|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
199.46.198.231
In Reply to: RE: Just for arguement's sake Mr Inmate51 :) posted by 3db on June 19, 2015 at 05:21:49
In most rooms, the frequency response you hear at the listening position is dominated by the overall power response radiated by the speaker into the room and how it interacts with the room. The overall power response is never flat.
Suppose you design a speaker that is perfectly flat when measured at 1m distance on the tweeter axis in an anechoic chamber, which is a design target for some companies. Unless the speaker has perfect constant directivity (none does), the response off the tweeter axis will not be flat. The dispersion characteristics of most speakers lead to an off-axis response that slopes downward with frequency, with the slope increasing as you move further off axis. Hopefully it's a smooth curve without any major peaks or suckouts, but few speakers achieve that. And the peaks and suckouts vary depending on whether you are moving off axis horizontally or vertically.
Also, as you move out from 1m distance, the on-axis response will change too. It will become generally down sloping, with some peaks and dips. This change with distance occurs even under anechoic conditions.
Good speaker designers pay as much attention to the off-axis response as the on-axis response, making trade-offs between flatness of the on-axis response against the shape of the total power response. If you chase perfectly flat on-axis pseudo-anechoic response and take what you get off-axis and at distance, the result ends up sounding colored in-room.
Now suppose you were to design a speaker that is both flat on-axis and you try to control off-axis response by limiting directivity as much as practical. The result will have a flatter power response, but will also sound unnaturally bright. Because music isn't being produced with that kind of target response in mind.
Follow Ups:
I concur that there is no such thing as a perfectly flat speaker. I just don't like designs where they purposely try and roll off the high end.
As has been pointed out several times in this thread, flat does not sound correct. Everybody designs for a roll-off. The question is how much top end roll-off is right in a speaker, and there is no objective answer because the end result is dependent on external variables such room, listening distance, positioning, and so on.
That's where the B&K and similar curves come into play. The B&K curve is one attempt to capture what response sounds the most natural. A designer who accepts the B&K curve as a reference will try to achieve a power response that follows the curve in a typical room. Of course, deciding what is "typical" is guesswork.
You seem to be hung up on thinking that there is an objective standard that you can measure loudspeaker frequency response against and there really isn't.
One might be forgiven for thinking that an objectively good speaker is one that measures flat on-axis at 1m in an anechoic chamber, but that is neither necessary or sufficient. It is a somewhat arbitrary design target. I can design two speakers that both measure flat on-axis at 1m pseudo-anechoic, but with very different power responses, one that rolls off slowly with increasing frequency which sounds too bright and one that rolls off rapidly and sounds too dark.
Similarly, I could design a speaker with an intentional rise or dip in the on-axis 1m anechoic response which compensates for a falling or flaring off-axis response such that the response at the listening position 3m away is smoother and flatter than if I had designed it with a flat on-axis 1m anechoic response.
"Good speaker designers pay as much attention to the off-axis response as the on-axis response,"
Seriously?!!
And this is news to whom?!
:)
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: