What is the reason for sloped baffle on speakers like the 250ti ?

[wsilva]

Could someone help me understand the reason for using sloped baffles on speakers ? I think it has been mentioned to time align the drivers, but I dont know what that means either.

Thanks for any replys:)

[BMWCCA]

It situates the "focus" point (sound source) of each individual driver equidistant from the listener's ears. A larger speaker will have a deeper cone so it needs to sit a bit further forward, and vice-verse. Didn't seem to bother us much thirty years ago. Can't say I notice it now. But it makes sense in theory.

[brutal]

It has more to do with time v.s. frequency than physical distance of the driver...

[BMWCCA]

It has more to do with time v.s. frequency than physical distance of the driver...

"Lucy, you got some 'splainin' to do . . . " for dummies like me.
So a nice LF soundwave from a LF driver should be 10-feet further back so the wave form hits at the same time??? :dont-know :D

Here's what I meant:
To make the transition between drivers as seamless as possible, system designers have attempted to time-align (or phase adjust) the drivers by moving one or more drivers forward or back, so that the acoustic center of each driver is in the same vertical plane. This may also involve tilting the face speaker back, or providing separate enclosure mounting for each driver, or, less commonly, using electronic techniques to achieve the same effect. These attempts account for some unusual cabinet designs.
http://en.wikipedia.org/wiki/Loudspeaker

[rdgrimes]

Higher freq = shorter wavelength. I've never had a system with "time aligned" drivers so can't say if I've heard any difference. There are certainly some very high-end systems that do not use this feature, so it's value is questionable. Given the realities of HT rooms with reflections and reverberations in abundance, I'd guess it has no discernible effect. If you listen in a anechoic sound lab, it probably does sound better.

[Hoerninger]

... so it's value is questionable.

But it is easily to detect as long as one speaker is movable:
Listen to pink noise or a female voice and let (best by someone else) move one speaker to and fro - you will easily hear where it sounds best.
____________
Peter

[jcrobso]

Higher freq = shorter wavelength. I've never had a system with "time aligned" drivers so can't say if I've heard any difference. There are certainly some very high-end systems that do not use this feature, so it's value is questionable. Given the realities of HT rooms with reflections and reverberations in abundance, I'd guess it has no discernible effect. If you listen in a anechoic sound lab, it probably does sound better.

I did this once, it was the strangest sound. No room reflections AT ALL!
I don't know how describe it, I would not ever want to have a listing room like that. The room seams to just suck the sound out of the air.:crying: John

[4313B]

Could someone help me understand the reason for using sloped baffles on speakers ?It doesn't get much easier than reading this - #7 (http://audioheritage.org/vbulletin/showpost.php?p=122582&postcount=7)

[BMWCCA]

It doesn't get much easier than reading this - #7 (http://audioheritage.org/vbulletin/showpost.php?p=122582&postcount=7)

I think some of you just re-wrote the laws of physics having to do with the speed of sound.
I don't know, you tell me who sounds like they got it more correct ;):

It situates the "focus" point (sound source) of each individual driver equidistant from the listener's ears. A larger speaker will have a deeper cone so it needs to sit a bit further forward, and vice-verse.or:
It has more to do with time v.s. frequency than physical distance of the driver... or:
Higher freq = shorter wavelength.
Here's the JBL techbot text referenced above:

[4313B]

I don't know, you tell me who sounds like they got it more correctJohn Eargle and Greg Timbers won? :)

[BMWCCA]

John Eargle and Greg Timbers won? :)
:applaud:I was gonna suggest that, but the site was too slow to preview and edit my post. Much better now. I see no discussion of variation in frequency-over-distance in the JBL text, unless that has to do with phase. I suspect it's the physical distance of the individual sound sources from the listener, though I do much prefer the Timbers/Eargle word choice to mine.



But then I am a simpleton. Still, chalk on up for Team Ignorant!

[SEAWOLF97]

I can say that I hear a difference on the 250ti's , thinking that would manifest itself in the smoothness , and also a lot on the Walsh's which used a very similar slope ( but on the driver, not the baffle) to work towards coherency (although on a very different driver)

see end of:

http://www.audioheritage.org/vbulletin/showpost.php?p=166153&postcount=133

[BMWCCA]

Nothing new about that technology at my house, either:
http://www.lansingheritage.org/images/jbl/specs/home-speakers/1992-l-series/page06.jpg
(http://www.lansingheritage.org/images/jbl/specs/home-speakers/1992-l-series/page06.jpg)

[Titanium Dome]

We'd do well to heed the words "over a large listening arc" which means there's not unlimited, universal application here. Pay attention to JBL's recommended set up. I know it may be hard to conceptualize, but these talented engineers do actually spend a lot of hours figuring this stuff out. Speakers tend to be designed for specific environments and listening conditions.

Then we f it all up by expecting them to be capable of excellent reproduction in all conditions. The room, the room, the room...

[4313B]

Note that the tilted baffle of the L300 doesn't correct timing errors.

There are some instances where tilting doesn't help.

Also note that people are still capable of thoroughly enjoying the L300 despite its shortcomings.