'The SHEARER': Sheer Nonsense !

**joyspring** · February 25th, 2004, 05:40 PM

`Are you saying that they are equally divided in output in the low and high frequency spectrum of the original speaker in question?'

No, not at all. Obviously the fundamental(s) have higher amplitude and sound pressure; if the fundamentals + harmonics had equal amplitude, the tap dance sound would no longer sound like a tap dance shoe striking a floor.

That's a point I was alluding to - that any sound is the sum of its fundamentals and harmonics over time. Fast Fourier Transform / `waterfall' plots illustrate this well.

Back to the conditions I outlined in the earlier post, I assert that 10.6mS delay will be audible:

1. When both the original signal and delayed signal (both full-range) are of the same amplitude at the listener's position.

2. When the signal is split into LF and HF components, and the HF signal is delayed.

In this instance, however, to accurately emulate the W.E. system in question, it is necessary to adjust the LF and HF sound pressure levels such that they sum to the original sound.

In the case of a tap dance shoe, that means that the LF output will be higher in amplitude overall than the HF output. And yes, the shoe does constitute a valid test since the shoe's timbre will change if LF and HF components are out-of-sync.

FOR BOTH TESTS, it is imperative that the listener does not know when the signal is being delayed or not. This is best accomplished using a digital delay so gains may be accurately matched and switching the delay in/out will be instantaneous. The proctor then switches the delay on or off and records the listener's responses (whether he/she can discern the delay).

This is the only way to ensure statistically valid results. And like it or not, this is how things are done in the industry. Audio reproduction is so much science as an art; perhaps even more so.

Mirrophonic's full-range test probably did not meet criteria #1 since he was `standing to one end' and, if the output of each loudspeaker was the same, heard the closer speaker at a much higher amplitude than the far speaker.

And finally, yes, case #2 represents a valid test so long as the output (amplitude) of LF and HF sections sum to the overall output of a tap dance shoe or whatever transient sound was chosen.

If not, it would not constitute a valid test and definitely would not properly emulate a W.E. system either.

Was Mirrophonic's original 300Hz test valid? Depends on whether the amplitude of LF and HF sections were set properly. However, if he was again `standing to one end' while having equal gain on both channels, then the test fails.

In conclusion, Mirrophonic was attempting to disprove that a 10mS delay is inaudible.

But his tests failed because he did not outline the essential criteria (amplitude of the signals) required to determine whether his results were indeed valid.

BobR

**Don McR** · February 25th, 2004, 10:35 PM

Audiophiles will not touch a 15" driver with 2" voice
coils because they're Krap.

<font size="2" face="Verdana, Helvetica, sans-serif">Well, by your own assessment, the WE woofers used in the Wide Range System are Krap. They all used two inch coils. You want proof:

Scale it out. The top image is of the 18" WE driver, the TA-4181. Given the known outside diameter, the coil diameters scales to 2". The bottom image is the 13.5" TA-4151. Again, the coil scales to 2". The TA-4153 is also a 13.5" driver with the same voice coil diameter. In other words you share an attribute with the 2" coil drivers. Guess what it is.

In case you haven't noticed, you have lost all credibility on this board. Here's a word of advice you can either use or ignore. When presented with evidence that your position is in error, admit your mistake, grow from the experience and move on. Continuing to argue a position clearly contradicted by the facts only makes you look stupid or insane - or possibly both.