The reason was, the "armchair" approach described by Wavebourn was not common yet, and they did not realize yet it's value, so they used approach of small rock clubs scaled for huge audiences.
there is this local audiophile who has a "wall of sound" system....32 speakers in total.....12 ML2's, 4 crown studio reference amps driving subwoofers... all in a room 10m W x 20m L x 4m high.....listening to it was an experience like no other....mind you, sound level was not ear splitting either....
It can be done with "normal" speakers too. Just went to the Sydney HiFi show, first proper one in, ooohhh, 20 years I'd say ... and things are improving. Nevertheless, the only setup that felt like it was capable of handling turning up the wick significantly did respond extremely well, demonstrating progress has been made. This was using Bryston 1000W into 8R monoblocks, on Dynaudio Confidence C4 speakers - a classic 89dB sensitivity, 4R 400W power handling, multiple good quality drivers. This easily out-PA'd conventional PA setups, a drumkit solo was as tight and visceral as the real thing, it had the true sharp bite and punch of the various pieces of the kit, at real volume levels: normally PAs just go all soggy and flabby when asked to do this sort of thing.
Along these lines, an ambitious JBL unit with horn drivers at the show just didn't cut it, much better sensitivity but the amp, an Accuphase didn't have the grunt, just another PA sound ...
Frank
Slightly OT:
"You think money is vulgar because you have a lot of it" - Howard Hughes, "The Aviator"
jan
Yes. But, if the reasons where good, solution where not, on my point of view.
I can understand the reasons (all witch follows are just a personal point of view and has to be taken as it):
PA horns and enclosures where so bad at this time. Wood of enclosures vibrating hardly, and very very bad horns, poorly designed and realized. The result was this PA sound, full of peaks and resonances, impossible to equalize gently with a 1/3 oct analyzer and equalizer.
At least, there had some quality: They had a directivity you can use to project the sound where you want, a big efficiency, allowing-you to decrease emission surface.
Not to forget they had a great efficiency, and you can reach hight transients with drums kits and clear sharp sound.
And there were able to project sound at a long distance.
The next 20 years, and a talented acoustic engineer, friend of mine, had taught-me it was possible to get rid of most of those horn distortions, resonances, and non linearity.*
Well big halls and giant concerts are not good places to listen to music, and i prefer little theaters with good acoustic)
It is unrealistic to hope some phase stereo when the right and left enclosures are far from each with no more phase coherency between them. Big hall PA systems cannot be set as home system, as Mr.Wavebourn noticed.
The solution of GD was brilliant and innovative, regarding this aspect, and no mix between instruments means no inter-modulation. The mistake was they do not took surfaces and phases in consideration, witch were terrific regarding waves length. and the all system generate incredible directivity lobes, because each individual enclosure was not enough directionnal.
Placing the wall of sound behind the musicians where not a so good idea too for the miking. This out of phase idea introduces a lot of inconvenience. each little change of distance of the singer from the mike introduced terrific response curve changes, and the all thing was too near from the Larsen point. Too, singing too close to an electrostatic cap does not produce a good sound. More than that, it seemed the humidity of the breath produced bad effects with the electrostatic caps and the sound deteriorate rapidly.
The result was, despite all the good you seem to think of yourself and everything you are part of, that i remember this concert 40 years later.
As one of most uncomfortable of my life.
I had spend all the time of the 1974 show; in this "Palais des sports", moving my head back and front, left and right, to try to find an exact position where i could hear all the instruments together. I was there with 5 of my friends musicians, we where all furious and desapointed at the end of the show.
Now, you thought that i would be full of admiration to hear you where part of this famous system ? I just think about it is was a disaster and awful mess of money. Sorry.
That is unfair. I tried to provide #technical explanations# (What you call "armchair criticism ?).
You are tired to discuss each time we approach a technical debate or disagree with one of your definitive 'opinions' ?
Are-you here only to promote yourself, fishing for compliments ?
I assure-you of all my admiration and i can put you just between God and Einstein in my personal hall of fame if it can provide-you some added auto satisfaction.
("Just for one day").
Have a good life, Mr Curl.
* Note: An other guy, here in this forum had produced very interesting studies about horns with the same scientific approach and results than my friend: [COLOR=#0000FF ]http://www.diyaudio.com/forums/multi-way/140190-jean-michel-lecleach-horns-new-post.html[/COLOR]
if you have a bit of curiosity left and a desire to improve your knowledge about horns, I advise you to read-it.
