GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Playback Listening
In the Thread: Some Observations about Science and Bass

Post Subject: Making Bass That Actually Works (Servo?)Posted by Paul S on: 7/18/2010

Nice rant about "scientists"; but I suppose you are preaching to the choir here.

I jumped in not to pile on the stupid "scientists" but to address the rendering of bass, and ULF in particular, in the context of home hi-fi.

A while back I got a splash of cold water in my face when I read a post from an audio "pro" who had run actual response tests on a number of popular "subs" (and the woofers they used). I was astounded to read the rather pitiful results, including doubled McCauley 6174s that were down 3 dB at 43 Hz. Using this data and driven by renewed interest in the subject, I began to run the numbers on what it would take to get down to 20 Hz. Within a few hours, I had pretty much abandonded the half-baked "conventional" methods I had earlier half-held on to as my future (U)LF ticket.

Sometimes when I suffer a setback I develop a sort of morbid facination with the problem, itself, where I simply gather and look at information on the subject with no real agenda. Following this pattern with respect to ULF I began once again to think of servo bass. Basically, I wonder if it has improved in terms of musical utility since the early Velodyne (etc.) "one-note" systems that were also impossible to integrate into a system.

These days, some of the servo systems come with user-adjustable bias and narrow enough ranges of adjustments to where it appears it might actually be useful. Sure, pure output is nice, but there is simply no getting away from the room and the rest of the system in the case of (U)LF, so it appears that any "universal" approach must include provisions for careful individual tailoring along with "enough" pure power to get the rote part of the job done. Distortion under these circumstances can be very high, practically speaking, and certain servo approaches at least appear to offer a chance to effectively lower ultimate power requirements and working distortion, both, via the same trick of putting the speaker itself in the feedback loop. So, now I wonder.

While a decent 40 Hz may be more difficult than many people realize, significant quality output at 20 Hz is another thing, altogether. How best to approach the mysterious "bottom octave" of music?

Rather than close now, when I should, I will take full advantage of the initial set-up by turning readers on to the strange and wild "scientist", Royal Rife; and I am always pleased to repeat the name of Rupert Sheldrake to any Students of Life who do not already know of him.

Best regards,
Paul S

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