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Which amps for new McIntosh ATMOS/DTS:x system?

Al Cons test is a test where consonants are spoken through a sound systems in a form of a word game. The listeners in the listening area write down what they thought they heard and the results are graded. If there are more than 15% error in word recognition, then the sound system fails the articulation test. Its preferable when older folks will be listening to the system that the loss should only be 10 %. Its easy to calculate and verify whether a sound system is meeting the mark. You take a spectrum analyzer and walk away from the system putting out pink noise on the 2 khz octave. Where the level stops dropping is the the Dc or where the direct sound energy equals the reflected energy. You take that distance and multiply it by 2.16 as I remember and that is the point where the 15% Articulation loss boundary is. Its it around 1.7 t0 1.8 times Dc, thats the 10% loss line. If you are designing a system there are formulas to calculate the future results and there are even programs where you enter the building design and parameters and the amount of absorption for each surface and the program will display the results in the pictured space. If you add another speaker system it will recalculate and display the results, too. The idea with using multiple channels is to keep the common signal confined to as few speakers as possible, and treat the other channels as noise generators. Oh I forgot you need a minimum of 25 db signal to noise for the 15% reading and closer to 30 db signal to noise ratio for the 10 % reading. So as you think about all this it will become apparent if the other speakers are putting out significant levels of noise, then your front speakers have to be very directional or you have to be very close to the front speakers, or in this case the center to reach the desired goal of intelligibility. . Your room needs to be very dead acoustically to give the front channels a chance to get the direct sound to the listeners position so the remaining speakers producing noise, special effects, or music don't cover up, smear, detract from, blur, or take away from the center speaker ability to perform. In Home theatre a lot of the movies audio is remixed so the voice track only comes from the center channel where in the movie house the voice track follows the actors location on the screen being produced by 3 or more speakers. Two actors on the screen will be produced by one speaker in the home while being produced by two separate speakers in the movie theatre. Therefore the home system suffers from the get go with one speaker trying to produce two voices simultaneously some times. There fore unless your listening room if very dead, using point source speakers for home theatre is a big no no. Bring on the line arrays and the Horns, just like in the movie theatres. That's why Audiophiles say you need two different systems for a Stereo and a HT system. I use line arrays for L+R and a semi spherical array for the center as we have a large C shaped listening area. The side and rear speakers are point source speakers. I have to run the center channel about 2 to 3 db higher than the front L&R to get the articulation we require. My room could be more absorbent, but that is not an option. We do have thick carpet, with thick padding and stuffed furniture. The rear surface has materials to breakup and absorb sound preventing reflections from the front speakers.
 
Go look at M&K website, there speakers were used in mastering sound tracks for Industrial light and Magic. Star Wars etc etc. There is one picture with a mixing console and set up of speakers. That system won't work in a home, but you will get an idea how difficult it is transferring the setups from mixing studio into the home to get the produced sound correct!.
 
Hey guys, your 105 db, is concert level for a full orchestra un amplified. Then you need another 10 db on top of that for peaks. Thats 115 db. I compromise with 110 db. My speakers are rated at 97 db or more at 2 watts with bi-amping 1 watt bass and 1 watt mid/hf/ at 4ft. so at 16 ft I should loose 12 db right? Wrong room acoustics mean I loose only about 7 or 8. So with 100 watts top and bottom that's 117 db one speaker. Never factor in two speakers because in HT each channel is doing some thing different. How I have 240 watts on each channel before the power guard kicks in. So that's 120 db at 4 ft+ and 113 db+ at the listening position. So guess what happens when I'm listeing to the 1812 overture recorded on telarc when the cannons fire and my average listeing level is 2 watts. All the Power guard lights come on. So unless you have speakers that have over 95 db sensitivity that can handle 600 + watts or Klipsch Kornerhorns with 100 watts, the idea of faithfully producing just regular stereophony in your home isn't possible, let alone home theatre.

Al cons is a test to discern the percentage loss of consonants produced by the sound system at 80 db of the human voice in a given space with at least 25 db signal to noise. The more omni directional the speaker is and the longer the reverb time, the room will prevent you from passing the 15% loss criteria. Today to take into account of most young folks hearing losses and older folks living longer, we try for less than 10 percent loss in the ability to recognize consonants. In large rooms if we can keep the reverb time around 1.5 seconds then most professional theatre horns speakers will past the test. In the home we try to keep the reverb time below 1/2 sec. Unfortunately muscians prefer any where from 2.2 to 4 seconds reverb time in a concert hall, But that doesn't apply to home owners. And really the only home speakers that are successful are either large line arrays with sufficient power handling or well designed horn systems.

