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69.156.15.182
Ok, here's my problem.
If human hearing occurs between 20 and 20 KhZ, than why do preamps boast ridiculous stuff like a frequency response of 1hZ-1000KhZ. Does it really matter? Wussup wit dat?
Follow Ups:
HiHuman hearing does not stop at 20KHz or 20Hz, those points were one set of “limits” attributed to ones ears at one point in history while basic hearing research was being conducted.
Ones ears are nothing like “flat” in there sensitivity, they are only sensitive in the mid range higher and lower, the sensitivity falls off a great deal.
If one used a loudspeaker rating, a good ear would be something like + - 40dB, 20-20KHz.
When one looks at an “equal loudness curve”, one can see that that how loud one judges a sound to be compared to how loud it is actually changes a great deal with frequency.
For example, at 100Hz it takes about 30dB actual SPL just to be detectable, this is about 1000 times more energy than it takes to be detectable in the 2 – 5KHz range.
At 20Hz, it takes about 80dB SPL to reach detection, at 10Hz it takes about 100dB and at 2Hz, it takes about 125dB to be detectable.What can you hear?
A number of scientific studies have concluded that some people hear inter-aural time delays so short they correspond to 200KHz, Gary Kendall at Northwestern U found high audio signals are associated with stereophonic hearing.
Dolby Labs concluded that sounds below 20Hz were both very common in everyday life and present at high intensities. The down side was that there was essentially no hope of producing them without audible distortion.Confusing science with selling products.
When I fist got into audio in the late 60’s, the “low cutoff” one “needed” was around 80Hz. There were a few speakers that went down a little lower but loud low bass was unheard of and unnecessary if one asked.
I had heard low bass and pursued it, in the mid 80’s, Dave Merry (sp?) president of a large speaker company came to Intersonics / Servodrive and proceeded to explain that it was unnecessary to reproduce below 75Hz, but they were going to release a subwoofer with a lower cutoff (the MTL-4) anyway. We then gave him a demo than where he heard low bass with a cutoff about an octave lower than the mtl-4 hehe.
There have been countless explanations of where fundamentals are for various instruments and so on arguing one way. On the other hand, the fundamental is the frequency “IF” the signal has a constant amplitude AND has existed sufficiently long in time. Changing the amplitude and or shortening the duration takes that “one” fundamental frequency and turns it into a much broader bandwidth.
For example Don Keele’s has used a pure tone with a gausian amplitude envelope as a test signal since the 80’s. Even thought is a “pure” tone, it has about a 1/3 octave wide bandwidth as a result of the amplitude modulation.
This is music and how it can have a wider BW than the fundamentals alone would suggest.My conclusion was that if you wanted to know what you can hear, look at the science, if you want to know what is practical to manufacture, what your suppose to buy, look at what is available and what the mfr’s say and what they have to talk about ( like a 1Hz to 10MHz bandwidth, man that’s got to be good, I mean the old one only went to 9MHz)
Remember too that numbers don’t lie but they are used to sell as well as specify.
One of the fellow at work is casually collecting measurements on popular Pro-sound subwoofers and he has found that very often one or more specifications are highly optimistic.
Frequently, when measured in real half space, at a distance large enough to remove the enclosure displacement error, one finds that the specified –3dB frequency may really be –-10dB or more.
For subwoofers, one often finds the sensitivity is rated based on what it does at the high end of its response, in some cases octaves above where it would even be used.
This mfr optimism is especially true when you compare the specified “peak SPL” (normally a calculated “perfect world” number) and what one can actually get with an instantaneous peak hold meter.
I don’t think a serious amplifier company would last long if it claimed 10 or 100 times more output than one could actually get, like is fairly common in the speaker industry.
Compare or measure side by side when you can.What do you need?
Who knows, like so many things in audio, it depends, this is what you hear not measure.
Also like so many other things, if you’re considering extending the low cutoff, you have no idea if it’s desirable or not until you have a way to switch back and forth between “with and without”.
Keep in mind, if the low extension seems to add “muddiness”, then you have gone well past the point of audible distortion in the subwoofers and that “free sound” being multiples of the drive signal frequency, is the mid bass muddiness.
Unfortunately loudspeakers are by far the weakest link in the reproduction chain.
