>
> My 15 year-old daughter frequently surprises me when she tells she was
> able to hear a 'faint' high frequency tone, that of an old casio quartz
> watch, whichever the place we are. I must be inside of a silent room,
> not too big and preferable out of the city, to be able to perceive that
> alarm tone.
>
I used to be able to hear a quartz watch operate. There is a very faint
whine to it. CRT televisions still drive me bonkers, though. When I was a
child I had two nasty ear infections which caused about a 30% hearing loss.
Fortunately, it was a wide-band loss and didn't affect my frequency range.
Until five years ago I could still hear 22kHz. Right now, it's down to
about 18kHz, but I have to crank the levels up a bit more to hear it.
What I strictly avoid is using those plug-in headphones in the street or
> anywhere, I refuse to use a .mp3 file for music (Apple helped regarding
> this decision), I prefer to stay in silent places if I can choose it,
> and -mainly- I don't listen to music everyday, nor at high volume. When
> I do, well, I sit to listen to music and nothing else.
I do have a set of decent earbuds, but I generally use those when I'm on a
long-winded conference call at work. I have the earbuds playing some soft
music while i have the telephone headset on. Kinda the worse of both
worlds. :) It is neat having this guilty pleasure which nobody else knows
about.
I carry earplugs nearly everywhere. If the sound level is high, in go the
plugs. I'm not shy about it.
> Why 250 - 300 W/Ch? Amps able to deliver such an amount of power are better
> constructed, therefore they distort less and have an amazing dynamic
> range. Of course, I take my exceptions - sometimes I feel in the mood
> for turning that volume knob clockwise ... :-)
It does depend on the amplifier design. Few amplifier designs are linear in
response in dynamic response. Your better amplifier designs will expand at
the lower levels and compress at the high levels. This is especially true
with tube amplifiers. Lower-quality solid-state amplifiers compress at the
lower levels and will expand at the higher levels and then when it clips, it
distorts noticably. Amplifiers designed for sound-reinforcement are
generally linear until they hit about 25% of maximum and then will slightly
compress mimicking tube amplifiers. Unlike a tube amplifier which will have
a continously smooth level of compression, solid-state amps tend to be a
little more harsh about it.
300 watts per channel is not really all that much for a home system. 25%
volume level (assuming linear amplifier response) is 75 watts. Your better
quality speakers have HUGE loss levels--this is part of the design which
uses passive means to control dynamic and frequency response. A lesser
speaker will be louder watt-for-watt than a high-quality speaker. For
example, Bose speakers (there I go again...) are power hogs. depending on
the speaker, they may require two to three times the wattage for the same
SPL than a traditional speaker design. As a result, these particular
speakers will get quite warm (hot!!!!) when played loudly. After all, a
speaker is nothing more than a linear electric motor.
Also, consider the subs. If you want to maintain a 25% level as an
operational max for the amplifier, you have to consider what 75 watts is
giving you. Most woofer designs, any more are tuned-tube designs (cannons)
which conserve space and require a much smaller cone. Instead of moving a
big cone a little, we're moving a small cone a lot. But these speaker
designs are horribly inefficient and need substantially more amplifier to
drive. I deal with this in sound-reinforcement systems for Houses of
Worship. (we pentecostals like it loud--come on out for your weekly
rock-n-roll concert). One church I work with has six dual-18" subs as well
as the flying speakers have their own 18" woofer, which is essentially
worthless since the cross-over is at about 80 Hz. We can do full-spectrum
to about 128dB anywhere in the room (1500 seat auditorium). But in another
venue, we installed the Bose system for the subs. The Bose system utilized
four small tubes which were computer aligned to the room. These four tubes
directed the bass sound to the listening position and not into the rafters.
The sound was extremely tight and bonded well to the rest of the main
speakers. It was an expensive way to go, and according to the specifications
wasn't all that good, but the proof is in the listening. Nobody has said a
bad word about it and the musicians like it because there is nearly no heavy
sub sound on the stage so we could use a lower SPL in the monitors. As the
tubes were flown, you don't blow dry the hair of the first three rows of
people.
So far, I am able to distinguish between compressed .mp3 music, as I am
> able to distinguish between those two CDPlayers in my first pano - not
> that the Yamaha is bad, the Meridian is awesome !
