If I have my ears in a horizontal plane which is half-way between the horizontal plane of the tweeters and the horizontal plane of the mid-range units, and equidistant from the left and right speakers, I can hear a nice stereo image. By this I mean that individual instruments appear to have distinct physical locations (at least in the left - right dimension). However, if I move my head by just a few centimetres, the image is lost and all the instruments become smeared and jumbled.
Presumably, high frequency content is important for this 'imaging'. At 3kHz a movement of just 5.6 centimetres takes us from a sound wave peak to a trough, and at 6kHz just 2.8 centimetres will do it.
It seems that there must be a physical limit on how big the sweet spot can be, based on sound wavelength considerations.
To me, an 'extended sweet spot' seems to be a physical impossibility.
Any thoughts or comments?
Presumably, high frequency content is important for this 'imaging'. At 3kHz a movement of just 5.6 centimetres takes us from a sound wave peak to a trough, and at 6kHz just 2.8 centimetres will do it.
It seems that there must be a physical limit on how big the sweet spot can be, based on sound wavelength considerations.
To me, an 'extended sweet spot' seems to be a physical impossibility.
Any thoughts or comments?
I've noticed ear/head position is critical to imaging. It is very revealing just to play a test tone (both channels) at quite high level (try different frequencies in the critical 1 to 5kHz region) and then move slowly around the room. You can find points where millimetre movements of the head can virtually null the sound altogether. Every room is different too of course, some are hard acoustically and others soft and absorbent.
(Try this... kneel down a foot or two in front of the speakers but facing away from them... do you hear a rock solid image behind you
)
(Try this... kneel down a foot or two in front of the speakers but facing away from them... do you hear a rock solid image behind you
)
When playing music, it's possible to get a very large "sweet spot" even out to the edges of the speakers, or past. Everything has to be just right though, and with a well recorded source.
Stereo wasn´t made to work while
- walking around or
-listening to test tones.
While you move your head from left to right and back and concentrate on the comb filter effects generated by the changing distance to the left and right loudspeaker, you won't experience good stereo. Keep your head at a fixed position. I can move my head 15 cm to the left and 15 cm to the right of the "sweetest spot" before the stereo scene STARTS to degrade.
A 3 kHz fundamental tone is a very rare thing in music. I don't know of more than a handful of instruments that have a 3 kHz fundamental. And I bet that you have difficulties to clearly locate a 3 kHz continuous sine sitting blindfolded in a room, even when played by a single speaker.
The medium of musical fundamentals is more like 300 Hz. There should be quite some harmonics below 3 kHz to help your brain put the instruments precisely on the stereo base.
Rudolf
- walking around or
-listening to test tones.
While you move your head from left to right and back and concentrate on the comb filter effects generated by the changing distance to the left and right loudspeaker, you won't experience good stereo. Keep your head at a fixed position. I can move my head 15 cm to the left and 15 cm to the right of the "sweetest spot" before the stereo scene STARTS to degrade.
A 3 kHz fundamental tone is a very rare thing in music. I don't know of more than a handful of instruments that have a 3 kHz fundamental. And I bet that you have difficulties to clearly locate a 3 kHz continuous sine sitting blindfolded in a room, even when played by a single speaker.
The medium of musical fundamentals is more like 300 Hz. There should be quite some harmonics below 3 kHz to help your brain put the instruments precisely on the stereo base.
You should be able to improve that. You probably need to tell us more about your speakers and the listening conditions.
Rudolf
If you listen to, say, mono music and want to hear a well centered and compact image then, yes, a few cm off the exact center is all you have. A centered virtual image requires pretty exact time alignment between left and right sources.
If on the other hand you just require a well spaced stereo spread with good balance from left to right, then you can shift around a fair amount. Most of the times you won't notice the exact center elements have "gone diffuse".
A big part of this is also the stereo triangle and how far apart (in degrees) your speakers are. If they aren't very spread (say 30 degrees) then each ear hears both speakers and a lot of interference will be heard as comb filtering. This is very effected by how exactly you are centered.
On the other hand, spread the speakers out to 60 degrees or a little more, and the comb filtering drops and you get a smooth gradual shift of the image from side to side as you move across the mid plane.
If on the other hand you just require a well spaced stereo spread with good balance from left to right, then you can shift around a fair amount. Most of the times you won't notice the exact center elements have "gone diffuse".
A big part of this is also the stereo triangle and how far apart (in degrees) your speakers are. If they aren't very spread (say 30 degrees) then each ear hears both speakers and a lot of interference will be heard as comb filtering. This is very effected by how exactly you are centered.
On the other hand, spread the speakers out to 60 degrees or a little more, and the comb filtering drops and you get a smooth gradual shift of the image from side to side as you move across the mid plane.
Yes, an equilateral triangle seems to be the best. Also, you get less of the room acoustics since you are closer.
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