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In Reply to: Does a loudspeaker's time coherence matter ? posted by bunni on February 22, 2007 at 17:36:31:
Ever walk down the street and pass a building and hear a piano playing through a partially open window around the corner and be able to tell it's a real piano being played inside, not a typical stereo system? Frequency response is surely shot to hell, yet you know it's the real thing because the tone and coherence is preserved. A lot of people cite the Quad ESL-57 as an example of a speaker you can pick a square wave out of, which could be given as a reason why its sound reproduction is considered to be superb and nonfatiguing. No, it doesn't do dynamics like a big horn system, nor does it do deep bass or play really loud. You don't want a recording of unamplified classical or folk music to sound like it's coming out of a rock concert sound system, so why try to mimic such a system to faithfully reproduce the music? If it's live blues I expect the sound to be loud and full of energy, but I want to hear what's picked up by the microphones (and mixed, if they choose to do so), not by what comes out of a PA system.
Best regards,
Follow Ups:
"Ever walk down the street and pass a building and hear a piano playing through a partially open window around the corner and be able to tell it's a real piano being played inside, not a typical stereo system? Frequency response is surely shot to hell, yet you know it's the real thing because the tone and coherence is preserved."I would argue it's the dynamics and lack of distortion.
"You don't want a recording of unamplified classical or folk music to sound like it's coming out of a rock concert sound system, so why try to mimic such a system to faithfully reproduce the music?"
That depends on the quality of the system. Note that the best home horn systems are based on theater and recording studio speakers, quite a difference from much PA gear which sometimes compromises some sound quality to gain greater power handling and reliability. In any event rock and roll PAs when done right sound like huge high quality stereos, I worked scores of shows when I was a bouncer for Jam and I heard some first-rate sound. Though not of classical or folk music.
In any event rock and roll PAs when done right sound like huge high quality stereos...PAs done right? Every one I've heard was miserable.
that's a drag for you!i've heard plenty of bad PAs, and in fact, more bad than good-- but as a musician, i've also heard quite a few really great ones all over the US in clubs run by people worried as much about the music as they did the bar tallies at the end of the night.
i've also seen immensely amazing works of architectural art created by people who wore both steel toed boots, and drove pickup trucks. kind of like myself, being a carpenter. and a musician. and a user of utility drivers of the 'for-hire audio people.' odd.. i also grew up playing unamplified classical music..
perhaps you ought to get out more to different venues- maybe you'd find a PA or two that'd suit your ears on occasion- saying there's only bad PA's is like saying there's only bad music. as for your anti-utilitarian bias, that sounds like a personal problem.. it ain't what it is, it's what it DOES.. and who does it and how.
I simply put utility in its place for the appointed task. My lawn tractor does a fine job of mowing. Pickup trucks are great for carrying stuff. How about using an F-100 where desirable performance characteristics such as handling, steering response, braking capability, and cornering are concerned? Right. Similarly, I think it is a safe bet to say that there are a sum total of ZERO olympic runners who wear steel toed boots. For obvious reasons. On the other hand, I do wear boots as protective gear when I ride my motorcycle. The argument that anything used "professionally" is somehow better is a myopic view at best....perhaps you ought to get out more to different venues-
Since I listen primarily to acoustical music, there is rarely a need to hear a PA based system. And keep a good supply of earplugs. I gave up rock concerts long ago. And don't spend much time in bars.
To each his own.
first of all-- a race car and an f100 are naturally NOT designed for the same purpose, nor are boots and running shoes. a lowther 8" and an altec 15" aren't either. but neither are a boat and an anvil. the analogy doesn't stand- as both good home and good PA drivers ARE capable of good performance USED PROPERLY, entirely dependant on the application and the driver. either can be great or horrid depending on the design of the system they're in. period. every venue, system, and/or listening room is different.
therein lies the crux.
nobody'd ever disagree to the statement that there are bad drivers in both pro and home audio.. there's tons o' junk out there. but i've heard just as many bad 'audiophile' systems as i've heard bad PA's.. the design and operation is the problem, and if that's the argument- i WISH i had a dollar for every bad soundman! but i'd be equally rich for every time a $50k system ripped my ears off!
the only reason i bring it up, is that the myopia of thinking that only expensive 'audiophile' drivers are good enough for good sound is just as pernicious as that that says only pro-audio is good enough! no offense meant, honestly-- but to say pro-audio drivers aren't every bit as good WHEN GOOD is exactly the same bias.
anyhoo.. i'm gonna go listen now..
