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In Reply to: RE: How to reproduce the full dynamics of a scissor cutting paper without clipping posted by Rafaro on April 17, 2017 at 15:33:05
Now, you're gone over the edge.
The teeny tiny miniscule sound output of scissors cutting a piece of paper is something like 0.0001 acoustic watt of output - if that.
You're mis-characterizing the scene, and I suspect that your motivation might be to drive traffic to the website, or that you're simply naive.
As a musique concrete student back in the day, I once recorded a key being inserted into a door lock. I can tell you that it didn't take much of a sound system to reproduce it! Even the two Cabasse speakers and Marantz amp was WAY more than enough.
Edits: 04/18/17Follow Ups:
I am afraid your confusing two different things, one, how loud something sounds to you subjectively and the second, how loud an original event actually was based on the microphones peak voltage level as seen on an oscilloscope. There is an ocean or small lake anyway between these two and the second one is what is required to actually reproduce that same event accurately.
For instance, I have an old brick type B&K sound level meter that has a peak hold function where it captures the instantaneous peak value instead of averaged fast or slow etc. Tossing a Table spoon on the tile floor produced a peak near 140dB, slamming the car door shut while in the car (with the windows rolled up) produced a peak over 140dB. Now, neither of these sounded that loud to me but that's my point, what we measure isn't what we hear and to reproduce those or any other sound accurately requires you produce ALL the signal, all the peaks no matter how silly the numbers required sound and how much they seem like over kill given ones subjective impression of "loudness".
Seriously, this (dynamic requirements of ordinary sounds) is an over looked area in hifi.
What distance was the mic from the spoon at the point of impact?
I don't know about you but when a spoon hits a tile floor from say a 1 meter drop, I cringe from the initial "KLANG". It is LOUD but short.
Scissors will only be remotely close to 150db with your ear right at the scissors. Move a few feet away and the SPL has dropped dramatically. The initial pressure where the sound is being generated is high but it is a very small point that it is expanding from (the contact area generating the sound is miniscule) and therefore dissipates rapidly as the wavefront expands.
Put the mic at arms length away and it is probably less than 100db peak.
I was wondering around the house and yard with a B&K 2204 SLM which has an impulse hold setting.
I was about 6 or 8 feet from where the spoon hit the tile, the sound level meter chest high.
Klang! Yes, my point though is that although that and slamming the car door were startling, one would have had NO idea how loud the instantaneous peak levels actually were. I mean I was used to measuring sound levels already and was taken aback by what I saw.
That is because our judgment of "loudness" is frequency dependent and duration dependent and we do not hear short loud sounds as "loudly" as when the same signal is present for a longer time.
It also depends what one wants to do, our hearing system is very forgiving, it is easy to produce the sound of a door being closed well enough so that everyone knows what it is, but it's another thing entirely to reproduce the sound of a door closing sufficiently accurately that a person looking the other way, will think a door was closed.
To reproduce at that level, one must reproduce essentially everything that is that sound including the short peaks.
Now like I said, I never measured the scissors thing or even heard of it until this thread but for sure, there are peaks in all kinds of sounds we record that were too impractical to include or reproduce in all but the most extreme cases. Thankfully at work we have a customer interested in "making it sound real" as possible on a large scale including large scale phantom and stereo images because I love this stuff.
"making it sound real" as possible on a large scale including large scale phantom and stereo images because I love this stuff.
Gee, from looking at all the stadium videos, I couldn't tell. LOL.
It's like when I was 19, I had to go play my new speakers, built in my garage at 20 cubic feet each, and horns with 400 Watts of power, which, I couldn't wait to put them in a large room so people could dance.
But the "toys" you design, Tom, are, to quote our new President, "HUGE" and have to be measure from 1,000 feet away outdoors so as not to "peg the needle."
Sonic Levitations in Pyramids notwithstanding and beyond the scope of this text.
Haha, hey thanks Claude.
Want to hear big, go to Disney and check out the Star wars spectacular or Rivers of light, these are big, closest listeners are about 500 feet from the speakers.
