need help buying a sub: class B or D amp?

[thedude65]

i currently have the klipsch ksw200 sub (12 -inch;ported;downward-firing;class D amp;200watt)along with B&W 602s3 fronts,601s3 rears, and the lcr600s3 center powered by the yamaha rx-v995 av receiver.I recently auditioned the B&W 650 sub(12-inch; front firing; sealed;200 watt;class B amp). I originally figured i saved money not changing my sub when i switched to B&W from klipsch. however, the klipsch tends to sound boomy for movies and sometimes slow when listening to music with a very fast bass beat. The B&W650 sounds more controlled and smooth, but does the class B amp draw more power and run hotter than the D amp? which amp is considered better quality? any advantages or disadvantages with either? Can anyone help me out? thanks!!

[topspeed]

For the nerd in you:
http://en.wikipedia.org/wiki/Class_B_amplifier

the klipsch tends to sound boomy for movies and sometimes slow when listening to music with a very fast bass beat. The B&W650 sounds more controlled and smooth

This has less to do with the amp topology than it does the overall design. You're comparing a bass reflex design (Klipsch) with an acoustic suspension (B&W). The latter is known for tighter, more controlled cone movement but also happens to require more power. The amp can contribute to the accuracy in the cone movement by having a higher damping factor.

but does the class B amp draw more power and run hotter than the D amp?

Yes and yes. Class D amps are switching amps, therefore they draw almost no power in standby mode and are far more effiicient. This is why they rarely get more than warm to the touch. Heat is simply wasted energy. Class A amps are so inefficient they can easily double as a space heater.

which amp is considered better quality?

Depends on the design. Class D's seem to be preferrable for subs in particular because of their efficiency and speed.

any advantages or disadvantages with either?

Class D's are more efficient and therefore cheaper to maintain. They draw less in standby and utilize more when in use. Sound wise, some feel Class B's have lower distortion, but we're talking about a sub here. How much distortion are you going to hear from a sub?

Really, you should pick a sub that sounds best to you in your room and not worry too much about what kind of amp is pushing it. Also, before you go dumping that Klipsh, are you sure you've done everything you can to maximize its performance? Subs, more than any other speaker, are heavily dependent on room placement. Modes and nodes can wreak havoc on the best sub in the world if it's in the wrong place. Do a search for Robert Greene on this board and read his articles on room acoustics. Also, check into a Behringer Feedback Destroyer (BFD). These little $100 wonders can make your sub sound a lot better than you ever thought it could.

Hope this helps.

[westcott]

Now, don't get me wrong, I love my subwoofer but I was really impressed by the Martin Logan Descent and Depth subwoofers with position feedback.

If you get a chance, I suggest you audition them too! Lots of good subwoofers out there now a days and most are using digital amplifiers. They are a good choice for subwoofer work, as topspeed pointed out, because of their efficiency and lower purchase and operating cost.