The McIntosh MHA200 is a high-performance tube headphone amplifier designed to deliver exceptional sound quality for a wide range of headphones. Crafted by McIntosh Laboratory, Inc., this amplifier focuses on providing a pure Class-A triode output stage and features proprietary Unity Coupled Output Transformers, making it a unique offering in the headphone amplifier market.
Function Description:
The MHA200's primary function is to amplify audio signals for headphones, ensuring optimal performance across various impedance loads. It is specifically designed to power headphones with impedances ranging from 32 to 600 Ohms, guaranteeing a consistent 500mW of power output for all these loads. The amplifier employs two 12AT7 tubes in the driver stage and two 12BH7 tubes in the power stage, which are visible and glow during operation, contributing to a warm and detailed playback experience.
Important Technical Specifications:
- Power Output: 500mW for 32 Ohm, 100 Ohm, 250 Ohm, and 600 Ohm loads.
- Output Load Impedance: Selectable options of 32, 100, 250, and 600 Ohms.
- Rated Power Band: 20Hz to 20kHz.
- Total Harmonic Distortion: 0.5%.
- Dynamic Headroom: 1dB (8 ohm load), 1.3dB (4 ohm load).
- Frequency Response: +0, -0.5dB from 20Hz to 20,000Hz.
- Input Sensitivity (for rated output): 1.0 Vrms Unbalanced, 2.0 Vrms Balanced.
- A-Weighted Signal to Noise Ratio: 94dB unbalanced.
- Voltage Gain: 12dB (32 Ohm), 17dB (100 Ohm), 21dB (250 Ohm), 25dB (600 Ohm).
- Trigger Output: 12VDC, 50mA maximum.
- Power Requirements: 50 watts at 100V, 110V, 120V, 220V, 230V, or 240V (50/60Hz). Standby power is less than 0.5 watts.
- Dimensions:
- Width: 6-1/8 inches (15.6cm)
- Height: 5-3/4 inches (14.6cm) including feet
- Depth: 9-1/8 inches (23.2cm) including antenna
- Weight: 10.5 pounds (4.8 kg) net, 12.0 pounds (5.5 kg) in shipping carton.
- Shipping Carton Dimensions:
- Width: 12 inches (30.5cm)
- Height: 10 inches (25.4cm)
- Depth: 9-1/2 inches (24.1cm)
Usage Features:
The MHA200 offers flexible connectivity and user-friendly controls:
- Inputs: It features both balanced XLR female connectors and unbalanced RCA jacks, allowing connection to a variety of audio sources. Users should choose either balanced or unbalanced input, as connecting both simultaneously is not optimal.
- Headphone Outputs: Three types of headphone connections are available:
- 1/4" 3-conductor (stereo) phone plug for unbalanced connections.
- A pair of 3-pin male XLR plugs for balanced connections (separate jacks for left and right).
- One 4-pin male XLR connector (Neutrik NC4MX) for balanced connections (single plug for both channels).
- Load Knob (Left Knob): This knob allows users to impedance match the MHA200 with their headphones. Options include 32, 100, 250, and 600 Ohms. Setting the knob to a value closest to the headphone's specified impedance is recommended, though exact matching isn't critical due to varying impedance across the frequency range. Choosing a higher impedance setting will result in louder output.
- Volume Knob (Right Knob): Controls the output volume. It can be used as the primary volume control for fixed output sources. For variable output sources (e.g., a preamplifier), the knob can be set to unity gain (notch at 12 o'clock), allowing the source to control the volume. To prevent damage to headphones and ears, users are advised not to start the MHA200 at a high volume; if the starting volume is above unity gain, the amplifier will ramp up to it gradually.
- Power Button and Standby LED: The Standby LED glows red when the unit is connected to AC power and in standby mode. Pressing the Power Button turns the unit on. During the tube warm-up phase, the tubes flash green, and the Power Button is inactive. Once ready, the tubes glow a steady green, and the Standby LED turns off. Pressing the Power Button again powers down the unit.
- Power Control (Trigger) Input/Output: The MHA200 includes a 3.5mm stereo mini phone plug for trigger input and output. The trigger input allows the amplifier to power on when receiving a +12 Volt/0 Volt signal from other McIntosh equipment. The trigger output sends a +12 Volt/0 Volt signal to control other McIntosh components, enabling synchronized power on/off.
- Automatic Power Off: The MHA200 will automatically power off after approximately 30 minutes of no input signal, unless it is being controlled by another device via Power Control.
Maintenance Features:
- Initial Setup: Before connecting the AC power supply cord, it is crucial to remove the special foam inserts surrounding the vacuum tubes. Failure to do so can create a fire hazard and damage the unit. This involves removing two tube covers by unscrewing them, lifting them off, and then pulling the foam straight up off the tubes. The tube covers and screws should then be replaced.
- Placement: The MHA200 should be placed upright on a sturdy, flat surface with adequate open space to ensure proper airflow. It requires at least 19 inches (48.3cm) above the top, 4 inches (10.2cm) for the rear and sides, and 1/2 inch (1.3cm) below for unobstructed airflow. The feet should not be removed.
- Tube Replacement: Tube replacement should only be performed by trained McIntosh authorized technicians.
- Repacking for Shipping: For shipping, it is highly recommended to pack the MHA200 in its original packaging to prevent damage. McIntosh Customer Service can provide replacement packing materials if needed. The manual provides a detailed diagram for repacking, including the shipping carton, foam pads (front and back), and foam tube protection covers.
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