Hey i am passing on your good catch on the euro guys web site.
"Hey i am passing on your good catch on the euro guys web site."
Good news. After all, those people appreciate good sound as much as we do, so if this causes them to go hear what all this fuss is about, so be it.
I have a pretty crappy scissors here - they don't make a "snip" so instead I popped a Coke can open 4 inches from the microphone.
In one second the levels went from a minimum of 14.7dBA minimum (FAST RMS) to a maximum of 87.5dBA FAST RMS. These FAST time weighted values will correlate (somewhat) to the loudness of the signal. The PEAK pressure on the microphone reached 114.3dB!
That means within less than a 1 second interval an amplifier would have to cover over a 100dB swing in level without clipping. The difference between the MAX level(during the peak) and the Max Peak was 27dB. That 30dB difference requires 1000:1 amplifier headroom! It is a rare recording that shows and preserves that difference.
The Gray "Cursor" and values for that second shown to the right.
The recording engineers place limiters and compressors on the recording or mastering process that prevent that almost 30dB crest factor (Peak to RMS Ratio) of something real! The do this because human hearing doesn't or won't hear the instantaneous peak anyway. And if they recorded the signal preserving the dynamics on the CD, you would be turning your volume knob full clockwise to hear the signal - and then your amplifier would be sure to clip!
The Sound Meter uses TWO 24bit A/D converters overlapped 30dB and sampled at 48kHz to cover the measurement range up to 144dB or so.
Note: the Crappy scissors cutting paper had a Peak level 77.9dB and Max RMS level of 56dB - still a 21dB crest factor - typical recordings are only 13-20dB!
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I am glad you posted here, you should have a good selection of toys.
I had not heard of the scissors test but I did find the peak levels indicated by the 2204 slm on impulse hold, were a lot louder than the subjective loudness would have suggested.
A problem is our sense of loudness is both frequency and time weighted and not strictly sound pressure like a microphone but if one wants to produce "the whole signal", one has to produce all of it.
Not knowing what / if any integration was in the meter on impulse hold, the cumbersome / failsafe way to judge instantaneous peak pressure is to capture the mic signal on a storage scope (or a repetitive signal is easy to capture on a regular scope) and use the mic sensitivity to calculate the peak pressure.
Lastly on the subjective audibility of very short things;
About 15 years ago, a well known amplifier company was going around with an abx box and their new amplifiers.
They came to the shop and from home I brought in my trusty Threshold stasis intended to be in the mix.
I set up a system I was familiar with and had a CD of wave files (of to me were revealing and difficult recordings). We had Crown's, a Chevin, the QSC's and a few others. Fast forward 6 hrs and the amps generally had two slightly different sounds, it was all very subtle behavior on the decay side of transients and only audible on a few tracks but repeatable. AND then there was the Threshold.
It sounded exactly the same as the better category amps but at a decent but not that loud level (on sensitive speakers) it sometimes was less dynamic.
Enough different that I grabbed an oscilloscope and looked at the amp outputs (as the front indicators said we were at peaks about -16dB) and saw that on the biggest peak, there was occasional instantaneous clipping.
It was these very short "limiting" events which were it, not at all audible as traditional "clipping" but instead were only detectable when you heard with and without as I was here, being able to switch to a much larger amplifier and back.
Since then I have urged people if they have a scope, to look at the amp signal (perhaps not with class D) and see if there is any clipping at listening levels.
And if you do the same thing with the microphone at a normal distance away (say 2 feet)?
I think Inmates point is that sure, at 5 inches the scissors will make 150 db peak but at 2 feet away it will be a LOT less.
You sort of have this backwards. Sure at two feet the level will be less. but you loudspeakers are 6-7-8 feet away so compared to two feet away they have to be putting out 6dB or more output than the Coke can at 1 or two feet. 114dB adjusts down to about 104dB in a typical room - then add 6dB for the loudspeaker distance distance and adding two loudspeakers (assuming a mom placement gets you back up to 110dB peak capability.
