipment on and off in quick succession because otherwise, this can shorten the useful life of the equipment.

  30.  IMPORTANT INFORMATION: Replace fuses only with fuses of the same type and rating. If a fuse blows repeatedly, please contact an authorized service center.

  31. To disconnect the equipment from the power mains completely, unplug the power cord or power adapter from the power outlet.

  32. If your device is equipped with a Volex power connector, the mating Volex equipment connector must be unlocked before it can be removed. However, this also means that the equipment can slide and fall down if the power cable is pulled, which can lead to personal injuries and/or  other damage. For this reason, always be careful when laying cables.

  33. Unplug the power cord and power adapter from the power outlet if there is a risk of a lightning strike or before extended periods of disuse.

  34. The appliance is not to be used by persons (including children) with reduced physical, sensory or mental capabilities, or lack of experience and knowledge.

  35. Children must be instructed not to play with the device.

      1.  If the power cord of the device is damaged, do not use the device. The power cord must be replaced by an adequate cable or assembly from an authorized service center.
        | CAUTION : To reduce the risk of electric shock, do not remove cover (or back). There are no user-serviceable parts inside. Maintenance and repairs should be exclusively carried out by qualified service personnel.
        ---|---
         | The warning triangle with the lightning symbol indicates dangerous uninsulated voltage inside the unit, which may cause an electrical shock.
        | The warning triangle with an exclamation mark indicates important operating and maintenance instructions.
        | Warning! This symbol indicates a hot surface. Certain parts of the housing can become hot during operation. After use, wait for a cool-down period of at least 10 minutes before handling or transporting the device.
        | Warning! This device is designed for use below 2000 meters in altitude.
        | Warning! This product is not intended for use in tropical climates.
        | FOR INDOOR USE ONLY
        This symbol indicates electrical equipment designed primarily for indoor use.

CAUTION! HIGH VOLUMES IN AUDIO PRODUCTS!
This device is meant for professional use. Therefore, commercial use of this equipment is subject to the respectively applicable national accident prevention rules and regulations. As a manufacturer, Adam Hall is obligated to notify you formally about the existence of potential health risks.
Hearing damage due to high volume and prolonged exposure: When in use, this product is capable of producing high sound-pressure levels (SPL) that can lead to irreversible hearing damage in performers, employees, and audience members. For this reason, avoid prolonged exposure to volumes in excess of 90 dB.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause
harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
– Reorient or relocate the receiving antenna.
– Increase the separation between the equipment and receiver.
– Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
– Consult the dealer or an experienced radio/TV technician for help.

INTRODUCTION

Permanent installations require solutions that offer a visually discrete design that blends into the background while still being flexible and versatile in their functions. You need to be able to connect different audio sources and manage them, to mute non-priority signals during announcements or emergency calls.
The PREST 1 is a 4-channel multi-functional stereo mixer preamplifier that allows users to mix 2 microphone/line sources together with an emergency line input and one of the 3 music sources available, including a Bluetooth receiver. These versatile connection options together with a four-level priority system, that combines contact closure inputs and VOX audio detection circuits, guarantee a seamless integration in almost any commercial audio application.
PRE ST 1 is equipped with two priority contacts: one for the emergency input, which mutes all the other signal sources, and one for the microphone inputs, which mutes the music signal sources. The stereo balanced line output includes a mono/stereo switch and separate tone controls for bass and treble. An automatic standby mode can also be activated in order to further reduce energy consumption when the device is not used. The intuitive design of its control panel ensures an easy operation, with input and master volume controls, clear signal level and priority indications, and a practical music source selection and Bluetooth pairing activation via capacitive buttons. On the other hand, the clarity of the rear panel and the compact 9.5” format ensures that the preamplifier can be easily installed.

