We can not hear group-delay under 100Hz?

[Robert the cat]

Phase Distortion Vs frequency interferes with the requirement that all the signals of different frequencies are required to arrive at the end of the pipe together in time.

Consider these items:

(1) Low frequency speakers are the most corrupted element in the loop. You can research this in the Free Wikipedia Dictionary.

(2) I am not Pushing Audio Cables, but history speaks well on this item.

"Interconnect cables and speaker cable phase corruption"__ according Mr. Bruce Bresson, CEO of MIT / Musical Interface Technology inc, owner of all the important Patents on cables in the world__ states in his first patent: "From 20,000 Hz all the way down to the lowest audio frequency of interest aka, 20 Hz, the magnetic field attending the audio current in the cable conductor Sinks toward the interior of the conductor" which by definition is:increasing inductance inversely proportional to frequency or increasing Group Delay with decreasing frequency.

MIT's first solution was to use a "hollow thin wall flexible pipe" which was executed by wrapping thin wire side by side around a Teflon rope some ten feet long, which he licensed to "Monster Cables inc.

This approach worked quite well down to some 300 Hz, His next patents extended the low frequency group delay with various networks.

Legend has it That "Transparent Audio Inc" added a chunk of Ferrite Magnetic Inductance Properties at the end of the Monster Cable with considerable success.

(3) Vacuum tubes are superior to solid state because there is no impediment to the Emission in the Vacuum, especially tubes with heavy filaments like a Type RCA 26 tube & the type 845 or the Western Electric 300-A & 300-B which have filaments of 11 layers of lamination construction good for 10,000 hours.

(4) Every component in the audio chain damages Group Delay including hook-up tiny conductors in amplifiers. I have a 1989 Sony TV with a tiny 2 inch square Chip 10 watt amplifier in which the chip components are inter-connected with 1/8 inch gold ribbons__ this amplifier offers superb audio sound and measures quite well for phase linearity and phase distortion__ impeccable Group Delay despite the solid state active devices