Pushing the limits either direction past what is easy with today’s driver technology or especially extending the low cutoff downward at high level with acceptable distortion gets something like exponentially difficult / large / costly.Anyway, it’s a long rambling answer but your question covers a lot of ground.
Happy ThanksgivingTom Danley
Danley sound Labs
Now, 5 microsecond ITD's (interaural time differences) do not require in any fashion 200kHz response of a system. It is relatively easy (10kHz center 1 millisecond gaussian pulse, for instance) to show that a signal with no content outside of 20-20K (to speak of) can and will still show this kind of ITD.So the fact that there are reports of 5 microsecond ITD's does not in any fashion support the contention that anyone can hear above 20kHz.
What's more, of course you can reproduce those ITD's inside a 44.1kHz digital system. Try it, it's easy. Don's test signal will show this to you, and it's been around for a long time, that signal, which, by the way, is not and never was a "pure tone". A "pure tone" by definition is infinitely long, so there is no such thing as a "pure tone". Not now, not ever. Any signal that happens in the real world has a finite bandwidth.
That doesn't, of course, affect the issue of hearing at all, since hearing also exists in the real world.
It is very likely that for anyone over the age of 10 or so, a few individuals perhaps excepted, audio signal above 20kHz is irrelevant.
There is, however, a very large BUT.
That's that filtering can cause audible in-band (i.e. below 20kHz) effects. A system that cuts off filters, in one way or another, by definition. Sometimes that filter can matter quite a bit.
Hence, having an extended range, especially in electronics, is often a good, sensible way to ensure that you don't get any in-band problems due to bandwidth limiting, even though the signal at higher frequency (if it's even present) may not be at all audible.
We can't hear sound lower than about 20 cycles, but we can definitely feel it through bone conduction. If you want to test this phenomenon, put in some foam earplugs and put on some firing range earmuffs over that, so you can't hear a damn thing, and then see how well your hearing is protected when you stand next to a cannon blast.I'm not sure if bone conduction applies for frequencies over 20K, but that's not to say there aren't other bodily ways for supersonic frequencies to reach our inner ears.
I have a related question to this if hearing response goes from 20hz to 20khz and more-over speakers roll off at 20khz what is the purpose of SACD/DVDA which go up 192 khz? Is the speaker going to give a different response w/ data going to that high of a frequency.
I think you're confusing sample rate with frequency response.-Bob
Perhaps I am, but these things are interrelated no? What I mean to say is that cd players and dats used use 44/48khz sample rates mostly because our hearing only went to 20 khz (aka nyquist) or so. Perhaps this is wrong but I was thinking w/ a 192 khz sample rate the appropriate dvd-a/sacd dac must be sending out a signal w/ a frequency response of 88khz or so. I'm just wondering what normal speakers are even capable of doing anything w/ that end of the spectrum? I've heard the argument about harmonics, but why aren't those harmonics in the audible range due being recorded using a normal sample rate?
is that an inherently higher bandwidth design obviates the need for the obligatory "brick wall" filter found in RBCDs.rw
Take a .5 millisecond 10kHz centered guassian pulse.Play it out the DAC on your computer. LIsten.
Now, fiter it with a (very long) FIR filter that will cut off between 20kHz and 20.1 kHz. Yes, it will be long, best done as fast convolution, etc, but in modern systems you can design and use such a filter.
Listen for pre-echo and see if you can hear any. :)
Exactly. When the DVD standard first came out the sampling rate was chosen by what the technology of the day allowed. The technology has gotten better since then. I don't see any reason why it may not eventually get to a megHz and eliminate the need for steep filters.
are not aware that the original Redbook standard was not determined by ideal circumstances - rather it was backed into based upon the data storage limits of the 80s media.Ok, you've got a 700 megabyte budget to spend and marketing has determined play length of 74 minutes. Arrive at the best compromise of word size and sample rate. Any musical frequencies produced past 22k (and there are plenty of instruments that create such) must be completely removed or they shall show up as 100% distortion. Whether or not we "hear" them is irrelevant.
rw
Dear All
The thing is that most people other than the rock in a groove guys catered for in other forums. Are judging the material
at 16bit 44.1khz. and some of the artefacts produced by files converted to this standard from much higher data flows sound a lot worse than decent apogee 16 bit dacs input to a DAW at 16bit to red book CD. Thus the continuing
high second hand value of the old 8 channel units.
