This is topic Altec 802 and power handling math session in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Steve Guttag (Member # 268) on 10-08-2001, 09:57 PM:
Hi all. One of the nice things that came out of the CP-50/CP-55 discussion between Paul and myself is that we got to hash out a few things...one of them was the good old Altec 802 and the Altec A-7 in general. As per his request, and for the benefit of the Film-Tech memebers here is some potentially useful information, use at your own risk.First off the Altec 802 was used in a great many Voice of the Theatre systems throughout the history of Cinema. It is a 1" compression driver and can normally be found mounted to the Altec 511 or 811 Sectroial horns. Most of the old-timers know it as being one that blew out a bunch and the newbies normally just see it as old.
Here are some of the facts on the 802. It came in 5 different forms and if one follows the Altec line, there are near identical drivers called 804, 806 and 902...the differences being in the magnet (ferrite or Alnico), phase plug and other evolutionary changes though the basic motor structure has been unchanged thoughout.
The 802 (and it's varients) handle a mere 15 watts AES continious pink noise when installed on the 511 horn (500Hz crossover). There was a small period (1977-1980) where the 802G series was available and that one used a different diaphragm that only handled 10-watts! (Close to Paul's recollection of 9-watts). In 1980 the 902T came out and the rating returned to 15-watts.
If this sounds like low-power handling...it is...espeically for theatre applications. As such, Altec also had, starting in 1969, the 807 and 808 series drivers (theatres using the 808, MI using the 807). The 808 is identical to the 802 except the diaphragm is Altec's Symbiotic and has an AES rating of 30-watts (double that of the 802). There was a cost of extreme high frequencies but in theatres, the screen is already killing that.
In 1988 Altec came out with it's "Pascalite" series of diaphragms and the A-7 could get the 909 series of driver...identical to the 902 but with the Pascalite diaphragm. The 909 is also rated at 30-watts AES power. The Pascalite diaphragms are an aluminum alloy so they have the aluminum sound but the power handling of the composite symbiotic diaphragms.
Since all of these drivers can take the 800/900 series diaphragms, one can substitute a preferred diaphragm in an exisiting driver to improve performance and power handling.
Currently, the standard Aluminum diaphragms (8 and 16-Ohms) as well as the Pascalite (8 and 16-Ohms) are supported with replacement parts...the aluminums are rated at 15-watts and the pascalites are rated at 30-watts AES.
So what does this mean to the A-7 owner? Well now is the math part of this discussion.
Presuming one already has the A-7, then just how big a room will it work in? If some recall a previous thread on a JBL subwoofer, I wen't through how to calculate how much power is needed to drive a cinema speaker (the formula is posted in that thread and in Dolby's document on "Technical Guidelines for Dolby Stereo Theatres". However, this is a different look at the same problem...we have the speaker and we want to know if the room and speaker combination will work.
I have rewritten the formula so we are looking for room depth
Room Depth (max) =
10 raised to:
(Sensitivitiy - SPL needed + 10Log(Power Handling))
------------------------------------------------------
20
Now this gives use the distance in meters to the back of the theatre. If we multiply by 7.38, we get the distance in feet to 2/3 of the way back in the auditorium and take into account that the HF driver is not playing the entire audio spectrum but just the portion from the crossover point (normally 500Hz) on up.
Most drivers are rated in a few different ways...above I have used the "AES" rating that is generally the most fair. It is a pink noise source over a specified bandwidth for a given length of time. For bass and subwoofer, it is the best number to use. For high-frequency drivers, it isn't a real-world situation except during tune-ups (and the occasional effect). However, we tune up at 85dB but we want to know how well the driver will do with program material that varies in level and frequency but may go as high as 103dB (measured from 20-20KHz). Most manufacturers give a "program" rating, the "Continious Program" rating is just the AES rating multiplied by 2. Thus for the 802, the power rating (program) is 30-watts. Now if you are going to do some RT-60 measurements...watch out...normally the level of the channel will get closer to 95dB to get a good reading and that is continous pink noise when the room is excited so the AES number is the one to use. To be on the conservative side the AES rating should be used since effects like in TWISTER could have sustained HF information at high levels.
One last number we need is sensitivity. The 802 mounted on an Altec 511 horn comes out to 106dB at 1-watt, 1-meter
OK lets see how we do:
First, lets see how the speaker will do running good old Dolby Stereo (type-A NR) (91dB). We plug in the numbers and we get:
A whopping 161 feet. No too bad from 15 watts. But what if the fader gets raised? Give ourselves 3-dB of margin and we are down to 114 feet.
Now lets put the speaker though the test with Dolby SR (94dB)
Well 114 feet is absolute maximum but again a 3-dB safety margin would have the figure be 80 feet. The odds that an A-7 would be in a theatre 100 feet long is quite good since in it's day most theatres were in the 100' plus range. So even with SR the speaker is being taxed.
