Specifications

Safety Instructions

1. Terminals marked with this symbol carry an electrical current of sufficient magnitude to constitute a risk of electric shock.
2. Use only high-quality professional speaker cables with ¼” TS or twist-locking plugs pre-installed. All other installation or modification should be performed only by qualified personnel.
3. This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure – voltage that may be sufficient to constitute a risk of shock.
4. This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Please read the manual.
5. Caution To reduce the risk of electric shock, do not remove the top cover (or the rear section). No user serviceable parts inside. Refer servicing to qualified personnel.
6. Caution To reduce the risk of fire or electric shock, do not expose this appliance to rain and moisture. The apparatus shall not be exposed to dripping or splashing liquids and no objects filled with liquids, such as vases, shall be placed on the apparatus.
7. Caution These service instructions are for use by qualified service personnel only. To reduce the risk of electric shock do not perform any servicing other than that contained in the operation instructions. Repairs have to be performed by qualified service personnel.
8. Warning: Please refer to the information on the exterior of the bottom enclosure for electrical and safety information before installing or operating the device.
   1. Please read and follow all instructions and warnings.
   2. Keep the apparatus away from water (except for outdoor products).
   3. Clean only with a dry cloth.
   4. Do not block ventilation openings. Do not install it in a confined space. Install only according to the manufacturer’s instructions.
   5. Protect the power cord from damage, particularly at plugs and appliance sockets.
   6. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.
   7. 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 (only for USA and Canada). 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 the replacement of the obsolete outlet.
   8. Use only attachments and accessories recommended by the manufacturer.
   9. Use only specified carts, stands, tripods, brackets, or tables. Use caution to prevent tip-over when moving the cart/ apparatus combination.
   10. Unplug during storms or if not in use for a long period.
   11. Only use qualified personnel for servicing, especially after damage.
   12. The apparatus with a protective earthing terminal shall be connected to a MAINS socket outlet with a protective earthing connection.
   13. Where the MAINS plug or an appliance coupler is used as the disconnect device, the disconnect device shall remain readily operable.
   14. Avoid installing it in confined spaces like bookcases.
   15. Do not place naked flame sources, such as lighted candles, on the apparatus.
   16. Operating temperature range 5° to 45°C (41° to 113°F).

LIMITED WARRANTY

For the applicable warranty terms and conditions and additional information regarding Music Tribe’s Limited Warranty, please see complete details online at community.musictribe.com/support.

Introduction
Thank you for purchasing a DL251/DL252 Audio System I/O.
The DL251 and DL252 Audio System I/Os are 19” rack units designed for use with Midas digital systems.
Your DL251/DL252 Audio System I/O was conceived by Midas to offer audio professionals high-performance audio equipment designed to provide no-compromise sonic quality with a feature set that offers all essential facilities and functions.
It represents the very best of British design and engineering combined with contemporary, efficient manufacturing methods and will give you many years of reliable service. So, to obtain the best results with a minimum of effort, please read this operator manual and, finally, enjoy your Midas DL251/DL252 Audio System I/O!
Key features
The DL251/DL252 Audio System I/Os have the following key features:

• Mic/line inputs The DL251 has 48 mic/line inputs, and the DL252 has 16 mic/line inputs.
• Line outputs The DL251 has 16 outputs, and the DL252 has 48 outputs.
• Operator interface A series of sections on the front panel have LEDs to convey the operating/ configuration status to the operator. Some sections have a configuration button for setting up the unit’s parameters, such as clock source, sample rate, etc.
• MIDI Both units have in, out and thru MIDI sockets supplied as standard. (For use with Midas consoles only.)
• AES50 Three AES50 inputs/outputs provide connection to the console/snake via EtherCon® XLRs, which are configured for N+1 cable redundancy.
• Sample rate: Switchable between 96 kHz and 48 kHz sample rates.
• Ethernet An Ethernet control socket on the rear panel allows Ethernet control via Cat 5e cable up to 100 m long.
• A/D Analogue to digital conversion is by default 24-bit, 96 kHz.
• Gain range From -2.5 dB to +45 dB in 2.5 dB steps.
• Mute A MUTE button on the rear panel will mute all outputs simultaneously for on-stage patching, if held in for longer than one second.
• Boot mode A recessed boot mode button on the rear panel selects between normal operation and a service personnel-only configuration boot mode.
• Diagnostics A D-type connector on the rear panel allows diagnostics (by service personnel only) to be carried out on the unit.
• Power supplies Dual redundant power supplies, each with dual locking mains connectors.

