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Onkyo TX-SR805 THX Ultra2 7.1 A/V Receiver

Part IV

September, 2007

Brian Florian

 

Audyssey MultEQ XT

Because of the intimate relation between them, I will lump my usual report on speaker setup and bass management in with our look at the Onkyo's implementation of the Audyssey MultEQ XT.

Unlike Onkyo's past offerings which included what I call "dumb" Auto-Setup and EQ, the 805 employs the only such system I am prepared to endorse at this time: Audyssey MultEQ, specifically, the XT flavor thereof.  In our article on generic Auto-EQ, we explain very plainly how, ultimately, it is impossible to "correct" a room through DSP, how speaker correction for one person makes things worse, not better, and how EQ in any capacity needs to be of a magnitude finer resolution that what is generally offered to be of any real value anywhere.

Audyssey sidesteps every pitfall by not attempting to do anything which simply cannot be done.  Audyssey themselves acknowledge that their system is not a substitute for physically addressing room acoustics (as in acoustical treatments).  Anyone who claims to be capable of such literal magic is (whether they know it or not) pushing their luck.

Audyssey does not blindly EQ for one person, but rather measures the entire listening area and figures out what will work best overall.  They use highly precise FFT filters in a dynamic allocation (meaning more precision is allotted to the bass where it is needed most, as opposed to spreading it out evenly).

As with all such systems, a microphone is supplied with a very long lead. It has a standard camera tripod thread, the use of which is practically mandatory in order to position the mic at head height (don't put the mic on the seat where your rear end would be).  $13 will get you a basic tripod at the camera store.

The process is as simple as plugging the mic in and following the on-screen (or on display) instructions.

One always starts with the mic at the center seat.  The system will play test noise from each speaker (be quiet and stay out of the way!)  It will then ask you to confirm that you in fact have the speakers it "found", and asks you to move the mic to the next seat where it takes another set of measurements. Then on to the third seat and so on.  Then it "crunches the numbers" for a while (10-20 minutes depending on how many seats you measure) and lets you review the level, delay, and crossover settings it chooses.

I found that, unlike the "dumb" generic Auto-Setups/EQs, Audyssey MultEQ was BANG ON when it came to speaker distance (adjustable in 0.5 ft increments by the way) and level (adjustable in 0.5 dB increments).  Crossover selections . . . I'm not so sure.

Sidestep just a moment to Manual mode (or if you simply override Audyssey's choices), crossover frequency can be set from 40 Hz to 100 Hz (10 Hz increments), and then 120 Hz, 150 Hz, and 200 Hz.

The crossover frequency can be set independently for each pair of speakers, the soundtrack's bass can be sent to both the main speakers and a subwoofer ("Double Bass" they call it), and the LFE channel can be low-passed at a different frequency from the rest of the bass being sent to the subwoofer . . . all of which we vehemently maintain are bad ideas, and we back that up in our essay on the subject: Miscellaneous Ramblings on Sub Crossover Frequencies.  It is no fault to the product's performance, but it questions Onkyo's marketing decision to give the people what they think they want even though it may mean they hang themselves with it (unawares as they may be).

Audyssey may in fact choose a different crossover setting for each speaker because it looks at each speaker's response independently and figures out, based on the resultant sum of the speaker/room combination, which frequency will provide the smoothest blend with a subwoofer. 

Despite my having three identical M&K MPS2510 front speakers, Audyssey wanted to set my L/Rs at 80 Hz and the center at a whopping high 150 Hz crossover.  This in and of itself is not surprising since we have preached countless times how even identical speakers, by virtue of their different position in the acoustic space, cannot possibly have identical output (which is the fundamental argument for summing all bass to a subwoofer system).  The question is, should Audyssey have set my center as it did? The answer, for me at least, is a qualified "No".

"Smoothest Blend" maybe, but 150 Hz is just too darn high (especially when the speaker in question can be driven well below that without distress).  Despite the sharp 4th order low-pass a-la THX, 150 Hz is into that realm where a subwoofer says, "Hey, I'm a subwoofer . . . over HERE!" instead of being non-localizable as it should be.

