The funny thing is that Dr. Toole in his answer obviously understands why judging speakers for music reproduction in mono which are later used for music reproduction in stereo is nonsense. He is referring to the point that “All direct sounds arriving from ±30 deg provide HRTF characterization for the wrong incident angle generating an unavoidable timbral error”. That’s correct at least to phantom sources being reproduced by a stereo system and localized in a ±10deg window around center. The closer you get to 30 deg from the center, the more likely sources created by any type of intensity stereophony are getting closer to ´the real thing´ in terms of timbre. In the recording community this is a well-accepted thing known for decades. Many recording engineers have their own methods to counter the fact that mono sources panned close to center using intensity stereophony change their timbre and perceived elevation. The easiest and wide-spread cure to that is using time-based stereophonic mic arrangements and panning in the first place. Funnily this is not a very common thing with popular music being recorded close-miked in an anechoic studio.
Judging a speaker in mono which later will be used for stereo will lead to inevitable misjudgment in most of the important aspects of reproduction quality, especially tonal balance, localization, depth-of-field and ambience.
Response errors like frequency-depending localization, width of phantom sources, blurred or alternating localization, compressed depth-of-field, too broad or too narrow imaging, overlaying reverb pattern of the listening room or stereo imaging appearing to be too close to the listener or too far away?
[moderated]
That’s simply untrue. A loudspeaker which creates a well-balance tonal perception coming in from 0 deg angle to the listener will lead to an unbalanced one in a ±30deg constellation (i.e. stereo). A loudspeaker creating a more or less stable and ideally sized localization in a mono environment will lead to unstable and overly broad phantom sources in stereo. A loudspeaker giving a fairly distanced and ´natural´ perception of depth in mono will lead to far-away, distant and undynamic spatial impression in stereo. I could continue this list endlessly…
No, the research and the comments by Dr. Toole say rather the opposite - you seem not to understand it.
So you hear in an anechoic environment?. That’s is of course one more step further away from common listening conditions and making you results even more invalid to everyone else.
Furthermore, die example shows that you seem to have no idea about time-related stereophony which is the most common method in recordings of acoustic concerts to create both ambience and ´natural´ tonal balance from all angles.
The right tonality is depending on the angle the sound from the speaker is coming in. If this is 0deg (mono), judgement of tonal balance is fundamentally differing from ±30deg (stereo), so verdicts are incompatible.
If a stereo setup in a random room cannot give any useful judgement on sound quality, how can a mono setup in a random room? It is acoustically even further from what will be the listening situation later.
There is a certain truth in the claim that verdict in one room cannot be transferred to others without reflecting the differences. That is why it is important to have basic understand of speaker directive, rooms RT, listening distance and possible interaction between room and speakers in the bass region before doing a listening test and before providing advices to others.
There is no such thing as ´smooth directivity´. The question whether [moderated] Amir can draw a straight line into a graph or not has nothing to do with the speaker´s interaction with the room.
If you want to judge a speaker´s interaction with the room you need to know directivity index in the relevant frequency band being either low, medium or high (or zero) as well as judging if we talk about fairly balanced or constant direcitivity, continuously increasing direcitivity, being any steps up in DI or alternating directivity as well as keeping the room´s RT60, ideally tonal data on early reflexions plus listening distance and wall distances in mind.
If ´smooth directivity´ is translating to anything that is either constant or increasing or sharply increasing, being high or low index, it does say nothing about sound. It can lead to a balanced reproduction or anything utterly dull, dark, muddy, murmuring, voluminous, midrange-heavy, present, aggressive or damped.
That’s what people will get if they follow your advice on ´perfect directivity´ being unlucky enough to choose the wrong speaker for their environment.
I have called this method of drawing a line into the graph and calling it smooth in order to predict sound quality in a room ´hifi-astrology´. [moderated]