About this manual
This is the operation manual for the DL251 Audio System I/O and DL252 Audio System I/O. It is intended to help get your unit installed and in operation as quickly as possible by giving you unpacking, installation, connection, setting up and operating instructions. To help familiarise you with the DL251/DL252 there is a description of the front and rear panels, along with easy-to-follow user instructions.

Getting started
This section shows you how to unpack, install, connect up, switch on, and configure the DL251/ DL252 unit. This equipment is supplied by a mains voltage that can cause electric shock injury. Before installing, setting u, or operating this equipment, make sure that you have read and fully understand all of this section and the “Important safety instructions” at the front of this manual. Refer to additional safety information on the top cover of the unit.

Unpacking
Carefully unpack your DL251/DL252 equipment package. Then, inspect the DL251/DL252 unit carefully for any signs of damage that may have occurred during trans,   and notify the courier immediately if you discover any.
Check the contents of your DL251/DL252 equipment package. If any parts are missing, incorrect, or faulty, please contact your local distributor or Midas at the address at the front of this manual. Please retain the original packing in case you should
need to return the equipment to the manufacturer or supplier, or transport or ship the unit later.

Installation

• Before installing and operating this equipment, make sure it is correctly connected to the protective earth conductor of the mains voltage supply socket outlet through each mains lead.
• Ideally, a cool area is preferred, away from power distribution equipment or other potential sources of interference.
• Do not install the equipment in places of poor ventilation.
• Do not install this equipment in a location subjected to excessive heat, dust, or mechanical vibration. Allow for adequate ventilation around the equipment, making sure that its fans and vents are not obstructed. Whenever possible, keep the equipment out of direct sunlight.
• Mount in rack only.

Power
Both supply cords must be unplugged to ensure complete de-energisation of the unit. The internal power supplies are of the switch mode type that automatically senses the incoming mains voltage and will work where the nominal voltage is in the range 100VAC to 240VAC.
Two mains inlets are provided on the rear panel. The correct leads for connection in the area to which the unit was shipped are supplied with the unit. The equipment should only be plugged into the mains outlets using the supplied leads. Each mains inlet must be sourced from its own separate wall-mounted mains outlet socket. Otherwise, their main sources must be suitably distributed to meet local safety regulations. Make sure the Volex locking-type plugs fitted on each supplied mains cable are securely fitted to the mains IEC connectors on the unit. When fitted properly, the Volex plug locks into place, preventing it from working loose or being inadvertently knocked loose or pulled out. When fitting or removing a Volex plug, always hold the plug itself and never use the cable,
as this may damage it. Never insert or remove an electric plug with wet hands. When switching the unit on/off, switch the mains power switches on/off one at a time. Do not switch them on/off simultaneously.

Handling the equipment

When lifting or moving the equipment, always take its size and weight into consideration. Completely isolate the equipment electrically and disconnect all cables from the equipment before moving it.
Do not insert your fingers or hands in any gaps or openings on the equipment, for example, vents.

Electric fields

Part 15 of the FCC Rules & Regulations, “changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.”
Should this product be used in an electromagnetic field that is amplitude modulated by an audio frequency signal (20 Hz to 20 kHz), the signal to noise ratio may be degraded. Degradation of up to 60 dB at a frequency corresponding to the modulation signal may be experienced under extreme conditions (3V/m, 90% modulation).

Connecting up
Connect up the rear panel of your unit as follows :

• Inputs — Connect your XLR mic/line inputs (up to 48 on DL251 and 16 on DL252).
• Outputs — Connect your XLR line outputs (up to 16 on DL251 and 48 on DL252).
• AES50 audio — Connect the AES50 audio sockets to the console/snake.
• Ethernet — connect the Ethernet control socket to an external computer for remote control when used in a snake configuration if required.
• MIDI — connect the three MIDI 5-pin DIN connectors to the MIDI equipment if required. (For use with Midas consoles only.)
• Mains power — connect the dual redundant IEC connectors of the mains cables into the rear of the unit and then plug them into separate mains power outlets .

Switching on/off
When switching the unit on/off, press the two mains on/off switches one after the other. Do not press them simultaneously. After you have connected up your DL251/DL252, it is ready to be switched on.

To switch the DL251/DL252 unit on
Switch on the mains on/off switches on the rear of the unit, one after the other. At the front of the unit, check that the LEDs in the PSUnel are all illuminated.

To switch the DL251/DL252 unit off
Switch off the mains on/off switches on the rear of the unit, one after the other.

To fit/remove a Volex locking-type mains plug
A Volex locking type plug is fitted on each supplied mains cable, which plugs into a mains IEC connector on the unit. When fitted properly the Volex plug locks into place, preventing it from working loose, or being inadvertently knocked loose or pulled out.
To fit a Volex plug, insert it into the mains IEC connector and push it in until it locks into place. Then, check to make sure it is securely locked in place. To remove a Volex plug, release its locking device and then pull it out. Don’t hold the cable, as this may damage it.