FEATURES

  • Line input for emergency signal with contact closure
  • 2 Mic/line input terminal blocks with microphone/line switching and switchable 24-V phantom power
  • Priority contact closure and switchable chime function for mic/line channels
  • 3 stereo music sources: 2 line inputs with RCA sockets plus Bluetooth 4.0 interface
  • Gain control and Clip LED for emergency and Mic/Line inputs
  • Balanced stereo line output (terminal block) with mono-stereo switching
  • Separate tone controls for treble and bass on the rear panel
  • 4 priority settings for versatile integration options
  • Switchable auto standby mode to save energy
  • User-friendly control interface – intuitive operation via capacitive controller (choice of music source and Bluetooth pairing)
  • Easy installation thanks to the clear layout and labeling of the connections and controls on the back
  • Universal wide-range switching power supply
  • Format: Half rack width, 2 RU
  • Optional: Rack installation kit (IMA RK) for the installation of one or two PRE ST1 or IMA 30/60 units in a 19” rack

CONNECTIONS, CONTROLS AND DISPLAY ELEMENTSLD Systems PRE ST 1 4 Channel
Stereo Mixer Preamplifier Ldprest1 - DISPLAY

  1. POWER CONNECTOR
    IEC socket to the power supply of the device (power cable included in the packaging).

  2. FUSE
    Fuse holder for 250 V fuses (5 × 20 mm). IMPORTANT NOTE: Only replace the fuse with a fuse of the same type (see note on the housing). If the fuse
    blows repeatedly, please contact an authorized service center.

  3.  ON/OFF
    Rocker switches to turn the device on and off.

  4. EMERGENCY
    5-pole terminal block connection for the installation of an acoustic emergency call system. The poles +, – and G correspond to a balanced line input. Poles C and + are used for the connection of a separate mute switch (terminal block included in the packaging). The contact closure of the EMERGENCY channel (Poles C and + closed) mutes all other input channels, regardless of the VOX settings.
    CLIP: The red CLIP LED indicates, the input is being operated at the distortion limit. You should reduce the signal level using the GAIN control or the volume control on the playback device so that the CLIP LED is no longer lit.
    VOX: The VOX control (Voice Operated Exchange) makes it possible to set a threshold for the emergency audio signal in order to activate an automatic mute switching circuit. When the level at the EMERGENCY input reaches the set threshold, all other microphone and line channels are muted. This ensures that the emergency signal can be heard clearly. In addition, in this case the EMERG indicator is lit on the front of the amplifier.
    As soon as the level of the emergency signal falls below the set threshold, the other channels are no longer muted and the EMERG indicator goes out. With this setting, the EMERGENCY channel always has the highest priority. The emergency signal is routed directly to the audio output LINE OUT internally.
    If the VOX control is set to minimum (turned all the way to the left), automatic muting via the VOX switching circuit is deactivated and the EMERGENCY channel can be used as an additional line channel.
    GAIN: Control to set the pre-amplification of the corresponding audio signal. Set the Gain control such that the Clip LED of the channel only lights up briefly when the signal level peaks. Avoid the Clip LED being permanently lit by reducing the pre-amplification. It may also be necessary to reduce the signal level on the playback device. The level of the emergency signal is not influenced by the current setting of the main volume control (master volume), but is set via the GAIN control.

