Dynacord 4260, 4245 User Manual

DPA 4245 / DPA 4260 POWER AMPLIFIER

Features

OWNER’S MANUAL

• 2 x 450 watts output power capacity DPA 4245

• 2 x 600 watts output power capacity DPA 4260

• floating 100 V / 70 V / 25 V power outputs (isolated outputs)

• low impedance outputs (direct outputs)

• bridged mode operation, switchable

• all outputs are protected against idling and short-circuit

• mains supply 230 V AC 50/60 Hz

• POWER REMOTE function

• service mains switch

• active ventilation via 2 temperature-controlled DC-fans

• electronically balanced inputs

• routing switch for parallel linked operation

• input gain controls

• integrated audio limiters

• power-on switching noise suppression

• protection circuitry: DC/HF, Back-EMF, output voltage overload limiters, initial inrush current limiter,

output peak current limiter

• 18 dB/oct. LO-cut filter at 45 Hz

• SIGNAL and LIMIT indication for optical monitoring

• thermal overload protection for the heat sink and the internal power supply, with PROTECT-function

• inputs transformers for balanced, floating operation are optionally available

• XLR-type and binding post clamping input connectors

• 19" frame size, 3 HU

CONTENTS

Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Installation Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Rear View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

IMPORTANT SAFETY INSTRUCTIONS

The lightning flash with arrowhead symbol, within an equilateral triangle is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.

The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintance (servicing) instructions in the literature accompanying the appliance.

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with a damp cloth.

7. Do not block any of the ventilation openings. Install in accordance with the manufactures instructions.

8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus that produce heat.

9. Only use attachments/accessories specified by the manufacturer.

10. 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.

For US and CANADA only:

Do not defeat the safety purpose of the grounding-type plug. A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong are provided for your safety. When the provided plug does not fit into your outlet, consult an electrican for replacement of the absolete outlet.

IMPORTANT SERVICE INSTRUCTIONS

CAUTION: These servicing instructions are for use by qualified personnel only. To reduce the

risk of electric shock, do not perform any servicing other than that contained in the Operating Instructions unless you are qualified to do so. Refer all servicing to qualified service personnel.

1. Security regulations as stated in the EN 60065 (VDE 0860 / IEC 65) and the CSA E65 - 94 have to be obeyed when servicing the appliance.

2. Use of a mains separator transformer is mandatory during maintenance while the appliance is opened, needs to be operated and is connected to the mains

3. Switch off the power before retrofitting any extensions, changing the mains voltage or the output voltage.

4. The minimum distance between parts carrying mains voltage and any accessible metal piece (metal enclosure), respectively between the mains poles has to be 3 mm and needs to be minded at all times. The minimum distance between parts carrying mains voltage and any switches or breakers that are not connected to the mains (secondary parts) has to be 6 mm and needs to be minded at all times.

5. Replacing special components that are marked in the circuit diagram using the security symbol (Note) is only permissible when using original parts.

6. Altering the circuitry without prior consent or advice is not legitimate.

7. Any work security regulations that are applicable at the location where the appliance is being serviced have to be strictly obeyed. This applies also to any regulations about the work place itself.

8. All instructions concerning the handling of MOS - circuits have to be observed.

Note:

SAFETY COMPONENT (HAS TO BE REPLACED WITH ORIGINAL PART ONLY)

DESCRIPTION

Especially designed for permanent installations, the DPA-Series power amplifiers offer performance-consistent and reliable operation of PA-systems with 2 individual loudspeaker lines, each. Therefore, DPA-Series power amplifiers are most suitable for company intercom, alarm and background music transmission installations in offices and commercial areas, congregation and sport centers, schools, houses of worship, hotels, hospitals, shopping malls and super markets, cruise ships, and other similar applications.

Each power amplifier incorporates two high-performance output transformers. Next to 100 V, 70 V, and 25 V floating outputs, the direct outputs provide the possibility to also drive loudspeaker systems with low-impedance down to a minimum of 4 ohms. Simultaneous operation of low-impedance speaker systems and floating loudspeaker lines on a single output channel of the power amplifiers is possible as well.

The integrated 45 Hz LO-cut filter with 18 dB/oct. slope protects the connected loudspeaker lines from unwanted ultra-low frequencies.

Comparator circuitry constantly monitors the input and output signals of the power amplifiers and activates their internal limiters whenever non-linear operation is encountered which reliably protects the connected loudspeaker systems against overload conditions and clipping, saturation of the power supply transformers, and overvoltage at the outputs. The DPA-Series power amplifiers’ transmission and sound qualities are absolutely superb. The employed comprehensive dimensioned power supply units with low-interference toroidal transformers ensure that the stated nominal performance specifications are accomplished, even in most demanding and critical installations. Since the DPA-Series power amplifiers do not employ V/I-Foldback-Limiter circuits, operation on complex loads up to ±90° phase angles is possible without a problem.

Quick optical information on the power amplifiers’ momentary operational status is provided through easily readable LED indicators, individually showing whether a channel is ready for operation, a signal is present at the output, if any of the limiter circuits and/or one of the protection circuits has been activated.

The inputs are electronically balanced and carried out as XLRF-type and as binding post clamping connectors as well. Parallel linking the two connector types at the input provides the possibility to utilize the carried-through signals to feed additional power amplifiers, without the necessity for special split-cables. Both inputs can be optionally retrofitted with input transformers. Through Input Routing switches it is possible to configure the DPA-Series power amplifiers for stereo, parallel-monaural, or bridged-mode operation.