What can be done short of changing the speaker? Try the 909 series diaphragm... we get...114 feet. This puts us over the top.
Now's the real test...Digital(103dB)
We are down to 40 feet! That is a pretty small theatre by any standards! The A-7 in the digital era is now religated to screening rooms. Does this mean that in a 60 foot long theatre the speaker will die instantly? No but it is being driven very hard and will tend to fail a bit often, depending on if your theatre sets is fader to 7 and what films you tend to run...art films arn't as taxing as whiz-bang special effects laden films.
Oh, and if you give yourself a 3-dB safety margin...you are down to about 28.5 feet! Dropping in a 909 diaphragm will get you about 57 feet without the safety margin or about 40.5 feet with the safety margin.
Your last ditch effort would be to raise the crossover point to 800Hz...that will get you about a 33% increase in power handling...so with the 909 and at 800Hz...with a 3-dB safety margin...46.68 feet.
One last point on the above...all of this presumes a "FLAT" EQ setting...no boosts on any EQ...boosts on the EQ come off the power handling! How many of you find you have to boost the high-end to push the sound through the screen? If you are like me and find that yup, even in the best environments a little treble shelving is needed to offset the screen loss...you have even less to work with.
Compare the above with the Altec 299 (1.4") with a MR94B Mantaray and you get out to 147 feet or 104 feet with a 3-dB safety margin. Check out the Lyric's photos in the galley to see the Altec 229 on an MR-94B
For those of you that have the old barn of a theatre and the dual driver 228C on a multicell....with a safety margin you are good out to 132 feet!
The Altec 299/MR94 combination, powerwise is on par with the JBL2446/2360 combination with the edge going to the JBL on power handling and, in my opinion, the sound quality going to Altec.
As a side note...the Altec Lansing badge has been retired from pro-Audio but the Voice of the theatre products are still supported via Telex and authorized repair facilities...diaphragms and bass driver recones are still available (and into the long forseeable future) with genuine Altec factory parts.
Hope this helps someone.
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Paul G. Thompson (Member # 655) on 10-08-2001, 11:01 PM:
Steve, thank you for the research on the subject. There is more to it than I ever imagined.
Posted by Barry Hans (Member # 477) on 10-09-2001, 05:54 AM:
If anyone is interested here's a link for some Altec info http://www.soundpractices.com/altec.html
Posted by Bill Purdy (Member # 202) on 10-09-2001, 11:05 AM:
Just as a sidelight, some of you might be mildly interested to know that the limitations of the Altec drivers are the reason behind the "Red Noise" capability of our SG-1 noise generator. The SG-1 was being designed when Clyde McKinney was still the technical director at THX and was establishing the original certification/recertification program. Because Altec speakers were still widely used, he was afraid of the possibility of blowing drivers with the sustained use of pink noise as Steve mentioned. So, use red noise and do the math. (For those not familiar with the term, we start with White noise. Applying a simple RC network gives us a 6dB roll off, or Red noise. This is not good for use with real time analyzers, so we concoct multi-stage rolloff networks to get a 3dB curve and this is Pink noise.)------------------
Bill Purdy
Component Engineering
Posted by Steve Guttag (Member # 268) on 12-16-2002, 01:09 AM:
Another post got me to look over this one and I noticed that I mentioned that Altec, as a badge, has been retired from the pro audio field....that is no longer the case. Altec Professional is back .
At present, they are starting it in the ceiling speaker market however they do have plans to return to the other pro-audio fields...The 299s and 515s are supposed to go back into production. No mention has been made about a re-entry into Cinema.
Altec pro is no longer part of the Telex familiy. It is now owned by the same people that have the Altec consumer line (computer speakers...etc). http://www.altecpro.com/
Posted by Michael Schaffer (Member # 1204) on 12-16-2002, 03:30 AM:
Very good article. If I may, I would also like to point you to some very good articles by John F. Allen on the subject which can be found on www.hps4000.com .
Posted by Richard Fowler (Member # 893) on 12-16-2002, 07:50 AM:
John Allen..... ![[puke]](graemlins/puke.gif)
Buy the stuff from Klipsch and save some money. I wish cinema owners would give me 2 to 4 days to tune one room....sorry you can't open this multiplex for 3 to fours weeks while I tune. ![[Wink]](wink.gif)
Posted by Christopher Seo (Member # 7) on 12-16-2002, 08:33 AM:
Steve,
Could you explain the 103 dB figure for digital? I thought it would be 105 dB (85 dB reference + 20 dB headroom).
Posted by Steve Guttag (Member # 268) on 12-16-2002, 10:47 AM:
The 103dB figure is Dolby's. If you reference Dolby's publication "Technical Guidelines for Dolby Stereo Theatres" 1994 edition (grey cover...red was an earlier version). They list 103dB for the stage speakers and 113dB for the subwoofers. Now DTS and SDDS may be able to play 2dB hotter. Perhaps there is built in headroom to ensure the digital signal never clips.
