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wide baffles and baffle step

Lengthy quotation from Peter Comeau, designer at Wharfedale.  Makes a lot of sense to me...

"Th[e] larger ported box, with its subsequent increased baffle size, helps solve a major problem in modern speakers, namely, the baffle step.

I grew up with large speakers with wide baffles, but, as speakers reduced in size over the years I noticed that something was missing from the sound and, when I stuck my head firmly into speaker design, I began to understand the acoustic problems caused by the baffle step.

Put simply, as the baffle size decreases, the point at which the acoustic radiation changes from hemispherical to spherical goes up in frequency. It also becomes sharper and narrower in bandwidth as the sides of the cabinet, and the walls and floor of the room, are further removed from the equation. So, this 6dB step in the power response becomes acoustically more obvious.

I believe that a thin speaker always sounds thinner throughout the midrange when directly compared to a speaker with more generous baffle width. Of course, as designers of modern, slim speakers, we compromise by adjusting for the baffle step in the crossover, but in doing so, we also compromise sensitivity. What starts out as a 90dB at 1W drive-unit often ends up as an 85dB system once we have adjusted for the power loss due to the baffle step."



twoleftears
tomic601's avatar
tomic601
13,166 posts
 
Duke - I disagree, unless you meant to say out of phase wave launch bounce... the big baffle has two “
advantages” the power response and the averaging engine that constructive and destructive interference off a large baffle creates. In a time and phase correct design, both of those are of course not positives.
Snell of course had more complex shapes but in the end it’s a two dimensional horn....
audiokinesis
2,764 posts
 
Tomic601, my understanding is that sound waves are longitudinal pressure fluctuations, not transverse waves (even though we tend to draw them that way), and therefore there is no phase change when they reflect or diffract.   

There is of course a time-delay built into the path length to the reflecting or diffracting discontinuity, and that time delay works against preservation of time and phase coherence.   

Imo the solution is to minimize edge diffraction effects either by having  minimal baffle dimensions or large-radius roundovers or sufficient directivity to avoid significant cabinet edge interaction in the first place.  Since I like the other benefits which come with having a wide baffle, I try to figure out ways to minimize the downsides. But it's a juggling of tradeoffs, and arguments can be made for either side.   

Duke
wolf_garcia
6,776 posts
 
For the record, around 100% of interior designers prefer ceiling speakers...sadly.
wolf_garcia
6,776 posts
 
For the record, nearly 100% of interior designers prefer ceiling speakers. Sadly.
twoleftears's avatar
twoleftears OP
5,320 posts
 

This is what I think is sad.

https://www.bluebirdmusic.com/edit/files/images/gallery/spendor_str_nov_18.jpg

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