  5. MIC/LINE 1
    Microphone/line channel with switchable chime function (signal tone). The connection can be made via the XLR/jack combo socket as well as the terminal block. In this case, the poles +, – and G are provided on the terminal block connection for the balanced input signal.
    Poles C and + are used for the connection of a separate mute switch (terminal block included in the packaging). The contact closure offers the possibility to mute the MUSIC channel using an external switch/button. In addition, the internal chime/signal tone function can be activated in this way when the circuit is enabled (see point 6 MIC/LINE 2, CHIME).
    MIC/LINE: If there is a line signal on the XLR/jack combo socket or the terminal block, switch the MIC/LINE channel 1 to LINE mode using the corresponding MIC/LINE switch (switch pressed). If a microphone is connected, activate MIC mode using the MIC/LINE switch (switch not pressed).
    PHANTOM ON/OFF: When using a condenser microphone, you need to activate the 24 V phantom power supply (PHANTOM ON/OFF switch pressed:
    ON). Always make sure that the microphone is connected and the channel volume is set to a minimum before turning on phantom power. Before you disconnect the microphone from the device again, deactivate the phantom power and turn the channel volume to a minimum.
    GAIN: Control to set the pre-amplification of the corresponding audio signal. Set the Gain control such that the Clip LED of the channel only lights up briefly when the signal level peaks. Avoid the Clip LED being permanently lit by reducing the pre-amplification. It may also be necessary to reduce the signal level on the playback device.
    CLIP: The red CLIP LED indicates, the input is being operated at the distortion limit. You should reduce the signal level on the GAIN control or the volume control on the playback device so that the CLIP LED is no longer lit.
    VOX: The VOX control makes it possible to set an audio threshold value for an automatic mute circuit for MIC/LINE input 1, that mutes MIC/LINE 2 and MUSIC channels as soon as its input signal reaches the predefined level. The PRIO LED is lit on the front if the contact closure or VOX circuit is activated. As soon as the input level of the emergency signal falls below the set threshold, the channels are no longer muted and the PRIO LED goes out. In such a configuration, MIC/LINE 1 has priority over MIC/LINE 2 and MUSIC. Adjust the volume of the channel using control 1 on the front of the device.

  6. MIC/LINE 2
    Microphone/line channel with switchable chime function (signal tone). The connection can be made via the RCA sockets (line level, a stereo signal is summed to mono) as well as the terminal block. In this case, the poles +, – and G are provided on the terminal block connection for the balanced input signal.
    MIC/LINE: If there is a line signal on the terminal block connection, switch the MIC/LINE channel 2 to LINE mode using the corresponding MIC/LINE switch (switch pressed). If a microphone is connected to the terminal block connection, activate MIC mode using the MIC/LINE switch (switch not pressed).
    PHANTOM ON/OFF: When using a condenser microphone, you need to activate the 24 V phantom power supply (PHANTOM ON/OFF switch pressed: ON). Always make sure that the microphone is connected and the channel volume is set to a minimum before turning on phantom power. Before you disconnect the microphone from the device again, deactivate the phantom power and turn the channel volume to a minimum.
    GAIN: Control to set the pre-amplification of the corresponding audio signal. Set the Gain control such that the Clip LED of the channel only lights up briefly when the signal level peaks. Avoid the Clip LED being permanently lit by reducing the pre-amplification. It may also be necessary to reduce the signal level on the playback device.
    CLIP: The red CLIP LED indicates, the input is being operated at the distortion limit. You should reduce the signal level on the GAIN control or the volume control on the playback device so that the CLIP LED is no longer lit.
    CHIME: The volume for the chime/signal tone is controlled via the CHIME control on the back of the amplifier. If the control is turned all the way to the left, the chime/signal tone circuit is disabled. If the internal chime/signal tone function is active, MIC/LINE 1, MIC/LINE 2 and MUSIC channels are muted for the duration of the signal tone. The signal tone is initiated with the help of a button that is connected to contacts C and + of the MIC/ LINE 1 channel. Adjust the volume of the channel using control 2 on the front of the device.

  7. MUSIC
    Stereo line channel for the connection of playback devices such as a CD or MP3 player. The MUSIC channel includes a Bluetooth module. RCA sockets are provided on the back for connecting two stereo line input signal sources (CD symbol or cable symbol). The desired signal source is selected using a touch- sensitive button on the front of the amplifier. Adjust the volume of the channel using control MUSIC on the front of the device.

  8. LINE OUT
    The balanced stereo line output LINE OUT with terminal block connection is used to send the audio output signal to an external amplifier or active loudspeaker system. Pin assignment: LEFT +, LEFT -, G (Ground), RIGHT +, RIGHT – (terminal block in packaging content).
    BASS/TREBLE: The tone settings of the output signal can be applied by using the BASS and TREBLE controls.
    ST/MONO: The output of the audio signal can either be in stereo (ST) or in mono (MONO). If the switch is set to MONO, the corresponding audio signal is summed to mono at both outputs LEFT and RIGHT.