The dB-scaled level controls – extremely precise and good to operate potentiometers – are located on the rear of the appliances. A Ground-Lift switch which helps eliminating ground noise loops by separating the amplifier circuit ground from the common ground of the enclosure is also to be found on the rear panels. Conveniently connecting the loudspeaker lines to the power amplifiers is provided through a binding post strip, where all voltages – 25 V, 70 V, 100 V – and the low-impedance output are present on individual screw-clamp connectors. The rear panel service mains switches allow turning the power amplifiers’ power on directly. Using the provided power remote input, remote-start is also possible.

Consistent thermal stability of the power amplifiers is obtained through extremely silent running fans which are automatically switched stepwise depending on the amplifiers’ operation mode. The front-to-rear air circulation guarantees trouble-free operation in rack-shelf enclosures of any size.

Several other features of the DPA-Series power amplifiers are revealed within this owner’s manual. Therefore, please take the time to carefully and entirely read the provided information.

Installation Notes

Generally, it is important to install the power amplifier in a way, that ensures unhindered front-to-rear air circulation.

When installing the power amplifier in a closed rack-shelf system, please make sure that adequate air-flow is guaranteed. The space between the rear panel of the amplifier and the inner wall of the rack-case has to be at least 60 mm x 330 mm. A free space of at least 100 mm above the rack-shelf system is needed to provide sufficient air circulation. Since, during operation, the temperature inside the rack system could easily rise up to 40° C, the maximum allowable ambient temperatures of the rest of the incorporated modules and appliances within a specific rack-shelf system have to be taken into careful consideration.

When mounting the power amplifier inside of a closed rack system, it is recommended to use special rack-rails or optionally available rack-mount ears NRS 90235 (112733) to prevent bending of the appliance’s front panel.

Note For maintained trouble-free operation of the appliance, the maximum admissible ambient

temperature of +40°C is not to be exceeded.

The amplifier has to be protected from:

- water drops or splashes

- direct sunlight

- high ambient temperatures and the direct radiation of heat sources

- high humidity and moisture

- heavy dust

- massive vibrations

Moving the amplifier from a cold into a warm environment can result in the occurrence of condensation on inner parts. Operating the appliance is only permissible after it has accommodated to the altered temperature (approximately after one hour). Should any foreign solid parts or liquids inadvertently intrude the enclosure, immediately unplug the device from the power source and have it checked at a DYNACORD service center, before further use. Cleaning the appliance should not be performed using chemical solvents or sprays, as this might damage the finish and could even cause hazard fire.

Before The First Operation

Before switching the amplifier’s power on, the included mains cord has to be connected to a 230 V - 50/60 Hz wall outlet. On the appliance itself, the cord has to be connected to the 3-pole mains socket. To remotely start the amplifier, it is necessary to connect an external 24 V power source to the terminal strip POWER REMOTE. Providing correct connection and with an external power supply being present, the POWER ON indicator will light and the power amplifier is ready for operation. The mains switch POWER on the rear of the appliance is meant for service and maintenance purposes only. Through bridging the mains switching relay this option provides the possibility to operate the amplifier without an external 24 V power supply connected.

Caution The mains switch POWER on the rear of the appliance is only meant for maintenance. Remotely switching off the device is not possible when the POWER switch is engaged.

The DPA-Series power amplifiers employ power-on switching delays of approximately 2 seconds.

Inputs INPUT CHANNEL A&B

With an input sensitivity of 775 mV = 0 dBu and an input impedance of 20 k ohms, the electronically balanced inputs – INPUT CHANNEL A&B – are meant for the connection of control amplifiers, audio controllers, mixing consoles, etc.

Peripheral pieces of audio equipment are either connected via the XLRtype input connectors or using the parallel-linked binding posts. For the latter option you can utilize the supplied screw-plugs. Thus, carrying the audio signals through to feed additional power amplifiers can be conveniently achieved without the need for special split-cables.

PIN 1: SHIELD PIN 2: a, +

The XLR-type input connectors’ pin-assignment is in accordance to the IEC 268 standard:

PIN 3: b, -

In case the controlling device does not supply balanced output connectors, it is also possible to configure the connectors for unbalanced operation. Therefore, the common ground (pin 1) has to be connected to the (–) input (pin 3). The audio signal is now solely fed through the (+) input (pin 2).

So, to be able to entirely make use of all the advantages the electronically balanced input stage offers – like the suppression of humming and interference noise – it is beneficial to re-establish balanced input connection whenever possible.

In case floating inputs are needed, the inputs are ready to be retrofitted with input transformers; one optional available extension kit NRS 90208 (308840) per channel is necessary.

Instructions On How To Install NRS 90208 Extension Kits

• unplug the power amplifier from the mains

• detach all screws holding the cover plate of the appliance

• lift and remove the cover plate

• disconnect the flat-wire cable of the printed board assembly 81340/1

• detach all screws holding the printed board assembly 81340/1

• remove the printed board assembly 81340/1 and unsolder the resistors R106 … R109

• attach insulators to the input transformers according to the corespondent marks on the printed board

assembly

• re-assemble the appliance by performing all steps described in the opposite order

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