While it could be the level that you are interested in, there is also the interest in preserving dynamics. Sure in a Public address world - the loudspeakers would have to be putting out a lot of SPL to make a coke cane sound realistic at 100 ft. So high efficiency is paramount in that application. But I feel that if we really had recordings the preserved the dynamic range of a piano or drum kit or even the bite of a reed, many audiophile stereo systems would be driven into clipping.
Another think the measurements bring out is that it is important to listen in a quiet environment to preserve dynamics. The best and most expensive listening rooms I have been in are designed for 10dBA or lower background noise levels - with the HVAC running! The standard microphone on the sound meter can't go that low but (as you see in the pic) we do make a mic that can go that low...
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
"You sort of have this backwards."
Not really. His point is simply that the sound of scissors cutting paper, at some "normal" distance, say from your hands to your ears, is a very small sound, and that, as you move the microphone (or your ears) closer, it's louder. At a normal distance, it ain't anywhere near 140 dB peak.
If you want to reproduce that sound, and hear it from 8 feet away AS IF you were 2 inches away, that's a different ballgame.
BTW, regarding studio rooms... When I was in Studio D at Fantasy in Beserkeley, it was like being in heaven! Quiet, spacious, nice visual asthetics, and Alison was easy on the eyes, too. Forget recording - I could hang out in that room just to unwind or have lunch!
Anyway, regarding sound levels... Did you know that the SPL of a trumpet can be up to 200 dB at the bell of the horn?! Holy crap! Somebody told me this years and years ago. Ever since, I've wondered if most trumpet players know this, 'cause especially these days, lots of them use "clip-on" microphones on their horns. I remember recording the Buddy Rich band, and the trumpet soloist was practically eating the microphone, and it sounded like a f-ing kazoo. On the other hand, Doc Severinsen uses a Sennheiser 441, and, doesn't eat it.
I heard 150db at the bell not 200db. What was your source for that number?
I don't recall the figure but it is quite high.
This high speed video captures what they called a shock wave produced by a trumpet however a traditional shock wave is visible on the rarefied side.
The second video is a system i developed the transducers and control electronics for which here is operating in the mid 160dB's at about 21Khz and at least up to 175dB, i never saw any kind of shock wave even at those pressures (although at 175dB one could light a cigarette with acoustic friction).
I don't remember, it was a long time ago. Anyway, I play the trumpet, and it can be VERY loud at the bell. Heck, it can be very loud 15 feet away. I went to a clinic/master class given by Doc Severinsen about 3-4 years ago. He picked up a student's horn, pointed it right at me, and darn near parted my hair with a scale going up to high C.
MrBurwenīs system seems to be a Unity horn want to be!! He seems to heading in the right direction with conical horns but places 2-16" woofers behind the tweets and MR but then places the 2-24" woofers in the walls close to where you would want then Unity wise. I wonder if he could place everything sequence wise correctly with time corrected crossovers? Also the tweets spacing might lead to cancellation etc and lobbing pattens (have not math looked into it). What effect this would have within the horn I donīt know. He obviously knows his stuff and is apparently satisfied with the sound compared to his sonīs real drum playing? A hell of a system even if it seems a wretched excess.
"I am afraid your confusing two different things,"
Actually, no. Obviously, the sound level picked up by a microphone will depend on the distance from the sound source. Scissors cutting a piece of paper is a very small sound - even with its peak level - at a more or less "normal" listening distance, to the point that, if there is conversation or other sounds in the room, it's practically inaudible and definitely ignorable. Take your B&K sound level meter, put it a meter or two from scissors cutting paper, and in an average home with average activity, it'll barely show up on the meter. Certainly, nothing like 140 dB peaks! Holy moly, we'd all be deaf by now, just from cutting paper in grade school!
(BTW, I remember those humongous B&K sound level meters! They were very cool - and precision!) and had WAAY more buttons than I needed!
