I'm considering a class D amp for a subwoofer - the small size and low heat
are the attractions. Any downside to using one (assuming a LPF of 80-100hz)?
I'm looking for good musical lows for rock/jazz rather than pounding bass.

 

^ Not that I am aware of, I recently decided on a Apline PDX amp due to size and power. From what I have read, they are extremely clean and very efficient - 88% efficient, the 12% "loss" is simply from running the amp internals.

 

I drive my 12" Polk SR DVC with an Alpine PDX 600w, lows are great: hits hard, very good sound quality

 

There are no downsides of class D for a sub. Class D was MADE for subs.

 

Get an efficient Class D amp from a reliable brand that puts out at least the RMS capability of your sub so the amp can comfortably provide clean power to the subwoofer without stressing out itself and the S's electricals. Don't worry about the minute differences in amp sound quality like S/N ratio, THD, etc (unless is way off like >2% THD) It's VERY unlikely that you'd hear the difference with all the noise in the cabin, unless you are planning to listen while parked :-) Would you rather hear the sub or not hear higher quality bass from the sub?

I'm assuming you have one or more 8" or 10" subs with at least 150W RMS. If not, you may want to get a more powerful, fast sub for jazz/rock.

I am onto my 3rd amp in the S and just picked the Alpine V-Power Series M650 (Class D), but then I have a 600W RMS sub. You may want to get the M450 or smaller amp. Other brands that I'd look at are JL (not JBL), Phoenix Gold, Precision Power.

 

That's 99% up to your sub driver and enclosure. The other 1% encompasses the character of the amp. Assuming you pick a quality amp, the only thing that really matters is actual output, not rated. Pick one that's within your size constraints, power requirements and obviously budget. Search around for sales on 2006 model amps that internet companies might be trying to get rid of since 2008 products are coming out soon.

Doing a 1 minute search resulted in this. Fosgate power T10001bd (rated 750Wx1@2ohm) the actual output per amp will vary, but this site lists it as 944W@2ohms. Less than 400.00 too!
http://www.cartronixplus.com/templates/det...616DA4A7E171EE8

I'm not a big fan of Fosgate woofers, but I am a big fan of their power series amps! Always very underated and built to handle the demands of competition. You can't go wrong with a Fosgate power series amp.

 

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[QUOTE=jwa4378,Sep 27 2007, 09:02 AM] I would be careful about making a blanket statement like that.

 

but I really do not feel that the box design alone governs 99% of the sound quality... like you said...

Sometimes though (more often than not), subs like to be overpowered. The design of the sub will dictate by how much, and how it will sound.

With that being said, if you have the same sub and the same box, powered by two different amps (one being something like a high-end Alpine and the other something crappy like a Sony), are you telling me that they will sound the same SQ wise (trying to understand)? I doubt it.

John

 

John,
My comment was based solely on the importance of the box, which I do believe is more important than amplification (to an extent) as I stated above relating to the power output of the amp and the rated power of the sub.
As far as comparing brand X amp to X in the same scenario in the exact same set-up, and the same power output, at say 200 watts RMS, most people will not be able to tell the difference in the SQ of the sub, S/N ratio is not the most important factor for a sub.
I do not agree with Looneybomber's statement of 99%, more 80-20, give or take.
Your comment of "the design of the sub will dictate by how much, and how it will sound" I don't agree with, the sub is a motor, there are outside parameters that will dictate how it will sound. If you build a box too big, the bass will not be tight and clean, it will be slow and sloppy.

Sam