This guy has a real scientific approach, and he is as modest as brilliant and open minded.
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Wow, now I know how you really feel! '-) Well, some liked it, especially in outside venues. As I said, I was not allowed by the guard to go into the audience to hear it in Paris, so I cannot verify what you heard.
But perhaps you were listening for the wrong thing. It was a MONO system for voice. Did you know that? Most of the structure was for the bass array and the musical instruments.
You seem to not know much about 'horn throat distortion'. Check it out. Personally, after the 'Wall of Sound' I spent 1 and 1/2 years doing audio research with John Meyer, later the founder of Meyersound. Then I spent 6 mo designing a monitor loudspeaker for a Paris recording studio using an Emilar horn and a quality woofer. I time aligned my loudspeaker, how about you?
Thanks for bringing up the subject of horn throat distortion. I will consult a few handy textbooks and get back to the subject.
But perhaps you were listening for the wrong thing. It was a MONO system for voice. Did you know that? Most of the structure was for the bass array and the musical instruments.
You seem to not know much about 'horn throat distortion'. Check it out. Personally, after the 'Wall of Sound' I spent 1 and 1/2 years doing audio research with John Meyer, later the founder of Meyersound. Then I spent 6 mo designing a monitor loudspeaker for a Paris recording studio using an Emilar horn and a quality woofer. I time aligned my loudspeaker, how about you?
Thanks for bringing up the subject of horn throat distortion. I will consult a few handy textbooks and get back to the subject.
Horn throat distortion is caused because air does not quite follow the ideal gas laws, the gamma coefficient means you could easily have 3% distortion at normal listening levels due to the pressure changes at the throat corresponding to 140 db quite easily. I dont currently have the text book at hand or the time to put down some typical horn dimensions and sound levels for each point as I am about to have breakfast.
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.. Witch is less than what produce any speaker cone at the same level, i believe....
About time alignment, it is a minimum requirement for a hifi home enclosure, of course. Not enough, on my point of view.
We can use use digital filters to linearize further both response curve (and reduce some room resonances) and group delay of the whole assembly. You can achieve this for the response curve (those curves are from the Moonlight project, i get similar results with my own system.):
http://www.moonaudio.fr/Photos%20taille%20affichage/Amplitude%20fr%E9quence%20@2m.jpg
and this for the group delay:
http://www.moonaudio.fr/Photos taille affichage/group delay.jpg
with as a result, on a 1KHz square wave:
http://www.moonaudio.fr/Photos%20taille%20affichage/Signal%20carr%E9%20miniMaX%201kHz.jpg
We can use use digital filters to linearize further both response curve (and reduce some room resonances) and group delay of the whole assembly. You can achieve this for the response curve (those curves are from the Moonlight project, i get similar results with my own system.):
http://www.moonaudio.fr/Photos%20taille%20affichage/Amplitude%20fr%E9quence%20@2m.jpg
and this for the group delay:
http://www.moonaudio.fr/Photos taille affichage/group delay.jpg
with as a result, on a 1KHz square wave:
http://www.moonaudio.fr/Photos%20taille%20affichage/Signal%20carr%E9%20miniMaX%201kHz.jpg
Each time i made distortions measurements, it is on an assembled system, one meter away. I don't know how to measure a distortion somewhere inside a driver motor. Yes distortion of the loudspeakers gives very bad numbers, whatever the technology, and i wonder how we can enjoy such numbers, while 0.1% in an amp can be so disagreeable....-)
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We used a lot of speaker cones in parallel to reduce the distortion to below 3-10% in the midrange that the horns produced. Horns and 10KW? I have some idea of the performance, as I spent the summer of '72 hanging around Kelsey and Morris in London, PA people for Pink Floyd at that time. They used horn bass bins and horn midranges, etc, driven by Phase Linear 700's. Not bad, but the GD wanted something 'better', and I found the weak spot in their system in the 1'' horn throated JBL horns that worked 1KHz and above. This is what needed 'fixing' and so we went to large arrays of direct radiators, and many paralleled horn tweeters (Electrovoice T35) above 4KHz.
Effectively, we removed the horn throat distortion in the critical 1K-4KHz region by using a very large array of JBL 5'' direct radiators, to replace the horns normally used by most PA companies. Worked pretty well too. That 'glare' from excessive energy in the 4-8KHz region was gone. The big trade-off was amplifier power needed for the midrange array. We NEEDED thousands of Watts, and so we had those Mac amps. We used tube Mac 3500 amps for the horn tweeters. Even the roadies could tell the difference between the transistor and tube Macs on the tweeters.