  9. STANDBY ON/OFF
    If the standby function is activated (STANDBY in ON position), the amplifier is automatically set to standby mode if there is no audio signal for 20 minutes. This reduces power consumption considerably. As soon as there is an audio signal, standby mode is automatically ended and the amplifier is once again operational after around 3 seconds (the STANDBY LED flashes white on the front of the device when starting). If the STANDBY LED is solid white, the device is ready for use. The LED is lit red in standby mode. In addition, the device can also be switched to standby mode manually by pressing the standby button on the front. In this case, auto standby mode is deactivated and the device no longer starts automatically. Please note: The standby circuit analyses the connection status of the Bluetooth unit. When a Bluetooth connection to an auxiliary device (smartphone, tablet) is detected, and Bluetooth is selected as the signal source, the device will not automatically go into standby mode.
    LD Systems PRE ST 1 4 Channel Stereo Mixer Preamplifier Ldprest1 -
Bluetooth

  10. CHANNEL 1
    Volume control for channel 1 with white SIG (signal) and red CLIP LED. As soon as there is an audio signal on channel 1 and volume control 1 is set to the desired volume, the white signal LED lights up. If the red CLIP LED lights up, the signal may be distorted. In this case, reduce the channel volume control (control 1). Should the audio signal still be distorted, please check the corresponding input level on the back of the amplifier (CLIP LED/GAIN).

  11. CHANNEL 2
    Volume control for channel 2 with white SIG (signal) and red CLIP LED. As soon as there is an audio signal on channel 2 and volume control 2 is set to the desired  volume, the white signal LED lights up. If the red CLIP LED lights up, the signal may be distorted. In this case, reduce the channel volume (control 2). Should the audio signal still be distorted, please check the corresponding input level on the back of the amplifier (CLIP LED/GAIN).

  12. MUSIC
    Volume control for MUSIC channel with white SIG (signal) and red CLIP LED. As soon as there is an audio signal on the MUSIC channel and the corresponding volume control is set to the desired volume, the white signal LED lights up. If the red CLIP LED lights up, the signal may be distorted. In this case, reduce the output level of the auxiliary device or the channel volume (MUSIC control).

  13. Touch-sensitive button for selecting the audio source of the MUSIC channel (Bluetooth module, input with CD symbol, input with cable symbol). To switch over the signal source, press the button for at least half a second. Activation of the individual signal sources takes place clockwise.

  14. Touch-sensitive button for activating the Bluetooth connection (pairing). To connect a Bluetooth auxiliary device (e.g. Smartphone, tablet, etc.) to the Bluetooth module of the device, select the Bluetooth signal source (see element 13). If no auxiliary device is connected to the Bluetooth module, this is indicated by the Bluetooth symbol flashing slowly. In this mode, the LD PRE ST1 is not visible to external auxiliary devices. Only previously connected auxiliary devices can be connected directly to the LD PRE ST1 without activating pairing mode. In order to prevent an unwanted or unexpected connection, this connection is not established automatically, but must be manually established in the Bluetooth menu of the auxiliary device (select LD PRE ST1).

To connect to a new auxiliary device, press the Bluetooth pairing button for around 2 seconds until the Bluetooth symbol flashes more rapidly.
The Bluetooth ID is now visible to other Bluetooth devices. Activate the Bluetooth function on the auxiliary device and search for nearby Bluetooth devices in the Bluetooth menu. When the LD PRE ST1 appears under “available devices”, you just need to select it and the connection will be made automatically. If this process is successful, the Bluetooth symbol is permanently lit on the front of the device and the Bluetooth ID is no longer visible to other devices. This prevents unauthorized connections to the Bluetooth module. Playback from the auxiliary device can now be started. To disconnect a currently paired Bluetooth device and to set the Bluetooth module ready to pair again, press the Bluetooth icon for around 2 seconds. Pair the playback device and connect it again by selecting LD PRE ST1 from “paired devices” in the Bluetooth menu of the playback device.