Configuration
After you have switched on the DL251/DL252, you can configure the following as required.

• ID number.
• Control mode.
• Clock source.
• Sample rate of clock source.

To configure an option
In the desired section, press the round button repeatedly to cycle through the options until the LED of the one you want is illuminated.

DL251/DL252 Front Panel

Front Panel

1. The psu panel monitors the two voltage supplies. There are five yellow LEDs per voltage supply, and each LED represents a voltage rail.An LED will illuminate when its respective voltage rail is active.
2. The ID select panel lets you select the ID number of the unit. This is a unique number that is recognised by the system and distinguishes it from any other similar unit(s) in the network. One of the four green LEDs will be illuminated to indicate the currently selected ID.
3. This control mode panel lets you select the control mode of the unit. Use this panel’s pushbutton to select mode 1 if the unit is connected to a console or mode 2 if the unit is used in a snake configuration. Either of the two green LEDs will illuminate to show which control mode is selected.
4. The clock panel lets you select the synchronisation source of the unit. Use this panel’s pushbutton to select the internal clock of the unit (int) or an external AES50 source (ext). The external source is the clock of the connected device (usually a Midas digital console), whose signal is transmitted via the AES50 audio connector. Either of the two green LEDs will illuminate to show which clock source is selected.
5. The sample rate panel has two green LEDs, which indicate the currently selected sample rate (96 kHz or 48 kHz).
6. The Ethernet control panel has a single green LED, which has three states of illumination: flashing = active; on = connected; and off =not connected.
7. The AES50 audio panel shows the health status of the communications of the AES50 connections. If the green ok LED is illuminated, communication is good. However, if the red error LED is illuminated, there is a problem with that connection.
8. There are four air intakes for fan cooling. Do not obstruct.
9. There are four cutouts for rack-mounting fixings.

DL251/DL252 Rear Panel

1. Unit serial number label.
2. Ventilation grills, which provide an air outtake for fan cooling of the inside of the unit.
3. Male XLR chassis connectors, which provide outputs for line equipment. Each socket has a red LED that illuminates when mute is on for that output.
4. Female XLR chassis connectors, which provide inputs for mic/line equipment. Each socket has a red LED that illuminates when +48V phantom power is on for that input.
5. The diagnostics connector is a 9-way D-type connector for connecting a laptop/PC by service personnel for diagnostics purposes. This is not an operator function and is only to be used by service personnel.
6. The MUTE button mutes all the outputs simultaneously when held down for longer than one second. It has an integral LED that illuminates when mute is active.
7. The boot mode switch selects between normal operation and a service personnel-only configuration boot mode. It has an adjacent red LED, which illuminates to show when the unit is in service-only configuration mode.
8. There are three MIDI (musical instrument digital interface) sockets — MIDI in, MIDI out and MIDI thru — for connection of a MIDI device, such as a synthesiser. The MIDI in socket receives MIDI data, and the MIDI thru socket gives out the same MIDI data  that is received by the MIDI in socket. The MIDI out socket gives out MIDI data generated by the attached Midas Digital Console.
9. Three AES50 audio EtherCon® sockets provide connection to the console/snake and pass audio and control data in both directions. Each socket has a pair of red and green LEDs, which indicate the following:
   • Green pulsating and red extinguished = valid audio and valid control data; active link.
   • Green constantly illuminated and red extinguished = valid audio and valid control data; standby link.
   • Green extinguished and red illuminated = no audio; link has failed.
10. The Ethernet control EtherCon® socket provides connection to an external computer for remote control when used in a snake configuration. This socket has a pair of red and green LEDs that indicate the following:
    • Green LED illuminated = cable connected at both ends.
    • Green LED extinguished = cable not connected at both ends.
    • Mains power
      Each mains inlet should be sourced from its own separate wall-mounted mains outlet socket. Otherwise, both mains sources must be suitably distributed so as to meet local safety regulations. The mains is supplied to the DL251/DL252 via dual redundant mains inlets.
11. Dual redundant power supplies.
12. Mains on/off isolator switch.
13. Mains IEC socket.

Important:
The unit has Volex locking-type plugs fitted on their supplied mains cables, which plug into the mains IEC connectors. When fitted properly, the Volex plug locks into place, preventing it from working loose or being inadvertently knocked loose or pulled out.

DL251 Connections

DL251 and digital console (96 kHz operation) Typical DL251 to digital console connection configuration. The AES50 audio connections provide 96 kHz operation and include a redundant spare. Each mains inlet must be sourced from its own separate wall-mounted
mains outlet socket. Otherwise, their main sources must be suitably distributed to meet local safety regulations.

