McIntosh C55 Audio Preamplifier Owner's Manual

Thank you for choosing McIntosh. The C55 Audio Preamplifier is a precision instrument designed to provide years of enjoyment and exceptional audio performance. Please take a moment to familiarize yourself with its features and instructions.

For technical assistance or questions about your setup, please contact your dealer. For service inquiries, McIntosh Laboratory, Inc. can be contacted directly.

Technical Assistance: (607) 723-3512

Customer Service: (607) 723-3515

Website: www.mcintoshlabs.com

Table of Contents

• General Information
• Connector and Cable Information
• Performance Features
• Dimensions
• Installation
• Front Panel Knobs and Buttons
• Inputs
• Outputs
• How to use the Remote Control
• Setup Menus
• Digital Setup Menu
• Inputs Setup Menu
• Outputs Setup Menu
• Triggers Setup Menu
• Data Out Setup Menu
• External Control Setup Menu
• System Configuration
• Connecting Components
• Network Information Menu
• Trim Functions Menu
• Equalizer Controls
• How to Operate the C55
• Troubleshooting
• Specifications
• Packing Instructions

General Information

1. Do not apply AC Power to the C55 and other Component(s) until they are connected to the C55 so operational malfunctioning does not occur.
2. Balanced and Unbalanced Inputs and Outputs can be mixed.
3. The C55 internal Digital to Analog Converter Circuitry is designed to decode PCM, DSD and DTS Digital Signals.
4. The C55 is factory configured for immediate use but can be customized via the Setup Menu.
5. The supplied Remote Control can operate other McIntosh components.
6. The IR Input is configured for non-McIntosh IR sensors.
7. For additional information on the C55 and other McIntosh Products, visit www.mcintoshlabs.com.

Connector and Cable Information

XLR Connectors

Pin configuration for the XLR Balanced Input and Output Connector:

• PIN 1: Shield/Ground
• PIN 2: + Input/Output
• PIN 3: - Input/Output

Power Control and Trigger Connectors

The C55 Power Control Out, Trigger and Passthru Output Jacks send Power On/Off Signals (+12 volt/0 volt) when connected to other Components. A 3.5mm stereo mini phone plug is used for connection.

Note: The Six Foot Cables are available from the McIntosh Parts Department. Part No. 170202.

Data Port Connectors

The C55 Data Out Ports send Remote Control Signals to Source Components. A 3.5mm stereo mini phone plug is used for connection.

IR IN Port Connectors

The IR IN Port also uses a 3.5mm stereo mini phone plug and allows the connection of other brand IR Receivers to the C55.

RS232 Data Port Cable

The RS232-C Data Cable is a 3.5mm stereo mini phone plug used to connect to external third party controllers.

Performance Features

• Electromagnetic Input Switching with Level Trim Adjustment: Digital Logic Circuits drive Electromagnetic Switches for reliable, noiseless, distortion-free switching. Analog Inputs can be matched in level.
• Phono Inputs with Adjustable Gain: Two precision Phono Preamplifier Circuits with adjustable gain for Moving Coil or Moving Magnet Cartridges.
• Selectable Phono Cartridge Loading: Adjustable Capacitance and Resistance Loading for phono cartridges.
• Digital Audio Inputs: Decodes PCM and DSD Signals. Supports up to 192kHz/24-Bit for Coaxial/Optical, and up to 384kHz/32-Bit with DSD512 for USB.
• Balanced Inputs: Allow connection of source components using long cable lengths without loss in sound quality.
• Precision Tracking VOLUME Knob: A Precision Balanced Digitally Controlled Attenuator System ensures 0.1dB tracking accuracy.
• Variable Rate Volume and Balance Controls: Provides an ideal rate of change with control rotation.
• Equalizer Controls: Eight Front Panel Equalizer Controls provide 12dB of boost or cut at center frequencies.
• HXD® for Headphones: Improves sound localization for Headphone Listening.
• Alphanumeric Fluorescent Display: Indicates Source Selection, Volume/Balance Levels, and Setup Menu Selections.
• Passthru Mode: Allows the C55 to become part of a Home Theater Multichannel Sound System.
• Remote Control with External Sensor Input: Allows system control from another room.
• Power Control Output and Trigger Assignment: For convenient Turn-On of McIntosh Power Amplifiers and Source Components.
• Special Power Supply: Fully regulated Power Supplies and an R-Core Power Transformer ensure stable, noise-free operation.
• Glass Front Panel with LED Illumination: Features the classic McIntosh Glass Front Panel evenly illuminated by LEDs.
• Bi-Amp Outputs: Built-in Adjustable Highpass and Lowpass Outputs for bi-amping speaker systems.