>
I can barely tolerate MP3 recordings of ANY compression level. But my ears
were poisened because:
In a previous life, I was the in-house MPEG SME (subject matter expert) for
a major manufacturer of recording and broadcast studio equipment. One
"tiny" aspect of my job was debugging MPEG algorithms and getting the
consortium to adopt the changes. My one major claim to fame was discovering
the major flaw in MPEG (I'm using MPEG generically for all flavors of MPEG)
Joint Mode. To this day, many MPEG-based algorithms (of which MP3 is the
most common) continue to have this flaw. The commercial stuff fixed theirs
11 years ago, as they all use two suppliers for their chips and both
suppliers fixed MPEG JOINT MODE upon my recommendations. But MP3 didn't get
fixed as the development for that came from a different direction and the
developers of that chose to ignore the whole issue.
Wonder what it is that is so insidious about Joint Mode? Two problems. 1.
Left and Right channels are one sample out of phase. 2. When presented with
identical audio 100% out of phase, several of the MPEG blocks will either
totally distort, create clicking noises or create a high-pitched whistle.
Depending on the source material it will do all three! (Fortunately MPEG
blocks are short so this distortion is usually fleeting.)
But I don't record out-of-phase audio! Uh, huh, right. Phase alignment is
how the human ear places sounds in the sphere of space around your head. If,
during post-production, I want to locate a sound left or right in the sound
scape, I have two major options--level adjustment (more to the left than
right) and timing adjustment (earlier arrival in the left speaker than the
right speaker). However, there is a third adjustment which is the phase
adjustment. Usually we use all three. If we want to place the sound in a
phantom position either farther to the outside of the speakers, above, below
or behind the listener we mess around with phase alignment as well as
specific notching of the frequencies. During the days when I taught this
stuff, we would create a commercial where we took a car horn and placed it
in front, to the left, to the right, above, below and behind the listener
position--all with stereo. A variation of that commercial ran only ONE time
on air in Dallas and station telephones rang off the hook from people
complaining that they almost had an accident! After that, I always told
people to never actually use it and cited that example. The effect is
definitely more powerul when wearing headphones or in a car where the
speakers are to the sides of the head, but is still applicable in a standard
stereo speaker configuration. (my algorithm was incorporated in a well-known
and used plugin several years later--I had spent hundreds of hours
researching the physiology of the human ear in coming up with it)
Even classical orchestra recordings have huge amounts of out-of-phase audio.
It depends on the miking technique, but a standard Decca tree will present a
nearly perfect out-of-phase alignment for several sections of instruments.
The Violas, for example, will arrive in the left speaker nearly 50% out of
phase with the sound in the right speaker. (it would be nearly 100% except
for the gain difference between left and right. The benefit of the Decca
microphone configuration is that it is better than standard spaced-pair as
it doesn't have the hole in the middle. I've personally been a fan of
old-school X-Y configuration if there is a chance that anything will get
mixed down to mono (like we still do for television). I'd personally rather
use X-Y for the main pickup and then spot locate microphones in sections to
add more presence. Unfortunately, with most orchestras being amplified by a
sound-reinforcement system these days, we're restricted to localized pickup
with panning into the mix. Inotherwords, true stereo space is no longer
experienced. This is why I am mostly a fan of the Decca recordings from the
late eighties when they still mastered on high-speed tape and spot miking
wasn't done yet. Sorry, but I am no fan of spot miking classical.
Same with drum-kit recording. The common technique for miking a drumkit is
two overheads, a kick, snare and hi-hat mike. However, there are indivuduals
with more microphones than brains who will individually mike each and every
item in the entire kit. Each microphone is then panned into position in the
mix and then the ambiant of the "acoustical space" is artifically created to
place this drumkit into the room with the rest of the instruments. However,
there are idiots who can't figure out that you don't hard-pan the drumkit
and then place it 20 feet back in the mix! "Dreamweaver" produced one album
mixed this way which I listened to for about five minutes and returned the
CD. Poison to the ears. In comparison, "Thriller" had one of the best
drum-recordings ever. It was done predominately with two PZM mikes located
about 10 feet away from the kit. The stereo image you hear of the drums in
that album is real. In fact, most sound elements in that album are RECORDED
in stereo, but post-processed into stereo.
Stereo albums from the late sixties and early seventies were horrid, A
guitar, for example, would be in the left speaker, but the echo (reverb) for
it was in the right speaker, and so forth... Sounded kinda cool, but one
major reason for this is that when summed to mono, the album still sounded
good on-air because there was no phase-alignment issues.
Sorry, I digressed....
Being a psychiatrist myself, my hearing ability is very very important :-)
>
Uh oh, We're a research project here on the list!
AG (Huh?) Schnozz
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