AXA25

Introduction

Last updated: July 29, 2022 10:23. Revision #5414

This guide is designed to make installing and using this product as easy as possible. Information in this document has been carefully checked for accuracy at the time of printing; however, Cambridge Audio's policy is one of continuous improvement, therefore design and specifications are subject to change without prior notice.

This document contains proprietary information protected by copyright. All rights are reserved. No part of this manual may be reproduced by any mechanical, electronic or other means, in any form, without prior written permission of the manufacturer. All trademarks and registered trademarks are the property of their respective owners.

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What's Included with the AXA25?

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Inside the box of your AXA25 you will receive:

• 1. AXA25 integrated amplifier.
• 2. Mains lead (UK, EU, CU, or JP depending on country of purchase).
• 3. Quick start guide.
• 4. Safety guide.

Diagram: Illustration showing the contents of the AXA25 box: the amplifier, mains leads, quick start guide, and safety guide.

Front Panel Controls

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1. Power button:

Switches the unit between Standby mode (indicated by dim LED) and On (indicated by bright LED). Standby mode is a low power mode where the power consumption is less than 0.5 Watts. The product has Auto Power Down (APD) enabled by default, switching to Standby after 20 minutes of inactivity. APD can be enabled or disabled by pressing and holding the Power button until the LED flashes. 5 flashes indicate APD disabled; 10 flashes indicate APD enabled. Ensure the unit is On before changing APD settings.

2. Bass and treble controls:

Allow subtle adjustments to the tonal balance of the sound. In the central (12 O'clock) position, these controls have no effect. They only modify sound through loudspeakers, not Rec Out connections. Adjust to compensate for poor recording quality or other sound factors.

3. Volume control:

Use to increase or decrease the audio output level. Note: The volume control does not affect the fixed level of the 'Rec Out' output.

4. Balance:

Adjusts the relative output levels of the left and right channels. In the central (12 O'clock) position, the output from each channel is equal. This control only modifies sound through loudspeakers, not Rec Out connections.

5. Source selector switch (A1, A2, A3, A4/AUX):

Selects the input source component. The selected signal is also fed to the Rec Out sockets for recording. Do not change the input while recording. Ensure the correct input source is selected for sound output.

6. Aux in:

A 3.5mm stereo Aux input on the front panel for connecting portable audio devices like smartphones. Once plugged in, this input is automatically selected. The A4/AUX option on the front panel also selects this input when a stereo jack is plugged in. Plugging a source into the front panel Aux input overrides the A4 input; remove the jack to re-enable the A4 input.

Diagram: Front panel of the AXA25 amplifier showing controls.

Rear Panel Connections

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1. Audio inputs (A1-A4):

Suitable for 'line level' source equipment like CD players, streaming devices (e.g., Chromecast Audio, requiring RCA Phono to jack cable).

2. Rec Out:

Connect to the recording input of a CD recorder, tape deck, or other recording device. Provides a constant high-level output unaffected by volume, balance, or tone controls. The AXA25 cannot be used as a Preamplifier only or with a subwoofer.

3. USB power 5V 500mA:

Designed to charge devices like smartphones, requiring 5V DC. This is not an audio input. Do not use this port for charging and audio source simultaneously, as it can cause ground loop interference.

4. Loudspeaker terminals:

Connect left and right channel loudspeakers. Red terminals are positive (+), black are negative (-). Ensure correct polarity for optimal sound. When using banana plugs, ensure terminals are fully tightened before inserting the plug. Avoid stray wire strands connecting terminals, which can cause damage. Loose screw terminals can affect sound quality.

5. AC power socket:

Connect the AC power cable here once all connections are complete. Use only the supplied power lead.

Diagram: Illustration of the rear panel of the AXA25, showing audio inputs (A1-A4), Rec Out, USB power, and loudspeaker terminals. Also shows a close-up of connecting a banana plug to a terminal.

