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Actually, this phenomenon of 'ultrasonic hearing' that Rupert Neve likes to bandy about is really nothing more than showmanship, if you attended the AES lectures, you'd know what I mean. The truth is that a 10khz square wave has a different RMS value than a 10khz sine, it is easy to hear the level shift. Also, the ringing in the unterminated input transformers (the 56khz response peak) causes TIM and slewing induced distortions in the AUDIBLE (20-20k) spectrum. Plug a 50khz oscillator into your marshall in addition to your guitar and play through it. I guarantee that you will hear a difference, even though the speakers roll off significantly above 6khz. Having said that, I'd like to direct all who are interested in supersonics towards this great sight: http://www.cco.caltech.edu/~boyk/spectra/spectra.htm There's Life Above 20 Kilohertz! A Survey of Musical Instrument Spectra to 102.4 KHz California Institute of Technology -Chuck Zwicky At 10:49 AM 3/10/98 -0800, you wrote: >>To add fuel about sounds and feels of sound, I read somewhere a great >>history for those who think that beyond 20 Khz (at best) there is no >>reason to possibly ear anything. > >I think it's actually Mr. Neve who talks about this. I think the deal is >that you can't hear a continuous tone over 20KHz (lower if you've abused >your ears like me....) but you can discern transients that have higher >frequencies. I think Neve would demonstrate this by switching a 15KHz sine >wave and a 15KHz square wave. All the frequencies that make it a square >wave are above the human range of hearing, so it should sound the same as >the sine wave, but supposedly it doesn't. > > >>felt something uncomfortable in the high end without being able to >>pinpoint what. In the end after testing of the unit. The people of >>(either Neve or SSL) discovered that the unit had on a few inputs, some >>bad soldering things that created a frequency peak at ... 56 KHz! > >If there is a big peak at 56KHz, it would very likely be having an affect >on frequencies below 20KHz, which might be what the guy was hearing. The >"skirt" of the filter.... > > >>We are certainly (I mean i am) talking highly trained ears, but that >>says a bit long on what we really know about the possiblity sounds can >>affect us. I mean this guy is paid to work with his ears. Where he >>would say "that doen't work" we just would say "I don't like too much >>that sound. And probably only would we note that in a rather unconscious >>way, so it just would be a discomfort feeling... See what I mean? >>The funny story is that is was digital signals... You know this things >>that don't run higher than 22050 kHz (or 48 if you sample @96kHz...). > >well, that's another thing with poor quality digital gear. If the audio >input is not filtered right and you put higher frequencies into it, they >will alias into the audio. Basically they mirror around the 1/2sample rate >frequency. It's sort of a cool affect, but a terrible thing to do to >music. >If the aliasing frequencies are low in the first place, the result will be >subtle and give you that uncomfortable feeling. > >kim > > >______________________________________________________________________ >Kim Flint | Looper's Delight >kflint@annihilist.com | http://www.annihilist.com/loop/loop.html >http://www.annihilist.com/ | Loopers-Delight-request@annihilist.com > > > > >