15 MASTER VOLUME CONTROL
The master volume control is used to adjust the volume of the summed signal of all channels except the EMERGENCY channel. The EMERGENCY channel bypasses the master volume control, and the signal is sent directly to the stereo line output, LINE OUT. The master volume control is equipped with a ring-shaped LED display. This LED ring remains dark when there is no signal or only a very weak signal at the output, and starts to light up white as soon as a sufficient signal level is detected.
16 PRIO
LED for the indication of an active priority mode related to MIC/LINE channels (priority levels 2, 3 and 4). Three situations cause the priority feature of the MIC/LINE channels to engage, thereby causing the PRIO display field on the front of the device to light up yellow.
1. The VOX circuit is active (input signal level MIC/LINE 1 exceeds the set VOX threshold value).
2. The contact between poles C and + of the terminal block connections for MIC/LINE 1 channel is closed using a mute switch/button.
3. The chime/signal tone is played.
Further information on the channel priorities and the EMERG and PRIO indicators on the front of the amplifier can be found in the PRIORITY LEVELS table in these operating instructions.
17 EMERG
Indicator for the priority function of the EMERGENCY channel. The EMERG indicator is lit yellow if priority level 1 is activated by the VOX emergency circuit or a connected mute switch/button (contact closure). All other input channels are muted during this time. As soon as the contact closure is opened again or the emergency signal level falls below the VOX threshold value, all channels will be unmuted, and the EMERG display will be turned off.
18 STANDBY BUTTON
Briefly press the standby button to put the amplifier into standby mode and mute the stereo line output, LINE OUT. If the standby button is briefly pressed again, the device is ready for operation again. If standby mode is activated by pressing the standby button, reactivation of the device via the automatic standby function is not available, even if an audio signal is detected.

PRIORITY LEVELS

Priority level| Trigger source| Muted signal sources| Active signal sources| Indication In the front panel
---|---|---|---|---
1| Emergency VOX circuit and Contact closure| MIC/LINE 1| EMERGENCY| EMERG
MIC/LINE 2
MUSIC
2| MIC/LINE 1 VOX| MIC/LINE 2| EMERGENCY| PRIO
MUSIC| MIC/LINE 1
3| MIC/LINE 1, contact closure during chime/signal tone output| MIC/LINE 1| EMERGENCY| PRIO
MIC/LINE 2
MUSIC
4| MIC/LINE 1, contact closure after chime/signal tone output| MUSIC| EMERGENCY| PRIO
MIC/LINE 1
MIC/LINE 2
5| –| –| EMERGENCY| –
MIC/LINE 1
MIC/LINE 2
MUSIC

CONNECTION EXAMPLESLD Systems PRE ST 1 4 Channel Stereo Mixer
Preamplifier Ldprest1 - BluetCONNECTIONooth The connection for a mute switch/button in MIC/LINE channel 1 can be used for two devices at the same time (muting of a music signal and/or activation of the chime/signal tone). In this case, the mute contacts of both devices must be connected to poles C and + of the terminal block connector for MIC/LINE 1.

When wiring terminal blocks, please ensure that the poles/terminals are correctly assigned. The manufacturer takes no responsibility for damage caused by faulty wiring! Information on the correct wiring of terminal block connections can be found in the section TERMINAL BLOCK CONNECTIONS in this user manual.