1. Unique unit ID to match the one configured on the control center’s configuration page.
2. Set to ext if DL251 is synchronizing with an AES50 connection to a clock master. Set to int if this DL251 is to be clock master.
3. MIDI device (for example, a keyboard).
4. AES50 audio.
5. Redundant spare.
6. Typical Midas digital console (for example, a PRO3).
7. Mic/line inputs.
8. Line outputs.
9. Separate mains outlets.

DL252 Connections

DL252 and digital console (96 kHz operation) Typical DL252 to digital console connection configuration. The AES50 audio connections provide 96 kHz operation and include a redundant spare. Each mains inlet must be sourced from its own separate wall-mounted mains outlet socket. Otherwise, their mains sources mustsuitably distributed todoto to meet local safety regulations.

1. Unique unit ID to match the one configured on the control center’s configuration page.
2. Set to ext if DL252 is synchronizing with an AES50 connection to a clock master. Set to int if this DL252 is to be the clock master.
3. MIDI device (for example, a keyboard).
4. AES50 audio.
5. Redundant spare.
6. Typical Midas digital console (for example, a PRO3).
7. Line outputs.
8. Mic/line inputs.
9. Separate mains outlets.

Connectors
To ensure the correct and reliable operation of the equipment, only high quality balanced, screened, twisted pair audio cable should be used. XLR connector shells should be of metal construction so that they provide a screen when connected to the console/snake and, where appropriate, they should have Pin 1 connected to the cable screen.

1. Line output audio connector. Female XLR plug and male XLR chassis connector with the following pinouts: 1 = ground, 2 = hot, and 3 = cold.
2. Mic/line input audio connector. Male XLR plug and female XLR chassis connector with the following pinouts: 1 = ground, 2 = hot, and 3 = cold.
3. Ethernet socket. RJ45 plug and EtherCon® socket.
4. MIDI connector (in, out, or thru). 5-pin plug and socket.
5. Diagnostics. 9-way, D-type plug and socket.

Using The DL251/DL252
Although the DL251/DL252 has only limited user functionality, this section shows how to mute all outputs simultaneously and how to use the boot mode.
To avoid an electrical shock, never operate the equipment with the covers removed. Do not operate the equipment or any of its parts if safety guards are ineffective or their effectiveness has been reduced.

Muting all outputs simultaneously
The mute feature mutes all outputs simultaneously and also disconnects all the mic amps from the AES50 interface. This will have the effect of muting any other outputs that are sourced from these inputs. The MUTE button will activate after being pressed for one second and will deactivate after it has been released for half a second. The button’s integral red LED will illuminate to show when the mute is active. Using the boot mode This service personnel only function is used to select between normal operation and configuration mode.

Product Cleaning

Use a dry cloth for cleaning. Do not use liquids for cleaning purposes.

Service Information
This section gives you servicing information for your unit. If you are in any doubt or have queries about any of the procedures in this section, contact Midas Technical Support. Contact details can be found at the front of this manual.
Routine maintenance

To help keep your unit in good working order and to make sure it gives you optimum performance, we recommend that you adhere to the following maintenance schedules.

Cleaning the unit

• Switch off the unit and electrically isolate it from the mains before cleaning.
• Clean the unit using a dry, lint-free cloth. Don’t use harsh abrasives or solvents.

Other important information

1. Register online. Please register your new Music Tribe equipment right after you purchase it by visiting musictribe.com. Registering your purchase using our simple online form helps us to process your repair claims more quickly and efficiently. Also, read the terms and conditions of our warranty, if applicable.
2. Malfunction. Should your Music Tribe Authorized Reseller not be located in your vicinity, you may contact the Music Tribe Authorized Fulfiller for your country listed under “Support” at musictribe.com. Should your country not be listed, please check if your problem can be dealt with by our “Online Support,” which may also be found under “Support” at musictribe.com. Alternatively, please submit an online warranty claim at musictribe.com BEFORE returning the product.
3. Power Connections. Before plugging the unit into a power socket, please make sure you are using the correct mains voltage for your particular model. Faulty fuses must be replaced with fuses of the same type and rating without exception.

FFC STATEMENT

This equipment has been tested and found to comply with the limits for a Class A digital devic underro part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and useaccording toby the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at his own expense.
This equipment complies with Part 15 of the FCC rules. Operation is subject to the following two c Thistions:

1. This device may not cause harmful interference, and
2. This device must accept any interference received including interference that may cause undesired operation.

Warning: Operation of this equipment in a residential environment could cause radio interference.
Important information
Changes or modifications to the equipment not expressly approved by Music Tribe can void the user’s authority to use the equipment.

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