Low-Noise Cable Frequently Asked Questions

1. What applications require Low-Noise Cables?
Low-Noise Coaxial and multiconductor cables are necessary in any small-signal application where an insulated flat braid wire or braided ground cable could experience mechanical shock (twisting, crushing, flexing, pulling, etc.)

Typical applications include:

• Medical Instrumentation – ECG, EEG, Pulse Oximetry
• Microphones
• Test and Measurement
• Sensors

2. What is a Low-Noise Cable?

A Low-Noise Cable is coiled flat braided wire or ground cables specifically designed to reduce electrical noise induced by mechanical stress on the cable.

3. What causes mechanically induced noise?

Typically, when either standard or custom cables experience mechanical shock, the individual layers move relative to each other (conductor and shield move relative to insulation). This movement charges the insulation, creating a charged capacitor that results in a voltage difference between two conductors or a conductor and shield.

4. How does a Low-Noise Cable reduce noise?

A conductive layer is added to the surface of the insulation. This layer is bonded to the insulation preventing movement between the two materials thus preventing charging. Charging caused by movement between the layers of the multiconductor cable and the conductor or shield is dissipated immediately preventing a voltage difference.

5. How much does a Low-Noise Cable reduce noise?

A typical cable can generate between 5 millivolts and 100 millivolts depending on the materials used.  Low-Noise flat braided wire and ground cables reduce the noise anywhere from 15 microvolts up to 250 microvolts.

6. Which is better: Coaxial cable or Multiconductor cable?

The voltage difference is dependent on the charge difference between the surfaces of the insulation.  Ideally, the charging would be the same on both surfaces resulting in a charge difference of zero. 

In a coaxial type cable, charging occurs due to movement between the conductor and insulation and between the shield and insulation. There is inherently more charging due to movement between the shield and insulation, therefore, there is a large charge difference yielding a higher voltage difference.

In a multiconductor cable, the insulated singles are of similar construction, therefore charging due to movement between the conductor and insulation essentially cancels itself out. The charging that creates most of the noise is due to movement between the insulation and other elements in the multiconductor cable (i.e. other insulated conductors, tapes, and shields). As charging does not occur between identical materials and the insulated conductors are only slightly in contact with tapes and shields, very little charging occurs.

However, both cable types can be easily redesigned as Low-Noise Cables to essentially eliminate any mechanically induced noise.

7. How do you strip/terminate Low-Noise Cables?

The outer low-noise layers must be stripped back at least 1/8” to ensure that shorts do not occur between the conductive layer and the conductor.  NEWtral® Low-Noise Cables are available with three types of low-noise layers to ensure that the layer can be easily stripped.

• Coated – A coated low-noise layer must be chemically stripped.  Recommended chemicals include: citrus solvents, mineral spirits, and MEK.  Sample citrus solvent pens are available by request.

• Extruded – An extruded low-noise layer can be stripped using conventional mechanical and laser stripping methods.  The layer is designed to be separable from the insulation.

• EZ-Strip – The insulation is extruded in two separable layers and then the coating is applied.  The cable can be stripped by either removing the coating with solvents or mechanically stripping the outer insulation layer.

8. What quality measures are in place?

All low-noise custom cables are tested to ensure that they can be easily stripped and terminated. The cables are also tested using a repeatable benchmarking procedure to ensure consistent performance from run-to-run.