MultEQ vs. MultEQ XT

Can anyone elaborate on the differences between MultEQ and MultEQ XT, beyond what it says on audyssey's site?

http://www.audyssey.com/technology/multEQ_products.html

I've found a couple posts that say the XT version is technically and subjectively superior, but I have issues spending a few hundred bucks for the extra resolution (esp. when the cost to implement xt is probably marginal)

The denon AVR-589 has multEQ, dynamic volume and dynamic EQ and costs $300. If I shell out an extra ~$250 and buy a tx-sr705 I get multEQ XT and I lose dynamic volume and dynamic EQ. So to get XT AND keep all the features of the avr-589 I'd probably realistically have to shell out an extra $500.

I'm sure you get more for your extra $500, but I really don't want all that extra stuff. I don't need extra wattage because my speakers are efficient. I don't need video switching or networking or faroudja video processors or THX certification or 18 audio inputs or gold plated knurled binding posts or bluetooth. I just want good sound at a reasonable price.

Sorry this turned into a bit of a rant, I'm just a bit frustrated by the pricing/feature packaging thing....

Anyone still want to answer my original question?

Hmm. My understanding is that xt has more sampling points and can generate a more detailed correction curve. This is useful whether the system equalizes itself or a professional does the job.

According to the chart in the link above the subwoofer correction is the same for both, but for the satellite channels its 2x vs 16x. I imagine 8x more resolution should make a dramatic difference, but that's just my guess.

Ok, I think these two threads just told me what I need to know:

http://www.avsforum.com/avs-vb/showthread.php?t=1053572

http://www.avsforum.com/avs-vb/showthread.php?t=1096540

In a nutshell, dynamic EQ and MultEQ are preferable to multEQ XT alone, IF you are listening below reference levels (at least that's what I gleaned from those threads). I almost always listen below reference levels to avoid pissing off everyone around me and I can't afford an amp with multEQ XT and dynamic EQ, so the problem is solved.

I am still curious to know what the actual resolution of MultEQ is on the satellites. I know it's 1/4 or 1/8 the resolution of XT, but that is somewhat meaningless since we don't know what the actual resolution is. If MultEQ has a trillion sample points and MultEQ XT has 8x that, then they're both better than they need to be. If MultEQ has two sample points and MultEQ XT has 8x that, then they're both essentially worthless.

Anyone want to provide more in depth information on the technology behind MultEQ?

Yes. Again, the only information available is:

1. MultEQ XT (AVR version) uses "high resolution" filters for the satellites, while MultEQ uses "mid resolution" filters for the satellites.

2. MultEQ XT (AVR version) has 16x resolution in the satellites and MultEQ has 2x (I assume this makes MultEQ XT 8 times the resolution of MultEQ?)

3. "Control points" are distributed such that lower frequencies have higher resolution (does this mean that the points are distributed logarithmically within each channel? Or just that the resolution of the sub channel is higher than that of the satellites?)

4. In the graphing section it states that "it is necessary to use hundreds of points." I'm guessing this means that the best versions of Audyssey have hundreds of "control points."



So, beyond that there is no information about the satellite channel filters, which makes me a tad suspicious. I can imagine a few reasons why Audyssey would not reveal the actual number of sampling points for their filters:

1. It is a trade secret, and revealing the number of "control points" will aid their competitors (somehow I doubt this).

2. Audyssey has a policy of not disclosing technical information beyond what is available on their website (this is just silly).

3. Audyssey has an agreement with manufacturers that they will not disclose certain technical information (this is possible, although I imagine this would only apply to information that would hurt their image).

4. The resolution varies depending on the customer's setup (crossover freq, room response, etc.), and is not easily explained in layman's terms.

4. The number of "control points" in the satellite channels of the MultEQ and 2EQ products is low, and Audyssey is protecting their reputation by not releasing resolution information (This seems most likely to me. That being said, Audyssey seems to be pretty down to earth and I would also guess that the number of control points is sufficient in their lower end products, even if the number sounds low).


Now time for some wild speculation. Audyssey has a graph on their site (which may or may not be representative of their products) showing control points on a room FR plot:

http://www.audyssey.com/technology/g...ges/graph2.gif

Audyssey does not tell us what product we are looking at, but we can make some educated guesses. We know it's not 2eq, because there is low frequency information on the graph, so lets assume it's either MultEQ, MultEQ XT AVR or the MultEQ XT equalizer.

If we also assume the crossover frequency is a standard 80hz THX crossover, we can count 112 "control points" between 80hz and 20khz and we have the following possibilities.

1. The graph is MultEQ which gives the following satellite channel resolutions for the product line:

2EQ (1x)

56 "control points"

MultEQ (2x)

112 "control points"

MultEQ XT AVR (16x)

896 "control points"

MultEQ XT EQ (32x)

1792 "control points"

2. The graph is MultEQ XT AVR which gives the following satellite channel resolutions for the product line:

2EQ (1x)

7 "control points"

MultEQ (2x)

14 "control points"

MultEQ XT AVR (16x)

112 "control points"

MultEQ XT EQ (32x)

224 "control points"

3. The graph is MultEQ XT Equalizer which gives the following satellite channel resolutions for the product line:

2EQ (1x)

3.5 "control points"

MultEQ (2x)

7 "control points"

MultEQ XT AVR (16x)

56 "control points"

MultEQ XT EQ (32x)

112 "control points"

Option number one is out because Audyssey advertises "hundreds of control points." If was thousands, they would let you know (MultEQ XT amps would probably say 896 band equalizer on the front). Option number two also seems unlikely since a 3.5 band EQ is worthless, and 112 hardly qualifies as "hundreds."

So the most likely case is that 2EQ has ~7 control points, MultEQ has 14 control points, MultEQ XT AVR has 112 and MultEQ XT EQ has 224. This makes sense. These numbers are adequate, but don't sound fantastic and therefore are not advertised (eg, 2EQ sounds sexier than "7 point equalizer," which connotes low budget car stereo). Remember, this is just a guess based on a graph that may not be accurate.

Now that I think about it, the # of control points are probably powers of 2 and the control points probably extend beyond the crossover point.

So instead of 7,14,112 and 224 control points its probably 8, 16, 128 and 256 control points.