1-1.4 wavelength spacing tends to be a popular compromise sweet spot. (It's not the only way though.)
How does this spacing make symmetry possible and what were they hoping to get out of the symmetry?
Sorry, should have been clearer. If you take a gander at the Eclipse cabinet, you'll note it has a modestly tilted baffle. With the relatively large spacing between the drivers it gave sufficient alignment of the acoustic centres for them to avoid significant asymmetry in the high & low pass slopes (acoustic & electrical). I can't honestly say I'd be especially bothered about the latter myself, though I suppose it can make design a mite easier depending on how you prefer to approach it.
Wikipedia:
"Acoustic lobing refers to the radiation pattern of a combination of two or more loudspeaker drivers at a certain frequency, as seen looking at the speaker from its side. In most multi-way speakers, it is at the crossover frequency that the effects of lobing are of greatest concern, since this determines how well the speaker preserves the tonality of the original recorded content.[1]
In practice, room-effects and interactions largely mean that the ideal loudspeaker (or combination thereof) is not practically possible. However a speaker that has the best dispersion at all frequencies of interest (especially the crossover frequency), will have the least colouration of sound - i.e., it will most faithfully reproduce the recorded material. Thus, an ideal speaker would have no lobes at all frequencies - in other words it will act as a point source radiating omnidirectionally at all frequencies. In practice all speakers will exhibit some amount of lobing at the crossover frequency. The primary reasons for this are the physical distance between the drivers, and the drivers' effective diameters relative to the frequency of interest.
Lobing is measured as having a comb filtering response (i.e., areas of peaks and dips) as the listening position varies vertically‡ w.r.t. the nominal on-axis position. Since a true spherical wavefront cannot be achieved in practice, designers try to make the lobe as wide as possible at the crossover frequency, such that at typical listening positions, the speaker appears omnidirectional.[citation needed] "
"Acoustic lobing refers to the radiation pattern of a combination of two or more loudspeaker drivers at a certain frequency, as seen looking at the speaker from its side. In most multi-way speakers, it is at the crossover frequency that the effects of lobing are of greatest concern, since this determines how well the speaker preserves the tonality of the original recorded content.[1]
In practice, room-effects and interactions largely mean that the ideal loudspeaker (or combination thereof) is not practically possible. However a speaker that has the best dispersion at all frequencies of interest (especially the crossover frequency), will have the least colouration of sound - i.e., it will most faithfully reproduce the recorded material. Thus, an ideal speaker would have no lobes at all frequencies - in other words it will act as a point source radiating omnidirectionally at all frequencies. In practice all speakers will exhibit some amount of lobing at the crossover frequency. The primary reasons for this are the physical distance between the drivers, and the drivers' effective diameters relative to the frequency of interest.
Lobing is measured as having a comb filtering response (i.e., areas of peaks and dips) as the listening position varies vertically‡ w.r.t. the nominal on-axis position. Since a true spherical wavefront cannot be achieved in practice, designers try to make the lobe as wide as possible at the crossover frequency, such that at typical listening positions, the speaker appears omnidirectional.[citation needed] "
I believe that more emphasis is placed on this oft-mentioned problem than actually exists, as it implies that all full range drivers are likely to sound dreadful due to the massive movement of the 'tweeter'.
Wiki entries about acoustics are a mixed bag. This current incarnation not so much.
Hi thank you very much indeed You have made me think better And you are very right
The problem is that in my limited mind i have associated a great soundstage with heavy mass and stiffness of a cabinet But then i think of planars and they are everything but massive and stiff So i am wavering ... for me a great well developed 3D virtual soundstage is almost everything
I really do not know what influences more soundstage ... FR? spectral decay? distortion ? cabinet weight or stiffness ? i am quite lost
do i have to conclude that full range drivers soundstage very well mounted on any cabinet ? i have practically no experience of full range speakers
Any good marketing department can always justify any engineering decision whether it's good or bad.
Been there. Done the courses. Got the diploma...
Absolutely. Although as far as Avalon go, the engineering reasons are fairly solid. Some may prefer alternatives, which is fair enough, but I doubt anybody would say the particular approach they've adopted is devoid of merit. Low diffraction? Check. High rigidity? Check. High mass to ensure a stable initial platform for the drivers & wavefront? Check. Relatively low cost, consistent material to keep overheads down as far as possible for construction of this type? Check. There are [far] worse approaches, that's for sure. Better ones too? Definitely, but it depends where priorities lie.