That detail notwithstanding, no one at Onkyo has come up with a novel new take on solving the problem of summing two (or more) filters at off-set frequencies and the inherent problems their "unaligned" phase shifts cause when summed electrically to a single subwoofer system.  Audyssey does not yet extend to the actual bass management itself, the requisite filters and implementation thereof being the province of the manufacturer, in this case Onkyo. Audyssey has in fact done published work and research with regard to improved bass management revolving around group-delay compensation on a per-channel basis which sounds (no pun intended) like it will finally solve the pitfalls of using more than one crossover frequency in a single-subwoofer system, but we’ll need to put a little more pressure on A/V receiver manufacturers before they are willing to surrender their traditional topologies.

Until then, the good news is Audyssey treats every channel as itself in terms of filtering.  In other words, if you change its selection for crossover frequency as I did for my center channel, it will adjust its application of EQ filters accordingly (though, in their words, they can "no longer guarantee optimal results").

In practice, this multiple crossover frequency thing is really not all that big of a deal, but if we are going to go through all this care to get the best D/A performance, the cleanest amplification, the tightest room (you DID acoustically treat your room, right?), and then top it off with intelligent FIR based EQ, why undermine it all on a technicality?

Moving on, Audyssey did perform exactly as we have come to expect: with discretion.  A/B'ing it on a system like mine does not produce the same, "Oh my goodness, what a difference," exclamations you get when doing so on a $500 HTIB setup.  I've put a bit of effort into my system, including acoustics, yet Audyssey still had something to offer me.  In particular, it was able to null out a hump at around 54 Hz I knew I had, and managed to smooth out the critical but difficult to nail 80 Hz - 300 Hz range.  Still not a ruler-flat transition through there, but in my estimation, with Audyssey, it's as good as it's going to get.

Switching gears to Onkyo's implementation of Audyssey MultEQ, I have a few notes for you.  First, you will not get a graph of what Audyssey is applying in terms of EQ filters.  We're told this was something of a joint decision between Onkyo and Audyssey because today's On-Screen display's, with their 1980's caliber computer graphics, simply cannot show what Audyssey is doing and to attempt to simply misleads and confuses the consumer.  

More disconcerting is Onkyo's omission of the choice for Audyssey's target curve.  Integral to the Audyssey MultEQ system is a choice of final curve it filters to:  the Audyssey curve, a Flat curve, or a Front curve.  The Flat curve, as its name implies, is a classic, "Let's make the system response as text-book neutral as we can," and is best for rooms which have already received a modicum of attention to their acoustics.  The Audyssey curve, which may be considered the default, is a shaped target which seeks to mitigate some of the inherent high frequency reverb of typical home spaces, not unlike what THX's Re-EQ's purpose is, but on a much more sophisticated level.  The concept of the Front curve is to filter the front speakers as little as possible and make the rest of the system conform to them.  Yet integral as it is to the Audyssey system, Onkyo does not give you this choice of target curve.  Since it is inherent to the Audyssey system, "cost" is not an excuse for its omission.  I can only imagine someone at some level of marketing injecting the notion that it would have been confusing to the end user or present too much choice (yet that same person apparently was OK with such fidelity-altering features as "Double Bass").

The saving grace is that while the Onkyo implements Audyssey with its default Audyssey curve, when in any THX Cinema mode, it implements the Flat curve.  This is good, because Audyssey's curve compounded with Re-EQ would result in a sound decidedly on the dryer side of things, especially if your room has decent acoustics to begin with.

Ultimately, I have no hesitation recommending the use of the Audyssey system to any 805 buyer, provided you, as THX recommends right in the owner's manual, do a double check of whatever is in your power to second guess, namely speaker settings, especially the subwoofer level.

[Editor's Note: Brian Florian is preparing a much more in-depth review of the Audyssey system, encompassing their stand-alone product, in an upcoming article.]

Go to Part V.

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