If you place a microphone very close to the source (scissors cutting paper), then we can hear all kinds of detail which is typically lost in a normal setting and distance, and the average-to-peak ratio becomes quite apparent, especially when one views the waveform on a screen using something like SoundForge or ProTools. Last year, just for the fun of it, I recorded a triangle (you know, like they use in the percussion section of a concert band) at various bit rates/depths. I seriously had to put the mic within about two feet just to minimize the ambient sounds.
So, if we record the sound at a very close distance (inches away), and try to play it back at a fairly loud level, where the listener is NOT at a very close or normal distance, then that's a whole different ballgame.
I think I still have the recording of putting a key into a door lock. I still remember Josie B. (violinist) coming down the hallway and saying "Hi", then, realizing that I was recording - softly saying "oh, I'm sorry". Hahahaha!
No, you do not understand.
As opposed to measured SPL, Subjective loudness is not only level dependent but also frequency dependent (as the equal loudness curves show) and relevant to this discussion also Time dependent where short sounds are not perceived as loud as the SAME ACTUAL SPL for a longer duration.
In the examples I gave, I WAS holding the meter and my ears were approximately the same distance away from the source, those levels were the instantaneous peak values and even if it had been set to "Fast", the meter would never have reached anywhere near that value.
Maybe this will be clearer. Microphones have a pressure sensitivity figure, if you measure the voltage coming out of one, one can calculate the pressure that caused that Voltage. Vu meters, SPL meters (generally) do this conversion and give a display but these have significant integration times, more like our ears.
If one examines the microphone voltage with an oscilloscope, one can capture the peak voltage any event produces and these peak pressures for many sounds are far greater than the average level over say a fraction of a second or longer.
Now, I have never measured a key in a lock or scissors but a reoccurring them with household sounds and percussive instruments was that the peak levels were often surprisingly high compared to what a normal "fast" SPL meter showed.
The best part, you don't have to take my word for it, anyone with some modest testing ability can make the same kind of tests and see for themselves what sounds are really like, what is really required and not just the part that is convenient to reproduce that at best only reminds you of a real event..
Possibly the biggest thief of subjective dynamic range (aside from the recording end) is instantaneous clipping which unlike prolonged clipping is inaudible as a flaw and only apparent when you compare with and without it. Here too an oscilloscope looking at your power amplifier output (fast triggered sweep) will show if there is clipping at any stage up to there.
That's an interesting concept, and something that Richard Heyser was interested in, which related to the paradoxes between the quantum domain and our macro world. As you come arbitrarily more precise in one domain, for instance the peak voltage measured by a test microphone, you also become less precise in the average level of an acoustic event in the time domain, at least as far as this relates to the to the "big picture" of our subjective hearing perception. So a car door slamming inside a car can be 140 dB peak, but the time averaged level of a jet aircraft taking off at several hundred feet distance can also be 140 dB.
Back in the 70's recording engineers had to get used to the then-new peak reading VU meters on some stuff, as opposed to the old school ballistics of the more averaging old school VU meters. It was well known that a violin section for instance could be pushed into the red with peaks on the VU meter, but you had to be much more conservative with a close mic'd drum kit for another instance as the peak dynamics could go right past the standard VU meter. The peak reading meters allowed for less leeway by the engineer, but this paved the way for the forthcoming CD digital age in recording where overload had to be avoided at all costs.
And, what you're telling us "new" is that you've figured that out?
Good on you!
"forthcoming CD digital age in recording where overload had to be avoided at all costs." ------ Paul Eizik
Or the terminally stupid "loudness wars" where the dynamic range is compressed to only a 1 db variation at minus 1/2 db from "all bits on.'
That's another can of worms which has been discussed here before. While audiophiles who believe in an "absolute sound" have been trying to put more dynamic range into recordings by promoting speakers with a tonal balance noted by J. Gordon Holt as having a tilt towards the bass plus a treble peak, there were others in the popular music end going the other way by cramming in more average energy into the recording. Back in the days when the distortion wars were in full swing in the 80's, transistor amps appeared with THD figures into three digits below the decimal, and they were touted as having distortion so low it was beyond the ability of human hearing to detect it. At the same time the Japanese were building SET amps which had much higher THD but some said sounded subjectively more like real music, but you really had to have horns to get the most out of them.
