resonance and sealed enclosures

Poor old Dr Bose had a really neat idea long ago. Instead of trying to lower the resonant frequency as much as possible, push it UP, to 200 Hz or higher. The advantage is that rolloff below resonance, although very great, is smooth and predictable, and can be compensated by electronic means. (This is quite different from the practice of a modest (3-6 dB) boost at 30 Hz or so commonly used with sealed subwoofers). Downside is that a lot of amplifier power is needed.

This idea always appealed to me, as I am a "contrarian". If everyone thinks that one approach is best, I try the opposite. This served me well in a long engineering career.

Isn't a properly designed port supposed to counteract the resonance?

The speaker in question is the Samson Resolv 120a, part of a cheap line of "studio monitors" though I would never spend money on any recording studio that used these things. They're really marketed at wannabe musicians.

Would a 10" sealed sub be an appropriate fit for main speakers with a 5.25" mid speaker or would the sub be too big? Desktop space is a concern here.

A port is typically tuned at the point of resonance that the woofer achieves within that given box. By "counter-acting" this resonance, two smaller resonances are created. It is this elevated bass plateau due to these resonances that typically results in greater extension. At the same time, more resonance equates to less control and definition, which is why most vented designs sound "sloppy" compared to a well designed sealed box. The sealed box loses when it comes to output levels though, so you have to choose which trade-offs you want to live with and go from there. As i've mentioned before, sealed vs vented is equivalent to quality vs quantity.

I don't think that a 10" sub would be out of place filling in the bottom for 5.25" mid-woofers. If you cross it over properly, you can play around with the placement and probably get it to work pretty well. As far as using it on a desk-top, that may be a bit much depending on the size of the cabinet and the size of the desk : ) Sean
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I have read a revuew about a similar setup from M-Audio, slightly more expensive, that features an 8" ported sub. The complaint is that the sub sounds right at middle volumen levels but is too weak at high volume levels and too strong at low volume. Is this a classic case of the type of distortion that is found when using ported subs?

This has to do with port velocity and turbulence within and / or near the port entrance and exits. Using a port that has radiused flares tends to reduce these problems quite a bit. This allows the port to maintain more consistent tuning / proper operation over a wider spl range. If such a port is not used, the output of the port will be far peakier in a specific spl range and lower the performance standard if used outside of a narrow range of average spl's. Using a port that is flared on one side rather than at the inlet and the outlet is better than a straight port, but it will still run into the same problems, albeit to a lesser extent. Sean
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