Getting Connected

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Loudspeakers

Check speaker impedance; 8 Ohms is recommended. Ensure correct polarity (+/-) for speaker connections to avoid weak or phased sound.

Using Bare Wire Connections

Prepare speaker cords by stripping approximately 10mm (3/8") or less of outer insulation. Twist wires tightly. Unscrew the speaker terminal, insert the cable, tighten the terminal, and secure the cable. All connections use standard loudspeaker cable.

Diagram: Illustration showing how to prepare speaker wire for connection, including stripping insulation and twisting wires.

Using Banana Plugs

Banana plugs are recommended for a secure connection and to prevent stray wires causing noise or interference. Connect stripped and twisted wires to banana plugs. Remove the dust cap from the speaker terminal and push the plug in firmly but without excessive force. Ensure speaker terminals are fully tightened before inserting the plug.

Basic Connection

The diagram illustrates a basic connection setup for the AXA25 to a CD player and a pair of loudspeakers. Any 'line level' source equipment can be connected to the amplifier's audio inputs (A1 to A4).

Diagram: Schematic showing the AXA25 connected to a CD player (AXC25) and two loudspeakers. Shows signal flow via RCA cables and speaker wires.

Technical Specifications

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Power output:

25 Watts (into 8Ω)

THD (unweighted):

0.015% @ 1kHz, 80% of rated power; <0.15% 20Hz – 20kHz, 80% of rated power; <0.1% 20Hz – 20kHz @ 10W

Frequency response:

(-3dB) 10Hz - 30kHz

S/N ratio:

(ref 1W) >82dB (unweighted)

Input impedances:

32k Ohms

Power Amp damping factor:

>100

Max. power consumption:

180W

Bass/Treble controls:

Shelving, ultimate boost/cut +/- 5.5dB @ 20Hz and 20kHz

Standby power consumption:

<0.5W

Inputs:

4x RCA, 1 x 3.5mm Aux input (front panel)

Outputs:

Speakers, Rec Out, USB 5V power

Dimensions (HxWxD):

83 x 430 x 340mm (3.3 x 16.9 x 13.4")

Weight:

5.1kg (11.2lbs)

Troubleshooting

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There is no power

• Ensure the AC power cord is connected securely.
• Ensure the plug is fully inserted into the wall socket and is switched on.
• Check fuse in the mains plug or adaptor.
• Check the power button is on at the front of the unit.

There is no sound

• Check the correct input is selected on the front panel of the amplifier.
• Check that the speakers are connected correctly.

The sound is distorted

• Check speaker connections.

There is a hum coming from the speaker

• Ensure that all cable connections are secure.

There is unwanted background noise and interference

• Move the unit away from other electrical equipment that is likely to cause interference.
• Ensure that all cable connections are secure.
• Ensure that you are not charging a device via the USB port and using it as an audio source at the same time.

Frequently Asked Questions (FAQ)

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How can I connect my turntable to the AXA25?

The AXA25 does not have a built-in Phono preamplifier (Phono Stage). Your turntable will require its own Phono Stage to connect directly to the audio inputs on the amplifier. Turntables without a built-in Phono Stage need an external Phono preamplifier to boost the signal level. This can then be connected to any of the AXA25's audio inputs.

Diagram: Illustration showing a turntable connected to an external phono stage, and then to the AXA25's audio inputs.

Why doesn't the AXA25's USB connection produce any sound?

The USB input on the rear of the AXA25 is not designed as an audio input. It is used solely for charging devices and maintaining power to components like streaming devices.

Can I insert a Bluetooth adaptor into the AXA25’s USB port to enable Bluetooth functionality?

No. The USB port on the rear of the AXA25 is designed only for charging devices such as smartphones. It is not possible to insert a Bluetooth adaptor into this port to enable Bluetooth functionality.

Can I use 4 or 6 Ohm speakers with the AXA25?

The AXA25 is rated for 8 Ohm speakers. Using 4 or 6 Ohm speakers is not recommended, as it could lead to the amplifier overheating and potential long-term damage.