Limits of passive directivity control, aka what happen to large baffle sizes ?

[Mnyb]

Hi posting this in beginners forum for obvious reasons .

Reading up on DI and directivity controll , cardiod speakers etc on our fora (thanks for the interesting treads all of you ) .

One question is this .

Why the mind numbingly complex schemes (Kii 3), when you can get a lot of it for free by simply have a large front baffle ?

You then of course need the complex woofer arrangements and DSP to continue this property lower in frequency . and more DSP for the smooth transition.
genelec bass units for example

But simple economical speakers could just have larger baffles . Example a Boston A400 is large but not more offensive than electrostats or planar speakers ?

GGNTK for example is doing the right thing , they have a slim speaker but the wide side is the front . and their next model will have a large midwoofer and wide baffle .

So whats is the limit for natural directivity control . with for example a a speaker 1meter high and 0,5 meter wide ( a size i consider domestically feasible )

I do realise that a large baffle in it self would not make the desired even directivity slope. thats up the speaker designer skill to match drivers waveguides and baffle sizes

 

[abdo123]

well baffles are usually forward firing at the frequency in which the wavelength is equal to the distance between the center of the woofer and the edge of the baffle.

so for a forward firing speaker at 200Hz you need roughly a 4 meters wide speaker. not so easy now is it?

 

[Mnyb]

well baffles are usually forward firing at the frequency in which the wavelength is equal to the distance between the center of the woofer and the edge of the baffle.

so for a forward firing speaker at 200Hz you need roughly a 4 meters wide speaker. not so easy now is it?

That would be perfect control then a case for the inwall speaker ? and thanks for your time answering noob questions .

When i see reviews here the loss of directivity is gradual until the speaker gets totally omnidirectional at some point . So you are correct but is not the loss of directivity gradual and a larger baffle would help ?

Is the baffle contribution so minimal that we very well can have these tiny 2 ways and slim tower that been in vouge the last decades ? if we keep the slope of DI even ?
or would backtracing a bit to the 70's 80's style with larger front area do some positives things ? and combine it with todays better understanding of avoiding large missmatches in DI between drivers at crossover ?

 

[abdo123]

That would be perfect control then a case for the inwall speaker ? and thanks for your time answering noob questions .

When i see reviews here the loss of directivity is gradual until the speaker gets totally omnidirectional at some point . So you are correct but is not the loss of directivity gradual and a larger baffle would help ?

Is the baffle contribution so minimal that we very well can have these tiny 2 ways and slim tower that been in vouge the last decades ? if we keep the slope of DI even ?
or would backtracing a bit to the 70's 80's style with larger front area do some positives things ? and combine it with todays better understanding of avoiding large missmatches in DI between drivers at crossover ?

the loss of directivity is gradual because the wave would go further than the baffle to the sides and the back before firing outwards.

and as you mentioned at a certain frequency the size of the speaker becomes completely smaller than the wave and it's just emitting the wave out off the speaker in a sphere/omni pattern.

Honestly i don't understand what the appeal was with wide baffles back then, I mean we didn't even round / bevel the edges back then causing waves to diffract off of the edges.

I'm not even aware if baffle step adjustment was even a thing back then. If not maybe wider baffles pushed diffraction and on-axis dip lower in frequency? and getting these distortions below the prescence region improved overall quality of sound?

 

[tuga]

Troels Gravesen cloned the 650mm-wide Sonus Faber Stradivari and discusses wide baffles here:

Troels Gravesen - Wide baffle speakers
http://www.troelsgravesen.dk/Acapella_WB.htm

Calling a 50-60 cm wide baffle an infinite baffle is a truth with some modifications. Having an infinite baffle would mean mounting the drivers on the wall, creating a true 2pi environment. By making a wide and curved baffle cabinet, edge diffraction is avoided and a virtual 2pi radiation pattern is produced. Any driver mounted on a baffle will have an f3 = 11,600/width of baffle in cm. A driver mounted on a baffle of 20 cm with will be down 3 dB at 11,600/20 = 580 Hz. Making the baffle 50 cm wide the f3 is reduced to 232 Hz. Enough for a midrange driver working from 300-400 Hz to release its full potential without baffle step compensation.

 

[tuga]

Here's the lateral response family of the Stradivari at 50", normalized to response on tweeter axis:

source: https://www.stereophile.com/content/sonus-faber-stradivari-homage-loudspeaker-measurements

 

[Mnyb]

Troels Gravesen cloned the 650mm-wide Sonus Faber Stradivari and discusses wide baffles here:

Troels Gravesen - Wide baffle speakers
http://www.troelsgravesen.dk/Acapella_WB.htm

Calling a 50-60 cm wide baffle an infinite baffle is a truth with some modifications. Having an infinite baffle would mean mounting the drivers on the wall, creating a true 2pi environment. By making a wide and curved baffle cabinet, edge diffraction is avoided and a virtual 2pi radiation pattern is produced. Any driver mounted on a baffle will have an f3 = 11,600/width of baffle in cm. A driver mounted on a baffle of 20 cm with will be down 3 dB at 11,600/20 = 580 Hz. Making the baffle 50 cm wide the f3 is reduced to 232 Hz. Enough for a midrange driver working from 300-400 Hz to release its full potential without baffle step compensation.

That's seams reasonable

 

[Mnyb]

Yes nowadays , speaker manufacturers stick to a very narrow profile , mutiplying 6,5" drivers on top of each other rather than go wider when you go up in the model series . Supose it's economy but also current design fashion.

Think a kef R with the coax and one single 10" ? and wider front

 

[tuga]

Yes nowadays , speaker manufacturers stick to a very narrow profile , mutiplying 6,5" drivers on top of each other rather than go wider when you go up in the model series . Supose it's economy but also current design fashion.

Think a kef R with the coax and one single 10" ? and wider front

Something like the 600mm-wide 4-way Kef 109?