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The distortion I am most concerened about is clipping. Increasing the gain of a receiver to where the music sounds distorted can put out MUCH more wattage than its power rating for clean/undistorted output (reference the area under the curve). Often people believe that when they hear distortion, it's caused by their speakers not being able to handle the power. But often it is the amplifier clipping" that's causing the distortion. Playing the receiver to the point of clipping will damage a speaker, even those speakers with a power rating greater than the receivers peak undistorted output. The waveforms of clipping distortion cause speaker voice coils to rapidly heat and quickly result in damage. For this reason, it's often safer to over power a speaker rather than under power it. When a speaker is getting too much undistorted power you can usually hear when the drivers begin sounding stressed and decrease the gain down before damage occurs. When speakers are under powered, the amplifier is more prone to clipping distortion during transients and during high gain levels, resulting in speaker damage. I am not so worried about other forms of distortion such as IM which tend to increase with multiple channels being supplied by a common power supply, etc. If the receiver is being driven into clipping, there is a real problem. If not, you are, relatively speaking, OK. But my primary focus, along with basic speaker design, is room acoustics. Assuming the possession of reasonably designed audio components, it is the most productive area of improvement and perhaps the largest source of acoustical error in the signal chain. Much effort has been spent even on cheap electrical components. But the norm is for little, if any, resources to be used to accurately identify and then to attempt to address the real (as opposed to the imagined) problems in the acoustical space! This is where I would focus my energy for the greatest return. THEN you can consider getting 2 Crown K1s and a K2 and consider upgrading to Jubilees & a few LaScalas! Of course, while you are at it, you may just want to jump right in and double the number of amps along with several active crossovers as well and bi/tri-amp.[]

OK, I'll play the curmudgeon.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> "What we have developed is a way to construct magnetic fields so that when you travel round the magnetic fields, starting and stopping at the same position, you have gained energy," McCarthy said. "The energy isn't being converted from any other source such as the energy within the magnet. It's literally created. Once the technology operates it provides a constant stream of clean energy." On the one hand, if I was to hazard a guess and extrapolate meaning from what was NOT said, this sounds amazingly like magnetic induction! But then, that is purely interpretation! On the other hand, what is actually said is extremely vague and offers VERY little substance. They speak of 'construct(ing) magnetic fields' as if they spontaneously come into existence without the pre-requisite application of energy and 'travel(ing) round the magnetic fields' as if no energy is required. Materials simply appear and move. And 'new' energy is 'literally created'. What kind of energy? Should we assume electrical energy? I love it when they use the advanced techno-babble! I can imagine Maxwell rolling about in his grave LHAO! "If there's no data involved it is either religious speculation or philosophy, but definitely not science." Richard Feynman Where is Feynman when we NEED him!? (OK, OK, I guess we know, but you know what I mean![] ) Even such marvelous machines that approach an apparent perpetual engine such as hydraulic rams used for pumping water, while both very elegant and clever designs, cease to be magical when the entire system is considered in total. Unfortunately, the magic bullets come and go. What seems like magic usually becomes slightly less so when the system is viewed in a total context as opposed to some artificially defined limited focus. And they can not get anyone interested? If such an idea is indeed valid, they will be awarded the Nobel Prize! Do you not think that they could interest a graduate student in their sponsorship of a doctoral thesis? In other words, "slave labor" to replicate and verify their 'discovery'!? Something is fishy here! This would surpass 'point source superconductivity'! Heck, they could enlist the folks on Stargate-Atlantis and SG1 to help in the researching and development of a ZPM! And they have issued the challenge for "12 physicists" to examine the claims? Why not open it to the scientific community? I hope they prove me wrong. But I have heard more substantial nonsensical claims before! In fact, one institution is so adept at them that they have the phenomena named after them! Its called the Utah Effect, after the illustrious <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />University of Utah. Heck, one wonders what it is like to have the nerve to walk out of that school with a degree in physics after others have so tainted the name. And unfortunately, the statement by this firm represented here sounds like someone speaking that has never had a physics class. When they make a coherent statement that possesses intelligible substance, it will be interesting to look at it. But thus far, even the various claims for 'advanced' AC power interconnects - you know, the magical current sources devoid of noise - sound more plausible than this. And at least those folks have gone to the trouble to at least use some terms that have a meaningful use (somewhere else) in physics! I love new ideas, but I sure wish this company would please provide some substance![] OK, that's my 2 cents meant with a grin. Oh, and quantum physics deals in probability, not chance! And the rules are very precise and accurate. The limitation is in the frame of reference. Relativistic quantum electrodynamic is a spectacularly accurate theory. Richard Feynman once described how accurate it was by saying: "If you asked me how far it was to the moon and I said "do you mean from my head or from my feet?" That accurate."