Steve
Posted by John F. Allen (Member # 218) on 12-16-2002, 04:22 PM:
Every manufacturer encounters false rumors from time to time. It seems that the most common one is when someone quietly spreads the idea that a rival company is going out of business or is in some kind of trouble. When the targeted company then continues in operation and the rumor is proven to be nothing more than an attempt to harm a competing business, everyone is damaged. The slandered company needs to spend time and resources to explain to their customers as well as their vendors that they are not in danger of going away, their customers are needlessly alarmed and, finally, those who are responsible for spreading false information are discredited.
So, aside from being irresponsible, it really does no good to write or say things when one has no direct experience, let alone proof, that the statements are true.
Like all manufacturers, I occasionally see or hear misinformation about my company. Often I blame myself for not doing a better job "educating" the industry about the things we do and how we do them. But since I have written and published more on the subject of cinema sound than anyone else I know for the past 22 years, it's hard for me to think that I haven't at least tried to communicate.
When I see a dismissive remark that pronounces that it takes me days to tune a sound system, I really can't believe my eyes. How could someone I have never had the pleasure of meeting or working with claim to know such a thing? Further more, how could I, or anyone so slow, remain in business if such a thing were true, or even remotely true? The statement is ridiculous and false on its face. Yet, as with any rumor, it damages everyone involved. If no one has any objection, I would like to set the record straight.
While I am proud to say that Klipsch did indeed build speakers for me some years ago, at the moment they are not manufacturing the speakers I use. However, they are my friends and my relationship with them remains strong.
I have been in the cinema sound business for over 22 years. My company offers unique products and advanced methods for creating the finest motion picture sound systems in the history of the industry. They are also the most reliable. Not a single driver in any HPS-4000® system has ever "blown" or been damaged by the demands of any soundtrack. I do not believe that any other sound system manufacturer or designer could make such a claim. In addition, of the 17 major "B" chain improvements introduced in these 22 years, from three-way and four-way speakers, to screen speakers with beamwidth correction for the screen, to the first feature film exhibited with digital sound, I have introduced all 17 of them. The industry as slowly copied about 10 of these enhancements so far, though often taking 10 to 15 years to do so. Some may wish to quibble, but those are the historical facts. The complete list of these firsts can be seen on my web site.
The sound systems we provide are each designed for their specific auditorium. Not only is each system carefully designed to match the space it's in, each system, wherever in the world it may be, is personally set up by me to ensure maximum performance and smooth frequency response. The setup and tuning methods used have been developed and improved over the past two decades and represent the most predictable, reliable and (most importantly) repeatable methods in use today. Typically, the "tuning" portion of the setup procedure takes about 20 minutes.
I was once involved with a demonstration of a new cinema processor. The client wished that it take place in a theatre with one of my sound systems. The setup time for that house had been the usual 20 minutes or so when the installation had been done. I arrived and did the setup for the new processor in about five or ten minutes. The settings were recorded. Then the processor company's chief studio technician gave it a try. He spent the next 2 1/2 hours "tuning" the system and, when finished, was quite satisfied with the measurements he had made as well as the work he had done. Then he, I, the senior executives of the processor company, their entire technical staff and a senior post production executive / film mixer all went into the auditorium and listened to their films with both my settings and their own. Their unanimous choice, after only one hearing, was to use my settings for the actual demonstration, settings arrived at in a mere few minutes -- not two to four days!
I have demonstrated these methods to audiences of industry professionals -- hundreds of people -- and compared them with typical practices. No one has ever contested the methods or findings. Indeed the SMPTE review of one such demonstration said "John explained and audibly demonstrated why these conventional formulae [tuning methods] may be flawed, resulting in unreliable and unnatural acoustic results. Several 2-3 minute scenes from recently released popular movies were screened, each with the system tuned to various industry-standard configurations. The final screening for each segment was tuned using John Allen's approach, yielding dramatic improvement in audible clarity, bass response and presence. In most cases, the audience heard sound elements such as birds, wind or rain which had not been discernible in the previous screenings. Audience reaction to this demonstration was enthusiastic."
John F. Allen
Posted by Richard Fowler (Member # 893) on 12-16-2002, 05:34 PM:
My apology to John for being so harsh. The note of taking days to finish a room tune is based on his answer to a question raised by a technician attending the ITEA seminar he gave in Boston a few years ago in which I was sitting next to Janine Masten, formerly of THX, Altec, EAW and now Krix. My personal preference is to tune a room at least twice before we close a job. Sorry I took it as generous if it was not clearly understood. I am a great proponent of education which should allow a Steve Guttag, Mark G and others to offer a layer to statements or to differ. I had the experience of installing one of the first Klipsch horn loaded systems in the middle 1970's and installed several more over the years when the situation called for such. The Klipsch KP-250 surround series was intially sold by our company built to our specifications. The past few years I have sold primarily JBL due to new lines such as the Screenarray series....and my association goes back with JBL when Norm Schneider ( Smart Devices ) was our JBL rep. Most manufacturers have something within their lines that should please most end users if used correctly....so truce
Posted by John F. Allen (Member # 218) on 12-16-2002, 06:51 PM:
Dear Mr. Fowler:
Apology accepted. Though we have never met, based on your contributions to this forum, I have considered you a gentleman and have often learned from what you had to say. Hence my surprise when I read your post.
