Thanks Uli, I was hoping you might add to this discussion as someone who I believe is on the quest that is the subject of this thread. Your input is greatly appreciated
I'm working on room correction now for many years already. Simply driven by the idea to get a good playback WITHOUT turning my living room into a studio. I truly believe that in most cases music is not played in optimal environments but changing the environment is not possible. If you can built your own dedicated listening room then just DO it. If you can't then room correction by applying digital filters is the right way to go. Of course also a mix is allowed.
Yes, I agree, most room treatments are not aesthetically acceptable to living rooms - fine for man caves but I want to share my music enjoyment with all the family. In a way I find that the room treatment can often be introduced in discussions as an impediment to discussions of improvements in other areas. Using your optical analogy below, it's like saying that a dark room is the only way to enjoy video or TV & any other discussions for improving the picture are trivial, by comparison. I'm not saying that you are doing this, btw - it's just an attitude that can permeate some audio forum discussions. I'm not against room treatment or speaker discussions, I just think that there are lots of other interesting areas for improvement also.
But is that the end of optimization? I have noticed the hot dicussions about the differences of analog and digital playback. How often is it argued that the band limitation of 16/44 is the drawback. And we must at least use 24/192 to grab all the musical details of a vinyl recording?
But I have also noticed that even a good setup including room correction can sound nasty or fatiguing. So what's behind ? That's what I'm trying to understand.
Of course the basic flaw of stereo playback is the crosstalk. It is studied and worked on for a long time now. We know that a crosstalk cancellation can improve the result but it also has drawbacks. How many stereo setups do you know or even use with speakers positioned close together (to optimize crosstalk cancellation) instead of the usual triangle?
Well, If putting the speakers closer together & using Ambisonics leads to a more realistic soundstage then I'm all for it - I don't consider that much of a problem but there may be other issues I'm not aware of?
Then I have come across publications by Sengpiel, see http://www.sengpielaudio.com/FrequenzabhHoerereignisrichtung.pdf and http://www.sengpielaudio.com/Shuffler.pdf. This is a topic independent of room correction. Indeed this topic is about SUBTLE but still important influences.
But dealing with digital filters of course also allows to play with introducing a frequency dependent crosstalk. That's why I have have got more and more interests on psychoacoustic aspects.
Thanks for the links - I will look for the translated papers as my German isn't so good. Yes, I'm with you on the psychoacoustic aspects & believe that it should be the next stage of development in audio reproduction
My personal actual model now uses an example from optics:
Imagine to look thru a pair of binoculars. Each ocular is perfect. We see 3D pretty well. Indeed we are lucky here, there is no crosstalk. No effort for the brain.
Now assume that each ocular has its own focus control. And now let's assume bad influences on the control. It may be influenced by noise, certain frequencies or jitter. Both focus controls may change sync'd or fully independent.
I believe everyone can easily image that the view thru the binoculars is not pleasing. The question is: how much of the distortions is allowed ? Big focus changes will immediately be unacceptable. But can you imagine that there is just a subtle distortion which is not noticed at first sight? Which will lead to fatigue without knowing why?
I hope you get the idea. I believe that's the same with listening by two ears (but not as obvious as the optical example). Our brain has to decode the sound. And if the sound contains a certain kind of distortions, different on each channel, the brain has to do more decoding work. I'm convinced that's the reason for annoyance and fatigue.
I agree. If our reproduction system follows all possible psychoacoustic principles (within the limitations of that system) then it will be optimal for that system. It's discovering what these principles are that fascinates me & where I believe progress can be made
So I'm also motivated by the same idea that has lead John to start this thread.
Right now I have found two answers. One answer is to add some frequency dependent crosstalk. I'm not fully happy, it seems that we still do not know enough what's the best compensation curves are and how much amount we have to add. Btw it is difficult to measure. Subtleties are always difficult to grab. So what are the best test signals and so on.
A second answer I have found thinking about the equality of playback channels. Assuming the existence of data dependent jitter and knowing that the stereo information is different (otherwise it is not stereo) the question arises: how much do we recognize the unequal distortions of a DA conversion. So I have made a test by coding the L-R channels to M-S before DA conversion and decoding the analog signals back to L-R right after the conversion by an analog circuit. The idea is to share the distortions on both L-R channels.