Dimensions

The following dimensions are provided to assist in determining the best location for your C55. Additional information for installing the C55 into cabinets is on the next page.

Note on Placement: Keep the unit out of direct sunlight and use appropriate gentle cleaners to prevent discoloration of the organic anodize finish.

Exterior Dimensions:

• Width: 17 1/2" (44.5 cm)
• Height: 7 5/8" (19.4 cm)
• Depth: 14 1/2" (36.8 cm)

Inside Dimension:

• Width: 17 1/8" (43.5 cm)
• Height: 6 5/16" (16 cm)
• Depth: 10 1/16" (26.8 cm)

Installation

The C55 should be installed upright on its four feet. Ensure adequate ventilation by allowing at least 3 inches (7.6cm) above, in front, and to the sides of the unit. Do not remove the feet to ensure proper airflow beneath the C55. Openings are required for cool air to enter (below) and warm air to escape (above).

Front Panel Knobs and Buttons

1. INPUT Knob: Selects source for listening and recording; used for menu navigation.
2. IR Sensor: Receives commands from a Remote Control.
3. NETwork Status LED: Indicates NET connection status.
4. VOLUME Knob: Adjusts listening level, Trim Mode, and SETUP Functions.
5. STANDBY/ON Button: Switches the C55 ON or OFF (Standby) and resets microprocessors.
6. MUTE Button: Mutes audio from loudspeakers and Headphones.
7. EQUALIZER Button: Engages or bypasses the equalizer circuit.
8. Eight Band Equalizer Knobs: Boost or cut individual frequencies.
9. Information Display: Shows Sources, Volume, Audio Settings, Operational Functions, and Setup Menu Settings.
10. OUTPUT 1 and 2 Buttons: Switch Preamplifier Outputs 1 and 2 On or Off.
11. HEADPHONES Connection: For private listening with low impedance dynamic headphones.

Inputs

The rear panel provides various input connections:

• 1. AC Input: Power cord connection.
• 2. BALANCED INPUTS (1-3): Accept high-level program source signals.
• 3. SERVICE USB: USB Type-A port for service use only.
• 4. POWER CONTROL Passthru: Receives On/Off signals from an Audio/Video Processor.
• 5. POWER CONTROL MAIN: Sends On/Off signals to McIntosh Components.
• 6. IR IN: Accepts external IR receiver via 3.5mm stereo mini phone plug.
• 7. PROCESSOR LOOP RETURN: Receives audio from an external equalizer or room correction processor.
• 8. NETWORK: Wired internet connection via ethernet.
• 9. UNBALANCED INPUTS (1-4): Accept high-level program source signals.
• 10. USB AUDIO Input: USB Type-B connector for streaming digital audio from a computer.
• 11. HDMI (ARC) Input: Connects with compatible ARC TV for synchronized video and digital audio.
• 12. MCT Input: Transfers signals from McIntosh products with an MCT connector for SACD audio.
• 13. COAX Inputs (1 & 2): Accept coaxial cables for digital signals.
• 14. OPTICAL Inputs (1 & 2): Accept optical connections for digital signals.
• 15. PHONO Inputs (Right & Left): Accept signals from a Phono Cartridge.