"...there's always a counter force": Thomas Pynchon
A quick visit to a garage band with live drums should tell you all you need to know about the reproduction of live dynamics. Since the Blue Ray format easily accommodates 130 db dynamics (but very few, except AIX) seem to use it, having speakers like Klipsch Jubilees or Danley Synergy Horns should tell you all you need to know about REPRODUCING those dynamics.
Even though they do "sound good." Those overprice little direct radiator speakers are not designed to emulate live music. But then again, they don't have to for that application.
Owning horns is like having a 200 MPH+ car with 6 gears. You may never take them out of 3rd gear on normal roads, but it's nice to have the option to open them up on a race track once in a while.
Guys with direct radiators don't have that option.
Don't attempt to talk down to me and others. Not all of us are audio morons. I'm listed as "audiophile" here mostly because I'm not currently a "manufacturer" or "industry professional", but I could get back into the biz if I wanted to. These days, I just do it for fun.
Loudness, frequency, perceived loudness, pitch? Duh. I learned that stuff in the early '70s.
As a musician (trumpet) and recording engineer, I totally "get" the whole waveform and peak thingy.
You don't need to yap at me about waveforms on an oscilloscope.
Sorry I didn't imply you were a moron I was trying to be clear.
I wasn't aware of your background (and still don't know) as it seemed like you had no idea what I was talking about and perhaps you didn't because this area of research was more like the 80's and 90's.
Like I said, the reality is there for anyone who is curious enough to look and it doesn't take much test equipment to do it and see what I am talking about.
You specifically stated:
"No, you do not understand."
On the contrary, I DO understand.
yes i did and that was in response to you saying something demonstrating you didn't understand the implications of how things work or what is actually required to reproduce common sounds.
Like i said, the sound level meter was in my hand, not close to the spoon or car door, those are the levels i heard but didn't judge to be "that loud" because a peak hold meter measures the sound pressure, we / our hearing system judges loudness.
Hate to have to post this, Tom. We can all see who's in the "ASShat chair" and it 'aint you. So don't respond to this troll.
Thanks Claude but when you say something another finds unbelievable but is sincere it's worth trying to explain a bit further.
Back in the 80's when the Servodrive subwoofer was born, imagine how hard it was to convince anyone that you could produce low and loud bass with a motor, now that was a challenge haha
Doing things "a different way" as opposed to parroting convention always requires explanation.
Data never lies, and you certainly have provided more of your share of that stuff!!
Really Who cares?! this system is abomination spliced together with Digital correction!, Yeah it will prob play very loud and IMO because its a horn system you would need to be across the street to hear it gel like normal folks systems wow
Your points are well taken in general horns donīt Gel immediately but in Danleyīs (tomservo) Unity type horns you can actually stick your head inside and will be unable to discern the mix of the different components. Mr Burwen system likely has the same effect. Remember this system has 50 years of a learning curve with a brilliant audio consultant working on it. By the way I have never met or had any business relations with Mr Burwen but do appreciate his work.
Hello Inmate 51: In reply to your edited non published versions
In regards to being a fan (boy) of Tom Danley I am guilty. Tom is an exceptional and kindly person a brilliant designer, inventor and a true acoustic scientist. I hold his designs in the highest regard. Additionally he takes the time to patiently pass his extensive knowledge to others as he tried to pass it on to you. I personally have learned a lot from him you would well to keep an open mind and do the same. Nobody knows everything we are all here to learn,share and enjoy. Best
Your comments are accurate about Tom sharing his knowledge openly on all these forums. He's the same way in person.
Plain text on the internet forums can run the gamut from industry giants to audio newbies. With and without egotistical personalities attached.
When I have to choose whose contribution is more valuable here, professionally speaking and with personal benefits attached, I'd rather trust someone who has designed and sold about 70 unique speakers and subwoofers over the last 15 years (many of which I own or have heard myself), with 63 of the in CURRENT production, rather than someone that claims to have done something in the past and nothing current except words.