Ferrofluid is definately not snake oil. But neither is it something to be used indescriminately. Some non-ferrofluid drivers may be modded, but I would definately check with the manufacturer first if you are not intimate with how the parameters will be modified. For a good summary description of its uses, benefits and performance characterisitcs, check out: http://www.ferrotec.com/products/ferrofluid/audio/audioBenefits.php

Typically, the lower the output impedance, the less the output will change with loading and therefore the flatter the response delivered to a speaker load. Aside from that, separates offer increased power supply regulation and capacitive reserve and thus reduced IM distortion - particularly on transients. But your average listening levels are not excessive. And if 100 dB is representative of the transients, this is not terribly excessive either. I would tend to suspect from your description that the biggest factor that you may encounter due to the relatively small impedance 'mismatch' will be increased distortion. And the real problem with this distortion is that it is detrimental to the long term use of the speakers. And while I do believe that the use of separate independently regulated output stages offer advantages, I am not prepared to state that you are significantly "missing anything" with the level of efficiency offered by the speakers and the output levels at which are listening to them without additional measurements. So, sure, if you want to spend the money, there will be an improvement. From a purist perspective I would agree with the idea of using separates and I would personally go with the Crown K1 or K2s. There, I said it. But are you going to necessarily hear and notice the difference...in other words, can I quantify the ROI? ...That is harder to predict. I am just hesitant to tell you that you "have" to go to separates based upon the limited information I have here. How is that for straddling the fence!?[]

Wouldn't that be the Jubilee? ...which could essentially be seen as the next step up from both the KHorn and the LaScala.

This all may be a moot debate! Yes, the Crown and QSC pro amps are stable down to the 1-2 ohm range. But if you are not experiencing a problem with your existing setup and you are satisfied with the results, I wouldn't change. If on the other hand you were experiencing problems...well, that would be another story. But as I said, if you are happy with things as they are presently, sit back and enjoy! I would not expect changing amplifiers to make a dramatic difference. Certainly not one worth spending say $5-700 on based simply upon a 'paper' spec! Quit making problems![][][]

According the the Klipsch Jubilee spec sheet, the acoustical origin offsets are 0 (reference) - LF 3.5 ms - MF 4.6 ms - HF PS. Regarding the ~1.9 ms 'master' propagation delay - there will be some propagation delay that you cannot eliminate. Unfortunately everything does not happen in zero (or negative[] ) time! But 1.9 ms is not allot of time! It should not result in everything appearing to be a badly dubbed martial arts flick! On the other hand, if you inverted the phase and fed the delay back into the signal ...you might be able to cancel time...let me find my HP-48...[]

They have adjustable output levels and you control the gain from the pre-amp! Just like the QSC PLX line! Maybe the best way to approach this is to ask how much you are willing to spend. Then it is easy to pare down what is available in the price range... I am assuming that you have a targeted budget...

The K series Crown has NO fan! The front panel is a cast integrated heat sink. I would NOT recommend anything less than the K series in the Crown line for audio purposes (unless you go with a D 75, and you wouldn't want those for subwoofers.) Check out EBay for the K1 & K2s. You should be able to get one in EXCELLENT condition for ~$750. If you get the original receipt they also carry a 3 year no fault warranty. And I have never had one require service even in SR applications. Also, I haven't had hands on with the Mackie amps, but if they are up to the same standards as their mixers, they should be fine units as well. (FWIW: I have MINT, neverout of the plastic or box - only the box cover has been opened, Crown Macrotech 24x6 with PIP card I would consider letting go for $1600 I dare say for bi-amp purposes, you can't do better. [] )

Wow! I just discovered this thread, and as I sit here in stunned amazement, I must completely agree with Kev... Who is Brian Lam? But then, I guess the further away he is, the better! I think I can honestly say that that review may be the most asinine review I have read in audio, even giving some of the marketing nonsense from Audio Advisor a run for the money (light insulated and water insulated cables included!). By the way, if anyone runs into any extra "fan shaped things", PLEASE give me a holler! I sure wish more would call me as too many places have pulled out their "old" Altec systems to install some new fangled trendy system over the past 15-20 years![] Before I got my LaScalas for home use, the A7 was THE speaker I lusted over! The nice thing is that they are easily constructed, but they are big (especially with the wings!). When I was younger I carried far too many of them up far too many auditorium staircases where they lacked a loadout! A7s and huge W boxes, whoopee!

The Crown K1 and K2 are EXCELLENT amps. I would not recommend the Micro or Macrotech series for home use. Don't get me wrong, they are Great amps! But UL requires a 30 amp rating on them, as under certain fault conditions they WILL draw this without shutting down! Although in a well behaved environment they can be adapted for 15/20 amp service. Crown ceased offering the adapter kits because of the UL liability issue. They were designed for dedicated applications where limitations in the electrical service is not a concern (Dedicated rack PAs, SR, etc. use). Stick with the K series and you will get all of the fidelity (maybe a little more) and not incur the insane electric bill and electrical service requirements. If you go with QSC, stick with the PLX series. Both companies' lesser amps are designed for less critical environments, including 'PA' use - and by that I litereally mean distributed PA use (think high school public address systems!) - not heavy duty SR (sound re-inforcement) applications. They do not exhibit the duty cycle characteristics necessary to handle heavy transients. I would avoid them, especially for sub-woofer use. I have experience trying to use them in 'in house' SR and audio applications, and they distort and saturate on heavy transients, and this will result in damage to your speakers! But if you are looking to power an intercom system, they are just what the doctor ordered for a reasonable price!