Outputs

• A. BALanced Outputs: XLR connector cables for balanced output.
• B. UNBALanced Outputs: RCA connector cables for unbalanced output.
• C. POWER CONTROL TRIG (1-4): Send On/Off signals to other McIntosh components.
• D. RS232 Connector: Communicates with external control devices via 3.5mm stereo mini phone plug.
• E. DATA PORTS: Retransmit remote control signals to source components.
• F. PROCESSOR LOOP SEND: Delivers audio to an external equalizer or room correction processor.

Navigating the Remote Control

The HR085 Remote Control is included for operating the C55 and other McIntosh Source Components.

Remote Control Buttons:

1. Switch Device: Selects the device for remote operation.
2. Setup Button: Enters the Setup Menu.
3. Level Up/Menu: Adjusts Trim Functions settings; accesses menus.
4. Trim/Guide: Enters Trim Functions menu; opens guide.
5. Info/Level Down: Adjusts Trim Functions settings; accesses info.
6. Input: Changes and selects different inputs.
7. Mute: Mutes audio playback.
8. Previous/Previous Preset: Returns to previous media selection.
9. Fast Reverse/Seek Down: Navigates backward through media.
10. Fast Forward/Seek Up: Navigates forward through media.
11. Next/Next Preset: Jumps to next media selection or tuner preset.
12. Volume: Adjusts listening volume.
13. Mode/Exit: Exits Trim Functions menu; displays information.
14. Select: Selects highlighted option.
15. Power Off: Turns off the selected device.
16. Power On: Turns on the selected device.

Note: The HR085 Remote Control has buttons for multiple devices. Refer to the HR085 Owner's Manual on the McIntosh website for full details.

Remote Control Batteries

The HR085 Remote Control is powered by two AAA batteries (not included). Open the battery compartment on the back of the remote to insert or remove batteries.

Additional Discrete Commands

Additional discrete commands for external control systems are available for BAL 1, 2, 3; UNBAL 1, 2, 3, 4; PHONO 1, 2; COAX 1, 2; OPT 1, 2; USB; MCT; HDMI; and Power (Cycle). These can be accessed using an optional McIntosh HR093 Service Remote Control. A list of commands and Pronto Hex Codes can be found on the McIntosh website.

Setup Menus

The C55 offers several Setup Menus to customize its operation:

• System
• Digital
• Inputs
• Outputs
• Triggers
• Data Out
• External Control

How to Navigate the Setup Menus

The C55 is factory configured for default settings. To make changes:

1. Press and hold the INPUT Knob until "SETUP: Menu Select" appears.
2. Rotate the INPUT Knob to select a submenu.
3. Press and hold the INPUT Knob to enter the selected submenu.
4. Rotate the INPUT knob to navigate options.
5. Rotate the VOLUME knob to change the selected option's value.
6. Press the INPUT Knob to exit the menu.

System Setup Menu

Product Information: Displays identifying information, including the System Firmware Version.

Update: The C55 periodically checks for updates. To disable automatic updates, set this option to 'Off'.

Passthru: Allows the C55 to be part of a Home Theater system, passing through audio from an Audio/Video Processor or Surround Decoder.

Auto Off: Automatically places the Preamplifier into Standby/Off Mode after a period of inactivity.

Power Save: Controls network connection during standby.

Restore Defaults: Resets all adjustable settings to factory defaults.

Factory Reset: Resets all adjustable settings and clears all network information.

Digital Setup Menu

DA Firmware Version: Displays the firmware number for the Digital Audio Circuitry.

DA Update: For service purposes only.

Digital Gain: Adjusts the gain for HDMI, OPTICAL 1, and OPTICAL 2 Inputs in 1dB steps.

HDMI (ARC) CEC Power: Enables or disables CEC Power Control for HDMI devices.

