Its realy difficult..
Of course the HIFI in another room is reality..with all the sonic distortions..
I guess the problem is we are trying to make one location sound like another..
Perhaps thats why the HIFI can't do this it has to be tuned to the room acoustics..If you move it it will sound out of "tune"..
We are back to the Bass & treble controls...
So if we make an amp or system flat and have zero distortion its flat with reference to what...
Regards
M. Gregg
Of course the HIFI in another room is reality..with all the sonic distortions..
I guess the problem is we are trying to make one location sound like another..
Perhaps thats why the HIFI can't do this it has to be tuned to the room acoustics..If you move it it will sound out of "tune"..
We are back to the Bass & treble controls...
So if we make an amp or system flat and have zero distortion its flat with reference to what...
Regards
M. Gregg
Excellent point. The audio equivalent is deliberate manipulations of the frequency response as alluded to by ThorstenL. There is no denying that certain non-flat response curves can sound impressive, or "larger than life" so to speak, in various different ways, but I find that the sense of being impressed is only short lived.
Our brain knows what sounds normal and eventually over time it "rebells" against it, whether it be by listening fatigue, or by attempting to psycho-acoustically compensate for the error - eg learning the error through constant exposure to it across all music types, and then factoring it out - which is something I'm sure that happens with bass response peaks and dips caused by room modes, which we eventually don't notice nearly as much with time. If we move the speakers thus re-arranging the peaks and dips it then throws them into stark relief, until we get used to the new arrangement.
Prolonged exposure to music on speakers that are tonally unbalanced I find gradually shifts my sense of what sounds balanced. For example too much bass eventually sounds more balanced, which then makes you feel like the bass needs turning up again to reach the previous perceptual balance etc...and can cause a slippery slope effect.
On the other hand prolonged exposure to a tonally balanced system doesn't seem to have that effect, at least on me - my perception of balance doesn't shift much at all even after hours of listening. This whole shift of perception / acclimatisation thing that happens with our hearing is an excellent reason why even if we're judging subjective quality through listening we still need measurements as an anchor to stop us sliding down the slippery slope...
Frequency response is of particular interest when it comes to "deliberate errors that might or might not sound pleasing" because some flaws in audio quality are irreversible and cumulative (like distortion and noise, dynamic range compression, excessive room reflections etc) whilst frequency response errors can be corrected by complimentary errors elsewhere in the reproduction chain.
It could be that someone that prefers a certain small "tweak" to the frequency response is actually unwittingly correcting for a complementary error elsewhere in the chain, rather than genuinely liking a non-flat end-to-end response. Because of the circle of confusion and the amount of processing that goes on in most recordings its very hard to know for sure though.
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If room acoustics are the problem..
What are the frequencies required to Null room sound or what frequencies will over come room acoustics (I know you can't remove them).
How do you create a flat frequency response that will remove room "sound"..
Then again what is needed to fool the ear into the close to reality sound..
Distortion....Humm an open window with a lorry driving by....we can tolerate some distraction<<<is this why after a point distortion is not a problem..Then again the ticking clock comes to mind removed by the mind after a point so you only notice when it stops... As long as the distortion is constant..with no change can the mind remove it like the clock..
Regards
M. Gregg
What are the frequencies required to Null room sound or what frequencies will over come room acoustics (I know you can't remove them).
How do you create a flat frequency response that will remove room "sound"..
Then again what is needed to fool the ear into the close to reality sound..
Distortion....Humm an open window with a lorry driving by....we can tolerate some distraction<<<is this why after a point distortion is not a problem..Then again the ticking clock comes to mind removed by the mind after a point so you only notice when it stops... As long as the distortion is constant..with no change can the mind remove it like the clock..
Regards
M. Gregg
Pollsters do it every day.
And the results are accurate, plus or minus 5%, 19 times out of 20.
How would we expect an audio amp to perform if the max power THD spec were given as 20W p/ch @ 5% THD with an asterisk that noted we really mean 20W p/ch @ 0 to 10% THD except every 20th song, in which case it will be [some value] greater than 10% up and including 100%?
Or, alternately, a panel of listeners consistently gave the amp high marks but every 20th time the same group listened it induced nausea?
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One other analogy..
The aeroplane...do you design a plane and not wind tunnel test it..
Test the wings separate the fuselage and tail plain all made with different people with a different plane in mind...then bring it all together and hope it works..
If you only test each HIFI component on its own and bring them all together..They have got to be flat response to work any thing else forget it..<<measurement
So how do you tune the HIFI? (with mods) or adding components that shape the sound.. adding and removing distortions and of course selection of components..and what transports work best with....<<<wind tunnel test..
Regards
M. Gregg
The aeroplane...do you design a plane and not wind tunnel test it..
Test the wings separate the fuselage and tail plain all made with different people with a different plane in mind...then bring it all together and hope it works..