Here is the link to Auralex and the specific products: http://www.auralex.com/partscience/spacearray.asp http://www.auralex.com/partscience/spacecoupler.asp (Application Note: Please notice the picture of them being used as a part of a suspended ceiling application as a space coupler - just be aware that they work great on wall/ceiling surfaces as well, as long as the incident waves are not at near 90 degree angles - so you don't want to use them on back wals or immediately adjacent to the speakers - the array configuration is optimal for that, with absorption needed Only for intense focused reflections. And that could easily be surgically applied After the room was nearly finished and a few measurements were available.) Regarding the data: I have an interest in the test results as I am waiting for the importable data library for use in EASE. And for a bit of my rambling: But as far as the practical aspect, they are already well proven with years of use in Russ's projects. And they are as effective as the alternatives from RPG, etc. - and that is meant as HIGH praise! ...As like Russ, Peter D'Antonio's work is Always first rate! Bottom line, they are effective as broadband diffusors and intended for use as part of an 'integrated system/package'.. For LF you Want to use bass traps, and there are a number of topologies for traps that you can chose from ranging from panels to wedges to tubes, as no wall surface treatment is going to effectively address them. OK, let me qualify that and save the Doc from having to do so...[], no reasonable wall surface treatment that anyone desires in their home is going to effectively treat the LF modal issues! The test results are not needed to validate the actual effectiveness of the product...as they have been employed in real world high end applications for sometime. Rather they are for marketing purposes for the commercial product on the one hand, and more comprehensively, they are needed as data libraries for their incorporation into room modeling programs such as EASE (or CATT), as the data will be provided in 3D volumetric cloud form, thus allowing accurate modeling of very complex large acoustical space integrated room/speaker systems. Who cares, I can hear most saying...and you are right! The point is, I would not hesitate to personally use the techniques now as they are a proven commodity that has simply not been heretofore commercially available at the retail level, but you are most certainly entitled to see the results for yourselves! But if someone had the initiative, they could be easily fabricated yourself at a very high level of craftsmanship for a very small cost, thus saving ALOT of money! Hint hint! Was that 'subtle' enough! And who can't benefit from 'alittle' cost savings! OK, I think I got the rambling bug out, at least for the moment...[][] If anyone has questions or more ideas, please feel free to PM me. I can also be reached by IM or phone if I haven't already scared you away![]

If I may, just a couple of questions... Where are you located (gnerally)? (If you don't mind telling...) If you can take a few pictures of the room so that it was possible to see where the ceiling mounts are currently located as well as the topology of the surfaces where the front and side/rear speakers would be located, as well as providing some information regarding the nature of the space above - is it a finished space, or attic, etc.; as well as the nature of the space beneath the room - be it slab, crawlspace, finished space, etc., it would really help in proposing possible 'real world' alternative solutions that would not cause more problems then they solve! I am guessing that your issue can be resolved without alot of pain. But we should see the exact situation before making promises![]

As you have already made some decisions, I certainly don't want run around kicking anyone's dog... But a few considerations. Especially as you mention the goal of a RFZ. Without a room plot, it sounds like you are attempting to absorb your way to this goal. The problem with this apporach is that too often the overall result is what plagued the very first generation of LEDE, whose goal was the same. It WAS dead! If you want what amounts to a step by step implimentation of an LEDE room that employs a RFZ, please PM me. It also explains in depth exactly what, and more importantly, WHY they are doing the various steps. Additionally, it is one of the best 'all in one' tutorials providing insight into the role of time based measurements as they apply to a room. They do use some measurements, but the concepts can easily be employed for general use. Only the commercially available treatments have changed since it was printed. Lacking the precise measurements, my suggestion is to use diffusion rather than absorption. For the low frequencies and standing waves please forget standard wall treatments! They lack sufficient mass to be effective. For LF, the way to go is via the use of traps. And if you have the means and the wherewithall to build the offset 'integrated' wall bass traps, it would still be easier to simply splay one long wall (front to back) by 1 foot(& ideally, both walls! And then combined with corner placement of the speakers, life becomes very easy). And if you did that you could even employ the cavity to make part of that wall into an effective bass trap/Helmholtz resonator(s). And pardon me for focusing on the potential to use that ceiling space as a coupled space! Since Russ Berger has decided to make some of his private tricks available commercially through his sideline PartScience and distributed by Auralex, the commercial tools are available (for a price!!!!!! But still half the cost of RPG!) But with a router and several sheets of luan and a weekend, you would be set with both diffraction grating for a ceiling and for side wall treatments. And if you chose to 'stuff' the grating, you would have a terrific treatment for the back wall. I apologize for rambling, as there are lots of effective paths and options, and I do enjoy debating the pros and cons of each. And this area is one discipline that even when it is incredibly frustrating, is still actually quite enjoyable! I won't bore you further here, but if I can answer any questions, or if it will make you feel better to tell me how crazy I am (the line forms here...), please feel free to PM or call me. Best of luck and have fun!