I do not remember the question you referred to at the Boston ITEA seminar. However, based on what you remember, I believe that I was referring to my practice of doing the first four theatres of a 16 plex and then starting over. The reason for this is to ensure that all the theatres in the complex will have the same tone. Since every acoustic environment is different to some degree, I feel that I have obtained a good "handle" of the tone and acoustic behavior of the rooms in a complex after I have heard my reference materials three or four. In the event that this learned experience may allow me to make further refinements to the theatres I've already done, I revisit those auditoriums for another listen. When all the theatres are done, we will run film in all of them at once, if possible, and listen to all of them once again. I do not consider the job complete until all the theatres sound the way they should with the same tone, and until all the properly recorded films can play in all formats with the faders at 7.0 or 0.0 when the levels are correct in the theatres.
If allowed to work uninterrupted, a 16 plex can be done in a few days, both "A" chains and "B" chains. However, if I happen to be on the job before the complex opens, there are constant interruptions, as everyone knows, and the work typically takes twice as long or more to complete.
John F. Allen
Posted by Steve Kraus (Member # 476) on 12-16-2002, 07:37 PM:
John, how much of your technique is subjective and how much is objectively measurable? Is your system a technique that another technician can use and obtain similar results as you claim and if not, why not?
Posted by Mark Gulbrandsen (Member # 72) on 12-16-2002, 07:40 PM:
Having installed quite a few systems in past years with John as I'm sure he will acknowledge, I would have to say that I was never satisfied, or really impressed with the low end performance. It was always boomy, not the deep bass that I prefer. In fact one theatre repeatedly received written complaints from patrons as to the loud bass problem. While I hardly concur with all patrons as to loud sound, the fact goes that when someone takes the time to actually write a letter, they may have a ligitimate complaint. I assume that these letters were answered by the chain but that part was out of my hands at the time. I once EQ'd a large Klipsch system with my R-2, and all agreed that it was far better sounding than before.
Getting back to deep bass.....physically I doubt that the large horn can do much around 30 hz anyway, or even below 60 hz. The high end definition also left alot to be desired at least for me, and dialog on ocasion sounded like it was eminating from a horn. Cup your hands around your mouth and talk.....it sounded like that to some extent and seemed dependent on the film being shown.
After hearing a really good direct radiator system at Todd-AO studios and chatting with the mix down engineers, and then seeing/hearing a movie at the Hollywood Chineese #2 I was very convinced that the direct radiator/biradial horn/etc was a much better way to go. Great dialog, and all the nuances that I never heard come thourgh in the HPS system. In a nutshell, this has been my experience over the last 20 years. I have yet to be steered back to horn loaded systems. While his horn loaded systems may be a bit more efficient (although he certainly specs in as many power amps as a normal direct radiator system has) my impressions still stand as to the boominess and lack of high frequency detail. Granted these were systems that were done in the 80's...not his systemns of today. Perhaps they are better in these departments now. But I still have alot of respect for John and his systems have definately earned a place in the industry. What everyone out there needs to realize is that sound is a very subjective, personal thing for everyone. There really is no right or wrong system, or right or wrong way of reproducing sound. It all what you like!
Mark
Posted by Richard Fowler (Member # 893) on 12-16-2002, 09:21 PM:
I also give John Allen the credit in presenting a systems approach to cinema sound with the packaging of amplifier / speaker packages and propagation layouts for the surround speakers to arrive at a standard no matter how subjective some may consider. My background includes much pro sound contracting projects where matters such as this was routinely addressed versus cinemas which where not as up to speed prior to the digital sound expansion period.
Posted by Michael Schaffer (Member # 1204) on 12-16-2002, 09:51 PM:
Actually I just wanted to point to the articles on John`s website which are very good reading and some of them address the same subject that Steve wrote about, I didn`t want to set you people to fight each other again! I noticed from earlier topics that there seem to be some enmities and emotionally laden subjects.
But since it happened now, I can`t resist saying that the HPS-4000 systems that I have heard are BY FAR the best cinema sound systems I have heard yet. On this subject, my opinion weighs very heavily because I am also a professionally trained classical musician. Maybe there are better ones somewhere, but I haven`t found them yet.
Posted by John F. Allen (Member # 218) on 12-17-2002, 12:12 AM:
Well, here we go I guess. Please believe me when I say that I had not intended to add anything more to this thread -- a thread that started with a most intriguing and learned discussion of Altec drivers. However, Steve Kraus raises a question that I have tried to answer before but was stopped. At the risk of being a bit long winded, I would like to answer.
