The Coles 4038 ribbon microphone is a legendary piece of audio equipment, originally designed by the BBC in the 1950s. Its exceptional sound quality and unique sonic characteristics have made it a favorite among recording engineers for decades. However, the 4038’s delicate ribbon transducer requires careful handling and specific precautions to maintain optimal performance and prevent damage.

As one of the few specialists in the world who repairs the Coles 4038, I’ve seen firsthand the damage that can occur when these microphones aren’t properly cared for. This guide compiles essential information from years of experience and discussions.

Understanding the Fragile Ribbon Transducer

The ribbon element in the 4038 is extremely delicate—significantly more fragile than the diaphragms in condenser or dynamic microphones. This aluminum ribbon, .6 microns, is suspended in a strong magnetic field, can be damaged by air movement, electrical faults, mechanical shock, and improper handling. Once damaged, the ribbon requires professional repair.

Safety Guidelines

1. Phantom Power Protection

It is best to connect the Coles 4038 to inputs with phantom power turned off.

• It is recommended that phantom power be turned OFF before connecting the microphone.
• Wait 1-2 minutes after turning off phantom power before connecting to allow residual voltage to dissipate
• Consider using the Coles 4072PB stand adaptor, which includes phantom power blocking protection.
• Double-check your preamp settings every time you connect the microphone.
• If your microphone is plugged in and phantom power is on, unplug at the microphone prior to turning off Phantom Power.

Why this matters: Phantom power has the potential to destroy the ribbon element, especially if there’s a fault in the cable or connector. This is not a repairable condition—the ribbon must be replaced.

2. Protection from Air Currents

The ribbon is highly sensitive to air movement. Strong air currents can stretch, tear, or displace the ribbon.

Avoid:

• Placing the microphone near air conditioning vents or open windows
• Positioning it too close to kick drums, loudspeaker bass ports, or any source where you can feel air movement
• Rapid movements when positioning the microphone
• Closing case lids abruptly near the microphone

Protect:

• Use a 6-inch pop filter when recording vocals to protect from breath blasts and plosives
• Employ an external windshield or screen in environments with air movement
• Keep the microphone covered with an open ended plastic bag when not in use
• Move the microphone slowly and deliberately

Rule of thumb: If you can feel air movement, don’t place the microphone there.

3. Sound Pressure Level Considerations

While the 4038 can handle high SPLs at higher frequencies, it is displacement-limited at low frequencies.

SPL Limits:

• At 110 Hz: 1% THD point is 125 dB SPL
• At 55 Hz: 1% THD point drops to 110 dB SPL

Best practices:

• Treat the microphone more as an area microphone, than a spot microphone.
• Avoid micing closely, anything with extremely high low-frequency SPLs
• Be cautious with sources that produce strong air movement along with sound

4. Proper Handling and Storage

Storage:

• Cover the microphone with an open ended plastic bag when not in use
• Covering the microphone prevents the strong internal magnet from attracting iron particles
• Store in a protective case when not in use
• Keep the storage environment clean and free of dust

Handling:

• Avoid rapid movements or jolts when positioning
• Be gentle with the connector

5. Mounting and Positioning

Stand requirements:

• The 4038 is relatively heavy, use a sturdy, stable microphone stand
• For overhead or high-offset positions, use counterweighted stands
• Ensure the stand adapter is securely attached

Connector handling:

• The 4038 uses a Western Electric Type-4069 connector
• To connect: Align the pins and push the connector in
• To disconnect: Squeeze the silver oval-shaped ring at its widest points and pull straight out
• Never force the connection, if it is not inserting, sometimes it helps to squeeze the release ring while inserting

6. Environmental Considerations

Indoor use:

• The 4038 is designed for indoor studio use
• Keep the recording environment clean to minimize dust and debris
• Avoid areas with strong air currents or temperature fluctuations

Outdoor use:

• Not recommended, but if necessary, use wind protection
• Multiple layers of wind protection may be required
• Monitor for any signs of ribbon damage after outdoor use

7. Vocal Recording Specifics

When using the 4038 for vocals:

• Always use a 6-inch pop filter (minimum)
• Maintain appropriate distance to prevent breath blasts
• Be aware that the figure-eight pattern will capture room ambiance
• Consider the proximity effect when positioning

Signs of Ribbon Damage

If you notice any of these symptoms, the ribbon may need professional servicing:

• Significant drop in output level, sometimes perceived as noise increase
• Compromised or loss of low-frequency response
• Distortion, sometimes frequency dependent
• Unusual frequency response changes
• Complete loss of signal

Conclusion

The Coles 4038 is a remarkable microphone that, with proper care, will provide decades of exceptional sound quality. The key to longevity is understanding and respecting the delicate nature of the ribbon transducer. By following these guidelines, you can significantly reduce the risk of damage and ensure your 4038 continues to deliver its legendary sound.

If your 4038 requires repair or servicing, please don’t hesitate to contact me. I have the experience and expertise to restore your 4038 to its original performance.