I realize that I am very late to the table here, but I must admit to being a bit confused by what has transpired. Ok, what do we know: There is the desire to conceal an exposed beam while also allowing access to systems.... First, it does not seem to have been established what the acoustic goal is. Materials which facilitate absorption, reflection and diffraction have been mentioned almost interchangably along with the issue of aethestics that seems to alternate with an acoustic goal. My first suggestion is to determine what needs to be done acoustically in the room. I am ASSUMING that sound transmission is not a primary factor and that 'in the room' response is paramount. But even this has not been clearly stated! Secondly, I would toss this notion that absorption is the Neosporin of acoustical treatment. This is like saying that the surgical removal of a kidney is the cure all for what ails you! Thirdly, a few room measurements would render this entire debate moot, as then you would know what would be the optimal need. But as it has already been stated that you need access to the additional space above, you also have the opportunity to use it to your advantage by coupling the space via the use of a phase grating (similar to Russ Berger's SpaceCoupler - see the thread on the A frame ceiling). Using such a panel system, you could have access to the space above while both providing a diffusive surface treatment that would simultaneously provide for an extended pseudo-reverberant field. If that was not desired (or appropriate - as a few measurements would tell us!), a panel system such as the 'stuffed coupler' equivalent to a space array (more details also mentioned in the 'A Frame' ceiling thread) could also be employed, thus providing effective acoustical treatment while also facilitating access to systems. But before any treatment is proposed, it sure would be nice to know what aspects of the acoustical room response SHOULD be amended in order to optimize the acoustics rather than simply running about suggesting whatever treatments come to mind.

As this has set for so long without a reply I will try to give you a few of my ideas...<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> First, my feelings about ceiling speakers They are great for zoned systems. Period. You have the disadvantage of playing to the short dimension with LOTS of reflections (especially from the floor) and a characteristic intensity distribution plot that is suited for - well, only for zoned systems!. [] Additionally, while in the wall systems have some real advantages with regards to dispersion and reflections; they also present some rather unique problems in mounting them without coupling them to the wall thus turning the drywall into a VERY slow secondary transducer. In the ceiling, one way to mount them might be to literally mount them to a frame suspended from a rafter in order to decouple the speaker from the ceiling. In addition, in order to seal the attic space from the room below, a rubber or EPDM membrane could be used to seal the seam around the speaker but you need to be careful here as this step risks re-coupling the speaker and ceiling. There are a few other options, but the complexity and cost goes up very quickly. Still, after you have done this, you are still left with a speaker providing very uneven coverage in the room. My suggestion, which may not be possible, would be to relocate the pre-wire tails slightly and either punch through the ceiling (and make sure the puncture is sealed) immediately adjacent to the front, side and rear walls (Note: be aware that these locations would be consistent with the 5.1, 7.1, THX, etc. standard that you choose to employ), or to drill though the wall header and effectively fish them a foot or so down the front and rear walls, thus allowing for the mounting of a traditional boxed speaker mounted at an angle high in the room. Of course, if you can have traditionally mounted speakers, I would simply fish the wire further down the walls to exit near the floor.( I am a bit confused as to why the wires would necessarily be "very obtrusive", but then I cannot easily visualize the room.) I suspect that there are objections to these suggestions, but not seeing the details or topology of the room I can only speak in generalizations. But a ceiling mount will present some very real limitations in that a 5.1 or 7.1 system is dependent upon a well behaved dispersion in the room. They were never designed for a fundamentally zoned system which is normally used to isolate and preclude such dispersion. And unfortunately, when they are not properly zoned for isolation, the result tends to be the terribly unintelligible systems so often encountered in airports, etc.! And regarding your question about Yamaha versus other brands... I will leave that for others who seem to relish that debate. Heck, I have almost told you to buy another house with my recommendations.[] I am certainly not going to tell you that you have to buy a new receiver too![] I know that this is not something you wanted to hear. But I would do what I could to relocate the wire tails close to, or into, the front and side/rear walls. The high mounting point can be addressed relatively easily, but the ceiling mount presents a more substantial problem. Good luck!

OK...regarding the measurements for Russ' baby... The exhaustive lab results were expected mid-August,soooo...hopefully within the next couple of weeks... Ron Sauro is doing the elaborate tests at NWAA, so they should be forthcoming soon, and apparently Ron is in the middle of debating how absorption testing should be conducted and whether one or multiple dodecs should be used to stimulate the materials...so...'ain't acoustics grand!? Unlike so many other sciences where most of the characteristics have been well understood for 100+ years, acoustics is still in an ongoing period of discovery! We have kind of jumped the gun on the grating and arrays, as they are that new. Although Russ has been employing them for some time now in his designs. So they are proven. And as I realized that I did not address at least one important aspect that should be rather obvious...[], the gratings can be use as diffusors where the angle of incidence is primarily greater or less, but not equal to 90 degrees! This should be pretty common sensical as they act as a pass through at that angle (90 deg)! Thus putting them on the back wall to act as a diffusor would be rather silly. Here you would definately want to use a broadband diffusor such as the array. [] And RPG is closed for the week, so I will followup with them next week.. I guess I should shut up and get back to the work I am supposed to be doing!

