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Benefits of a cardioid subwoofer?

By "cardioid" I mean cardioid radiation characteristics. Specifically, I am thinking of replacing my JL Audio F110's with a pair of ME Geithain Basis 11K subwoofers. More information can be found here:

http://me-geithain.de/highend/index.php?option=com_content&view=article&id=67&Itemid=107&lang=en

The unique thing about this subwoofers is the cardioid radiation pattern, which supposedly reduces the interaction with the room from the back wave. To obtain a cardioid pattern, the subwoofer has to combine a monopole with a dipole. The interaction between the two rear waves cancels out the rear radiation thus producing a cardioid pattern.

I have never heard nor seen anything like this. Does anyone have any opinions?
amfibius
rwwear
2,880 posts
 
The Legacy Whispers use Cardioid woofers.
At the 2011 Axpona, the Whisper, seen here with designer Bill Dudleston who is showing off one of the speaker's dual-woofer cardioid bass sections
http://www.stereophile.com/category/axpona-2011
martykl
3,578 posts
 
Honestly, I'm not sure that the idea is even workable. Low frequencies (long wavelengths) wrap around the baffle and become omnidirectional regardless of the launch pattern. Below 100hz, I'd think front baffle mounted, cardioid (bi/di-polar), and omni drivers all behave very similarly. Just an observation.

Marty
audiokinesis
2,753 posts
 
Martykl, I believe that the rear-firing woofer's output is time-delayed in order to obtain the cardioid pattern.

Speaking from theory rather than experience here, I would think that the benefits of a cardioid pattern at bass frequencies are rather small in a home listening room. You see, the ear cannot detect the presence of bass from less than one wavelength, and it takes several cycles for the ear to discern pitch. Given the size of our home listening rooms in relation to a wavelength, by the time we hear bass tones the energy has been reflected multiple times. So the initial radiation pattern of that bass energy doesn't make a great deal of difference.

I'm not saying there would be no improvement... just probably not as much improvement in a home audio setting as implied by the superior radiation pattern control of a cardioid subwoofer.

Duke
dealer/manufacturer
amfibius OP
282 posts
 
Thanks RWW, Marty, and Duke. I have my suspicions about how well these subwoofers would work in a listening room. They are designed as professional audio subs, so the designers probably had a much larger room in mind than my poky little listening room. Maybe I will look at the larger JL's instead.
martykl
3,578 posts
 
Duke,

Thanks for clarifying, but that raises another question:

Both waves will still be omnidirection. So, the wave from the forward woofer goes outward (not forward), there is a computed delay, and then the back wave goes outward (not forward). This does not look much like the behavior of a di-pole at higher frequencies, and doesn't compute to a cardiod pattern, either.

What am I missing?

Marty
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