Effectively, we removed the horn throat distortion in the critical 1K-4KHz region by using a very large array of JBL 5'' direct radiators, to replace the horns normally used by most PA companies. Worked pretty well too. That 'glare' from excessive energy in the 4-8KHz region was gone. The big trade-off was amplifier power needed for the midrange array. We NEEDED thousands of Watts, and so we had those Mac amps. We used tube Mac 3500 amps for the horn tweeters. Even the roadies could tell the difference between the transistor and tube Macs on the tweeters.
So, at the end, we are on the same wavelengths, John ?
Talking about distortion, of an electo-acoustic device is depressive. Cones or drivers give, at the end, and at the comfortable level we like, similar order distortions ( from my experiences and various measurements, i'm unable to make a decision on that criteria) ).
Cones or drivers present different issues. We Chose our poison. But talking about PA system with hight fidelity in mind is just a joke.. Agree ?
Let-us return to home systems.
Some will prefer to listen to classical "musique de chambre", and will be pleased with a sytem, low level, with very sweet trebles, and focus to detailed room reverberations. They don't care with impact. They will love Quad speakers,as an example.
I was a sound engineer, in contact daily with real instruments, mainly in the "Rock end Roll/ Jazz area. I was looking for a home (or studio) system able to reproduce at real level drums and basses, flat enough for i can judge the tonal balance of my mixs. Analitic enough for i can evaluate my work on reverberations and delays, with enough separation between instruments for i can follow each one with not too much effort to isolate-them in my brain.
I was very uncomfortable with most of the studio monitors, and, believe-me, bored with the harsh sound of compression drivers. Those awfull Tannoy, JBL, Urei...
If i had chosen my actual system, it is because it was the best compromise i found, after, may-be 20 different home enclosures.(from Quad to Elipson, Cabasse etc...) and a lot of mods on them.
My actual system will be the last one. Very dynamic, horns and drums are so real, killing, cymbals are like in the life, you can hear all the dimension and metal, with a clear impact of the stick on it. Not those pshhh pshh pshhh produced by dome tweeters.
Same with the piano. You believe a Steinway or a Bechstein is in your room. And you can immediately identify-them.
Presence of the voices are even too much. (apart Aretha and very few others, i do not care too much about singers).
You can hear the slightest breath and bubbles of saliva...Attacks on the guitar chords are impressive... each instrument is in the space, with space between them.
They don't go flat higher than 16Khz, they are not sweet, you cannot listen to music during hours.
They are two ways, because less crossover, better it is, and it was very difficult to achieve, at the limit of the speakers capability, a coherency. They use a horn for the 1500- 20000 range, but, believe-me you will never notice a Donald Duck "compression" sound in any manner.
You don't believe-me ? Here a revue of the big system (it is in French, use Google translation), build with the same concepts, driver and horn calculations, my enclosures sound very very close:
http://www.esperado.fr/temp/critique.html
Thanks to my very talented friend Francois Delamare for his exceptional talent, innovative ideas and help.
Talking about distortion, of an electo-acoustic device is depressive. Cones or drivers give, at the end, and at the comfortable level we like, similar order distortions ( from my experiences and various measurements, i'm unable to make a decision on that criteria) ).
Cones or drivers present different issues. We Chose our poison. But talking about PA system with hight fidelity in mind is just a joke.. Agree ?
Let-us return to home systems.
Some will prefer to listen to classical "musique de chambre", and will be pleased with a sytem, low level, with very sweet trebles, and focus to detailed room reverberations. They don't care with impact. They will love Quad speakers,as an example.
I was a sound engineer, in contact daily with real instruments, mainly in the "Rock end Roll/ Jazz area. I was looking for a home (or studio) system able to reproduce at real level drums and basses, flat enough for i can judge the tonal balance of my mixs. Analitic enough for i can evaluate my work on reverberations and delays, with enough separation between instruments for i can follow each one with not too much effort to isolate-them in my brain.
I was very uncomfortable with most of the studio monitors, and, believe-me, bored with the harsh sound of compression drivers. Those awfull Tannoy, JBL, Urei...
If i had chosen my actual system, it is because it was the best compromise i found, after, may-be 20 different home enclosures.(from Quad to Elipson, Cabasse etc...) and a lot of mods on them.