Are you sure it wasn't for microwaves...[] There is Millimeter Wave technology's MF-500 Microwave Absorbing Paint that might prove useful for those of you who can't drive the speed limit and have to deal with traditional radar.[]

pardon me...this was meant as an update on the auralex soundarray & soundcoupler in the A ceiling thread...please disregard...[:$]

Regarding the Space Coupler style phase grating...<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> I have to admit that I have become quite enamored with this design. It is elegant in its simplicity and quite effective in a wide range of applications to achieve a variety of desired affects. Plus they can be more easily emplyed so that your home does not end up looking like the Museum of Modern art. Garyrc: They can be applied directly to a surface for diffusion. It can be applied with spacing away from a surface and the diffusive effects increase, as a portion of the signal is reflected through the grating and it bounces about until the incident angle is such that it reemerges - darn this sounds like doubletalk without a simple draw tool! And here is an ingeneous technique pioneered by Russ especially in such venues as the ever shrinking home studio. If the coupled space is larger (such as a crawl space, adjoining room, 'attic' space above a suspended or fixed ceiling, the additional time that the waveforms 'bounce around' and finally reemerge through the phase grating results in a 'longer' trailing (and correspondingly lower intensity) diffused field - thus, depending upon the volue of the adjoining space, effectively creating an artificial reverberant field that is impossible to achieve in a small acoustical space. The result is an acoustic space that performs as if it were a larger space, while utilizing otherwise 'unusable' space. And while my intent is not to sell anything nor to tell you to avoid buying these products, an ingenious individual could easily fabricate many of the RPG and space coupler/array designs for their own use....as they are quite expensive! (figure ~$200 retail for one 2'x2'x3" space coupler!!!! Cheaper than many, but ouch!) Just like making plantation shutters, a few hours fabricating a router jig and an hour more routing and wella! And its prime for a first time hobbyist! Also, a CNC would make short work of these, and they could be made in a myriad solid, veneered, MDF formats for natural finishing or painting. And for home use, readily available inexpensive 4x8 sheets of luan would be ideal. And I would use Styrofoam blacks cut and inserted into the grating with a pressure fit to complete the arrays. The blocks could easily be faced with any number of maerials, be they veneer, fabric, or other desired finishes. ...Regarding the measured specs - we were playing with a variety of toys and Russ happened to pull out a few of the then soon to be announced arrays and couplers. And we had the opportunity to shoot a mess of configurations in the demo & workshop as well as shoot the breeze over lunches and dinners for several days...so I don't have them recorded in any coherent fashion. Suffice it to say that the empiracal results were great! they are sufficient in themselves, leaving only LF traps as a missing piece. Please allow me to digress from my digression and elaborate just a little bit here. The diffusers work great where one would normally install absorption. In all but the nastiest situation, the diffuser will diffuse a hard reflected signal so that the result is no longer of sufficient intensity to require absorption. Of course, if the signal is of sufficient intensity to still require absorption, that is always an option. But it is rare in general applications. But you raise a very good point. Let me check into what I can do to obtain them! (They are most generally available in a library form for importation into such programs as EASE or CATT as opposed to being stand alone.) And yes, the measurements are taken just like the polar measurements are taken for a speaker...in degree increments over an ~ 180 degree arc. In the case of pass-through, the reflected response (reverse side) will be a mirror image of the front. This can become much more complex than it sounds depending upon the precise resolution you desire as you are adjusting not only the incident angle of the source signal, but also the angle of the reflected measurement mic - so a sound field array is a NICE tool to have if you don't have 6 months to measure each sample![] But it is very easy to dial them in with a few measurements and extrapolate between them in order to establish a useable trend analysis. The neat thing about the coupler and arrays is that, unlike many treatments - and I refer especially to absorptive treatments, it is hard to screw anything up with them. No mean feat! You may reach a point of maximum effectiveness and then, if more are applied, a point of diminishing ROI, but you are not going to negatively impact the room acoustical response! And its not often that you run into that scenario! The reason is that a well behaved diffuse sound field is a very nice thing! In such an environment, (assuming a nice decay - hence 'well behaved') you really only need to identify and address 'hard' (focused) reflections. These can be diffused or absorbed as necessary. And time based measurement tools make this a very hit and run affair. Oh, and one more thing...These can be covered with an acoustically transparent fire retardant membrane if you desired to hide the slightly modern art appearance. And if a natural finished wood or painted 'textured' surface appeals to you, the grating could be applied directly to the extended ceiling surfaces, leaving only the LF modes to worry about. Let me do a bit of checking and I will report back. But if you are considering such diffusive 'tools', I would not hesistate to tell you to go ahead. Oh, and yes, I emphatically agree with the Doc. Time based measurements such as are afforded by such tools as ETF, TEF and Easera are definately worth their weight in gold! Not only do they offer you tools that can take you even further in this porcess then just the surface treatments, but it is certainly easier to get where you want to go when you have precise reliable tools to tell you where you are as well as to confirm when you have arrived! Although they may take away some of the fun [][][]

