Microphone Cable Extrusion Line

Microphone Cable Extrusion Line

A microphone cable is a high-quality audio connection cable specifically designed to connect condenser microphones (or dynamic microphones) to devices such as mixing consoles, audio interfaces, and recorders. Its core mission is to transmit the extremely weak electrical signals picked up by the microphone without loss and free from interference.
Core Characteristics
The most significant difference from ordinary audio cables (such as guitar cables) is that professional microphone cables universally employ balanced transmission technology. This is the key to their ability to resist interference over long-distance transmission.
Structure:
Hot Signal: Carries the original audio signal.
Cold Signal: Carries the original signal phase-inverted by 180 degrees.
Ground: Serves as the reference point and connects to the shielding.
Anti-interference Principle:
When the cable is subjected to external electromagnetic interference during transmission, identical noise is superimposed onto both the hot and cold signals. At the receiving equipment end, the cold signal is phase-inverted again by 180 degrees and combined with the hot signal. At this point, the useful audio signal, having been phase-inverted twice, adds together and is enhanced, while the introduced noise, now out of phase, cancels itself out. This process effectively eliminates the interference.

Microphone Cable Extrusion Line

The microphone cable extrusion production line is a complete set of equipment specifically used for manufacturing high-performance microphone cables. Its core process is similar to that of ordinary audio cables, both involving the "extrusion" method to coat the conductor with molten insulating material or sheathing material. Core Objective: To produce cables with extremely low capacitance, stable characteristic impedance, excellent shielding effect, and high flexibility, ensuring signals remain pure and undamaged over long-distance transmission.

Core Components

A complete microphone cable production line is far more than just an extruder; it is a collaborative system. The core components are introduced below according to the typical process flow:
Precision Pay-off System
Function: Used to release bare copper wire (for core wires) or pre-stranded core wire sets (for sheathing).
Special Requirements: Microphone cables require extremely high structural consistency, so pay-off tension control must be extremely stable and precise. Servo motor-driven active pay-off systems are typically used to avoid diameter variation caused by tension fluctuations.
Conductor Preheating and Tension Control Device
Preheater: Heats the conductor before it enters the extruder, removing moisture, enhancing the adhesion between the plastic melt and the conductor, and reducing internal stress. This is crucial for ensuring the concentricity of the insulation layer and its electrical properties.
Dancer Roll/Tension Sensor: Provides real-time feedback and adjusts tension to ensure constant pulling force.
Core Equipment: Precision Extruder
Function: The "heart" of the production line, it melts and steadily extrudes insulating or sheathing materials like PVC, PE, etc.
High-Precision Requirements:
Screw Design: Optimized for different plastic compounds (e.g., LLDPE) to ensure uniform plasticization and no bubbles.
Temperature Control System: Temperature control for each heating zone and the die head must be very precise (±1°C) to ensure stable melt flow stability, which is key to controlling diameter accuracy.
Drive Motor: Uses servo motors to ensure smooth, fluctuation-free screw rotation.
High-Precision Die Head and Mold
Function: The core component determining the cable structure. The concentricity of the microphone cable's insulated core wire (whether the conductor is perfectly centered within the insulation layer) is a key parameter affecting capacitance and electrical performance.
Mold Selection: Tubular dies are commonly used, combined with vacuum sizing technology, which can achieve uniform insulation thickness, a smooth surface, and extremely high concentricity, offering performance superior to pressure dies.
Progressive Cooling Trough
Function: Gradually cools and sets the high-temperature cable.
Special Requirements: Must use segmented cooling, with water temperature decreasing from high to low, to avoid generating micro-stresses within the insulation layer due to rapid cooling, which could affect electrical performance (e.g., capacitance value) or long-term stability.
Online Detection System
This is the quality guardian in microphone cable production, typically including:
Laser Diameter Gauge: Monitors the diameter of the insulation layer or sheath in real time and feeds data back to the control system, automatically fine-tuning the haul-off speed or screw speed to achieve closed-loop control and ensure minimal diameter tolerance.
Spark Tester: Conducts online high-voltage tests on the insulation layer, detecting any tiny pinholes or breaks to ensure insulation integrity.
Precision Haul-off / Puller
Function: Provides smooth traction to pull the cable through the entire production line.
Key Requirement: Speed must be perfectly synchronized with the extruder's output; even minor speed jitter can cause diameter non-uniformity. Dual-wheel or caterpillar haul-offs are typically used to ensure no slippage.
Take-up System
Function: Neatly winds the finished cable onto a reel.
Requirement: Take-up tension needs to be constant and adjustable to avoid damaging the cable from being too tight or causing tangles from being too loose. Uses active take-up synchronized with the haul-off.
Central Control System
Function: The brain of the production line. Integrates PLC and touchscreen for centralized setting and monitoring of all parameters: temperature, speed, tension, synchronization ratios, etc. Can store recipes for different products, enabling quick changeovers.
Key Auxiliary Process Equipment (Non-extrusion core, but part of a complete line)
Stranding Machine: Twists two (for balanced audio) or more insulated core wires together with a precise pitch, forming the basis of the balanced transmission structure.
Braiding Machine / Taping Machine: Braids a high-density copper braid or wraps an aluminum foil around the stranded core wires to form the shielding layer. This is the decisive process for the microphone cable's anti-interference capability.

