48426RE: John Dunlavy interview
- Feb 15 8:52 AM
One aspect of sealed subs and some sealed woofers is that to get loud and deep bass from a curiously small box with big drivers, one generally must EQ like crazy, which is the reason for the huge amplifiers. If the bass boost happens to be of a resonant sort similar to what one achieves with a port, then this has an equivalent degrading effect on the transient response and group delay. The driver might also be operated above, through, and below its resonant frequency, which can create interesting interactions with an amplifier. I suppose all this could account in some cases for a valid verdict of unnaturalness from some sealed boxes.
IMO, the trick is to make sure the resonant frequency of a woofer in situ is low, below the generally accepted audio range, clearly the case with the aforementioned Magico, and whether or not the system has low distortion at the deep end of the bass, there's a very good chance it will sound nice and natural. The Magico's extra distortion below 50 Hz might just create the magical combination of 2nd and 3rd harmonics that the human ear (if not the chest) perceives as a solid fundamental, a trick employed by Bose in the famous 901, and which might account for reports I've heard that the Magico has amazing bass, in spite of its measured frequency response.
About the CV, and not that I've studied its design, but ports aren't necessarily high Q, and it is possible to arrange things so that a port does only moderate damage to the group delay and transient response, yet assists considerably in bass extension. The main remaining drawback might be the nearly complete lack of driver control below resonance, but this is not much of a problem if this resonance is kept below about 30 Hz.
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