First, however, I have to say that Mark's experiences and his opinions of the installations we worked on together in the 80s, are his, and do not reflect the findings of virtually everyone else I have worked with. Nor are they consistent with the continued success of my business -- a business that has allowed me to accumulate over 1.2 million miles flying all over the place doing what I'd do for free if I could. But, I also need to say that I do agree (to a point) with some of his comments.
As Mark points out, things have evolved since the 80's. We have improved every aspect of our loudspeaker designs and their construction techniques. The smoothness of the woofers has certainly been improved. So has the way my systems are tuned. The other thing that has improved, perhaps even more than my speaker systems, are the power amplifiers that BGW builds especially for the HPS-4000® sound systems. In fact, we are now working on the next generation of amplifiers that, incredible as it is, sound even better than the Millennium 3-HPS® units that we are using today. How they keep doing it, I don't know.
As for Steve's question regarding my setup methods, the short answer is yes, anyone with good ears and some training could do what I do. Also, yes, there is a way to measure what's going on. I use a measurement technique that is far far better at "measuring" what we need to know than the steady state pink noise based methods that remain the standard in this industry. However, it is still limited in its accuracy, particularly in the mid bass region. In fact, I have yet to see a measurement method that is really usable in these frequencies. It remains as true as ever that there is no system available that can measure what something sounds like. As Don and Carolyn Davis have always insisted, it is the "analyzer between the ears that is most important."
Therefore, my methods have gone beyond mere measurements and knob turning because they have had to. My good fortune is that I have "calibrated my ears" in Boston's Symphony Hall listening to live music. The Boston Hall, as I have verified by listening to other halls all over the world, is the best I have heard. It is the hall every acoustical consultant hopes to duplicate and every orchestra loves to play in. I would add that earlier this year, I discovered the incredible Konzerthaus in Berlin that sounds as beautiful, though, being smaller, cannot sound as big as the Boston hall.
By being so totally familiar with Symphony Hall and its sound, a sound that reaches the greatest potential available in symphonic music, I can bring this knowledge and experience to my work in motion picture auditoriums. Anyone with such a background will have a distinct advantage when attempting to build sound systems to reproduce recorded music as well as movie soundtracks. It is also with this experience that I have learned that direct radiator woofers cannot reproduce music. Neither, for that matter, can horn loaded woofers, nor can any loudspeaker. However, a well designed horn -- and there are few -- comes the closest.
As many may know, I serve as the sound director for the Boston Ballet. The Boston Ballet is a live company. There is a live symphony orchestra playing in a large pit that was actually designed by the Ballet's music director Jonathan McPhee. The only reason they need a sound director is that the theatre's acoustics do not provide a way to direct sufficient sound into the main floor areas under the balcony. The theatre is huge, with some 3800 seats and a balcony that bisects the rear two-thirds of the room. I have designed and setup a nine channel method of not only directing the sound into the weak areas, but also reinforcing the acoustics of the room to create a more concert hall environment and effect -- all while maintaining the auditory perspective of the orchestra throughout the theatre. What we have then, is a sound system that coexists with a live symphony orchestra. If there is a more demanding challenge in this profession, I don't know what it could possibly be.
The pit and sound system have proven so successful that both Jonathan and I were virtually commanded to appear at a special symposium convened at MIT by the Acoustical Society of America, honoring the centennial of Wallace Sabine. We had a standing room only crowd from around the world, lots of questions and even one virtual confrontation. However, the conference chairman and others who had heard the results of our work stood behind us.
There are many reasons why the audience doesn't know that the system is on, but one of the most important is that the horn loaded woofers don't color the bass the way direct radiators do. Not only do horns have an advantage with much larger radiating areas, the benefits in the way horns couple to the room, the amount of air they move, their inherently lower distortion and the shape of the planer waves they produce cannot be found with direct radiator systems in anywhere near the same space. Furthermore, to suggest that our horn loaded woofers can't do much below 60 Hz is pure baloney.
Getting back to tuning: One of the problems we face in the absence of a competent measuring system, is the tone of speech when played through sound systems. Because the mid bass region is so critical to this tone, and since this region remains the most impossible to measure, I do listen with known reference materials. I do make adjustments as required to achieve natural tone. This must be done. Typically these adjustments are in the one or two dB range. Until I began doing this, I found that too many of my systems could sound heavy in these frequencies, and could even create the "honky" sound mentioned by Mark that movie theatre systems are still so famous for. Happily, this problem has been solved for a long time. Finding the best reference materials took years. This is one of the reasons the SMPTE review noted the dramatic improvement in clarity and presence. But the review also said that the audience could hear elements in the sound with the HPS® tuning that were not present when listening to the results of industry-standard tuning methods. This is no joke and should not be ignored.