Production Process

Taking the production of a typical twin-core shielded microphone cable as an example, the process involves multiple extrusions and auxiliary processes:
Step 1: Conductor Insulation
Pay-off: Pay off two reels of high-purity oxygen-free copper conductor.
Extrusion: Pass through two precision extruders respectively to extrude the insulation layer (commonly PE), forming two independent insulated core wires.
Cooling and Detection: After cooling, 100% inspection is performed via the laser diameter gauge and spark tester.
Step 2: Stranding and Shielding
Stranding: Twist the two qualified insulated core wires together using a stranding machine.
Braiding Shield: Pass the stranded core wires through a braiding machine to braid a dense layer of tinned copper braid shield around the outside.
Step 3: Sheath Extrusion
Pay-off: Pay off the shielded cable core.
Extrusion: Pass through another extruder to extrude a flexible PVC or rubber outer sheath, protecting the internal structure.
Cooling and Final Detection: Cool again, and a final spark test on the sheath can be performed.
Take-up: The finished cable is wound onto large reels by the take-up system.
Subsequent Processes (Completed offline): The wound cable is cut to length, and XLR or TRS connectors are soldered, finally resulting in the finished microphone cable.

Microphone Cable Extrusion Line Datasheet

Model	30	40	50	60	70	80	90
Screw Diameter (mm)	φ30	φ40	φ50	φ60	φ70	φ80	φ90
Screw L/D Ratio	25:1	25:1	26:1	26:1	26:1	26:1	26:1
Extrusion Amount (kg/hr)	25	40	70	100	140	200	250
Outlet Wire (mm)	0.2-1	0.4-3	0.8-5	1-8	2-15	3-25	5-35
Total Power (KW)	18	20	25	33	40	55	63
Traction Power (KW)	2.2	2.2	4	4	4	5.5	5.5
Production Speed (m/min (Max.))	600	600	600	500	500	300	300
Take-up Spool (mm)	φ200-400	φ300-500	φ400-630	φ400-630	φ500-630	φ800-1000	φ1000-1250

Microphone Cable Extrusion Line Application

The core application of the microphone cable extrusion production line lies in the manufacturing of specialized, high-performance audio cables. Its products are specifically designed for scenarios that require long-distance, high-fidelity, and anti-interference transmission of weak audio signals.

Core Application Areas

Professional Recording and Broadcasting
Recording Studios: Connects condenser microphones, microphone preamps, mixing consoles, and audio interfaces. The low-capacitance, highly shielded cables produced by the line are key to preserving the original quality of the recording.
Radio/Television Stations: Used for audio connections in studios, for interview microphones, and within outside broadcast vans. These applications demand extremely reliable cables that can resist complex electromagnetic interference on site.
Film Location Sound Recording: On-site environments are complex, requiring very rugged and interference-resistant cables to connect shotgun microphones to recorders.
Live Sound and Stage Audio
Theaters/Concert Halls: Heavily rely on long microphone cables to connect microphones on stage to the control room at the back. This places extremely high demands on balanced transmission and shielding performance.
Concerts/Music Festivals: Cables need to withstand frequent plugging/unplugging, stepping on, and coiling. They require a wear-resistant, flexible outer jacket while maintaining stable electrical performance.
Public Address Systems: Venues like conference centers and stadiums require long-distance installation of microphone cables, with clear requirements for anti-interference and durability.
High-End Consumer and Commercial Audio
Professional-grade KTV/Live Sound Equipment: More refined than household cables, they use microphone cables with better shielding to improve sound quality.
Internal Cables for High-end USB Microphones and Podcasting Equipment: The precision core wires manufactured by the production line can serve as structural components inside these devices.

Specific Product Types Manufactured

This production line not only produces finished microphone cables but also manufactures their core components:
Core Product: Balanced Audio Core Wires
Produces insulated core wires with specific characteristic impedance (e.g., the common 90-120Ω) and low capacitance. This is the foundation for constructing XLR microphone cables and TRS cables.
Finished Cable Manufacturing
Standard XLR Microphone Cables: The most common type, featuring a dual-core or triple-core (with a separate ground) shielded structure.
Multi-Channel Snake Cables: Bundles multiple independent shielded core wires (e.g., 8, 12, 24 channels) within a single, robust outer jacket extruded by a large extruder. Used for connecting the stage to the mixing console.
Instrument Cables: Utilize a structure similar to microphone cables (e.g., using shielded twin-core cable), but may differ in conductor gauge and flexibility based on specific needs.