If you only test each HIFI component on its own and bring them all together..They have got to be flat response to work any thing else forget it..<<measurement
So how do you tune the HIFI? (with mods) or adding components that shape the sound.. adding and removing distortions and of course selection of components..and what transports work best with....<<<wind tunnel test..
Regards
M. Gregg
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Not I!
Sorry, it probably read like that. Sound Quality Index was just my shorthand for relating what we can measure to what we perceive as quality sound. I don't think one number will do it, no way.I would dearly love to see some suite of measurements that DO give us a good indication of sound quality. But I need to do a lot of thinking before I post any more nonsense.
My business is images and they are a lot easier to judge. Not without problems and subjective debates, tho - even there.
Although the room can introduce aberrations that interfere with a good reproductive performance, it is the same aberration that would happen with live music in the same room. I don't feel these are problems that relate to the reproduction of recorded music vs a live performance, since a bad sounding room sounds bad regardless; you would not want to listen to your cousin singing and playing guitar in that room either, if overall quality of the sound was important, or if you were attempting to record the performance.
This is different from audio amplifiers (etc) where there may be an issue with the amplified performance that is absent from the live one, and the goal is to eliminate the issue with the amplifier.
Similarly, our brains smooth over many inputs ... otherwise merely sitting at the keyboard and typing this sentence would be impossible. Without this ability, is doubtful even the act of listening to a hifi would be possible at all. So, this is not only normal, it's necessary.
We don't expect the same fidelity from an office radio than we do from a hifi, and much of that is due to the fact we are deliberately listening to the hifi rather than allowing our brains to essentially ignore the details and giving us the smoothed over result only, as with the office radio. Indeed, if everyone actually critically listened to the radio, the purpose of being in the office ... get some work done ... would be the task that is smoothed over, done without thinking.
If the average office radio were all we wanted, there would be no hifi industry at all and the whole discussion would have no earthly use; an adequate modern office radio that serves as a background to the primary task of work is a done deal and needs no further refinement.
Although room problems and sensory distractions are an everyday fact of life, they are not reasons to say we've done all we can do with regard to hifi reproductive quality, nor are they excuses for failure to continue to seek improvement. That they are issues with overall reproductive quality is undeniable; that they are significant to the point where no further work on amplifier distortion is needed is giving them too much credit.
Since an amplifier can create distortions that no room could, we should be trying to eliminate (or find a metric to measure) those specifically. Maybe those that are left once that set is solved or determined, are benign and don't matter as much. It is in that sense the issues you raised have their value. For example, there are some who say flat frequency response is not so important compared to other forms of distortion; perhaps the typical room problem, which introduces alterations in flat response yet is not necessarily bothersome, is illustrative of why; it's a normal, natural issue we tolerate well.
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Musicians here on the forum understand well that they would sound in different rooms differently. Like, in one hall they sound nice, in another like a cat's cry. Why should we expect the same real sound in different rooms? And is equipment guilty if in bathroom the orchestra sounds like an orchestra in bathroom?
You have hit the nail on the head..."Good" sound is dependant on the ability of the equipment to make the sound regardless of room..
The only thing is how do you judge "good" sound, its based upon what the listener hears...If it sounds like an orchestra in a bathroom its good sound....however if when it moves from room to room it dosen't sound like an orchestra what then?
This only leaves measurement...its either electricaly good ar bad...Your ear can transfer sound with electrical signals....Is what I hear the same as what you hear with the same sound?
Regards
M. Gregg
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I agree..
Then its down to emotion.. how good does it sound to the listener...Fairground ride
...especially when construction by your schematic was designed by another guy who believes that the wire drawn on schematic diagram is the same wire in all it's points.
I remember professor Vintizenko in our institute, he designed layout software called KARL running on mainframe computer. It required myriads of parameters to be entered in order to calculate optimal layout. I always thought it was crazy, since intuition based on experience plus several iterations of prototyping and measurements allows to make things much faster and cheaper.
...but may be it is me who is crazy; I still regard SPICE in electronics design as funny toy.
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I don't understand why it would. As far as I can tell, it does not. 10 cycles is short and hard to analyze, but I made a 4KHz burst 12 cycles long - zero to zero crossing - and it appears pure, no other tones.
What am I missing?
You are missing the word starting
Pure tone may be strictly pure only and only when it started infinite time ago and did not change since then.
I guess if you are looking at the amplifier, then you have to look at the amplifier and speaker combined...Amplifier damping or to much of it is a factor phase shift and speed of response..transient capability.. It goes on
It would be interesting to build an amp with "controls" for 2nd and 3rd harmonic and tweek in a listening test..I think alot of this is personal taste..
It would be interesting if you could remove both and find out nobody liked it..
Why can't I have a Krell the size of a shoe box?
Find my old thread about Harmonizer.
It is possible, but nobody in reality likes added harmonics, when such a knob presents. Try it and report. The only when it may be useful, to change timbre of soloist recorded in a damped studio booth. Such devices sometimes are added to channel strips.
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