I had the opportunity to start a test during a 3-day audio presentation with Acourate workshops. The audience did not know about the principles. So the people could only hear the sound with or without the "black box". After the show the box has got the name "cleaner" by the audience ! And indeed I have got a new product, the AcourateCleaner
Ok, I think I got what you are doing - using minus & sum of L & R channels as the input signal into a D/A converter & untangling the output back to L & R channels so as to ensure any distortion is equal across both channels. Interesting approach. The next step (but you've already thought of this, I'm sure) would be to use balanced or differential signals so that the equal distortions on both channels cancel (to some extent, anyway)
In the meantime I have got some more questions. E.g. there is aliasing. Aliasing means that frequencies get mirrored back into the audible frequency range. Again left and right channel contain different information, again we get different distortions. Can we perceive it?
For sure images & noise above half the nyquist frequency can be detrimental to our audio perception through all sorts of mechanisms. Getting rid of these images in a way that is not detrimental to the audio signal would seem to be sensible.
At the end: is that all psychoacoustic? Or is is the question how much decoding effort is necessary?
Indeed, I tried to say this awkwardly in my first post - I guess it's the study of how we hear what we hear in the natural environment & how that can best inform what way our audi reproduction should use these principles to create the best illusion possible.
I've been of the opinion that understanding our physiology has a lot to do with getting better performance from audio systems.
Is the discussion of distortion germane/allowed on this thread?
Crosstalk and delay times have influenced the design of loudspeakers. See Peter B's 'Perfect 8' thread on this forum, also Audiokinesis Zephrim loudspeakers.
Just a note on my system and I do not fully understand the how,what why. I have two 67 inch tall satellite speakers as my primary right and left. I place them about 46 inches from my back wall ,slightly toed in. The speakers are 3 ways with 4 5 inch woofers,1 d54 mid,and 1 d21/2 tweeter. I use two pair of psycho speakers. The first pair is mounted up above the satellite about 7.5 ft on the wall and about 1.5ft outside of the satellite. The other pair is mounted in between the satellites,centered equally between and at the height of the d54 and d21/2 satellite drivers. I have the center psychos toed in,but the upper psychos less so. Each psycho pair has a primary or secondary role,the left output level is lower then the right and both seem to have very little diectionality then the satellites.
I use one power amplifier to drive both pairs of psychos and the amplifier has output level controls. I also have the center pair connected to a Niles switch which also has a volume pot. I run the amplifier output at about 40 percent and the Niles volume at level 2 which is low. I can make adjustment if I want to increase midrange presence or depth of field. I believe from outside to outside of the satellites is about 7ft.
The outcome of all this is I have a complete wall of sound from top to bottom and side to side which is about 14ft. The so called sweet spot has a boundry to the outside edge of the satellites,but can minimize depending on the recording. The clarity,low level detail is exceptional and dynamics as well. The soundstage is as 3D is as possible and the recording has a time and distance quality that seems lifelike.
Doing this in the digital domain should prove exciting to sound enthusiasts. I would think the greatest challenge would be to only use the two primary speakers. I have often thought this would be a good project for a high end speaker manufacturer.
Yes, absolutely, if by physiology you don't just mean the mechanical operation of the ear but rather the full mechanism of the perception of hearing? Both work in unison, of course & are reliant on both working correctly for the perception we call hearing but I'm of the opinion that the real important elements of our perception are to be found after the signal enters the auditory nerve. It's the processing stages & in-built "algorithms" that I'm interested in.
Is the discussion of distortion germane/allowed on this thread?
Of course - we can learn from all of the various presentations of sound
Crosstalk and delay times have influenced the design of loudspeakers. See Peter B's 'Perfect 8' thread on this forum, also Audiokinesis Zephrim loudspeakers.
Yep, I mentioned these already & thought they were interesting & noted Griesinger's research into spaciousness & envelopment which echoes (sorry for pun) the late reflections which is apparently one factor in the operation of these speakers
Roger, it sounds interesting but I'm not sure I understand your setup but then I'm very tired after a full day's physical work, which I'm not used to
I presume you or someone designed your setup? Psycho speakers, quesque c'est (to badly quote David Byrne) - not some sort of insane speaker, I presume?