HDMI (ARC) CEC Volume: Enables or disables CEC Volume control for HDMI devices.

HDMI (ARC) Lip Sync Mode: Configures lip sync delay for HDMI input.

Inputs Setup Menu

This menu allows you to configure input settings:

• BAL 1-3, UNBAL 1-4, PHONO 1, 2, COAX 1, 2, OPT 1, 2, USB, MCT, HDMI(ARC): Settings for each input can be set to 'On/Name' (functioning normally, with option to rename) or 'Off' (deactivated).

Outputs Setup Menu

This menu allows adjustment of Output 1, Output 2, and Headphone functions.

• Output Mode: Switched, Unswitched, Bi-Amped (Fixed), Bi-Amped (Split).
• Output Trim Level: Adjusts the level of Output 1 relative to the Main Output.
• Bi-Amp Circuitry: Features internal, adjustable crossover for tailoring output frequency ranges.
• Dual Mono: Configures Output 2 as stereo or mono.
• Headphones: Mute All Outputs or Mute No Outputs when headphones are plugged in.

Triggers Setup Menu

The C55 has four Power Control Triggers. These settings control the operational power to components connected to the C55 Trigger Output Connectors. Triggers can be assigned to Outputs or Inputs.

Data Out Setup Menu

Data Port Connections allow basic function control of source components using the C55 Remote Control. By default, all four Data Ports send the same data. You can dedicate each Data Port for a specific source component.

External Control Setup Menu

Front IR: Enables or disables the Front Panel IR Sensor.

RS232 Baud Rate: Sets the communication speed for RS232 control.

IR Codes: Selects between NORMAL and ALTERNATE McIntosh Control Codes to prevent interference when using multiple McIntosh units.

System Configuration

The C55 can be integrated into various audio systems. Below are two typical configurations:

Example 1

A system with Audio Sources connected to the C55, which then connects to a Power Amplifier (Full Range) and Speaker.

Example 2

A system with Audio Sources connected to the C55, which then connects to a Power Amplifier (High Pass) and Speaker, and a Power Amplifier (Low Pass) and Powered Subwoofer.

Connecting Components

The C55 can automatically switch power On/Off to Source Components via Power Control connections. Data Port Connections allow remote operation of basic functions. With an external sensor, system control is possible from another room or when the C55 is in a cabinet.

Network Information Menu

This menu lists information about network connection. Press the VOLUME Knob to open the menu. Navigate settings using the INPUT Knob.

• Connection Type
• IP Address
• Ethernet MAC Address
• Wi-Fi MAC Address

McIntosh Connect App: Press and hold the VOLUME Knob to put the C55 into Network Setup Mode. The NETwork Status LED will blink, indicating network settings can be configured via the McIntosh Connect App.

Trim Functions Menu

Trim Settings are stored independently for each Input Source Selected. Meter Illumination and Display Brightness settings are the same for all inputs.

How to Select and Adjust Trim Functions

1. Press the Front Panel INPUT Knob to open the Trim Menu.
2. Rotate to select the desired Trim Function.
3. Rotate the VOLUME Knob to change the setting.

Note: The Remote Control TRIM Button and LEVEL UP/DN Button can also be used.

Trim Functions Menu Options

• Balance: L, Center, R
• Input Trim: -6dB to +6dB in 1dB intervals
• Equalizer Mode: On, Off
• Mono/Stereo Mode: Stereo, Mono
• Processor Loop: On, Off
• Meter Lights: On, Off
• Brightness: 4 Levels (Dim to Bright)
• Phono Capacitance: 50pF to 400pF
• Phono Resistance: 25Ω, 50Ω, 100Ω, 200Ω, 400Ω, 1kΩ, 47kΩ
• Phono Gain: 40dB to 64dB
• Lip Sync Delay: 0 to 150ms
• HXD Mode: On, Off (appears only when headphones are plugged in)

Balance

Adjusts listening balance for approximately equal volume levels in each loudspeaker.

