Originally Posted by Freddy Ford
This is exactly what Audyssey told me a few years ago when I inquired about how the EQ works. I was told my XT32 will cut peaks only, no boosting to smooth things out. My local dealer also said the same, but I wanted to confirm.
Originally Posted by DonH50
Audyssey, at least the old XT I had, would not boost dips, only cut peaks, but the AVR would boost the overall gain at the end to (re)set the reference level. I do not remember what YPAO and MCACC did; I have a vague memory the MCACC would also only cut using their PEQ (standing wave EQ), not sure about their graphic EQ. No idea on YPAO, never measured it (too many years ago). Be careful when boosting the bass (or anything else); remember +3 dB doubles the power, +6 dB quadruples it, and +10 dB requires ten times the power.
There has always been a lot of misinformation about Audyssey floating around, and this is a good example. Audyssey both boosts and cuts in an effort to achieve a flat frequency response. Different versions of Audyssey have different numbers of control points, which in turn affect the extent to which boosts and cuts can be performed on a macro or micro level with respect to individual frequencies.
But, in all versions of Audyssey, the software can cut peaks by up to 20db, but can only boost dips by up to 9db. That information comes straight from Audyssey, and from its creator Chris Kyriakis. That is true for all channels, but is especially pertinent to the .1 (subwoofer) channel.
Another misconception is that Audyssey gets crossovers wrong, when it sets speakers to Large, or when it sets crossovers below 80Hz. Audyssey doesn't actually set any crossovers at all. It simply reports the measured F3 point for each channel to the AVR, which then sets the channel as Large, or as Small with a crossover, based on its own internal programming. And, that programming can vary a bit from company to company. All that initial setting is intended to do is to inform the user of the capabilities of his audio system.
The final crossover settings will depend on any number of factors, including personal preference. Recommended Audyssey protocol has always been to set channels at a nominal 80Hz (or higher, depending on the initial AVR setting). But, there are two different and completely independent software programs involved in setting crossovers, and that is at the insistence of the AVR makers.
Getting back to the issue of where to set the damping control (also called room gain compensation) I would reiterate Mark Seaton's advice to start at about the mid-point, prior to running Audyssey. And then, to experiment from there. Any method selected will be a compromise, with some potential advantages and disadvantages. But, Mark has worked with Audyssey systems in the installation of many subwoofers, and believes that is the most flexible initial setting to use in order to preserve your options.
One final point that I think is worth making is that there is nothing inherently wrong with using the damping factor, or a miniDSP, or Audyssey, to boost below 20Hz. As was previously pointed out, very low frequency boosts do consume more amplifier power. But, as with any boosts, it is very much a question of individual system headroom. Where a large room provides relatively little room gain, or where there is a relatively shallow dip at 20Hz or lower, some boost may be desirable, assuming that the subwoofers have enough headroom to accommodate that boost.
Audyssey specifically limits the amount of boost that it can add (to a maximum of 9db) in an attempt to keep from over-driving a subwoofer. And, Audyssey will set no control points (and consequently make no boosts) below the measured F3 roll-off point (where the SPL is consistently rolling-off by 3db, and is not just momentarily dipping) of the combined subs in an audio system. But, whether or not a specific boost may be desirable at a specific frequency above that F3 point is for individual determination on a trial-and-error basis. If measurements, port chuffing, or anything else, indicates that too much stress is being placed on the subwoofers in a system, the owner can always back off the damping control, or the sub gain, in order to compensate.