I don't know what a Neils is - is this the psycho box you mentioned before?
Roger, it sounds interesting but I'm not sure I understand your setup but then I'm very tired after a full day's physical work, which I'm not used to
I presume you or someone designed your setup? Psycho speakers, quesque c'est (to badly quote David Byrne) - not some sort of insane speaker, I presume?
I don't know what a Neils is - is this the psycho box you mentioned before?
Yes my engineer friend who was in audio from the 1970's to 1995 designed the system. The center pair is my addition. The psycho-acoustic is my shorthand. The Niles is not my passive black box,that is seperate.
Roger, it sounds interesting but I'm not sure I understand your setup but then I'm very tired after a full day's physical work, which I'm not used to
I presume you or someone designed your setup? Psycho speakers, quesque c'est (to badly quote David Byrne) - not some sort of insane speaker, I presume?
I don't know what a Neils is - is this the psycho box you mentioned before?
I don't understand psycho speakers either. Are the fed a signal that is different from what goes to the mains? And are you saying your sweet spot is the full width of the main speaker placement?
I don't understand psycho speakers either. Are the fed a signal that is different from what goes to the mains? And are you saying your sweet spot is the full width of the main speaker placement?
The signal to the black box is a full signal, what signal comes out to the psychos is processed. The satellites are full signal. Yes the sweet spot is the full width of the satellite speaker placement,recording dependent it seems.
....The outcome of all this is I have a complete wall of sound from top to bottom and side to side which is about 14ft. The so called sweet spot has a boundry to the outside edge of the satellites,but can minimize depending on the recording. The clarity,low level detail is exceptional and dynamics as well. The soundstage is as 3D is as possible and the recording has a time and distance quality that seems lifelike.
...
thats spot on with my results as well. recording dependent as you noted, but yeah, its normally quite magnificent and at times can be down right spooky.
thats spot on with my results as well. recording dependent as you noted, but yeah, its normally quite magnificent and at times can be down right spooky.
Dingus, how are you implementing Ambiosonics - a bespoke solution like Roger or an off-the shelf solution?
I see this entry-level DSP box for sale & wonder if anyone has experience of it?
There also seems to be software on the Ambiosonics site - again, anybody used any of these apps?
I presume that standard music is being processed in real-time in both Your & Roger's system?
Dingus, how are you implementing Ambiosonics - a bespoke solution like Roger or an off-the shelf solution?
I see this entry-level DSP box for sale & wonder if anyone has experience of it?
There also seems to be software on the Ambiosonics site - again, anybody used any of these apps?
I presume that standard music is being processed in real-time in both Your & Roger's system?
you would have to go through the pdf above to get the idea behind my speaker system. sorry, i did not intend to imply that i used ambiophonic software in my system or other DSP beyond what my HT receiver and Oppo player can do. the key to my system is getting the optimum channel delay / distances dialed in, which is done via the HT receiver and speaker placement.
For me my system was designed in the 1980's ,but I remember that Helmholtz was well studied and mentioned. I will make a hardcopy. What a fine reference,thank you.
Yes, absolutely, if by physiology you don't just mean the mechanical operation of the ear but rather the full mechanism of the perception of hearing? (...)
Somebody mentioned that a small bit of reverb seems to sound better (was it here or the Uli thread?). Has anybody got any measure of what level of reverb is just enough or is there a reference for this?
Reverb sounds natural because that is what we have been accustomed to in nature. Question is, how much is too much?
From a production standpoint reverb is recorded and sometimes artificially added. From a reproduction standpoint, it is the listeners call. The listener can spec his room, choose the loudspeakers knowingly or not because of what the radiation pattern brings to the table, add it electrically, etc. etc. in order to mimic or approximate what he has come to expect from an entire life's worth of aural experience.
A broad stroke quantification of what would in a broad way constitute a typical experience paradigm with regards to the reverb in actual venues, would be a comparative RT60 chart.
