"Harry Lavo" wrote in message

M2CW.

"Bob-Stanton" wrote in message
...
"Wylie Williams" wrote in message
...
I have read in many posts that once an electronic audio component
reaches a certain level any further improvement is inaudible. Not
a point of diminishing return, but a definite point of no further
improvement. Apparently these are knowns, but I have not seen much
in the way of specifics about these on RAHE. Or possibly they are
old news and have been well documented in previous discussions.
Is anyone willing and able to describe some criteria for
determining at least the general vicinity of this point ?

I will throw out some criteria, everyone is welcome to disagree with
me.

Signal to Noise ratio: That is fairly easy to determine, for
yourself, by listening to test a CD, with various white noise
levels. White noise of -60 dB begins to be difficult to hear. I
find white noise of
-80 db inaudible. 16 bit CD's have a white noise less than -90 dB.

Harmonic and Intermodulation Distortion: If you can find his posts, I
remember John Dunlavy writing that tests showed -90 dB beat levels
were inaudible.

I would say that as a general rule, if the beats created by any
combination of three test tones are -90 dB, than the distortion
created by a music signal is inaudible.

Flatness: +/- 0.5 dB flatness (from 20 Hz to 20 kHz) is the point of
inaudibiliy.

I'd tighten this up to +/- 0.25 dB

I agree with that if we allow the deviations from flatness to be arbitrary.
IOW if the response spec allows 0.5 dB deviations over a few octaves in the
midrange, then there will be audible coloration.

OTOH, nobody is going to hear 0.5 dB down at 20 Khz or 20 Hz when the range
in between is smooth and flat, as it often is.

Jitter: Some CD's may have more jitter than cheap CD players can
correct. Work needs to be done to determine the level of audibility
for jitter.

Yep, but I bet we find audibility at very low levels.

The classic AES conference paper from Dolby labs was quite thorough, and
says the exact opposite.

Transient Response: When tested with a squarewave, some amplifiers,
and most loudspeakers overshoot and ring to a stop. With amplifiers
and CD players the ringing can be zero. Only a few loudspeaker
systems have near zero ringing. I don't know the threshold of
audibility for ringing.

The ear tolerates ringing quite well partially since most musical
instruments right LOTS, and what's a little more ringing when there's
already so much in the source material?

Since overshoot and ringing can be near zero for amplifiers and CD
players, that should be the required standard.

In practice, violent overkill.

Loudspeaker Polar Response: No one seems to know the ideal polar
response for a loudspeaker. Since each living room is different,
there may never be an answer to this question.

Frequency response?

Very meaningful, both on and off axis.

Time-Alignment?

Nearly irrelevant, except as it affects frequency response.

Phase linearity?

See above.

Power-handling (in spl) at various frequencies and linearity of same.

Meaningful, but an area where the ear is remarkably tolerant because music
is full of harmonics.