Input Trim Level

Allows adjustment of levels for each Source Input for consistent relative volume.

Mono/Stereo Mode

Assigns Input Sources to Mono Mode of operation.

Processor Loop

Connects or disconnects an external equalizer or room correction processor.

Meter Illumination

Switches McIntosh Power Amplifier Meter Illumination On or Off.

Information Display Illumination

Adjusts the brightness of the Front Panel Information Display (4 levels).

Phono Adjustments

Select Phono 1 or Phono 2 and adjust Capacitance, Resistance, and Gain settings.

Lip Sync Delay

Adjusts HDMI Audio Lip Sync Delay when in Manual mode.

HXD Mode

Enhances the acoustical depth and spatiality of music for headphone listening.

Equalizer Mode

Engages or bypasses the built-in eight band Frequency Equalizer.

Equalizer Controls

The C55 features an eight band Frequency Equalizer with controls for 25Hz, 50Hz, 100Hz, 200Hz, 400Hz, 1,000Hz, 2,500Hz, and 10,000Hz. Each control can raise or lower the amplitude by 12 dB. The tone circuit components are removed from the signal path when controls are at the center detent or flat position.

How to Operate the C55

Power On and Off

To switch ON: Press the STANDBY/ON Button on the Front Panel or the Power Button on the Remote Control. The C55 will initialize and display the last used source and volume setting.

To switch OFF: Press the STANDBY/ON Button on the Front Panel or the Power - Red Button on the Remote Control.

Source Selection

Rotate the INPUT Knob or use the INPUT Up/Down Button on the Remote Control to select the desired source.

VOLUME Knob

Rotate the Front Panel VOLUME Knob or use the VOLUME Up/Down Buttons on the Remote Control to adjust the listening level.

Mute

Press the MUTE Button on the Front Panel or Remote Control to mute all outputs except SEND FIXED OUT. The display will show "MUTE". Press Mute again or adjust Volume to unmute.

Output 1 and 2

Press the Front Panel OUTPUT 1 or OUTPUT 2 Button, or use the Remote Control (after pressing SETUP/BLUE) to send audio to separate Power Amplifiers or activate Power Control Triggers.

Passthru

Refer to the Setup Section (page 14) to activate Passthru mode. The C55 will automatically turn On and switch to the previously setup Passthru Input when the McIntosh A/V Processor or Multichannel Surround Decoder is turned on.

Headphone Jack

Connect a pair of dynamic headphones (1/4” stereo plug) to the Headphones Jack for private listening. The default setting mutes all Power Amplifier Output Connections.

How To Make a Recording

1. Select the desired signal source using the INPUT Knob or Remote Control.
2. Adjust the recorder level control and proceed with the recording.
3. Listen to the playback of the recorded program source.

Digital Inputs

When a Digital Input is selected, the Front Panel Information Display indicates the sample rate or audio format.

MCT Input

For multi-layer SACD, select the stereo (SACD) or CD layer. The multi-channel layer will not reproduce sound.

Optical

The two Optical Inputs support high-resolution digital audio up to 192kHz/24-bit. They process standard S/PDIF PCM, Dolby Digital, and DTS bitstreams.

Coaxial

The two Digital Coaxial Inputs support high-resolution digital audio up to 192kHz/24-bit. They process standard S/PDIF PCM, Dolby Digital, and DTS bitstreams.

HDMI ARC

The HDMI ARC (Audio Return Channel) allows the use of the entire audio system to play TV sound. Ensure connection to the TV's HDMI input labeled “ARC”. TV setup menus may need adjustment. The unit will automatically turn On and Off with the TV when set to HDMI input.

• Supported audio formats: PCM (2 channel), Dolby Digital (up to 5.1 channel), DTS Digital Surround (up to 5.1 channel).

USB Audio

The USB Audio Input receives digital music/sound from a connected computer. Apple computers with OS-10.6.8 communicate without installation. Windows PCs require the McIntosh USB Audio driver.

