subwoofer question


hi everyone, i have a chance to buy 2 m&k mx-150thx(mark I) subs for $900 shipped.
first off is this a good deal or am i over paying.
next, because these subs are old (10-15 years), can they compete with the new subs which use better technology.
i only use my system for home theater.
my room is 14x12.
will these subs be great for my room or should i get one really great "USED" sub like a jl fathom, or velodyne dd series, svs, etc.

thanks so much
nineballg
Marty sorry im not following when you say Box size is not key then say 13" Box will be more damped than 11" for a 10" driver, i.e bigger Box more damped. So if i read you correctly you say a f113 can be faster than a f110 due to having a larger volume relative to its driver? I guess the other parameters will be pretty similar between these two subs so pretty well controlled experiment here. The other hypothesis might be that the smaller element is lighter and therefore moves faster. Do you see any drawbacks with a highly damped sub versus a ledset damped?
I also prefer a highly damped, or "tight" subwoofer, which also applies to woofers in main speakers.

IMO, I think the tradeoff is that ported subs/woofers may have a real or perceived lower depth and/or higher loudness than non-ported models (all other things being equal), but to me they sound looser.
Sorry, Perrew.

To clarify:

The conceptual design goal of a highly damped subwoofer system is that, once the musical signal is stopped, the system will restrict the tendency of the driver to keep moving. The idea is that momentum is defeated and bass will be tighter (maybe "faster" to some) as the woofer quickly settles.

Hence my suspicion that some people equate big drivers (with lots of momentum) with slow bass. Some subwoofer tests include a measure ("group delay") of a sub's ability to accellerate, reproduce an input signal, and "settle" after the signal stops, but there is disagreement on the usefulness (and threshold audibility) of this spec. Highly damped systems typically show very low group delay relative to less highly damped systems.

Both the driver's inherent "springiness" and the box's ability to inhibit driver travel (this alone is a complex function of the box's size, shape, loading scheme, stiffness, etc.) contribute to the overall system damping. Therefore, there is no universal correlation between driver size, box size, and system damping. I don't want to overstate my technical expertise on the subject, so I'd suggest that you search a bit for technical info on "loudspeaker damping".

A little more bad news. IMHO, a subwoofer can be "overdamped" (too fast in my parlance) depending on the main speaker to which it's being mated. Again IMHO. Again, YMMV.

Good Luck

Marty
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Bob is correct. My previous posts were my attempt to explain why there may be a common idea that a large driver mean larges inertia, means "slow" bass and why that idea may not hold water. I covered the momentum side. Bob closed the loop by explaining that the extra mass of a larger driver may be accellerated just as quickly as the lower mass of a smaller driver, provided that the force applied to it (the motor assembly) is also proportionately larger.

Bottom line: IMHO driver size and "speed" are not related. I am 100% sure that others will disagree.

Marty