TERMINAL BLOCK CONNECTIONS

LD Systems PRE ST 1 4 Channel Stereo Mixer
Preamplifier Ldprest1 - TERMINAL BLOCK CONNECTIONS

**LINE OUT CONNECTIONS


RACK INSTALLATION (LDIMARK rack installation kit available as an option)
The optionally available LDIMARK rank installation kit contains rack-mount brackets and connecting pieces for fixed installation of PREST 1, IMA 30, and IMA 60 mixing amplifiers (single or two side by side) in a 19” rack. The installation kit includes the following components: 2 rack-mount brackets with short sides **A, 1**rack-mount bracket with long side **B , 2**small plates for the back**C , 2**rectangular plates for the bottom**D, 4** M4 flathead screws for the rack-mount brackets, 8 M3 countersunk screws for the plates **D**LD Systems PRE ST 1 4 Channel Stereo Mixer Preamplifier
Ldprest1 - LDIMARK

The installation of a single amplifier requires one rack-mount bracket with short sides A and the rack-mount bracket with long side B . Screw the bracket with the short sides to either the left or right side of the amplifier and the bracket with the long side to the opposite side. Use the M4 flathead screws for this.LD Systems PRE ST 1 4 Channel Stereo Mixer Preamplifier Ldprest1 -
amplifier

If you want to install two amplifiers side by side in a 19” rack, you will need the two small plates to connect the amplifiers together at the back C , the two rectangular plates for connection at the bottom D and the two rack- mount brackets with short sides A . Loosen the corresponding screws on the back and secure the plates with these screws C . Screw the connecting plates D in with the supplied M3 countersunk screws to the intended positions on the amplifiers, as shown below. Screw the rack-mount brackets with the short sides A to the sides of the device using the M4 flathead screws.LD Systems PRE ST
1 4 Channel Stereo Mixer Preamplifier Ldprest1 - bottomLD Systems PRE ST 1 4 Channel
Stereo Mixer Preamplifier Ldprest1 - TABLE

UNDER-TABLE INSTALLATION (rack-mount bracket included in the optionally available rack mount kit LDIMARK).
Two M4 threaded holes are provided at the top of the corners of the amplifier housing for under-table installation. Screw the two rack-mount brackets A with the short sides to the two sides of the housing using the M4 flathead screws provided (see figure). The amplifier can now be installed in the desired position under a table.

CARE, MAINTENANCE AND REPAIR

To guarantee the flawless operation of the device over a long period, it must be cared for and maintained regularly.
CARE (TO BE CARRIED OUT BY THE USER)
WARNING : Before any care measures take place, the power supply and any device connections must be disconnected.
NOTE! Improper care can damage the device and even destroy it.

  1. Housing surfaces must be cleaned with a clean, damp cloth. Make sure that no moisture enters the device.
  2. Air inlets and outlets must be cleared of dust and dirt regularly. If compressed air is used, prevent any damage to the device (e.g. fans must be blocked in this case).
  3. Cables and plug-in contacts must be cleaned regularly and cleared of dust and dirt.
  4. Generally, no cleaning agents or agents with a grinding effect should be used as this may cause damage to surfaces.
  5.  Devices must generally be stored in a dry place protected from dust and dirt.

MAINTENANCE AND REPAIR (TO BE CARRIED OUT BY SPECIALISTS ONLY)

DANGER! The device contains live components. Even after disconnecting the power cables, residual voltage may remain in the  device, e.g. through charged capacitors
NOTE! There are no user-serviceable parts in the device.
NOTE! Maintenance and repair measures may only be carried out by authorized specialists. In case of doubt, contact the manufacturer.
NOTE! Improperly performed maintenance work can affect the warranty.

TECHNICAL DATA

Item number LDPREST1
Product type Installation mixer preamplifier
Emergency input 1 balanced line input
Mic/Line inputs 2
Music sources 2 unbalanced stereo line inputs + 1 Bluetooth interface v4.0
Line outputs 2 (Stereo/Mono switchable)
Cooling system Convection cooling
Priority levels 4

