One method of quadraphonic recording on vinyl involved recording from 20Khz to 40Khz, but this information was Frequency Modulated, using a special preamp to decode it. Because it was FM, flat frequency response and low distortion was not required. (Like FM radio).
Nevertheless, the requirement for some kind of sensitivity up to 40KHz caused large improvements in pickup technology, which has benefited us long after quad vinyl died.
Some audiophile recordings have claimed flat response to 22KHz. This is fairly easy to measure simply by looking at the grooves with a microscope. |
Do you think our amps and speakers today can reproduce the 20Khz and below frequency? |
Amps...no problem. Many speakers roll off by a few dB at 20KHz. Some supertweeters are good to 30Kc and higher. "Ultrasonic" transducers go much higher, but noone (except bats) cares about sonic fidelity at these frequencies. |
Why then, (a little unrelated) does the Avalon Eidelon Diamond series speaker boast a supertweeter that goes to 100Khz? The 'regular' Eidelon goes up to about 40Khz.
How high is the regular CD player capable of ??...... vs a phono cartridge??
How high can we hear? |
JB: The presumed advantage of that diamond tweeter would have to include its performance in the audible range, not just its allegedly greater extension. The exact Hz figures I'm guessing are mostly 'specsmanship'. One of the real benefits of designing a tweeter diaphragm with the highest possible rigidity-to-mass ratio is the potential to move its fundamental resonance frequency out as far above the audioband as possible (allowing it to act most like a pure piston within the audioband), and I assume that's the reason for the "diamond" construction. There's nothing of musical value going on at 100KHz anyway, even if the software could capture it, the rest of the system could transmit it, and we could hear it (we can't). A CD and its player can only capture and transmit information up to between 20KHz and 22KHz due to the Red Book sampling frequency standard, but it's generally thought that the audioband side effects of the steep filtering above that frequency limit - rather than the loss of any higher frequencies per se - is mostly to blame for any audible artifacts that degrade CD HF reproduction. Human hearing is nominally considered to extend to 20KHz max., but while a few individuals (probably mostly young, and maybe mostly female) may be able to hear up to a somewhat higher frequency limit, most of us adult males actually get by with hearing response that begins rolling-off well before those heights, maybe between 12KHz and 16KHz, and a lot of us are completely deaf to info above 16KHz-18KHz or even lower. |
There is the old story of Geoff Emerick the Beatles guy calling Rupert Neve in to suss a fault on a console,that he designed,and Emerick's "golden ears" were not happy with.It turned out that Emerick could hear a fault in 3 panels generated by a 3dB glitch at 54Khz.Some transformers were wired wrongly and he could hear it even though it seemed to be o.k.and people thought he was being fussy.Ultrasonics do effect hearing.stefanl |
Zaikesman...As you say, response to several octive above the highest frequency of interest is an indication of good performance up to that frequency.
When I was in college (many moons ago) I was a subject in some research project relating to hearing, and, as part of this project, my ears were "calibrated". At that time my hearing did extend well beyond 20 KHz, which was the highest frequency of interest to the experiments. Perhaps because of this early experience I have maintained an interest in the subject of human hearing ability.
Over the years the highest frequency pure tone that I can hear has moved steadily down. By now I guess it is around 12 or 14KHz. But, while I cannot hear a 16 KHz tone, I can sense the effect on white noise of a low pass filter at 18 KHz. This is why honest response to 20 KHz is necessary, and why a supertweeter good to 30KHz can be desirable if the source can match this.
Response to 100 KHz is no big deal for an ultrasonic transducer, but it would be a stretch to call it a loudspeaker. |
Stefanl: I'm sorry, but to me that story is likely mostly apocryphal. There were no monitors Emerick could have been using that would reproduce 54KHz flat even if he could hear that high (which I don't believe), and I doubt the response of his board was extended flat beyond that frequency either. If the story has a germ of basis in fact, I would have to assume that whatever was the fault in the board (a ringing spike caused by incipient oscillation? - certainly not a -3dB dip), it must have been precipitating some audible artifacts affecting frequencies down much closer to the range of normal human hearing.
Eldartford: I can understand that smooth ultrasonic extension will aid in maintaining waveform linearity lower in the audioband, and that glitch-free gradual ultrasonic roll-off beginning well above the audioband is probably never a bad quality to cultivate everywhere throughout the recording/reproduction chain (even if a lot of what goes on up there is probably noise). But to me it seems that when it comes time for such a signal to exit a speaker, most conventional designs will be capable of only such limited dispersion that one would have to listen perfectly on-axis with their head in a vise to receive much of the theoretical benefit... |
The story about Geoff Emerick is true I have seen 2 Rupert Neve interviews online where he repeats it,and a discussion on a Pro-Audio forum talking about it and how well thought of he is.Anyway in a transcript I have,Mr.Neve talks about his 5106 Console and it goes 5Hz to 150Khz.He says all his designs of this time were of that order.The 5106 being designed by Geoff Watts who worked for Mr.Neve at that time.There is a Neve Webpage and redesigned versions of the early Consoles may be offered.stefanl |
Fine as the console may have been, that doesn't answer the monitor question. Again, I don't doubt that there may be a germ of basis in fact for this story, but no matter what Mr. Neve theorizes, I don't believe it's because Mr. Emerick can hear minor response variations *at* 54KHz, even if the audible problem did turn out to be *correlated with* or *caused by* something occurring at that frequecy. Mr. Neve may be in a position to know what the end result of episode was, but IMO can't be certain about the mechanism for its original detection. It makes for a nice story though... |
Yes,Mr.Neve says that he does not really know what makes us perceive sounds the way we do,but is a firm believer in wide bandwidth for commercial recordings.Anyway what goes on an LP in terms of bandwidth which was my original question and we seemed to have wandered off the topic.stefanl |
So, getting back to the original topic, then LP is the 'superior' recording medium because it will reproduce music in more extented frequencies than CD is capable of?
Is this correct? |
A vinyl disc can produce higher frequencies than a CD. The CD limit is 22 KHz, and it is a "brick wall"...nothing at all above it. However, fidelity does not degrade until this limit is reached. The fidelity of vinyl degrades gradually, and what you can get higher than 20KHz depends on the pickup used, and in any event will be of degraded fidelity. Also, high frequency information on a vinyl record degrades with repeated playing. Finally, there is some argument as to whether response over 20KHz is audible (to the majority of listeners).
"Superior" involves a lot more than frequency response. For use in an automobile, a CD is clearly superior. |
JB: The problem seems to have more to do with the CD standard's implementation of the steep ultrasonic filter so close to the audioband, rather than the loss of the ultrasonic frequencies per se. However, the solution takes care of both problems: Simply increasing the sampling frequency (in a PCM format) of the recording, storage media, and playback machine, as is done with hi-rez DVD-A, to at least double the 44KHz CD standard will both extend the ultrasonic response into LP territory, and move the anti-aliasing filter well above the audioband allowing for a much gentler and less problematic filter slope. |
The frequencies in the ultrasonic area of LP's do not seem to "wear out" after repeated plays.The article by Stereophile's editor-in-chief John Atkinson called "What's going on up there" found in their archives section on-line is absolutely essential reading.He used the end track of a record he had played on in the 70's (he could'nt locate the master tape).It had clicks and had been played many times, the frequency spectrum showed an extended frequency response for this LP that reached 40Khz.This was consistent with other recordings.The sonic information caused mainly by electric guitar and drums cymbals it was rock music.Anyway a classical sample he had extended out to 30 Khz.This is the area where LP looks very similar to DVD-A.stefanl |
