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Multi-Way Conventional loudspeakers with crossovers

Zero Baffle Width, Zero Edges...Sort of..
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Old 1st October 2008, 06:10 PM   #11
forr is offline forr  France
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I find Pluto visually a marvel. Auditively maybe. At one condition : just like same author's Orions, far away from any wall. And I think it is exactly the same for any speaker with small front baffle.
Such positioning is not possible for many people who have space constraints with their room. For this case, I have been investigating the radically opposite way, the two pi emission, just like the Sonus Faber Stradivari Homage
http://www.sonusfaber.com/eng/home.html
My current speakers are 2 ft wide with 1/2 ft rounded corners, slightly angled and about 2 1/2 away from the rear wall.
I think I won't soon come back to smaller baffles in my current room.
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Old 2nd October 2008, 12:46 PM   #12
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by BlueWizard

a) Essentially, the baffle width and the woofer width are one and the same.


b) ...... or infinitely small ........



Steve/bluewizard
Hi,

a) Is true but it is the worst shape for baffle step ripple and has an abrupt edge.

b) Is not possible, the smallest baffle size is the size of the driver.

The design has excellent inherent rigidity but not the smoothest
diffraction response, that is a truncated ovoid or sphere.

sreten.
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Old 2nd October 2008, 01:03 PM   #13
dlr is offline dlr  United States
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Quote:
Originally posted by sreten


Hi,

a) Is true but it is the worst shape for baffle step ripple and has an abrupt edge.

b) Is not possible, the smallest baffle size is the size of the driver.

The design has excellent inherent rigidity but not the smoothest
diffraction response, that is a truncated ovoid or sphere.

sreten.
The shape and size alone aren't the sole determinants of diffraction artifacts. The B&W driver midwoofer unit shown is fairly large and will become more directional at lower frequencies due to both depth and diameter. It's a waveguide of sorts designed to have an increasingly narrow radiating area as frequency rises.

Measurements of lesser quality drivers of this size that I've made show diffraction even on modest boxes to be minimal for drivers that size other than baffle step. I would expect no diffraction artifacts other than step for that B&W unit mounted as it is.

The tweeter will also show little impact. It's 4-pi very early due to the configuration. The diffracted signal that is quickly in the 4-pi range will be very highly dispersed, so the impact on any single specific axis will be minimal as well.

B&W takes just about everything into consideration in their designs. Significant diffraction would be dealt with in their better systems. I'd say that they've handled diffraction quite well in this case, aesthetics notwithstanding.

Dave
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Old 2nd June 2017, 11:01 PM   #14
crazyhub is offline crazyhub  France
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Hello guys,

I know well the issues of baffle step in the frequency domain. But what about this matter in the time domain?
For instance, assume a very narrow baffle with full BSC and a very large baffle with no BSC giving the same fr response. Will the narrow baffle be more time coherent/accurate than the large baffle?
Thanks.
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Old 3rd June 2017, 03:20 AM   #15
TMM is offline TMM  Australia
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Quote:
Originally Posted by crazyhub View Post
Hello guys,

I know well the issues of baffle step in the frequency domain. But what about this matter in the time domain?
For instance, assume a very narrow baffle with full BSC and a very large baffle with no BSC giving the same fr response. Will the narrow baffle be more time coherent/accurate than the large baffle?
Thanks.
That's difficult to answer because first you need to define what is 'narrow' and 'large'. To do without BSC to a low enough F3 (say 40Hz) requires baffles several metres wide.

The actual BSC compensation network will not subjectively change the coherence of the speaker as it will only change the phase maybe 20 or 30degrees at the BSC corner frequency. This is not subjectively audible.

What is subjectively audible are late reflections (several hundreds of degrees phase delays), created by the room. So ultimately it comes down to if either baffle configuration allows you to place the speaker in your listening space as to reduce room effects more than the other one.
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Old 3rd June 2017, 09:06 AM   #16
AllenB is offline AllenB  Australia
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If they both had the same response shape because their diffraction was insignificant then the only difference would be their directivity index. I agree with TMM on that being more important.
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Old 3rd June 2017, 09:42 AM   #17
john k... is offline john k...  United States
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A narrow baffle will generally have worse transient response than a significantly wider baffle. The cleanest transient response will obviously be for an infinite baffle where diffraction is eliminated.
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Old 3rd June 2017, 11:01 AM   #18
crazyhub is offline crazyhub  France
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Thanks guys for your replies.
I guess I have to specify my question.
Assume a perfect similar frequency response from a large baffle and from a narrow one in a definite bandpass. The narrow baffle uses BSC, the large one uses no BSC.
Instead of looking at the 4pi radian as a loss, look at the 2pi radian as a gain. This gain comes from the waves rebouncing on the baffle.
Is it correct to say that these waves bounces are delayed in time and that the ones with BSC aren't delayed?
Thanks.
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Old 3rd June 2017, 11:43 AM   #19
Grasso789 is offline Grasso789  Germany
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Old 3rd June 2017, 12:05 PM   #20
GDO is offline GDO
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Quote:
Originally Posted by crazyhub View Post
Thanks guys for your replies.
I guess I have to specify my question.
Assume a perfect similar frequency response from a large baffle and from a narrow one in a definite bandpass. The narrow baffle uses BSC, the large one uses no BSC.
Instead of looking at the 4pi radian as a loss, look at the 2pi radian as a gain. This gain comes from the waves rebouncing on the baffle.
Is it correct to say that these waves bounces are delayed in time and that the ones with BSC aren't delayed?
Thanks.
Time domain issues no longer make me wake up at night...

What i find a real nightmare is that there is no real cure for baffle step since BSC or not, you will never get both constant power and flat spl response: whatever you do you get a 3db mismatch.

This is imho the real issue with narrow baffles...
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Last edited by GDO; 3rd June 2017 at 12:11 PM.
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