What was true in 1958, is true today, mostly, only well designed horn system can produce life like levels. Today we have added line arrays. But point source speakers such as AR-1, 2 and 3 etc etc couldn't cut the mustard back then just like B&W and Magico can't cut the mustard now. Magico says they can reach down to 50 HZ with their new S7 at 120 db, but what happens at 25, 20, or 16 hz. Move over here comes the Mac line arrays. I think three JBL DD67000 for the front would be my preference.. And what about using B&W 801's in a recording studio. Well the listening distance is extremely short, the rooms reflections are well controlled, and the only way to achieve that at home is with very soft acoustics and short listening distances with speakers that can handle lots of power. You'll note on a lot of photos there are miniature speakers sitting on the edge of the mixing console to adapt the mix to what the engineers think an average home system represents. Is that how you want them to mix the sound for your system: with a listening distance of 4 ft and with the bass tuned for a speaker that can't produce much below 60 hz. I don't.
 
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twiiii - I don't think most people think about any of what you just posted. I know that I don't. A home theater system is either loud enough or it isn't. The science behind what you discuss is far outside of the grasp of most audio enthusiasts.

When I'm watching a movie in my living room with my family, the most common question I'm asked is, "Does it have to be so loud?" Now keep in mind that I don't set the volume anywhere near reference levels like you might at a theater - more like 10dB less. This leads me to a discussion of dynamic range, compression, how soundtracks are mixed, etc. [Watch that same movie on cable in the kids room on their TV and volume is never an issue. No matter how many times I try and explain this to my SO and the kids, they simply don't grasp it.]

Does the Al Cons test that you and c_dk speak of apply to living rooms or theater rooms in domestic residences, or does it apply to commercial theaters? I know that if I attend a movie at a commercial theater that has few members in the audience, the volume is quite excessive. It would only seem obvious that the reference levels chosen are designed to provide realistic playback levels at packed theaters. To listen at that same level in a far smaller environment, such as a living room, is just downright unnecessary.

I can remember getting all hot and heavy into home theater - back when HiFi VCR was the best source. I remember playing Terminator 2 at levels that scared most folks (sometimes even myself). Today, I simply don't listen that loud anymore as I'm concerned for my hearing.

You are correct in your summation in regards to horn systems. My XRT22s cannot come anywhere near the output levels my Altecs are capable of - that I can tell you with certainty.
 
I depends on how you chose to measure or calculate the reverberation of your space. Normally we don't worry about Articulation when the Reverb time gets below 1.5 seconds, as other factors such as signal to noise, atmospheric absorption usually work in favor of the listener in smaller rooms. But even in small spaces, commercial versions of Bose 901's can be a real disappointment as are other semi omni systems. Small room acoustic is a science unto itself. And its only been with the Development of the TEF and FFT analyzers that we are beginning to perfect design criteria that is predictable and desirable. McIntosh is one of the few manufacturers trying to develop speakers that will work in our compromised listening spaces at home. The majority want us to spend vast sums of money to improve our rooms acoustically. JBL and Klipsch using horns to focus sound to the desired listening area are trying to help us, too. Folks like B&W, KEF, Magico, etc demand that we follow their rules and spend monies to make our spaces follow their rules to approach perfection. Its our money! They should be following our lead.
 
We are using 4 CS100 McIntosh 8" three way ceiling speakers in factory 2k Auro-Atmaos 3D theater. We use 2 MC302 to power these and they work great. I think anything over 150 watts would be fine with these as the height effect channels are content frequency limited.
As far as how big or how much power should a center channel have, it should have 150% of the power used on the front left and right main speakers. This is assuming the center is crossed over at 80Hz to a sub and the center and mains have identical sensitivity from 80Hz on up. This is pretty much how movies are mixed. If you use a small center this will limit the output of the whole system.

thanks,
Ron-C
 
ron-c said:
As far as how big or how much power should a center channel have, it should have 150% of the power used on the front left and right main speakers. This is assuming the center is crossed over at 80Hz to a sub and the center and mains have identical sensitivity from 80Hz on up. This is pretty much how movies are mixed. If you use a small center this will limit the output of the whole system.

thanks,
Ron-C
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That's crazy talk for a domestic setting!
 
