Bosso wrote:
Yes, I did. I used a high quality measurement mic connected to my interface/computer vs. the optional Denon mic into the receiver, and tweaked the EQ manually, mostly for curiosity's sake.

Question: what software program etc... are you using to test and set up a HT with? Can you set up the system so that every seat is a sweet spot?

Bosso wrote:
Parametric EQ is a bandaid to fix the fact that the room isn't suited (placement/acoustic treatments/leaks/bad hardware, etc.) to a MC audio system. The majority of HTs out there are just a living room with hardware in it. Most of those enthusiasts have no clue how to employ an 8 band PEQ and Denon knows it.

Certainly, if you're one of the many who fit this category, the Denon receiver (a mid-fi, low powered MC receiver that uses bells and whistles to make up for it's sonic deficiencies, like Yammie, Onk, Sony, etc.) is for you.

Response: The Audyssey system is not a Parametric EQ system. See below.

I can not help but feel that some of your comments in your post are meant to be insulting and are combative.

In order to clear up one of your accusations regarding myself and others slamming the Outlaw 990.I feel compelled to state, that I have never slammed any product from any manufacturer, and never will, nor have I used wording like crap to describe a product. I understand the theory that one mans treasure is another's junk. I respect others and there product choices. If it sounds good to them, and they enjoy it that is what counts nothing else. I would not insult there choice. I fully intend on reviewing the 990 in my theater. I will at that time decide if the unit works for me or not, period. My statement that the 990 appears to be dated before it even hits the warehouse floor is not a slam, nor intended to be, just my feelings regarding it's current features

I will also add, that maybe Outlaw is waiting for Audyssey to release there new products in the very near future, and will at that point offer an upgrade. I don't know, only the powers that be in Outlaw know for sure.

Please find below some information about Audyssey Labs', and there Multi EQ program. Hopefully this information will clear up some of the confusion surrounding the Audyssey Multi EQ system.

Audyssey is a spin-off of USC’s Inmersive Audio Lab which Tom Holman (a Professor of Film Sound at the University of Southern California’s School of Cinema-Television and father of THX) and Chris Kyriakakis co-founded nine years ago. MultiEQ has been in the works for the last 5 or 6 years and is the result of Sunil Bharitkar's PhD thesis. Sunil was a doctoral student with Chris at USC and is a co-founder of Audyssey. Yes, Audyssey is a start-up, but this effort differs from most in that it has multi-million dollar funding backing it through an endowment from the National Science Foundation.

Below is a few excerpts from a few interviews with Tom Holman,and Chris Kyriakakiis.
an adjunct application to MultEQ intended for HTIB systems. It’s called PrevEQ. “The main problem with home theater-in-a-box systems is the huge hole between the sub and sat. With a HTIB system we would have the luxury of having the speaker systems in advance so we could pre-characterize the speakers and boost the subwoofer to make it go up higher in frequency (to match with the satellites).” Tom and Chris then both clarify that "the filter placed on the content side is 120Hz for Dolby and 80Hz for DTS which is a problem for movie theaters also.


“The approach to solving this problem in the past has been based on parametric EQ which is an extension of what was done with analog equalizers just, done digitally. The first problem is that you never have enough bands, typically 10, using an IIR (infinite impulse response) filter. IIR filters allow you to do things in the frequency domain but it does unknown things to the time domain. In many cases it manifests itself in ringing or smearing.”

“Our approach is based on FIR filters which in the past have been computationally intensive but this is not an issue any more because the DSP power has increased so dramatically. FIR filters allow us to correct the time domain and frequency domain at the same time. 'Well, you might say, FIR filters don’t give you enough resolution if you want to keep them relatively short.' And that’s true. This is the reason we implemented Dynamic Frequency Allocation (another of the imbedded technologies) which gives non-linear spacing. So instead of having only 80Hz or so resolution we can get down, at low frequencies (where it matters), to under 5Hz of resolution. It’s on a Bark Scale but the resolution starts below 5Hz at the lowest frequencies and goes up to a few tens of Hertz at 20KHz." (The Bark Scale ranges from 1 to 24 barks, corresponding to the first 24 critical bands of hearing. For computing all-pass transformations, it is preferable to optimize the all-pass fit to the inverse of the map, i.e. Barks vs. Hz, so that the mapping error will be measured in Barks versus Hz.)