Sorry...[:$] Yes, the higher the STC rating (typically rated in terms of dB), the more isolation. Thanks Duke![]

Waves carry energy and momentum, and whenever a wave encounters an obstacle, they are reflected by the obstacle. This reflection of the object can be analyzed in terms of momentum and energy conservation. If the wall is a hard fixed boundary and the collision is perfectly elastic, then the wall absorbs none of the energy and all of the incident energy and momentum is reflected with an identical velocity with the reflection being 180 degrees out of phase from the incident wave.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> If the wall is a non-fixed/non-rigid boundary, then the collision is inelastic, the restorative force is zero and the wall absorbs some of the incident energy and momentum and the waves lose some energy and velocity with the reflection being in phase with the incident waveform. If the reflective surface is neither perfectly hard nor perfectly soft, and is somewhere in between, the restorative force is less than equity and part of the wave is reflected and part of the wave is absorbed or transmitted through the boundary surface. The exact behavior of reflection and transmission depends on the material properties on both sides of the boundary. The sum of this behavior is termed the acoustical impedance, which is essentially the total opposition of the wall system to sound waves comprised of resistive and reactive components.. And just like what you may be used to in electronics, the acoustical impedance also has an acoustical resistance component, which is the real component associated with the opposition and dissipation of kinetic sound energy upon striking a wall, as well as an acoustical reactance, which is a value related to the mass of the wall, along with the relative elasticity of the surface which comprises the imaginary component corresponding to the stored potential stored energy in the system. As others have observed, the acoustical impedance of the wall system is characterized by very complex non-linear dependencies with respect to frequency. And while charts can provide some useful relative measure of a materials effectiveness regarding reflection and sound transmission characteristics, the actual effect is a complex sum of the various wall components. By far, the easiest way to determine the performance of a reflective surface is to measure it. Generally speaking, you do not want to randomly deaden and absorb the acoustic energy. Low frequencies are absorbed by mass and best dealt with by various types of bass traps, but the MFs & HFs do much better to have their energy dissipated in a diffuse field that minimizes focused reflections while surgically absorbing only** those first order reflections that reach the listening spot in less than a certain amount of time (called the initial time delay gap). Often in a small space this may be all of the first order reflections, but this is not always the case. The purpose of removing these early reflections that arrive less than ~20 milliseconds after the direct signal arrival is to avoid the what is called the Haas effect. Think of the Hass effect as the limit to your ears and brain being able to separate the signals into discrete signals. Thus they are combined into a single smeared signal where your brain cannot determine the point of origin of the component signals. In effect, you ears lose their depth perception and ability to localize the sound. Maybe an easier way to think of this is to think of your eyes. If you cover one eye, you lose your depth perception. (So too, if you lose hearing in one ear, you lose your ability to localize sound). With your ears, there is a minimum amount of time that must pass between signals for your ears to be able to resolve them as separate signals and to localize them. So in this case, what you cant hear (as separate discrete signals), does hurt you in the form of lowered intelligibility. (please note, this is a corollary to the 'Henry Precedence Effect' - please do not confuse the masking of subsequent signals within the time frame with the intelligibility of the summed signals.) (By the way, not controlling those early reflections is precisely the cause of the lack of intelligibility in large rooms where, for instance, you go to a gymnasium, airport, auditorium, etc. and you hear a PA system with plenty of gain (you Can hear it!) but you cant understand a word they are saying! The early signal arrival is either confused by the intensity of the early reflections, or you have a multi-point system which in effect creates many signals arriving within the ~20 ms period characterized by the Haas effect.) This is cleaned up by controlling the reflected signals or by effectively isolating the multipoint signal origins into discrete minimally overlapping zones. But I am beginning ( beginning?? ;-) ) to go beyond what you care about.) To go on just a bit further, it is also typical to arrange for a distinct reflection to define the end of the ITD gap (typically 2-3 ms longer than the room's charateristic ITD) to form what is referred to as a Haas kicker, after which the desire is to have the reflections consist of a diffuse sound field that decays in a well behaved fashion absent of any higher energy focused reflections. In other words, the diffuse sound field simply decays in a smooth fashion. Your idea of using the interior of the walls for absorption is not a bad one. But unfortunately, as the ability of the wall to absorb sound varies with frequency, in order for it to be effective you would have to effectively build a bass trap, consisting of mass and a cavity thus requiring the wall to be much thicker than you are probably prepared to make it. Additionally, as the frequency of the incident waveforms increase, the less effective it will be as an absorber. Thus you would actually be better off employing bass traps to control the rooms bass modes and very selectively absorbing only the necessary first order reflections and using diffusive surfaces in the remaining areas. But you do not want to employ wholesale absorption to deaden the room. This is precisely the problem encountered in the first attempt to create a Live End Dead End (LEDE) room. Acoustically dead rooms sound, well, dead. Thus the balance is more 90% diffusion, and a very surgical 10% absorption of specific reflections. Also, if you have additional space above your ceiling, there is also a wonderful technique pioneered by Russ Berger to couple this space acoustically and to use it to provide the sense of a much larger room through the use of a diffraction grating (that looks great and is easily made, saving money) that provides for a much longer diffuse field decay rate thus creating a pseudo reverberant field into the small space. (This can also be done using an adjoining room as well there are many interesting possibilities!) The bottom line. The internal construction of the wall is much more important for the sound transmission qualities! (And for that, refer to the charts and tables posted in the Home Theater Steel Stud thread. There is also much more info regarding floor and ceiling construction techniques as well, if needed.) But do not worry too much about the interior of the wall for internal reflective purposes. This is where you are become more concerned with surface treatments. Well, perhaps I have rambled too long and not said enough. Sorry for the long post! **Occasionally this tenet is violated by a sumation of several reflections. In this case, the individual component reflections must be resolved and each treated accordingly.