My actual system will be the last one. Very dynamic, horns and drums are so real, killing, cymbals are like in the life, you can hear all the dimension and metal, with a clear impact of the stick on it. Not those pshhh pshh pshhh produced by dome tweeters.
Same with the piano. You believe a Steinway or a Bechstein is in your room. And you can immediately identify-them.
Presence of the voices are even too much. (apart Aretha and very few others, i do not care too much about singers).
You can hear the slightest breath and bubbles of saliva...Attacks on the guitar chords are impressive... each instrument is in the space, with space between them.
They don't go flat higher than 16Khz, they are not sweet, you cannot listen to music during hours.
They are two ways, because less crossover, better it is, and it was very difficult to achieve, at the limit of the speakers capability, a coherency. They use a horn for the 1500- 20000 range, but, believe-me you will never notice a Donald Duck "compression" sound in any manner.
You don't believe-me ? Here a revue of the big system (it is in French, use Google translation), build with the same concepts, driver and horn calculations, my enclosures sound very very close:
http://www.esperado.fr/temp/critique.html
Thanks to my very talented friend Francois Delamare for his exceptional talent, innovative ideas and help.
... The enclosures of this article were from "Maison du haut parleur." in Paris. They are still available under this reference. But do not try to listen to them or buy them any more. After François leaved the company, they have changed the bass speaker, and destroyed the sophisticated huge passive symmetrical filter with impedance compensation...
I built the same sort of design for Gunther Loof for the Paris studio, in 1975. The biggest difference is that I used an Emilar horn with a 1'' throat, and a super-tweeter.
John Meyer and I built the JM/C 3 horn (time aligned with a transient perfect xover) combination, at IHEM in 1974-1975. It was even better, but designed for MUCH higher output levels.
John Meyer and I built the JM/C 3 horn (time aligned with a transient perfect xover) combination, at IHEM in 1974-1975. It was even better, but designed for MUCH higher output levels.
While 'time aligned' horn systems are ideal for home listening, they are almost impossible to build successfully. Either, the 'time alignment' and you get something like a K-horn, or you get a 'successful' 2 way horn-direct radiator combination with a complex crossover.
Transient 'perfect' or simple 6dB/octave crossovers create BIG problems with frequency cancellations due to imperfect acoustic summing of the horn to the direct radiator. I found that 3-pole Bessel filters in the crossover worked best.
Of course, horn throat distortion is relatively small with a home system, BUT when the same horns are used in PA systems, it dominates the distortion spectrum, normally.
Transient 'perfect' or simple 6dB/octave crossovers create BIG problems with frequency cancellations due to imperfect acoustic summing of the horn to the direct radiator. I found that 3-pole Bessel filters in the crossover worked best.
Of course, horn throat distortion is relatively small with a home system, BUT when the same horns are used in PA systems, it dominates the distortion spectrum, normally.
I have tried an English translation of the revue here:
http://www.esperado.fr/temp/critique-en.html
(They don't talked about 3% distortion ;-)
Ps: the JBL 2426 J driver is an 1" 16 ohm, for the 6 ohm enclosure.
We had tried near all available driver at this time, before to chose this one.
Other 1" drivers where not good enough or able at low frequency (we do not wanted the bass driver to fractionate), and all the 2" unable to go high enough.
The quality's coherency of those drivers was problematic. Francois was obliged to go to Harman with his Bruel &kjaer equipment to measure and sort the drivers he wanted to order.
More than half of the membranes were rejected.
http://www.esperado.fr/temp/critique-en.html
(They don't talked about 3% distortion ;-)
Ps: the JBL 2426 J driver is an 1" 16 ohm, for the 6 ohm enclosure.
We had tried near all available driver at this time, before to chose this one.
Other 1" drivers where not good enough or able at low frequency (we do not wanted the bass driver to fractionate), and all the 2" unable to go high enough.
The quality's coherency of those drivers was problematic. Francois was obliged to go to Harman with his Bruel &kjaer equipment to measure and sort the drivers he wanted to order.
More than half of the membranes were rejected.
Esperado, it appears that you do not take horn throat distortion seriously, or have never read any engineering textbook that describes it properly. I personally measured 3% distortion with a similar JBL driver and an LE-85 horn connected, 40 years ago, at a sound check for the GD, with 2W input to the horn, with an oscillator and a wave analyzer. Referencing my measurements to Harry Olsen's 'Acoustical Engineering' and Beranek's 'Acoustics' at the time, I found a good correlation with their graphs of horn throat distortion.
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