Perceived quality has a great deal to do with the frequencies from
say 100hz to 10khz I don’t know of anybody who hears great differences in audio quality between super tweeters its just either there or not. I am a great deal more impressed by the sound of an RCA 44 with an OP-6 pre amp from 1938 than I am
with the sound of a modern transformerless Chinese transistor condenser. Thus the price difference second hand. You see its down to the fact that bats for all the guano they produce have never organised them selves in any way financially and until such time as they become a major force on Wall St will not be guiding the audio industry second hand market. Although they will probably be influencing new equipment and review pages in recording magazines. Go on please a passing Bat.
Regards.•:*¨¨*:•. ¸¸.•´¯`•.Mark Harwood, Engineer Springvale Studios
I think you're missing my point. Let me recap:1. A bunch of instruments produce output waaay past 20k.
2. With RBCD, you must remove ALL of that or what remains will be pure distortion.
3. Brickwall filters used to achieve #2 do nasty things down in the critical 100 hz to 10 khz audible range.rw
1. A bunch of instruments produce output waaay past 20k.
2. With RBCD, you must remove ALL of that or what remains will be pure distortion.
3. Brickwall filters used to achieve #2 do nasty things down in the critical 100 hz to 10 khz audible range.
BTW Happy holidays :)Just to follow up, it makes sense to me that you need an equivalent of a brickwall filter to remove everything above what is capable
of being recorded at the sampling frequency (to prevent aliasing/noise). But how do these filters change the recorded sampling in the audible range?I did a bit of hunting and noticed there was an issue w/ Phase deviations, which occur w/ analog brick wall filters but I dont think this is an issue w/ digital filters but I may be mistaken. What are the general problems w/ lopping off the > 20 khz or so frequencies using a digital filter?
-best
-avi
to those engineers like Jack Renner who find the results better using much higher sample rates.rw
Dear RW
You have not quite got it have you. What are your customers listening to your output on. CD Sky Digital Mp3 if its a film DVD.
All of these systems have limitations and until they change those the job of the audio recording professional is to make a product that sounds
A) Good in the A&R department office. (44.1Khz) You might get more work.
B) To the CD review page editors home system (44.1Khz) the record company sent him a CD
C) to the end user. He bought a CD(44.1khz) and did not return it as faulty.
I think anti aliasing filters are about as good as they are going to get right now. So I will work with what actually exists. When audio designers produce a system that finds a way into the A&R Office
I will have to think about that.
Meanwhile I will continue working on the work I have at hand. I am making a recording with Neil Innes for the cartoon series The Mistermen in which all the audio is made from sounds emanating from either bodily functions or percussion trom belly slapping. Most of the sounds of the hip hop drum loop are.
A) Kik low frequency artificial trouser trumps
B) Snare gated raspberry and mouth pop slaps.
C) Hi hat various mixed sneezes
Not sure of the frequency response is as for some reason I forgot to use waves plug in paz freq in the master inserts.
Regards.•:*¨¨*:•. ¸¸.•´¯`•.Mark Harwood, Engineer Springvale Studios
PS I have never had a booking for a dog whistle ensemble.
maybe that’s where I am going wrong.
to figure out my answers.Good luck on your latest project.
rw
¿4v? I thought this was the pro audio asylum. So I was under the impression. We would be talking about the actual practical considerations of recording. With the best will in the world
Data flow rates are finitely fixed by others and are without our control. My best microphones don’t have anything like a response
to the figures bandied about here. And they are all the most sought after makes and types my best sounding Pre amp has a transformer in its output and is not doing anything after 22 K.
I don’t make the stuff. I just use it .OK lets talk about this. I don’t think there ever will be a microphone or recording system/set of speakers that can in any way reproduce the audio and physiological effects of firing a simultaneous salvo of 18" shells from the three three barrelled foredeck guns of my great uncle Admiral Sir Henry Harwoods Command HMS Rodney. On the bridge if you did not keep your mouth open it broke your teeth and the gun flash gave you an instant sun burn. So where in audio terms are we going from there.
To the Cable Asylum I should not wonder.