As in the world of photography, Ansel Adams really knew how to "hang em on the wall"
In Toms case, he really knows how to make large spaces sound as good as high end hi fi in your living room. That is quite a feat in itself.
Tom has been a mentor to me indirectly from his patents and publishings and also from the occasional direct helpful contact. As an amateur speaker designer he helped me accomplish my goals but perhaps the most important thing I learned from him was this
Danley Mission Statement: To find favor and a good name in the sight of God and man. Proverbs 3:4 (This from the 2009 Danley Products Brochure donīt see it anymore in the present brochure)
Very impressive statement when the person behind it really lives up to it as he has throughout the years. I can be an intolerant aggressive prick but have learned to mellow and guide others as he has with objective patience and understanding. This perhaps has been my greatest accomplishment!!
And you are correct about Ansel Adams...had his Black and White book of fotos.
I seriously gotta post a pic.
Looks like a good idea. As a professional photographer, I do believe a picture is worth more than words (although most photographs don't merit the full 1,000 either).
There's an old saying "In God we trust, all others provide data." LOL.
I don't know what the problem is with that post. Try as I did, it doesn't show up correctly on my 'puter. Here is more-or-less what I intended:
"Your points are well taken in general horns don
OJK, it still doesn't show up correctly. Maybe there's a goofball character which is screwing it up.
Anyway, part of what I wrote was that I think Tom has a good horn design idea. I just don't think he knows everything or is a god of loudspeaker design, and it's irritating that he says I don't know what I'm talking about. As a musician and recording engineer (read my profile), that's a big slap in the face.
Regardless, based on the words you posted, it would seem you have a fragile ego and have a huge tendency to over react negatively and insultingly to anyone's perceived verbal shortcomings while trying to make their point more clear to everyone here.
Yes the message posting seems to be going crazy. I read Tomīs postings to you. He is a teacher by nature and was just making sure you got the meaning of what he was saying. Think of all the effort and time he took to pass that info to you. How may people would care or even try. I have never in more than 10 years of posting seen him insult or treat somebody as ignorant or inferior!
Today itīs still not widely known about the "silent unheard" instantaneous short term peak in the dynamics of sound events. It certainly was not tought in Sound Engineering when I was there. Mr Burwen was way ahead of his times trying to reproduce this in the 70s. Only in the late 80s and 90s was it really talked about a little. Like Tom pointed out our hearing is not linear but varies in sensitivity with volume, freq and time and will not "hear" those "instantaneous" dynamic peaks yet recordings will be "perceived" to be more realistic when the equipment can reproduce them. Just something to keep in mind especially in Sound Engineering. Best
"Today it's still not widely known about the "silent unheard" instantaneous short term peak in the dynamics of sound events"
That's is probably true for live or live mic feeds but with recorded music it's easy to know where they are and it's easy to see them.
In the age of digital recording and CDs, we know that the highest peaks are all contained within peak output of the CD player.
If a system has a gain structure such that amplifier clipping cannot be reached even when the CD player is outputing it's max (recorded signal at digital "0") and the volume control is turned all the way up, then we know for sure that those "instantaneous short term peaks" are being reproduced without the amplifier clipping.
Have Fun and Enjoy the Music
"Still Working the Problem"
"Your points are well taken in general horns donīt Gel immediately but in Danleyīs (tomservo) Unity type horns you can actually"
Ah, now we're getting somewhere: You're a tomservo fanboy.
"don't Gel immediately?" What does that even mean?
Read this closely: I think Tom Danley has a great horn design idea. I just don't think he knows everything or is the god of loudspeaker design.
(Edit: This is edited because it was somehow truncated when I originally posted it.)
It is not hard to pick the obsessives on this forum.
Before recovering from Audiophila Nerviosa my Home theater consisted of five Altec A5 cabs, 8-15" woofers in infinitive baffle in the attic, Tons of amps etc. The cure was the Bitch took everything in the divorce. Jajaja
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