"good home and good PA drivers ARE capable of good performance USED PROPERLY, entirely dependant on the application and the driver. either can be great or horrid depending on the design of the system they're in. period. every venue, system, and/or listening room is different"
I agree.....but the thread is about time coherence and NO high power handling PA system is time/phase coherent. Zero. Zilch. Notta one. Not even close.
"and NO high power handling PA system is time/phase coherent. Zero. Zilch. Notta one. Not even close."Not so fast. Tom Danley makes phase coherent PA gear. Many PAs use time coherent digital crossovers that also feature time alingnment. And of course PA speaker makers have been aware of time alingment and featured it in their designs ever since the Eleanor Powell "double tap" incident at MGM in the 1930s.
Tom,
From reading their design paper reprinted in the AES Anthology, John Hilliard and his engineers reduced the interdriver time delay to just a little less than one millisecond, whereupon the double-tap of the tap dancer went away. Since 1933, the transient distortions of the entire recording and reproduction chain have been vastly reduced, so even that much time delay today is considered audible, especially when that inter-driver time delay is also constantly changing at different frequencies, via high-order crossovers in the case of speakers. While no amplifier, cable, CD player or recording machine has this problem of varying the time delay with frequency, two examples of varying time delay exist in the musical-instrument world: in the flanger effect box for guitars, and in the controls of a synthesizer. One can sweep a time delay through the frequency range, purposely changing the time-relationships between a fundamental and all of its harmonics, and between the harmonics themselves. The change in sound is plainly audible. It's called 'phasey.'
Phase/time coherent and PA systems do not go together, for true time/phase alignment can come only by using a 1st order crossover. I know of no PA speaker systems that utilize 1st oder crossovers. It would be counterproductive to do so, as PA speaker systems need to be designed for very high power handling capacities, and generally use high order filters to achive this. Can you show me a 1st order crossover PA system? Give me a link.
"Phase/time coherent and PA systems do not go together, for true time/phase alignment can come only by using a 1st order crossover."
A false premise. The use of digital crossovers allows the use of high order crossovers without the phase problems of high order analog crossovers.Ed Long and Doug Stax claimed phase coherency, or at least time alingment, with Long's Urei monitors and Stax's Mastering Lab crossovers for the Altec 604 coax, this was the setup in the Big Reds.
Tom Danley makes phase coherent PA gear and understands this issue on a level far over my head. There is some info from Tom over on the HE asylum right now about his take on this. If you want to go over there and question him, he can explain it far better than I.
Steep slope filters are what cause the majority of phase shift in loudspeakers, be it digital or analog filters.
The Dolby Lake processor has linear phase filters. Linear phase digital filters is probably what Tom is referring to with digital filters.
To utilize a horn enclosure containing all of the drivers in the same "mouth" intended to address the usual challenges of dissimilar radiation patterns and incoherency. And clever guy that he is, fashion the enclosure in a trapezoidal shape to easily accommodate multiple bins for large arrays.
a race car and an f100 are naturally NOT designed for the same purposeWho said anything about race cars? As a driving enthusiast, I would never choose to drive a pickup over a sports car to the grocery because of the mediocre handling and response. Zero fun. It's an appliance.
The primary criteria for professional sound reinforcement applications have nothing at all to due with achieving the best sound. Instead, they are based upon practicality and utility.
1. Cost
2. Ruggedness to survive roadies
3. Quantity and coverage of sound field
4. Ability to drive multiple PA binsNone of which apply to the best audio gear at all.
...thinking that only expensive 'audiophile' drivers are good enough for good sound
Well, I suspect that many PA systems I've heard would sound better if they weren't overdriven. And yes, you can potentially get "good" sound from a PA. On the other hand, the most realistic sound (using unamplified music as the reference)can only be found with the best audio gear in my experience.