If you asked ten speaker designers you would likely get ten different priorities!
In my experience speaker positioning can make the difference between music-from-boxes to the speakers apparently disappearing, even the £60 used Tannoys I played with for months as an experiment - specs aren't everything! Distance from the back wall and toe-in had least influence; absolute speaker spacing and listening position the most - I ended up with the speakers closer together and also a closer listening position than which seemed intuitive to me in this large space. (The room is a 100m2 warehouse top floor with close-boarded double-pitched roof and the speakers on the long side, so side reflections were largely irrelevant here. Wall treatment in a smaller room at the main side wall reflection points is essential).
In conclusion, there are many more critical things to worry about than a few micron's movement of the baffle - particularly the room acoustics - and any speakers we build ourselves are very likely to sound wonderful anyway...😉
I have similar experiences.
In the first place, it is the electronics that have an effect. If the source (the music and the electronics) cannot provide a good sound image, it is useless to try to recreate it by moving the speakers here and there.
When you have found a source that creates a deep and accurate sound image, then you move the speakers to find the ultimate sound image.
Each speaker pair has its own distance between them that works best.
There is no distance that works best for all speakers.
Last edited:
"Cabinet Materials Measurement"
... by knocking.
Knocking, tapping with fingers, scraper, other objects. The entire case. This is another way to get a very good impression of the sonic properties of a cabinet.
Besides: we unconsciously balance the sound of materials: For example, a wooden cabinet with metal plugs and sockets.
... by knocking.
Knocking, tapping with fingers, scraper, other objects. The entire case. This is another way to get a very good impression of the sonic properties of a cabinet.
Besides: we unconsciously balance the sound of materials: For example, a wooden cabinet with metal plugs and sockets.
Hi thanks for the very helpful advice If i understand well you mean that ANY speaker if placed rightly in the room can disappear even a cheap one Very interesting and promising indeed
I just would like to explain what i mean for a speaker to disappear to me Sometimes i have got the feeling that the speakers where completely disconnect from the amps That is my disappearing act At the point that i have checked connections, the speaker wires were in place ... i took one out and the sound stopped That is a very astonishing experience And quite easy to perceive also
It is well described at 21:26 in this video
But with the same exact speakers only loaded with 10kg of lead foils glued to the inside panel of the cabinets the effect was immediately much more evident Since then i started to believe in choosing speakers also by weight
Then i have an idea that i don't how good can be to check for cabinet vibration Actually two ideas
1) put a glass of water above it and excite the speaker with very low Hz at high SPLs and watch the liquid surface inside the glass for any ripple If it stays still it means that the speaker does not trasmit vibrations to the glass You could use a little biadesive tape between the top side of the cabinet and the glass
2) a quality laser pointer is needed Stick a little mirror with biadesive tape on the front baffle between the woofer and the tweeter Then point the laser with a small degree to the mirror and locate where the reflected laser beam ends Then again excite the speaker with a 50Hz high level signal test And watch if the reflected laser point moves The less the reflected point moves the less the front baffle vibrates
It is a very trivial test but could be interesting to try anyway Laser interferometry on the cheap
Last edited:
"Speaker positioning"
Puts the speakers together at the beginning: about 50 cm. Then listen to music for a while. Now move the speakers apart: 80 cm. Listens for a while. Now puts the speakers further apart: 100 cm. Listens for a while. Now put the speakers apart: 120 cm. At the latest now the "stage" is torn apart for the vast majority. The mono parts of the music, of the recordings no longer play together - most signals are mono, with minimal channel deviations.
Dare to angle the ls very strongly, so that e.g. the outer surfaces can be seen very well. Play with the angles. For example, I prefer a positioning where the LS axes cross 1 - 2 meters in front of my nose;-)
Puts the speakers together at the beginning: about 50 cm. Then listen to music for a while. Now move the speakers apart: 80 cm. Listens for a while. Now puts the speakers further apart: 100 cm. Listens for a while. Now put the speakers apart: 120 cm. At the latest now the "stage" is torn apart for the vast majority. The mono parts of the music, of the recordings no longer play together - most signals are mono, with minimal channel deviations.
Dare to angle the ls very strongly, so that e.g. the outer surfaces can be seen very well. Play with the angles. For example, I prefer a positioning where the LS axes cross 1 - 2 meters in front of my nose;-)