Dynaudio (Evoke) + ExpertPro 220

[Confused]

@Jean-Marie ,

I accept that it's a thought experiment but take a look at the impedance plots in Stereophile speaker reviews. There are usually huge swings in impedance in the below 150 Hz range, regardless of speaker type so, as a thought experiment on my part, I find it hard to believe that there are all that many speakers which are going to require so little phase correction in that region that the effect of SAM at 0% would be indistinguishable from the result with SAM off, PROVIDED the right thing is measured and that it is measured in a way which can reveal the difference.

I make those 2 provisions because of my experience with SAM at 0% and at very low levels (below 25% or so). The main thing I notice with SAM at that level isn't a change in bass levels but rather greater bass clarity and definition and I'm not certain that frequency response is what we need to measure in order to demonstrate that. My second proviso about measuring things in the right way relates to the fact that measuring the same thing in different ways can reveal different things which are important, as can easily be seen when you compare a measurement of total THD which is a simple % and compare it to a measurement of THD showing the spectrum of the distortion which reveals significantly different information and which tends to be much more indicative of the sort of sound to expect from that amount of distortion.

@David A

We are in violent agreement, especially the fact that the frequency response within the listening room is probably one of the least significant measurements to study the impact of phase correction. 

I am not surprised that SAM at 0% gives you more bass clarity. 
I’m using it at 100%, and believe it or not, but on some pieces it results in less bass than without SAM because SAM is correcting some kind of what I would call overshooting of the speaker for certain frequencies. 

Jean-Marie

One thing I have just noticed is that we (based on a not very representative sample of only three!) seem to be getting different results.  In my case, SAM 0% appears to give a slight increase in bass versus SAM off (much as @David A expected and Floyd Toole predicted) @jvoki (previous page) gets the opposite result, more bass with SAM off versus SAM 0%.  Then we have @Delija who reports that SAM 0% and SAM off yield the same result, in terms of FR at least.

So three results, and all different.  Interesting, but I am not at all sure what to make of this!