Yes, when the ICT component of AACS is implemented, only HDMI will support the host client handshake authenticating authorized components. Unfortunately, the standard as devised does not support DVI. Regarding whether you can directly connect a player such as Blu-ray directly to the display... That depends upon a few factors, AACS not withstanding. First, from an AACS point of view, the ability to connect the two devices would require both an HDMI connection as well as a host and client AACS component to facilitate the handshake. In additional, it would also depend upon the format of the players output. The remaining wildcard is the ability of the display to directly process formats such as Dolby, MPEG-2 and MPEG4. Depending upon the format of the players video and audio output, the monitor may or may not be able to directly process it. If the output of the player is in 'raw' form, the display may not be able to process the data. In their broadest sense, here we enter into a distinction between many monitors and 'TV's.The data must be modulated onto a carrier(s) that the TV's tuner can process. The 'intermediate' receiver may or may not assume those modulation functions. If the output of the player is modulated into a form which the display can directly process, and both components are able to establish the AACS authenitication handshake, you should be able to watch the movie in its HD format...albeit without the benefit of the switching (and processing) capabilities of the processor. Oh, and an addendum that I am sure will really make you excited! An additional blip in AACS that MrMcGoo alluded to above, has been the addition of what is called BD+. BD+ is a dynamic encryption scheme that allows for changing program encryption schemes midstream should the encryption be cracked. Neat, huh... But again, this aspect is focused on the actual on disc program material encoding which is a separate concern from the basic hardware authentication issue. Hey, don't get mad at me![] I'm just a messenger who wants You to get the most you can for your hard earned money, as AACS is all about the owner's of the copyrghted material covering their posteriors and getting the most that they can!

Doc wrote: "But if I understand correctly, are you claiming that (future) HD material will be unplayable through recievers and pre/pros supporting only DVI, even when a DVI to HDMI adaptor is implemented between the reciever and display device? " The existing AACS standard defines this! I am not 'claiming' this.[] It has nothing to do with my or anyone else's opinion! I do have opinions regarding this, but they are superfluous to the intended scope of this thread. This is not meant to be a debate over the standard. That is a moot exercise. Rather it was intended simply to present what the standard says as it currently exists in its final form! It is not a proposed or an evolving standard like the proposed 802.11n wireless routers. The debate is over! The standard has been approved and finalized! Anything that may follow this new standard that has not yet been fully implemented is pure speculation. ...Thus the purpose of my intended 'heads up'! I simply desired to assist those who are interested in investing in the new technologies in performing their due diligence and to be aware of the exisiting standard that has yet to be fully implemented! And the retailers are not telling customers this at the risk of losing sales! Caveat emptor! And Doc, PM me. I will be glad to try to answer all of your questions.

