Audio cables are crucial for transmitting high-quality sound in audio systems. In addition to factors like cable composition and shielding, the use of an air-filled tube as a conductor has a significant impact on the cable’s frequency response. In this article, we will discuss the advantages of utilizing a conductor suspended within an air-filled tube in the audio range.
Air-Filled Tube Technology in Audio Cables:
Air-filled tube technology involves the use of a hollow tube as a conduit for the cable’s conductor. The conductor is suspended within the tube, ensuring that it remains surrounded by air throughout the cable’s length. This innovative design provides several benefits that can have a positive impact on the cable’s frequency response and overall audio performance.
Advantages of Air-Filled Tube Technology:
- Reduced Dielectric Constant:
By replacing the conventional solid dielectric material with air, the cable’s dielectric constant is dramatically reduced. Air has a dielectric constant of approximately 1, while solid dielectric materials range between 2 and 10. This significant reduction in dielectric constant minimizes signal degradation, ensuring fast and accurate signal transmission. A fumed insulator can get as low as 1.9 for Teflon. Furutech uses fumed polyethylene which is approximately 2.
The lower dielectric constant associated with air-filled tubes results in enhanced impedance characteristics, leading to improved frequency response and reduced phase distortions commonly encountered with traditional cable designs.
- Lower Capacitance and Improved High-Frequency Response:
Air-filled tube technology also reduces the cable’s capacitance, which is the ability to store electrical energy. Capacitance inversely affects high-frequency response, as higher capacitance values introduce a low-pass filtering effect, attenuating high-frequency signals. By suspending the conductor in air, the capacitance is significantly decreased, resulting in a flatter frequency response across the audible range.
The reduced capacitance afforded by air-filled tubes ensures the preservation of critical audio details, contributing to greater transparency, improved transient response, and improved audio accuracy.
- Improved EMI Rejection and Signal Integrity:
The absence of solid dielectric materials within the air-filled tube design offers inherent electromagnetic interference (EMI) rejection benefits. Air acts as a natural insulator, providing superior isolation from external electromagnetic fields that can cause signal degradation. This leads to enhanced signal integrity and improved audio quality, with minimized distortions, noise, and interference.
Additionally, air-filled tubes help mitigate reflections and standing waves within the cable, reducing signal losses caused by impedance mismatches. This ensures a more precise transfer of audio signals and maintains a consistent frequency response throughout the cable’s length.
Air-filled tube technology offers significant advantages for audio cables operating in the audio frequency range. By suspending the conductor within an air-filled conduit, the dielectric constant is reduced, resulting in improved signal transmission speeds and reduced phase distortions. Lower capacitance ensures a flatter frequency response and better high-frequency reproduction, while superior EMI rejection preserves the integrity of the audio signal. When considering audio cable options, the use of conductor-in-air technology presents a compelling choice to achieve optimal audio quality and fidelity.
The picture is a copper conductor in tube speaker cable design which is an example of the speaker cable used in my personal systems. The pictured cable is in an intermediate fabrication stage, note there are 6 conductor tube assemblies wrapped around a seventh empty tube. This is an extremely low capacitance cable which means it is very fast and has extremely low distortion.