Emergency Input

Nominal input sensitivity -3 dBu (Sine 1 kHz, Gain max)
Nominal input clipping 20 dBu (Sine 1kHz)
THD+N < 0.02% (Line OUT, -16 dBu, Gain max, 20 kHz BW)
Frequency response 18 Hz – 20 kHz (Line OUT, -3 dB)
Input Impedance 10 kohms (Balanced)
SNR >100 dB (LINE OUT, -6 dBu, CH Gain set 10 dB, Master Vol min (-inf), 20

kHz BW, a-weighted)
SNR (Best conditions)| >105 dB (LINE OUT, +18 dBu, Gain center (0 dB), 22 kHz BW, a-weighted)
CMRR| > 48 dB (LINE OUT, -6 dBu 1 kHz)
Gain| -40 to 15 dB
VOX Threshold| 0%: Off, 25%: -6 dBu, 50%: -27 dBu, 100%: -35 dBu
Priority Contact closure| +5VDC Normally Open for dry contact
Connector| 5-pin Terminal Block, pitch 5.08mm
Standby wake up threshold| -40 dBu

Mic/Line inputs 1-2

Nominal input sensitivity| Mic: -26 dBu (Sine 1 kHz, Gain max)
Mic: -26 dBu (Sine 1 kHz, Gain max)
---|---
Nominal input clipping| Mic: -5 dBu (Sine 1kHz)
Line: +19dBu (Sine 1kHz)
THD+N| Mic: < 0.02% (LINE OUT, -38 dBu, 20-20 kHz, Gain max, 20 kHz BW)
Line: < 0.01% (LINE OUT, +4 dBu, 20-20 kHz, CH Gain center (0dB), 20 kHz BW)
Frequency response| Mic: 165 Hz – 20 kHz (LINE OUT, -3 dB)
Line: 20 Hz – 20 kHz (LINE OUT, -3 dB)
Input Impedance| Mic: 1.2 kohms (Balanced)
Line: 10 kohms (Balanced)
SNR| Mic: 80 dB (LINE OUT, -38 dBu, Gain max, 22 kHz BW, a-weighted)
Line: >89 dB (LINE OUT, +4 dBu, CH Gain max, 20 kHz BW, a-weighted)
SNR (Best conditions)| Mic: >102 dB (LINE OUT, -5 dBu, Gain Center (22 dB), 20 kHz BW, a-weighted)
Line: >103 dB (LINE OUT, +18 dBu, CH Gain Center (0 dB), 20 kHz BW, a-weighted)
CMRR| Mic: > 40 dB
Line: > 45 dB
Gain| Mic: 43 dB (LINE Out, Max. Gain)
Line: 19 dB (LINE Out, Max. Gain)
Phantom Power| +24V, 10mA Switchable
VOX Threshold| Mic: 0%: Off, 25%: -40 dBu, 50%: -52 dBu, 100%: -66 dBu
Line: 0%: Off, 25%: -6 dBu, 50%: -27 dBu, 100%: -35 dBu
Priority Contact closure| +5VDC Normally Open for dry contact
Connector| Mic/Line1: 5-pin Terminal Block, pitch 5.08mm + 1 XLR/6.3mm Jack combo connector
Mic/Line2: 3-pin Terminal Block, pitch 5.08mm + 1 dual RCA Mono Summed
Standby wake up threshold| Mic: -70 dBu
Line: -35 dBu (Line), – 40 dBu (Mono Sum)
Chime|
---|---
Play time| 2s
Resolution| 12 Bit

Music inputs – CD/AUX

Nominal input clipping 8 dBV (Sine 1kHz)
Connector 2 x dual RCA
THD+N < 0.005% (LINE OUT, 0 dBV, 20-20 kHz, CH Gain max, 20 kHz BW)
Frequency response 20 Hz – 20 kHz (LINE OUT, -3 dB)
Input Impedance 20 kohms (Unbalanced)
SNR >93 dB (LINE OUT, 0 dBV, CH Vol max., 20 kHz BW, a-weighted)
SNR (Best conditions) >102 dB (LINE OUT, +8 dBV, 20 kHz BW, a-weighted)
Gain -Inf to 6 dB
Standby wake up threshold – 45 dBu