YMMV
choose your poison.if you think 'audiophile' drivers aren't subject to bean counters, you're incorrect.
last i checked, roadies can't usually get at the cones inside the boxes. they'd just rather they work. so best not put your foot through it. and don't throw an audiophile speaker either. same result will occur. this i know.
quantity? we're not talking ARENA boxes in your living room. i don't mean BOXES-- nobody wants giant boxes in their living room (well.. some do..). i mean DRIVERS.
besidedly-- your assessment of what the necessities of 'pro sound' drivers are the same for ALL drivers. guaranteed- the production of all drivers are informed by bean counters-- this is economics, they are all as rugged as they need to be, very little MORE than that, and last i checked, a 12" audiophile driver has similar coverage to a 12" pro sound driver.
i think you are subscribing to an idea of which isn't informed by sonics, but solely by a false idea of the expectations on a driver. there are good drivers in both camps pro and audiophile. depending on your needs-- you choose them as necessary. there ARE great 'pro sound' drivers, which have been staples of 'audiophiles' for many years. its a completely semantic argument, honestly. because people put drivers in PA boxes does NOT make them any less well designed (especially in previous generations)-- and i don't mean a yorkville or pioneer bottom-of-the-liners- obviously there's tiers of quality. the top tiers of both are, in fact, not so very different, and in fact, overlap in uses home and high end PA's.again- its systematic. i've heard FANTASTIC drivers driven HORRIBLY by bad amps, crossovers, cabling.. the works. they sound terrible in that context. in the hands of a conscientious user, they can be equally great. it all comes down to application.
d
Having referred to them more than a dozen times in our discussion. I'm referring to sound resulting from the entire system. There is a whole lot more to what is responsible for the end product than merely the drivers. Or the absence of said in the case of my electrostats. Focus on components upstream as the primary sources of the hard, unrefined sound. Forget first octave bass in any event.i think you are subscribing to an idea of which isn't informed by sonics
My opinion is based entirely upon observation and experience.
rw--What can I say, I've heard many good ones, the people who do such things often know what they're doing, it being their living and all.Perhaps you come to it with preconceived notions, prejudices? It may be that if you've never heard a good pro system that it's your perceptions that are skewed. Just something to think about, I'm not trying to bust your balls.
What are some other professional tools?1. Steel toed boots
2. Pickup trucks
3. Checker Marathon cabsNone of those "professional" tools have the least bit to do with performance, just practicality.
I simply report what I've heard in countless examples of music, theatre, sports, and general PA venues. Which is why I don't spend much time in those places anymore. I would scream if any of my music systems sounded that bad.
No possibility that your perceptions are off base then eh? Perceptions which then lead you to the paradoxical position of preferring your hi-fi to live music. Odd.Audio is one of the few fields in which the amateurs presume to lecture the pros. It's as though a weekend warrior who repaired his lawn furniture with a buzz-box sqirtgun were to lecture boilermakers and pipefitters on welding.
Perceptions which then lead you to the paradoxical position of preferring your hi-fi to live music.I listen to primarily acoustic music where "live" does not involve kilowatts of mediocre, hard sounding Crown amps and JBL speakers. I'm accustomed to non-electronic sound. Do I prefer my system to hearing my wife playing her baby grand, an acoustical quartet, or attending a symphony? Of course, not. I overwhelmingly , however, prefer to hear pop or rock music through my system because I hear far more clarity and details that are completely absent in PA based "live" concerts. At 85-87 db peak levels at that. It is truly difficult to hear any detail in a 120 db environment where you must use earplugs to protect your hearing.
Audio is one of the few fields in which the amateurs presume to lecture the pros.
Lecture the pros? For some reason, the "pros" have failed to convince any symphony that I'm aware of to start piping the sound through a PA! Why on earth would they choose to do that? Maybe you know of one. :)
"I overwhelmingly, however, prefer to hear pop or rock music through my system because I hear far more clarity and details that are completely absent in PA based "live" concerts."Ahh, you listen to rock and roll to hear detail. I see why we disagree. To me a band doing a good live performence is always superior to recordings of the same music, even though the "sound" may be worse. I can't tell you how many times I've come home from an insprired show and didn't want to listen to the band's recordings because recordings are so lame, even the best ones.
We're never gonna see eye to eye.
Kind Regards
And varying sensitivities as to the quality of the sound. Music for me is entirely an aural experience. I hear music. Watching rock performers play or dance is secondary. Or distracting. I usually close my eyes when I listen anyway.Vive la difference!
I don't believe the original Quad electrostatic speaker (ESL-57) can reproduce a square wave. It has separate bass and treble panels. It was the later model, the ESL-63 with its delay lines and such, which could. However the original Quad is nearly universally regarded as the better sounding model.
I don't have the graphs available to include in this post but I can assure you the old Quads produce a near perfect square wave. In this respect I believe they are superior to the 63s. If I can find the technical paper where this is discussed, I will post this info here.
I've done some searching on the web and am surprised to see how little measurement data is posted for the original Quad ESL.If someone has an available unit in Los Angeles, I can measure it in our lab and post the graphs.
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