The conversation now turned to the bottom line technology within MultEQ. The ability to have every seat be a good seat. Again Tom provided his historical perspective from tuning theaters in the early eighties. “While real-time analysis is ‘time-blind’ (so you have to know something about the time domain before you use it) nevertheless, if you clean it up, it has some advantages over the FFT-based analyzers. The THX R2 (from the eighties) was readily able to do spatial averaging and temporal averaging and we realized if we made an extension of it using a laptop with an add-on spectrum analyzer peripheral that we could send signals across dynamically from the analyzer and do a lot of mathematics to it and therefore clean up the signal."

[MultEQ]Chris takes over, “So part 1 was, we knew if you EQ for the single sweet spot then every other position would suffer from much poorer frequency response. (And that was one of the reasons for the bad name 1/3 rd octave equalizers were given.-Tom) Initially Denon and every other potential customer thought 'let’s have two modes'. One for a sole listener and one for when you have several listeners in a room. Well, it turns out if you EQ a whole room the audiophile seat gets better. If you take more of the problems of the room into account you’re fixing a bigger area than just the audiophile seat so there’s no need for two modes.”

Chris continues, “The approach other people have taken is to throw DSP at it. There are room correction units on the market that do just that. They can do 8000-tap FIRs and you need 3 DSPs per channel. But if you want to be in a consumer product you have to make some computing decisions. So that was the thinking that went into Audyssey’s Dynamic Frequency Allocation.

I then asked “Does it give the same response at each listening location? How is it possible, for instance, if you have a standard D’Apollito-style center channel which is known to have a lobe which points mostly toward the audiophile seat.” Chris responds, “By measuring the response at different locations we use a fuzzy-logic based clustering approach which, after computation, makes the sound at the audiophile seat better. The average assigns equal importance to each seat, an importance of 1. Now by applying a weighting factor automatically we use an approach based on pattern recognition. It doesn’t have anything to do with what we know about acoustics,” Chris stresses. "This is the leap of faith. It is the first application of fuzzy logic that I know of in audio.”

“If we were to treat the time domain version of these responses and say which of the criteria are closer to each other as far as pattern similarity, then I find for instance that seats 1, 3 and 5 in the room are "clustered" as far as similarity, seat 2 is by itself and seats 2 and 4 are similarly grouped together."

I interject and ask if the sound the system is reading is mainly direct sound and first order reflections and the answer was “No”. "The response that we’re taking is quite long. It’s 8000 samples over 200 milliseconds. If you look at the time response, it has a pattern. But if the seats have similar problems, they will fall into similar clusters as set up by our pattern recognition method. Where it gets fuzzy is that a particular seat can belong to more than one cluster. In other words, what it says is that based on our theory that seat #2 has 80% of the characteristics of seat #3 but 20% of the characteristics of seat #1. So there are no hard boundaries."

"So now we have six responses which we’ve clustered into 3 groups. From each response we elect a representative of the cluster. It’s not any one (exactly within the cluster), it’s one that represents each one in the cluster in the optimal way. That’s called a cluster centroid. So now, of the 3 clusters you have, you have 3 representative responses. So you do it again until you finally end up with the “President response” which represents the constituent responses in the optimal way. So the final representative response is the one we take and invert. When we invert we are inverting proportionally and non-linearly.”

Yes this Audyssey system is more complex and complete than the one currently found on the Lexicon piece. The Lexicon system only corrects for bass response while the Audyssey is full range, and uses FIR mulit taps. We have been researching this for quite awhile. Currently this is the most innovative and advanced room correction system in the industry.