With respect to future standards not in existence... Sure, they may develop some new standard in the future. And we will have to address that if and when it transpires. But in the meantime, the NEWEST standard that was finalized last June, 2005 is the AACS standard, with ALL of the major studios and hardware manufacturers formally joining. At present it is a standard and it is only a matter of when it is fully implemented. It is a real agreement as opposed to speculation. And as it is not speculation, they are not debating over what features or formats should or should not be included! So to ignore it in favor of worrying about some future unknown incarnation is a bit irresponsible. Thus, if you are buying in the near term, you ignore it at your own risk. And I don't think that is a prudent or responsible approach. But, that being said, if you choose to ignore the current agreed upon standard, hey, have fun. Just don't show up later pleading ignorance and whining that your exorbitantly priced HDTV is now only good for displaying upconverted SDTV or EDTV signals! MrMcGoo wrote: "For example, DVD encryption was broken when the key to the encryption was leaked. HD DVD has the ability to update the encryption key via download. Such a change in copy protection would be benign. Blur-ray would be a different matter. You may have to buy a new machine and a new TV monitor." This is precisely what AACS will require! The 'penalty' for not having AACS compliant host and client hardware will require the replacement of said equipment in order to display AACS encoded HD pre-recorded material for either HD-DVD or Blu-Ray source material. Also: (Regarding compatible interfaces:) "It is a mistake to assume that a stable standard will be set in the forseeable future." This is incorrect! You may certainly debate the meaning of the word "stable", and you may posit that there are many available interfaces, but the FACT remains that the AACS Standard HAS defined the only compliant interface for TVs as the newer HDMI - to the exclusion of DVI and the others! It is not a matter of conjecture. It is fact. And this article is about compatibility with AACS. Not the development of in the future of something that has not yet even begun to be proposed! And please note: AACS has several aspects to it! I am not here to discuss the 'on-disc' encryption scheme. Rather my focus is upon the hardware compatibility issue, and whether your display is capable of completing the necessary authentication handshake to display the HD decoded output. This system is hardware/firmware based and it is independent of the encoded HD program material. Thus although related by the umbrella of AACS/HDCP, the topics are separate. Doc: Regarding your question about the direct transfer of digital material... ("I suppose a possible work around would be to connect the hd-dvd/bluray player directly to the display device") That is precisely what the AACS/HDCP authentication handshake is designed to prevent! Typically, the way pre-recorded material is duplicated, is for a recording device to be attached to the digital output of the decoding device, thus providing an identical digital copy. If an AACS compliant device is not detected and the hanshake completed, the output signal is degraded via the use of the ICT. But AACS is not simply an anti-piracy standard! It also provides for very agile content regulation. To provide a simple example, think of a time regulated or number of plays regulated program material - a sort of software based pay-per-view system. And yes, the present AACS standard requires an HDMI digital connection in order to be compatible with the standard. It is not a proposal or a suggestion. It IS the standard as it currently exists today! Please realize, this AACS standard is being driven by the copyrighted program material owners and producers who are seeking not only to prevent the unauthorized use of their material, but to gain increased agile playback control options for their material. The intent of AACS goes FAR beyond simply preventing unauthorized copying! It extends to what may essentially be considered as an extensive control system very akin to an independent, non-tethered agile 'software' sourced 'pay-per-view' system! The rules would be encoded on the disk. Up to now, the control over playback has been limited to streamed communications with the playback device (e.g. pay-per-view via remote data configuration and communication with the provided supplied device - be it a cable converter or satellite tuner). A goal of AACS is to remove this limitation and to ultimately enable the configuration of playback options within the recorded material itself. In other words, to have it follow the disk! AACS is not being driven by the hardware manufacturers! It They are as much at the mercy, if you will, of AACS and HDCP as consumers! They are not obliged to make compliant hardware. But if they (and the consumer) want their hardware to be compatible with the encoded software/HD program material, they must employ it! Just as current manufacturers are not required to make an SACD compliant playback device. But if they and you want to play the SACD material, you must employ a device with SACD decoding capability. It ultimately is the customer's responsibility to be aware of their needs and to purchase equipment that is capable of fulfilling that need. Hence this article! Without getting into the internals of the host and client handshake, the host which resides in the decoder side, be it video card, HD player, etc., MUST see and establish a viable handshake with an authorized client that resides in the playback display device. Thus, the monitor must be recognized as an approved playback device, otherwise the ICT flag is 'tripped' and the signal is downconverted to standard 480i resolution. It is precisely this client-side component that is missing in most current market HDTVs and computer monitors! By the way, it misses the intended point of this thread to debate the merits or limitations of AACS or Intel's HDCP. If you want to do that, reference Scott Crosby's and Ed Felton's mathematical analysis of the standards! Or attend the Intel Developer Forum. This avenue is moot for the average consumer! And my entire focus of this information was simply to provide the average consumer with additional information in order to make an informed consumer purchase based upon the real finalized standards as they exist TODAY! It was NOT to begin another obtuse debate over the merits of DRM in general or HDCP/AACS in particular! The average person neither cares, nor will they probably understand, the internals of either system, and thus a discussion of them is a topic for another time beyond the intended scope of this thread! The scope of this thread is very specifically limited to the standards as they exist TODAY! ...not speculation of what may develop in the future! Speculation about what may or may not transpire in the future is simply gossip and NOT a responsible basis on which consumers should base a purchase. There is ample opportunity for those who wish to simply speculate to start a thread and speculate away! And please don't misinterpret my intent here. I love to debate the internals! But it serves merely as a diversion and a point of confusion for those who are just becoming aware of the fundamental STANDARD itself! And, in the intended scope of the thread, it is not appropriate here. The bottom line: The standard exists today! If you are going to buy a TV or a computer monitor in the foreseeable future and you desire to have the capability to view encoded pre-recorded HD content, become aware of the HDCP/AACS protocol!