Regards The Countess, of Burford & Mark Fairfax-Harwood.
to fully decode your posts, but yes, there are mics and mic preamps used in commercial recordings that have output past 22k.If you don't use Neumann, ATC, or Sennheiser mics nor preamps like Millenia Media, then perhaps you don't have to worry about such things.
rw
I used to work for Sennheiser, and as I recall, their mics in most cases actually do not have significant response beyond 22 kHz. Even among the RF condenser mics, all but the MKH 816 shotgun have sharply falling response at 20 kHz (the MKH 816 actually has a dip at 15 kHz and rising response at 20 kHz).A couple times there I got calls from guys who insisted that a good mic should have response down to 0 Hz. I had to gently point out that the mic would have to also include a barometer to do that. ;^)
-Bob
Dear Rw
I use Neuman and Sennheiser Mics. I have monitors with ATC midrainge Soft domes. The tweeters are Scanspeak I think.
Pre amps by STC, Neve, RCA, Gates, Symetrics, BE, Never heard of Milenia Media and I have been in this business 33 years full time. Just checked Dreamhire and Blackbird audio rentals Nashville.
They have everything a grown audio engineer could possibly desire.
Including several Fairchild 670s and 18 of the mic I would most like to own ELAM251. Nothing by Millenia media for hire.
Can't remember seeing that name on British hire company lists.
Regards Mark
PS What is it again that makes this pre amp so sought after.
They use the preamps, as do quite a few other folks.rw
Dear RW
Yes I am and a very good old boy was Thomas. Though
far too Swedish for my taste. Hardly a sense of humour at all.
Regards Mark
It was rather dry, but it was definately there.I got to talk to him a few times about why he designed the Soundstream stuff the way he did. It's a bit tragic that that work never got put into publication form.
was on hand in Atlanta back in '78 when the ASO did The Firebird . I had the good fortune of playing a minor role during the recording and meeting Woods and Fenner.rw
Dear DW
That must have been a fantastic experience I am dead jealous. Back then I was a gopher/tape op at Polydor studio two stratford place and very willing and much abused. I never got to go on any interesting outside jobs. I just went that translucent white like one of those termites in a mound. And still had to moonlight to make my rent.
EEEE those times were hard if you told the youth of today they just wouldn’t believe us.
Regards Mark
There are people who claim that it makes a difference for high-crest impulses, and that it improves linearity in the audio range. There may actually be some truth to that. After all, not all audio sources break down to the sine wave components, since some are basically impulses (drum rim shot, fireworks explosions, a hammer hitting a nail, etc.). Unfortunately, the only one that pops to mind at the moment is a psuedo-science "white paper" (I love that term) from Eric Blackmer at Earthworks (microphones), but I don't want to color your judgement. (Hopefully, this gives you some food for thought.)On the other hand, even if it's a bunch of crap, wouldn't it be great to be able to tell your date, as you serve the lobster and Fume Blanc, that your pre-amp goes from DC to light? The quizical look on her face will provide the perfect opportunity to show her how smart and insightful you really are, and to imply that you have other amazing talents as well. ;)
Unless you're an elephant or a canine super extended frequency response doesn't mean that much to you, but if an amp is flat from 1Hz to 100kHz than it will obviously be flat where you actually need it to be as well. Peformance claims that range from mere hyperbolae to flat out silly are a fact of life, no one wants to be the guy whose amp is 'only' flat from 2Hz to 50kHz.
So, I'm just a musician, what do I know? But I have spent time in a sound lab, I know what sounds like what.For the low end, yes, there are sounds we feel rather than realy hear. I't kinda cool to feel the T-Rex walking in Jurassic Park. But I don't want to ride around in some punk kids car with the sub thumping away like a kid kicking the back of the car seat. Those subs may produce low notes, but they ring forever, and don't sound like the kick drum in the studio.
On the high end, that same kid that has been listening at 130 db for a few years probably can't hear over 9khz-10khz anyway, maybe less.
Actually, for most music, you can filter out anything over 16khz and not affect the sound a bit.
And most people confuse loud peaky bass in the 80-150 hz range for real bass in the 40hz range.
Here are some real numbers... the low E string of an electric bass or string bass is 41 hz. But if you listen to a real string bass, that low E does not sound nearly as loud as the A string above it even if you pluck both strings as hard. The speaker of most bass amps does not produce a very good 41 hz either. Bass drum has a lot of energy as far down as 30 hz.
Nobody listens to pipe organ music anymore. I'll bet they sell a whopping 2 doz organ CD's a year now.
Realistically, speakers that are flat from 50hz-14khz are pretty good.
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