I was speaking about the 36 seat theater at McIntosh in Binghamton. It uses the XRT2K + XCS2K speakers across the front, all powered by 2K mono amps. 2 left and right channels speakers, XLS 340s built into the walls with two MC402 driving these. In the rear are two WS350 three way in-walls running on another MC402. Under the floor are 6 custom sub cabinets, each with twin 1000 watt 12" woofers. Six 1.2K amps drive the 6 subwoofers.
The 4 ceiling CS100s are driven by two MC302s which seem right in step with the rest of the system.

Thanks,
Ron-C
 
We could never get away with a 85 alcons test.....most all of the bid specs I bid were expecting a 90+ score.

It has been a number of years since I worked a audio showroom sales floor.....it was always interesting watching the interplay between husband and wife. In almost all cases I can remembers the wife had much more acuity in understanding and discerning the actors spoken words.....the meat so to speak of any theatrical performance. So many of the husbands had serious hearing issues, whether from shooting guns, the factory floor or other damaging events, they most always tried to compensate by cranking up the volume.

Ego was involved in most cases and it was always a challenge to find the correct center speaker to help overcome his hearing loses.

I like to use the analogy of a good steak, I believe if it comes out sizzling it tastes better but if the steak is tough, well it is a disappointing tough steak.

There is a lot of marketing effort nowadays, I believe, in enlarging, improving the sizzle but much ignoring of the fundementals of good presentation and intelligibility.
 
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Right on. Women unless suffering hearing loss can always discern sound issues better than men. Not only do their ears experience fewer traumas, but I think they listen differently. My better half played reed instruments from a child into her early adult years and when we listen to music we just listen for different things. I was a lower .brass player. She is very sensitive to how alto and bass clarinet sounds, bassoon, english horn, and Eb clarinet coloring are .reproduced. We have both stood in front of pipe organs in choirs, and have listened to many live hours of pianists tinkling the keys. But, we don't disagree on the sound of different speakers but just note the differences, All it takes is about 30 seconds of listening to throw out the bad ones. That includes Mac, magic, magnepan, Kef, B&W among many others. The only speaker we have both given positive marks to was a Snell A7 Phamtom, soom years ago.

As to the Articulation; the 15% margin is for the room that is absent of an audience. So usually we would be way below 10 %. When the space was filled with people. We had to figure them that way because in Churches you never knew if the only participant were the Priest and a few parishioners celebrating early Morning mass each day before work, or a full Cathedral for Sunday Mass. And Catholic Churches don't use padded pews or carpet with padding in our part of the world. So that meant a lot of ceiling systems to shorten D2. The other choices were highly directive Mantaray horns or in the old days very carefully laid out multi cells. I cut my teeth working with Dr. Boner. He loved to install systems above and behind the celebrants to keep the arrival times between the talker and the speakers close to equal. Then he'd use his narrow filters to get the gain and balance he wanted as the mikes were relatively close to the speakers. Other consultants wanted the speakers high and in front the steps to the dais, which I preferred. Musicians in Protestant Churches were always screwing up when they installed systems. There was nothing natural about the sound with multi speaker systems blasting the folks in front, people in the center being exposed to multiple blurred imaging and folks in the back hearing nothing but a reverberant loud blur. Toward the end we were using Renkus Heinz focused line arrays for Catholic churches with bad acoustics that wanted realism as ceiling systems were becoming incapable of producing musical performances with life like imagery. Big line arrays and clusters were persona non grata from JBL, Altec, EV etc. They dominated the architectural space and were shunned by architects and parishioners. Big speakers were out. Sounds like consumer home systems.

I'm glad I retired in 2004. I knew what worked and got tired of trying to make silk purses of sows ears of systems installed and designed by others. Every small church thought Bose was the answer. Give me a brake.
 
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scanido said:
Well, I did some testing last night and disconnected my L&R speakers from the system to see how much material was actually being output to the center. What I found was quite surprising. On some of my fav movie tracks like, Tron, The Avengers, X-men on more demanding scenes, the amount of effects coming from my HTM2D was extensive. In addition to the main duties of presenting accurate dialogue, the center channel is also required to be able to reproduce a lot of dynamic effects. I emphasize on the dynamics because what I heard

So this finding has really answered my own question in that the center channel amp, as most of you alluded to, can justify the same level of performance as the main channels. I'm strongly leaning towards adding another MC601 at this point.

Any more suggestions on the two options is most welcome.

Thanks all.
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What did you ultimately decide?
 
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