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In Reply to: RE: high frequency of Bose speakers: revealing posted by dave789 on August 27, 2016 at 14:30:25
I wouldn't call them revealing at all. The physical arrangement of the drivers and their size predicts a chaotic interference among them in the HF. That alone would preclude the coherence necessary for it to be revealing.
Relocating the HF to a single purpose-designed dome driver can only be an improvement.
Follow Ups:
"The physical arrangement of the drivers and their size predicts a chaotic interference among them in the HF."
Why "chaotic?" There are a finite number of drivers arranged in an organized way. Have you any test results that show this results in HF chaos?
Now if you were to say that the physical arrangement of the drivers and their size predicts a highly reverberant HF presentation, which by its nature will obscure HF detail, I wouldn't argue with you.
However, I don't think Bose ever sold the 901s as being revealing, but as being realistic. The gravamen of their claims is that in a live environment, actual instruments do not sound like the closely miked representations so often present in audio, but instead play within highly reverberant sound fields.
The Bose 901 first debuted in 1968. It can still be purchased today, for roughly the same price in US$ as when it was first released. Not many audio components can make comparable claims. Somebody must like these things.
"Audiophiles" can deride Bose 901 buyers as stupid, or suckers, but I think they are simply music lovers with different priorities than "audiophiles." Bose 901 lovers could care less about ultimate resolution, but instead value a broad sound stage that is consistent from place to place in the listening room. They want to know their companions are hearing an end result comparable to what they too are hearing.
While I myself identify with the audiophile, parked in the sweet spot, greedily sucking in as much detail and nuance as I can, I also have to admire the 901 buyer who accepts a lower level of fidelity that all of his friends and family can share in.
JE
"A difference which makes no difference is no difference at all." - William James
What Kal is referring to is a very complex interference pattern, which varies greatly with frequency and direction, resulting from a multiplicity of drivers arranged in a manner where they don't compliment each other's output, but rather interfere both constructively and destructively, depending on angle of measurement and frequency. This type of interference is termed "chaotic" because of its non-uniform and difficult/impossible to predict/measure nature. It's a physics term.:)
Edits: 08/29/16
...are not a significant issue for the 901s if used as designed. While there may indeed be lots of nulls and reinforcements resuting from the rear array of the 8 full range drivers, if set up and used as designed, you're not listening to the direct radiation of these drivers. Since they're aimed rearward at walls and whatever else is behind them, there's an "averaging" effect where the array artifacts are homogenized into a reverberant mish-mash. If the setup is correct, the forward facing drivers can be clearly discerned over this room sound providing some degree of localization and imaging.
1. The HF inference due to multiple drivers arranged so that they are more distant from each other than the wavelengths being produced is well documented.
2. Using the argument that music played in a reverberant venue should be reproduced in one confuses the creation of sound a performance with the attempt to reproduce that sound. It results in the superimposition of a listening room's acoustic signature upon that of the the performance space and is, by definition, unrealistic.
3. The observation that a significant number of listeners like the results is not disputed. However, that does not mitigate the logical arguments about the flaws of this approach.
In the case of 901, the first arrival to the ear is from single 4.5" cone.
The four rear facing drivers in the half of the rear are on flat baffle to increase directivity in the mid. The increased directivity helps the first arrival of mid be just from the front facing single cone.
Just to be clear, aren't there eight rear firing drivers in each 901?
When I've heard them sounding their best one set of four was firing into the corner of the room, and one set of four was firing toward the wall in the center of the room. The ninth speaker (nine oh one, get it?! ;-)) of course faced forward.
The resultant sound field was a far cry from the typical audiophile approach, which can frankly sound less than stellar when not seated in the sweet spot. On the other hand, the 901s could never seem to have that focus and snap you can get from a good sweet spot. However, for energizing an entire room with music where ever I sat or stood I thought the 901s did pretty well. Certainly, they never made my ears bleed as many an audiophile approved speaker has done.
JE
"A difference which makes no difference is no difference at all." - William James
"Just to be clear, aren't there eight rear firing drivers in each 901? "
That is right. In my post: The four rear facing drivers in the half of the rear
4 drivers "in the half of the rear "
"The HF inference due to multiple drivers arranged so that they are more distant from each other than the wavelengths being produced is well documented."
I'm curious. Does this also apply to planar drivers as well? A lot of folks rave over their Maggies, Quads, Sound Labs, etc., and one of the more frequently cited claims is their excellent high frequency sound. I don't know the proper term, if there is one, but shouldn't there be some sort of summing or averaging of the response as you move away from the speaker that would smooth out the response? Wouldn't this make the multiple drivers behave as a virtual planar driver, at least in dispersion?
What do you think of the current McIntosh Labs speaker line? This would seem to be an extreme amount of effort if the concept itself is basically flawed.
JE
"A difference which makes no difference is no difference at all." - William James
Sony SS-NA2ES
Stereophile Recommended Components 2016 Class A (Restricted Extreme LF)
For the wavelength, the sound source is very "multiple," and very physically separated away in space.
the purely vertical array results in interference primarily in the vertical plane. Set at or aimed at ear level, the interference is not noted unless one lies down or stands up. Horizontal driver displacements would be an problem with normal head movements (leading to the failures of many speakers supposedly designed for center-channel use).Multiple horizontal/vertical/oblique arrays? Fuggedaboutit!
Edits: 09/05/16
I'm sorry, no offense was intended with my post on the number of drivers in the 901.
"For the wavelength, the sound source is very "multiple," and very physically separated away in space."
Could you elaborate on this please? I'm sorry, but I don't see what the point is that you are making. What does this have to do with the question I posed to Kal Rubinson?
As I understand Kal's argument, multiple drivers, that are arrayed farther from each other than the wavelengths being produced, will result in high frequency "inference." (I think Kal meant "interference.")
My question is, couldn't this argument be applied to pretty much every single point on a planar diaphragm? If eight separate drivers compromise the high frequency sound of a speaker, should not the literally thousands of virtual drivers contained in a planar diaphragm compromise the high frequency sound even more? Yet many brands of planar speakers are celebrated for their revealing high frequency response. Why are they said to perform well and the Bose 901s are said not to perform well?
It's too bad Kal Rubinson has seemingly stopped posting to this thread, as a reply from him could be very edifying to me and to the rest of this asylum.
JE
"A difference which makes no difference is no difference at all." - William James
The diaphagm of a planar driver is continuous so, in a way, there is no spacing between the virtual sources.
I did not feel your post was an offense. My post is not against your question to Kal.What you wrote indicates that you understand what I wrote.
Edits: 08/31/16
Thank you for your theoretical guess. I appreciate it.
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