Music input – BT

THD+N < 0.2%
Frequency response 25 Hz – 20 kHz (AUX OUT, -3 dB)
SNR >80 dB (LINE, -10 dBFS, Gain max, 20 kHz BW, a-weighted)
SNR (Best conditions) >93 dB (LINE OUT, 0 dBFs, Gain max (0 dB), 20 kHz BW,

a-weighted)

Line Output

Outputs Stereo Line Level, Mono Switchable
Connector 5-pin Terminal block, pitch 5.08mm
Max. output Level 16dBu
Frequency response 18 Hz – 25 kHz (-1,5dB)
Crosstalk, Stereo Separation 100Hz: 72dB, 1kHz: 90dB, 10kHz: 75dB
Output Noise Level < -90 dBu / A-Weighted
Tone Control BASS: +-10dB (100Hz), TREBLE: +-10dB (10kHz)

Power Supply

Type SMPS (Switch-mode power supply)
Voltage Range 100 VAC – 240 VAC (+-10%), 50-60 Hz
Mains fuse T0.5A 250V
Connector IEC Jack
Safety Class Class 1
Max power consumption 6 W
Idle power consumption 5 W (no signal input)
Standby power consuption < 1W
Operating Temperature 0°C – 40°C; < 85% humidity, non condensing

General

Time to standby 20 Min
Material Steel chassis, Plastic Front panel
Dimensions (W x H x D) 210 x 95 x 266.76 mm (height with rubber feet)
Weight 2.08 kg
Optional Accessories Rack mounting hardware (LDIMARK)

DISPOSAL
PACKAGING:

  1. Packaging can be disposed of via the usual waste disposal channels.
  2. Please separate the packaging according to the waste disposal and materials regulations in your country.

DEVICE:

  1.  This device is subject to the European Directive on Waste Electrical and Electronic Equipment in its applicable version. WEEE Directive- Waste Electrical and Electronical Equipment. Old devices and batteries do not belong in household waste. The old device or batteries must be disposed of via an approved waste disposal service or a municipal waste disposal facility. Follow the directives in your country!
  2. Follow the disposal laws in your country.
  3. As a private customer, you can obtain information on environmentally friendly disposal options from the retailer from whom you purchased the product or from the relevant regional authorities.

MANUFACTURER’S DECLARATIONS
MANUFACTURER’S WARRANTY & LIMITATION OF LIABILITY
Adam Hall GmbH, Adam-Hall-Str. 1, D-61267 Neu Anspach / Email Info@adamhall.com / +49 (0)6081 / 9419-0.
Our current warranty conditions and limitation of liability can be found at:
https://cdn-shop.adamhall.com/media/pdf/MANUFACTURERS- DECLARATIONS_LD_SYSTEMS.pdf.
For servicing, contact your sales partner.
CE CONFORMITY
Adam Hall GmbH hereby confirms that this product complies with the following directive (where applicable).
Low Voltage Directive (2014/35/EU)
EMC Directive (2014/30/EU)
RoHS (2011/65/EU)
RED (2014/53/EU)

SIMPLIFIED UK DECLARATION OF CONFORMITY
Hereby, Adam Hall Ltd. declares that the radio equipment type ( Radio Equipment Regulations 2017) is in compliance with
Directive SI2017/1206. The full text of the UK declaration of conformity is available at the following internet adress:
www.adamhall.com/compliance/
CE DECLARATION OF CONFORMITY
Declarations of conformity for products subject to the LVD, EMC, RoHS Directives can be requested from info@adamhall.com.
Declarations of conformity for products subject to the RED Directive can be requested from www.adamhall.com/compliance/
EU DECLARATION OF CONFORMITY
Adam Hall GmbH hereby confirms that this radio equipment complies with Directive 2014/53/EU.
The full text of the EU declaration of conformity is available at: www.adamhall.com/compliance/
Printing errors and mistakes, as well as technical or other changes are reserved!

Adam Hall GmbH | Adam-Hall-Str. 1 | 61267 Neu-Anspach | Germany
Phone: +49 6081 9419-0 |adamhall.com

References

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