Originally Posted by pepar
Feri asked me this on Facebook Audyssey Tech Talk. It could be that they have a damaged mic (humidity or static spark can kill the HF mic response resulting in a boost). Or it could be that the speakers are set to Large and so the sub is not doing anything. Without data it's hard to say.
There is nothing specific about a big room that would cause the algorithm to behave this way.
May 02, 2012 10:13 pm
After over-thinking and re-parsing Feri's question and your reply, it was thought that the question should be asked a different way.
The context for the mulligan is Pro's initial curve options based on room volume, comments regarding Audyssey Reference being a translation of X-Curve for the average residential-sized space and the user's space being considerably larger than that.
So Pro allows fine-tuning, but the absence of this in the consumer version is not a possible factor in what the user is experiencing?
May 03, 2012 05:05 am
The standard Audyssey target curve rolls off the highs so it wouldn't be causing a boost unless the starting (before) response has severely rolled off highs. That would not be due to the large room, but to the speaker or the measurement (far off axis).
Depending on how large and reverberant the room is it could certainly need more high frequency roll off to balance the response perceptually. This is something one could do with the Pro software by, for example, selecting the SPMTE 202M preset or manually adding the roll off.
However, the way it was presented to me earlier it was implied that Audyssey is actually boosting the highs because the room is so large. That is not the case unless there is something wrong with the mic.
Thanks for sharing! I do not understand his answer, though, as the logic employed seems very chicken-or-egg to me:
1. The target curve for a smaller room is "flat out to about 8 kHz, then dips to about –2 dB at 10 kHz and then a little more at 20 kHz."
Source: last post here
2. For sake of argument, lets say the recommended target curve for a larger room is flat out to 8 kHz, dips to -4 dB at 10kHz and then a little more at 20 kHz.
Source: numbers are just a guess, but representative and feasible based on visual inspection of the 3 target curves in the pro kit manual
3. In his reply above, he acknowledges a larger room "could certainly need more high frequency roll off to balance the response perceptually".
4. Thus, how does using curve 1 in a larger room not directly equal
greater boost (or less cut) in the high frequencies when using Audyssey
? In this example, would we not expect 2 extra dB's of 10kHz energy from the loudspeakers when using the original (small room) target curve vs using the recommended (large room) curve? It's clear that the room is not creating that extra 2 dB's...Audyssey's EQ is creating that extra energy because we are telling it to through our choice in target curve.
I agree with his first paragraph--that a room cannot boost HF on it's own accord. Likewise, I have never experienced HF boost issues in any setup with EQ bypassed. It's only when Audyssey or some other EQ is engaged does it (potentially) become an issue.
I acknowledge that my large room speakers are more polite than my small room speakers, and maybe this is playing in to the equation as well. In theory, though, if Audyssey is boosting the HF of my polite speakers to get them to an intended, optimal (i.e. non-bright) level, then it should not be offensive and bright but rather pleasing instead (like a veil has been lifted)--since they are finally at an optimal level. But the degree of EQ needed to get there is acknowledge by Chris to vary by room size/reverberation characteristics in the high frequencies. That said, is reference level minus 2 dB the correct level for 10kHz in my room or is reference level minus 4 dB right? It sure sounded a lot worse at minus 2 dB versus minus 4 dB (i.e. too bright).
Great further reading on the topic here
, which I have slowly been trying to digest.
Finally, "However, the way it was presented to me earlier it was implied that Audyssey is actually boosting the highs because the room is so large. That is not the case unless there is something wrong with the mic."
Would a bad mic and/or faulty equipment not have deleterious effects regardless of the room size? I think this response misses the intended point."However, the way it was presented to me earlier it was implied that Audyssey is actually boosting the highs because the room is so large."
and"There is nothing specific about a big room that would cause the algorithm to behave this way."
Well sort of. To summarize the entirety of the above:
A major goal of the Audyssey algorithm is to achieve a target frequency response. Audyssey recommends different target frequency responses based on room size to "achieve correct spectral balance". By definition, then, the algorithm intentionally creates more HF energy using curve 1 than using curve 2 or 3. Thus, using curve 1 in a large room (or a small room for that matter) will be brighter (i.e. more boost/less cut) than using curve 2 in that same room, all else being equal. How a consumer user is expected to deal with this is beyond me, since they have only 2 curves from which to work--the flat curve and the brightest "roll-off" curve. The curves intended for larger rooms, which have greater HF roll-off, are simply not there. Thus, their systems will be perceived as brighter than intended, all else equal.