John F. Allen
PS: Thanks Michael!
Posted by Gordon McLeod (Member # 33) on 12-17-2002, 12:17 AM:
John said"Indeed the SMPTE review of one such demonstration said "John explained and audibly demonstrated why these conventional formulae [tuning methods] may be flawed, resulting in unreliable and unnatural acoustic results. Several 2-3 minute scenes from recently released popular movies were screened, each with the system tuned to various industry-standard configurations. The final screening for each segment was tuned using John Allen's approach, yielding dramatic improvement in audible clarity, bass response and presence. In most cases, the audience heard sound elements such as birds, wind or rain which had not been discernible in the previous screenings. Audience reaction to this demonstration was enthusiastic."
If memory serves me correct that was a section review not a statment endorsed by any enginering comitee or the board of governors of SMPTE
The SMPTE standard still recomends a minimum of 4 mics placed in the reverberant field of the room in question not in the near field. This is still the standard endorsed by almost every equipment manufacturer and studio recording factility
Posted by Michael Schaffer (Member # 1204) on 12-17-2002, 03:19 AM:
You are right Gordon, and that practice should also be generally adhered to since very few people even have the ability to fine-tune a sound system by ear. It takes a very, very long time and a lot of practice to learn to hear analytically and the vast majority of people simply can not hear well enough. However, if somebody has cultivated that ability then coupled with a technical understanding of a given system it can be a very satisfying method.
Posted by Mark Gulbrandsen (Member # 72) on 12-17-2002, 08:37 AM:
John,
Air miles hardly translate into how someone feels about how anything sounds, or how well a buisness is doing or not, but if ya want to know about air miles just ask any THX Technician, and many independent techs like Gord, or Richard. I think they blew right past you on the last flight. I'm fortunate enough to have left the airlines behind after traveling on them for many years so directors could watch their film at their location. I now drive around the mountain states servicing theatres and enjoying the incredible scenery and the wonderful people that live around here.
As far as your customers liking your systems that is good. They bought them because they like them and the sound. But I will bring up a major point here again in that what if something happened to John, or his hearing. Who would tune his systems?
Kindest regards,
Mark
Posted by Michael Schaffer (Member # 1204) on 12-17-2002, 10:49 AM:
People who have the advanced hearing ability I described above. For instance, a really good recording engineer or a well-trained musician. It may be difficult to imagine, but it is actually possible to learn to hear so precisely that sound has a very defined "shape" and characteristics which are evident to the trained ear. But as I said, it takes a very long time and a lot of practice to obtain that ability. But this kind of fine-tuning is something good musicians do every day when they play. It is one of the reasons why specific symphony orchestras have a particularly good sound.
Posted by Mark Gulbrandsen (Member # 72) on 12-17-2002, 02:38 PM:
Michael, You hit the nail on the head and have only reinforced what I said. After talking to three Academy Award winning lead mixers at Todd-AO who have VERY golden ears, plus what I hear with my own ears thats why I went the route of direct radiators. That is what the films are mixed with these days and its the only way to hear what the Director intended. These and all other "Golden Eared" mixers are using Direct radiator systems of one sort or another. There was and may still be a stage at Goldwyn that was set up with Klipsch stuff but not sure if that is still there or not. John could confirm this one way or the other though.
Mark
Posted by Scott Norwood (Member # 30) on 12-17-2002, 03:05 PM:
On the topic of the subjective nature of sound quality: does anyone know what equipment was in place at the Cinerama Dome in LA as of January, 2000 (pre-renovation)? This was by far the best sounding (to my ears) movie theatre I have ever heard, which is especially impressive considering the odd shape of the auditorium (I was sitting dead center in the front section). Picture quality there was sorely lacking, but the sound blew me away. Oddly, the THX-certified Chinese theatre nearby (also pre-renovation) had one of the worst-sounding systems I've heard.
The Uptown in DC is probably my second-favorite theatre for sound quality, but it's not quite in the same league as the Cinerama Dome.
Posted by Mark Gulbrandsen (Member # 72) on 12-17-2002, 06:48 PM:
Don't know what was in there but years ago I saw Rodger Rannit there and it was amazing to say the least. The original Chineese never had good sound, thats one of the reasons they had the chineese 2 and 3 next door. They were excellent. For those thata re not aware the reason that it sounds as good as it does out there is cause the mix engineers actually go into the theatre and fine tune the EQ themselves before the opening of a major film. They try to get it as close to how it sounded in the mix down stage. Indeed this is a good tribute to how JA does his EQ'ing but he always hated them tampering with his settings for his systems.......
