NXAMP4x1 User Manual

GENERAL DESCRIPTION

GENERAL DESCRIPTION

Global architecture

NXAMP4X1 Global architecture

The diagram bellow shows the global architecture of the NXAMP4X1 amplifier.

NXAMP4X4 Global architecture

The diagram bellow shows the global architecture of the NXAMP4X4 amplifier.

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GENERAL DESCRIPTION

Power Supply Block

Power Supply is certainly the most important part of an amplifier. Most of the time, the

Power supply is limiting the power of an amplifier, more than the amplifying circuit itself.

• On NXAMP4X1, two large power supplies are used, one for channel (1 and 2) and the other for channel (3 and 4).

• On NXAMP4X4, four large power supplies are used, one for each channel.

They all are full resonant type with half bridge converter. The ZCS (Zero crossing

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GENERAL DESCRIPTION switches) design ensures high efficiency and low noise. Moreover, because the two converters work in opposite phase, some noise is cancelled; this is preferable for both sound quality and EMC (Electro magnetic compatibility).

Analog Input block

After linking the two XLRs for each channel, the analog input block has an EMC filter and a precision input buffer that will remove the common noise on the input signal. The maximum level allowed for the input signal is + 28 dBU (55 Volts peak to peak). The pin out of the input XLR is given bellow.

Control block

The control block contains several sub-block that are detailed bellow.

The plain lines show the audio or sense signal (sense are voltage or current signal measured at the output of each amplifier). The dashed lines show the digital communication signal among several block.

You can see the audio input on the left; there are four analog inputs (from input XLR) named Analog A, Analog B and so on… and four digital inputs (Digital A, Digital B and so on…) from the expansion slot. These eight signals can be patched inside the DSP to any

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GENERAL DESCRIPTION channel of processing/amplifying (see further for a block diagram of what is inside the

DSP).

All signals, audio or sense, use 24 bits converters. The CPU can also set up the analog input and output gain for each channel, thus ensuring that the dynamic range of the system is always optimized (regarding volume, gain, patch and bridge settings).

Monitoring of the amplifier modules and power supplies (including multiple measurement such as temperature, voltages, current, integrate current, …) are done both by the CPU and the DSPs.

Power amplifier blocks

The power amplifier part is a custom design to fit the very unique concept of digital protection of an analog amplifier. On the pure amplification side, it utilizes custom transistor (thin chip and small thermal resistance), and the well known Yamaha EEEngine technology, that offers the sonic quality of the conventional class AB amplifier with the efficiency of the class D. You can learn more about the EEEngine technology at the following address: http://www.yamahaproaudio.com/topics/leading_technology/learn_more_about_eeengine/index.html

Power outputs block

The power outputs block is used for current and voltage sensing at the output of the amplifier. These datas will be used by the DSP for protecting both the amplifier and the NEXO loudspeaker connected.

This stage features also a programmable routing unit that allows using the amplifier in bridge mode on the same speakon pins than in non bridge mode.

When using the NXAMP Powered TDcontroller in four channels mode, here is the output routing:

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GENERAL DESCRIPTION

Note the symmetrical structure between channel 1 and 2 on one hand and channel 3 and 4 on the other hand.

When using the NXAMP Powered TDcontroller in bridge mode, here is the output routing:

Now amplifier channel 1 and 2 works together in bridge mode (channel 2 is marked

“Bridge” above). This is same for channel 3 and 4. The pin-out on the speakon is the same as the channel 1 and 3 in non bridge mode, thanks to the programmable routing unit (not drawn here).

You can see with the dashed line on the above drawing that unused pins on output speakon are shorted together, but are not connected to ground. Therefore be careful as very high voltage might be present on these unused pins.

User interface block

The user interface block has already been described through the front panel description in the first part of this document. Please note that all the commands and displays are available through the ESmonitor software by Auvitran, through the Ethersound™ network

(except the mains switch).

Communication block

The communication block regroups the RS232 port (on a sub-D9 plug) and the GPIO port

(on a sub-D25 plug).

The RS232 port is mainly used to upgrade the firmware of the unit from a PC computer.

But it could also be used in the future for local communication with other equipments. The

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pin-out is given bellow:

GENERAL DESCRIPTION

The RxD pin is the “Receive data” pin from the NXAMP point of view. Thus this is an input.

The TxD pin is the “Transmit data” pin from the NXAMP point of view. Thus this is an output. GND is the ground.

A crossover cable (connecting RxD pin of NXAMP to TxD pin of computer, and so on) is needed to use this serial port. Please see further the dedicated part of this document on that subject.

The GPIO port is a Global Purpose Input/Output signals system that can be use for a wide range of application, mainly interfacing the NXAMP with security systems. There are the following signals available:

• 8 x General purpose output signals from NXAMP (5 Volts signals)

• 5 x General purpose input signals to NXAMP (5 Volts signals)

• 4 x 5 Volts outputs

• 8 x GND (ground) signals.

The pin out of these signals is given bellow:

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