Troubleshooting

Reset of Microprocessors

If the C55 controls stop functioning, reset the microprocessors by pressing and holding the STANDBY/ON Button until the LED extinguishes, then release it. Press the STANDBY/ON Button again to switch the C55 back On.

Meter Lights

For non-McIntosh units where meter lighting may be defeated, use a 173419 Trigger Adapter Cable in-line with the 170202 Power Control cable. This adapter leaves the ring terminal unconnected, allowing meter lights to remain illuminated.

Specifications

Frequency Response: +0, -0.5dB from 20Hz to 20,000Hz; +0, -3dB from 15Hz to 100,000Hz

Total Harmonic Distortion: 0.005% from 20Hz to 20,000Hz

Rated Output: 2.5V Unbalanced, 5V Balanced (Main); 450mV (Fixed Output)

Maximum Voltage Output: 8V RMS Unbalanced, 16V RMS Balanced

Sensitivity (for rated output): High Level, 450mV Unbalanced, 900mV Balanced; Phono MM, 4.5mV; Phono MC, 0.45mV

Signal To Noise Ratio (A-Weighted): High Level - 100dB; MM Phono - 82dB; MC Phono - 80dB

Input Impedance: High Level 22K ohms Unbalanced, 44k ohms Balanced; Phono 1, 2 (MM and MC) 25, 50, 100, 200, 400, 1k or 47k ohms, 50 to 400pF

Maximum Input Signal: High Level, 5V Unbalanced, 10V Balanced; Phono MM, 80mV; Phono MC, 8mV

Equalizer Controls: 25Hz, 50Hz, 100Hz, 200Hz, 400Hz, 1,000Hz, 2,500Hz and 10,000Hz

Voltage Gain: High Level to Fixed Output: 0dB; High Level to Main Output: 15dB

Phono Gain: Selectable 40dB, 46dB, 52dB, 58dB, or 64dB

Output Impedance: 100 ohms Unbalanced, 200 ohms Balanced

Headphone Load Impedance: 100 ohms to 600 ohms

Digital Input Sample Rates: Coaxial/Optical: PCM - 44.1kHz to 192kHz; USB: PCM - 44.1kHz to 384kHz; MCT: PCM, SACD - 44.1kHz to 192kHz; DXD: DXD352.8kHz, DXD384kHz; DSD: DSD64, DSD128, DSD256, DSD512; HDMI: PCM 24bit, 44.1kHz - 192kHz, DTS, Dolby Digital

Power Control and Trigger Output: 12VDC, 25mA

Power Requirements: Field AC Voltage conversion is not possible. Unit is configured for 100, 110, 120, 220, 230, or 240 Volts, 50/60Hz at 75 watts. Standby Power: less than 0.5 watts.

Overall Dimensions: Width: 17 1/2 inches (44.4cm); Height: 7 5/8 inches (19.4cm); Depth: 18 inches (45.72cm)

Weight: 28 pounds (12.5 kg) net; 43.5 pounds (19.7 kg) shipping carton

Shipping Carton Dimensions: Width: 27 inches (68.6cm); Height: 12 inches (30.5cm); Depth: 25 inches (63.5cm)

Trademarks of McIntosh Laboratory, Inc. are registered worldwide.

Packing Instructions

To repack the equipment for shipment, use the original shipping carton and interior parts if they are in good condition. Ensure the four plastic feet are attached to the bottom of the equipment for proper location on the bottom pad. Failure to do so may result in shipping damage.

Parts List:

McIntosh Laboratory, Inc. reserves the right to improve product design without notice. The C55 is designed to employ non-McIntosh-provided services, and McIntosh cannot control the providers of these services. The owner assumes all risks related to the use of these services.

Printed in the U.S.A.

© 2023 McIntosh Laboratory, Inc.

McIntosh Part No. 24124000