Mark
Posted by Paul G. Thompson (Member # 655) on 12-17-2002, 08:01 PM:
Michael, I, too have nothing but great comments about the HPS-4000 system. I ran a theatre that had two of John's systems, one in the SR"D" format and the other in DTS. They were are awesome! They were smoooooooth sounding, powerful (very, I might add) with absolutely no "Booming" on the low end. I'll never forget the launch scene in the movie "Apollo 13" - It felt like shook the floors, seats, you name it! I was so proud of the beautiful tuning job John did on that system, everytime for every movie on the nights I worked, the crew of the theatre knew where I was - in the auditorium "proofing" the sound of that particular sequence. I was proud that I was the one who installed it, and John was the one who tuned it.
When Kevin Bacon said in the movie "Now that was a jolt" on separation of the booster, his voice was clear and distinct, at a perfect mix. Great job by the sound track mixing engineers, the cast, and of course, John Allen!
At some commercial screenings, (including Sho-West last year) the sound was good. Nice and loud, but it had an "edge" and some minor "booming" in it and was hard for me to listen to. John's system had no edge or booming on any part of the audio spectrum in the two HPS houses he tuned for me.
In short, I am very impressed with the HPS-4000 system. If I owned a theatre that was capable of running the SRD, SRA, or DTS formats, I would have nothing but HPS-4000 systems.
There was one more screening room I have been in that the sound was superior. It was, by far, the very best I have heard among the non-HPS-4000 houses. Although it was not a HPS 4000 system, I would rank it in the same ballpark as the HPS-4000 system. It was perfectly tuned. ![[Smile]](smile.gif)
End of enthusiastic Rave...
Posted by Steve Guttag (Member # 268) on 12-17-2002, 08:51 PM:
Might I ask what any of this HPS or John Allen versus whatever or whomever else has to do with Altec Lansing the 802 driver or its power handling?
A new thread or a beaten to death old thread (on the very same HPS or John Allen's methods) could have been revived.
Now everyone...get out of the pool!
Steve
Posted by Paul G. Thompson (Member # 655) on 12-17-2002, 09:01 PM:
Good question, Steve. I was wondering that, too. ![[Big Grin]](biggrin.gif)
But in all honesty, John showed me the RTA readout, and invited me to look at the EQ pots in the CP-55. I could not believe what I saw.
When we built that theatre, John asked us for the auditorium specs, which we provided. He jammed all of this into his computer, and it spit out where to place the surround speakers and stage speakers, (at precise locations and angles down to the inch and degree, practically) and where to put BAT material in the auditoruim and where NOT to put it. Also, John indicated a few "tricks" we could use to build the speaker platforms to prevent them from becoming "resonant" to audio frequencies. We followed John's suggestions to the letter. It worked! Jeeze, those systems were nice....
I don't know, but is there a possibility that the booming Mark and others mentioned were due to fixed parameters of the auditorium that could not be changed? We did ours from new construction, and not an upgrade.
I recall absolutely NO complaints from our customers whatsoever about the sound quality in those two houses unless we had an equipment failure. However, we had sound complaints from time to time in the other four houses and many of those complaints were justified according to my ears. The majority of the complaints were the levels were too high, or too low, or the mix was just "not quite right..It does not sound near as good as the bigger houses."
Posted by Michael Schaffer (Member # 1204) on 12-17-2002, 10:09 PM:
Mark, what kind of systems are these (I mean what components, which manufacturers)?
Steve, sorry, it is my fault, but I had just pointed to some articles on John`s website where further reading about the actual topic can be found.
Posted by Mark Gulbrandsen (Member # 72) on 12-17-2002, 11:25 PM:
Back then they were mainly JBL. or EV components. That was back in the mid 80's at Todd-AO.I had a friend that worked at Todd-AO as a lead mixer, so I had a sort of an in there. Saul Zaentz's big mix theatre where they did Amadeus was using A-4's with the latest Altec drivers in them. Sorry Steve G. but they didn't begin to compare to the sound at Todd-AO. The Altecs had difficulty doing some of the stuff at higher levels. Dolby Labs took us to Zaentz in 84. Todd-AO used a variety of different systems but were not unlike the larger systems found in better theatres of the time. At the Lucasfilm Stag Theatre they had(may still have)JBL bass cabinets with E-V horns using JBL hf drivers. They claimed that made for the best dialog reproduction that could be had. Since I have seen/heard a couple of films there I will definately agree with them. Later on I did a number of similar systems back in the Midwest also with excellent results.
In the last couple of years direct radiator systems have both gotten much better and far worse since those days. The cheapo direct radiators of both JBL, and EV are pretty bad(raw response). However the good old 2 way(4675 JBL), and the better 3 way JBL systems such as the 5672 and 5674 are amazing to say the least and I have been lucky enough to have used both of these amazing systems in new installations. Raw R-2 response readings on these systems generally only require some simple cut only eq'ing in several bands as long as room acoustics are applied properly. Similar to Johns systems.
Attached is a photo of one of the three way systems.......
Mark
Posted by Steve Guttag (Member # 268) on 12-18-2002, 07:49 AM:
I have yet to hear a theatre that could not be outdone by what I have heard out of an Altec A-4...including the STAG. The STAG no longer has the JBL/EV system you spoke of Mark G (they don't have Altecs either).
