What measurements correlate with X?

[cat6man]

can someone provide background or links regarding which types of measurements correlate with some specific attributes of stereo?

In particular: what helps/harms the image stability and specificity of instruments/vocals?  when i hear (or think i hear) an instrument in a certain location (relative to width or depth of the music), is there a measurement that correlates with this?  or the decay of a note or a vocal line as it diminishes?

 

if i were to speculate, i wonder if something in the correlation between left and right channels is critical?  is correlated noise/distortion worse than random noise/distortion in a stereo reproduction?

 

cheers

 

[cat6man]

On 3/4/2020 at 6:08 AM, John Dyson said:

I am glad that you mentioned IMD as a source of damage to a stereo image -- I have been developing software that in it's natural, most degenerate state will produce IMD very easily.   Even a slight amount of IMD has a strong effect on the ambiance/clarity of a recording.   Clarity has somewhat of an effect on imaging.   IMD damages something good about audio that I have problems actually describing, and it doesn't take much of the IMD to do the damage.

 

IMD is insidious...  IMD isn't just insidious, it is develishly insidious.   Given a minor about of IMD, I have difficulty in detecting it unless doing a direct A/B comparison.   Some forms of IMD appear as a 'fog' over the sound (if I can get my act together when I am less busy, I might be able to create an example.)  It is really interesting what happens to audio when it has been processed in certain ways.  Those forms of processing were ALMOST thought to be benign, but really were/are not benign at all.   Some methods (unfortunately sometimes necessary to do), produce very stealthy, but damaging IMD type distortions.

 

Since ambiance is significantly affected by certain kinds of IMD behaviors, then it can have some effect on the image.

This is actually one of my own frustrations against alot of commercial recordings.

 

John

 

 

john,

can you give us a ballpark idea of what levels of IMD can cause the problems you describe?

[cat6man]

On 3/4/2020 at 5:19 PM, fas42 said:

I of course disagree with John - if you want to want to call the distortion anomalies IMD that's fine - but this "IMD" as audible unpleasantness is a function of the integrity of the playback chain, irrespective of the nature of the recording - a sub-par setup will make a very high percentage of recordings irritating to listen to, AND lose much of the musical detail; if the integrity of the chain is lifted to a high enough level, then you win everywhere: all the detail is perfectly clear, tonality is fully natural, and every recording becomes a pleasure to listen to.

 

what is that 'high enough level'?

has anyone quantified it?

[cat6man]

4 hours ago, John Dyson said:

I should probably measure it -- but it isnt very much.  It is the amount that is generated by a gain control at approx 1msecs attack/40msec rleease over a 10dB gain range.  (I cannot get more specific than that.)  It is very repeatable -- everytime you hear a DolbyA decoded tape, you are hearing it (sadly.)  Maybe that is why they dont decode much pop music, but just EQ it away?

 

 

thanks.......i'm very (or rather, was a very long time ago) familiar with the SQ degradation of DolbyA.

 

if you do measure it, could you try to get a peak as well as average measurement?  in most cases, i have a very low comfort level with the idea that average measurements capture the types of SQ effects i'm interested in.

in other words, i believe good average measurements are necessary but not sufficient.