Narrow baffles typically aid in imaging and dispersion at higher frequencies. Taking such an approach can hurt bass response though AND it can also play havoc with higher frequencies too. That is, IF the speakers are placed close to the wall behind them and / or are of a bipolar design.
In either case, the time & distance between the front wave that is in phase and the rear wave ( dipolar radiation OR reflections from the wall behind the speaker ), which is out of phase, can cause major "rippling" due to cancellation at many different frequencies. By making the return path of the reflection longer by adding width to the baffle, you minimize these problems. This also increases the time & distance between the rear out of phase signal of a dipole and the in-phase front wave, offering the same benefits.
Rather than minimize baffle area on his designs, which can improve imaging but allow the above mentioned problems to come into play, Arnie Nudell used stationary "wings" or extended baffles on his big Infinity and Genesis designs. Problem with increasing baffle size at higher frequencies is that you can also run into diffraction problems. Arnie took care of that by radiusing the baffles i.e. gradually sloping them backwards in a gentle bend. In effect, the radiation pattern of the speaker is not drastically effected, even though it has a larger baffle, and the rear wave reflections / cancellation problems are drastically reduced.
Another way to get around this is to control the dispersion of the speaker. By manipulating the radiation pattern through baffle shape and size AND applying acoustic treatments to the baffle, you achieve much the same effect as that above without the larger surface area of the "wings" or radiused baffle extensions. This makes it harder for the sound to "bend around" the baffle due to being aimed in one direction. The signal that does try to bend around is absorbed by the acoustic treatments. This design approach can be found in old AR ( Acoustic Research ) designs utilizing their "Acoustic Blanket" technology and in many of the Dunlavy designs. Ken Kantor, who was previously employed by AR and later helped design some of the NHT products, also took these factors into consideration on some of their models too.
These are two vastly different approaches that achieve very similar results in real world listening environments. It is this type of thinking / design engineering that separates "good" products from the typical "slapped together" products that most manufacturers foist upon the public. Sean
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PS... One can "typically" gain some benefits similar to those mentioned above by surrounding the midrange / tweeter drivers with foam or felt. Varying the density, height and area covered are ways to fine tune just what frequencies are affected and the desired level of off-axis attenuation. The end results of such treatment typically result in a much smoother sound with improved imaging. You might have even seen the ads for AIM "Imagers", which are nothing more than foam rings that attach to the baffle around your tweeters. As mentioned though, this type of approach works FAR more effectively on the upper mids and treble. To get the benefits at lower frequencies, there is now way around increasing the baffle area via baffle extensions aka "wings".
In either case, the time & distance between the front wave that is in phase and the rear wave ( dipolar radiation OR reflections from the wall behind the speaker ), which is out of phase, can cause major "rippling" due to cancellation at many different frequencies. By making the return path of the reflection longer by adding width to the baffle, you minimize these problems. This also increases the time & distance between the rear out of phase signal of a dipole and the in-phase front wave, offering the same benefits.
Rather than minimize baffle area on his designs, which can improve imaging but allow the above mentioned problems to come into play, Arnie Nudell used stationary "wings" or extended baffles on his big Infinity and Genesis designs. Problem with increasing baffle size at higher frequencies is that you can also run into diffraction problems. Arnie took care of that by radiusing the baffles i.e. gradually sloping them backwards in a gentle bend. In effect, the radiation pattern of the speaker is not drastically effected, even though it has a larger baffle, and the rear wave reflections / cancellation problems are drastically reduced.
Another way to get around this is to control the dispersion of the speaker. By manipulating the radiation pattern through baffle shape and size AND applying acoustic treatments to the baffle, you achieve much the same effect as that above without the larger surface area of the "wings" or radiused baffle extensions. This makes it harder for the sound to "bend around" the baffle due to being aimed in one direction. The signal that does try to bend around is absorbed by the acoustic treatments. This design approach can be found in old AR ( Acoustic Research ) designs utilizing their "Acoustic Blanket" technology and in many of the Dunlavy designs. Ken Kantor, who was previously employed by AR and later helped design some of the NHT products, also took these factors into consideration on some of their models too.
These are two vastly different approaches that achieve very similar results in real world listening environments. It is this type of thinking / design engineering that separates "good" products from the typical "slapped together" products that most manufacturers foist upon the public. Sean
>
PS... One can "typically" gain some benefits similar to those mentioned above by surrounding the midrange / tweeter drivers with foam or felt. Varying the density, height and area covered are ways to fine tune just what frequencies are affected and the desired level of off-axis attenuation. The end results of such treatment typically result in a much smoother sound with improved imaging. You might have even seen the ads for AIM "Imagers", which are nothing more than foam rings that attach to the baffle around your tweeters. As mentioned though, this type of approach works FAR more effectively on the upper mids and treble. To get the benefits at lower frequencies, there is now way around increasing the baffle area via baffle extensions aka "wings".