I'll put an Altec A-4/MR94 up against any large system or an Altec A-5/MR94 up against any smaller system any day. And as to medium horns...the MRII594 is unbeatable in my book.
I do desire to hear the JBL 5000 series stuff...on the surface, it looks very well designed and has the makings of a great system based on the choice of components and construction. One curiousity is in the HF section...there appears to be a notch in the HF response (based on the specs) right above 10KHz. The JBL4675 is the best sounding JBL speaker I have personally heard
I still prefer the sound of Altec and hence why I started this thread over a year ago...to show what the little drivers can and can not do in this digital age.
Steve
Posted by Mark Gulbrandsen (Member # 72) on 12-18-2002, 09:16 AM:
Steve,
I was not making any criticism of the Altecs sound. I too like the sound of Altec A-4's...no problem there, especially on a deep stage. However they had problems with them at The Zaentz soundstage. They could not take the levels these guys like to mix at...woofers bottoming out, etc. I remember Mark Berger saying that they wanted a real world system in there to do mixes hence the A-4's. He also said they would probably be replacing them as for the problems they were experiencing. As for the reel(s) of mag of Amadeus I heard there, it was amazing!
Unfortunately not many A-4 systems out here. Lots of older A-5's and A-7's in the older theatres out here.
Yes, do a system or two with the JBL 5600 series stuff when you get the chance. Its alot of work just assembling them and the midrange horn is larger than some proples house, but it is all very worth the effort. Also, I did not use the JBL digital EQ, went with the analog version instead. You know I hate anything Digital in the chain. I don't remember a dip in the hf on them, if it was there it wasn't much after setting the levels on the x-over. I'll go back and look at the R-2 files and see if there was much of a dip though and report back.
Whats in the Stag now? Did they go to the three way stuff? It sounded REALLY good in there with the two way, and absolutely no background noise at all on mag playback!
Mark
Posted by Steve Guttag (Member # 268) on 12-18-2002, 10:55 PM:
As to the A-4s bottoming out...if they were indeed updated (as stated earlier)...bottoming out wouldn't really be too possible in a mixing stage...a 4675 couldn't put out more volume...particularly with the Altec having 515-16GHP woofers...they are 200-watt AES drivers each or 400-watts for the cabinet, which translates to 1600-watts peak program. Whereas the A-4 as an 8dB advantage in sensitivity over the 4675 (and most other direct radiators)...they most certainly could take the levels of today and then.
JBL has canned their analog crossover BTW (I'm pretty sure they nixed them this year). It is of no consequence though...I've always been a fan of RANE products and the AC22B and 23B were/are superior to the JBL 552 or 553. RANE also has their DSP stuff with the RPM 26 series. The new one, the RPM-26Z has drag and drop programming. I just did a set of JBL 4632Ts with the Rane RPM-26V and the performance with that unit was dramatically superior than a typical crossover. The Rane unit has parametric EQs available for each speaker section to make 1/3 octave EQ wholey unecessary with virtually no EQ at all. The channel to channel timbre was startlingly close with the RANE crossover...anyway this is probably also best discussed on another thread.
Steve
Posted by Steve Guttag (Member # 268) on 12-19-2002, 07:57 AM:
I just did a quick check and the M series crossovers, the M552 and M553 are indeed, no more. Not to be left out, the upper-end digital crossover, the DSC-280 is also not listed. Have no fear though, the DSC-260A is still alive for your digital 3-way processing needs!
Steve
Posted by Mark Gulbrandsen (Member # 72) on 12-19-2002, 09:28 PM:
Steve, Thanks for the tip!! I've been way too busy to even look at the new(if any) JBL price lists since starting at CLACO. Rane stuff is ok, and I'd have no problem using that, there are also others that are worth looking into. I prefer to keep as few A to D / D to A conversions as is possible in any chain. There's already enough of that going on before the signal would even reach the X-over.
Mark
Posted by Steve Guttag (Member # 268) on 12-20-2002, 09:08 AM:
Mark,
I agree with you on that...use as little DSP as possible (none unless necessary) and minimize A/D conversions. I used the RANE RPM-26 on what I would call a difficult speaker. With only paying one DSP "hit" I eliminated a whole buncha 1/3rd octave time-shifts and noise hits. The other alternative I looked into was stacking a 5-band parametric on top of an analog crossover but then you pay in the noise department and have less flexibility. If you have a cinema processor that has digital outputs (like the CP-650 with the studio board in place) then you don't pay the A/D or D/A "hit." Even the newer THX crossover the THX-D1138 can take AES3 inputs.
Again, in this particular situation, the DSP unit did what I wanted and was pretty painless. I'll give RANE credit though...they have figured out how to get the user to set up their DSP stuff so you have maximum dynamic range and not have you clip the DSP section.
Steve