I was thinking about methods to align the acoustic centers of drivers. I'm not entirely sure that I will get any closer to time or phase alignment but all in all it seems like a good idea. So I was wondering what the merits of a couple different approaches might be.
-Angled baffles.
Seems easy enough to make.
-Stepped baffles.
looks funny to me. Seems that the shelf would cause diffraction.
-Waveguides.
Seems like it might be a great choice but might cause a lot of other issues. Also to get the mouth large enough for a given xover that the ctc distance would have to be pretty big too. Problem or not?
-nothing.
Too much hassle for too little benefit.
Would really love to hear peoples thoughts and experiences on this.
MrKramer
-Angled baffles.
Seems easy enough to make.
-Stepped baffles.
looks funny to me. Seems that the shelf would cause diffraction.
-Waveguides.
Seems like it might be a great choice but might cause a lot of other issues. Also to get the mouth large enough for a given xover that the ctc distance would have to be pretty big too. Problem or not?
-nothing.
Too much hassle for too little benefit.
Would really love to hear peoples thoughts and experiences on this.
MrKramer
Art Ludwig does it with angled steps.
http://www.silcom.com/~aludwig/Loudspeaker_construction.html#Time_alignment
http://www.silcom.com/~aludwig/Loudspeaker_construction.html#Time_alignment
Sorry, while a sphere as the external image of an enclosure could be a good thing when it comes to spread diffaction with regards to frequency, a sphere or a tube as the internal shape of an enclosure isn´t the best shape because standing waves will be gathered at certain frequences. Having visited conserts in "the Globe" in Stockholm and the lectue-theatre that has a dome as aprominent part to it.
About the time alignment the problem is that time delays because of a crossover e.g. is not cured by a "step function" as it is a continuous rather than a descrete function.
About the time alignment the problem is that time delays because of a crossover e.g. is not cured by a "step function" as it is a continuous rather than a descrete function.
Is a delay on an active system equal to physical alignment of drivers? Is there is more to it than that?
Nobody mentioned waveguides. I could see shallow guides as an option as well. Too much of a can of worms?
trusound: I like your "RGB"s. Interesting look. Nice to see some non box shapes.
MrKramer
Nobody mentioned waveguides. I could see shallow guides as an option as well. Too much of a can of worms?
trusound: I like your "RGB"s. Interesting look. Nice to see some non box shapes.
MrKramer
trusound said:
not when you build the inside like I built my last pair
There is still a high degree of symmetry which in my opinion should be avoided.
About stuffing; there might be a problem with reflection from the stuffing material itself and this is probably greater if an enclousure is densly stuffed.
I like a little more chaos in the interior structure like in the Kharma loudspeakers.
http://www.kharma.com/_images/reviews/exquisite/absolute_sound/page_2.jpg
abefroeman said:
Active delay is not the same as physical alignment anywhere except at the design point. When drivers are not physically aligned, the off-axis will have an even larger variation due to the change in excess-phase from changing distances that is complicated by the now-not-optimal electrical time delays at all off-axis points.
If the drivers are physically aligned, the off-axis variation will likely be lessened vs. non-aligned but time-delayed.
One can debate the relative merits, benefits and problems of each, but not the physics of it.
Dave
In the simplistic world of many hi-fi journalist phase shifts can be cured by placing the drivers at different distances from the listener. I read a German hi-fi mag where the drivers could be set to a millimeter resolution and indeed was placed this way as well.
In the real world phase errors can´t be solved so very easely.
Many years ago I had a pair of loudspeakers each being composed of two boxes. One for the woofer, one for the midrange and a moveable "rider" on top of the triangular mid boxes and the rider hold the tweeter. I spent a lot of time trying to determine how the drivers should be aligned in relation to each other. There were significant differences to the sound when moving the drivers back and forth. But the problem was that it was very hard to determine the absolute best position. As said I used many hours in listening and in order to find the optimal positions. But it was a never ending story.
My new speakers have a similar approach in divideing the drivers into separate boxes. Being a four-way system it´s now easy for me to know that I should make other priorities. Mixing a lot of materials for the enclosures and thinking of asymmetry for the area where the wave length is short enough to be effected by some "tricks" is now in focus. Rigidity and internal dampening as well as irregular shapes where it counts is now the order. Or order should be exchanged for chaos to some extent.
Credit to mrkramer for trying something different. You may learn a lot from this!
In the real world phase errors can´t be solved so very easely.
Many years ago I had a pair of loudspeakers each being composed of two boxes. One for the woofer, one for the midrange and a moveable "rider" on top of the triangular mid boxes and the rider hold the tweeter. I spent a lot of time trying to determine how the drivers should be aligned in relation to each other. There were significant differences to the sound when moving the drivers back and forth. But the problem was that it was very hard to determine the absolute best position. As said I used many hours in listening and in order to find the optimal positions. But it was a never ending story.
My new speakers have a similar approach in divideing the drivers into separate boxes. Being a four-way system it´s now easy for me to know that I should make other priorities. Mixing a lot of materials for the enclosures and thinking of asymmetry for the area where the wave length is short enough to be effected by some "tricks" is now in focus. Rigidity and internal dampening as well as irregular shapes where it counts is now the order. Or order should be exchanged for chaos to some extent.
Credit to mrkramer for trying something different. You may learn a lot from this!
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