hi ppl

ummmm before anyone asks I tried to do a search regarding this and didn't turn up much. i'm guessing the differences in SQ between class B and D amps are indistinguishable at these low frequencies? Just asking because I'm in the process of making an SQ with dynaudio or morel main splits, but would like some serious grunt for the subs.....like maybe DD or RE subs with a class D amp. any advice appreciated

What about Pure Class A

Class A is too inefficient for a sub.
Maybe if you use it for a heater under your seat.

lol good point overkill for a sub

Quite simply Class A/B seems to provide better control, although with Tripath chips now, Class D (or T if you like) is really stepping up.
Just look at Zapco's Class T, Altomobiles Class T...
Both full range amps with efficiency to die for.

This said, for a sub, Class D seems the best due to it's efficiency.
The difference in sq isn't that great between A/B and D that you'll hardly notice a difference when driving a sub.

to me it is a day and night difference. me and my friend can hear the difference after i upgraded from an earthquake amp to a Xenon 100.4 (class A/B) amp. the bass is far more accurate and tighter. but if u want loud, a class A/B amp might not be able to provide 1K watts for the loudness some people want.

If you're going DD or RE and want big bass, just go with a big D.

ok, so here's a question from me...
If I use a class D for the subs instead of A/B, will it be enough of a difference to lose points in SQ comp?

Ill let you know when I hear it lol Personally I cant help but wonder why you would need Kw's for an SQ car. You can make any car bump fine with far less. Hell my 600w is more than enough for SQ and cranking duties. If you need more then you must surely be chasing SPL. My vote is for class AB and leave the Ds for the SPL guys. I have never been a fan of sloppy bass thou, regardless of how loud it gets
peace
Cyberpunky

i admit i've heard a difference with class D's compared to A/B, really big a/b amps especially like us amps etc, they definatly sound different but wether theres a definate good and bad i dont know :| but i dont think upmost sound quality was in mind when designing class d amps, bulk power and efficency was.

you would never get a reduction in points though, theres to many other varibles to consider.

Class D may sound as good as Class AB, or maybe it does not. But i know for sure an amp which plays from 20-200Hz only, at BEST, could equal a Class AB in that limited frequency only. Why pay for an amp which doesnt even play more than a few octaves? The only justification is if you need lots of power, using the '$ per watt' measure, Class D amps are incredible value.

So why run Class AB? Firstly because it actually plays full range, rather than 1/10th of the audible spectrum. Secondly because Class AB will always be at least equal, and probably better than Class D from a sonic standpoint. And last of all, who the hell *really* needs 2000W RMS for music? The way people go overboard on power these days is a little scary to a small fry like me . In real music, even at ear splitting levels, you will never use more than a tiny fraction, so why get 2000 cheap watts when you could get 1000 for the same price, and would sound just as loud for your music (SPL competitors excepted), and probably sound better as well? I know my MRV-1507 with about 900W RMS bridged can make my subs go louder than i would ever want to

Only logical reason to me for getting Class D is if it's cheaper than Class AB (not always,Some high end manufacturer Class D amps are more expensive than Class AB (Zapco, Arc Audio, etc), and the cheaper Class Ds, with a few exceptions, are nasty looking ghetto machines), if efficiency is very important to me (it's not), and if i am an SPL competitor (I'm not).

The classic audio phrase "its all about tradeoffs" has a big part to play here i think. Based on the advantages and disadvantes, one has to choose the right set of tradeoffs based on one's needs.

I'm still waiting for a defninitive stance based on something other than "watts for dollar value", thats relevant to

a) the question : sound quality
IN
B) The applications requirements (subwoofer control, playing ONLY at low freqs, etc)

This whole threads been a little ambigous.

mabey because most of the poeple that purchase big a$$ D's are not considering there sonic qualities :|
D class will allways never be up to the quality of a A/B sound wise, its the way there designed the signal after being amplfied is nasty and harsh like a triangle wave and must pass through many filters before it exits the amp and resebles something like a sine wave but devoid of many of the wonderfull harmonics that other classes of amps have that give them there better sound
the good thing is that there used for subs making there sound less noticible but i have never heard enough different brands or ever done some kind of comparison to diffintivly state that one brands sounds better than another.
also note that not all class D amps are 2000w!! there are many that are only in the 300-500wrms range.
but still there are to many 'other' factors to take into account to dismiss using a D class or any other one for that matter in a car sub setup.

I was just noting a lot of people were noting SQ across the whole spectrum, but not discussing the SQ differences in spectrum we're considering, the lower ranges.

Class D is digital yes, on or off? I can imagine how that might sound harsher than a class a/b...but as you say, filters would counteract much of this, i would imagine.

most class d designed amps have a 12db/oct passive output filter set id say around 200-500hz.

this is more like an analogue re-construction filter

cyber notes that class d is comparatively sloppy playing bass notes when compared to the typical class a/b designs. Unfotunately due to the fact that these class d designs require the passive output filter their dampning factor dramatically decreases. this results in low impedence loads seeing a very low dampening factor, which is regarded as below 100 .

i was under the impression that as an amp goes below 100 rating in dampening factor that the amps ability to control back emf is greatly diminished. This results in this sloppy bass. this might also be due to phase angles created by the passive output filters too.

might be wrong so id need clarification by an expert. The tru-tec guy might be able to shed some light on to this

What do you want? A conclusive answer? This is an audio forum, and audio is rife with inconclusive opinions and findings

If you really want 'black or white', then here's a nugget of info: In a blind A-B test, with levels matched between amps, so far no one has been able to prove there is a difference between class AB and class D with statistical validity. That 'answers' your first question. Now, if you believe that, then the answer to your second question is obvious: If there is no audible difference, then application requirements make class D more attractive since they sound exactly the same, and are cheaper for the same amount of wattage.

If you don't believe that, then listen to the valuable opinions in this thread and try to come up with your own answers.

I have used class D and have found them to be fine. I have heard a number of class A/B on subs and at the volume they judge SQ comps i doubt it will make any difference.

its been more popular to use class a/b for sub duties in a sq car

the hard core sq nuts seem to swear by the class a/bs over any other class amp to drive their speakers.

ive personally chosen a class d sub amp. One advantage is that i can use the same amp for spl comps if i have the money and time.

the class d seem to have the dollar per watt advantage and seem to come in bigger sizes

It depends what you want, if you are only competing in SQ comps and its not a system you will want to have blow your ears drums totally then go a class A/B.

Yet if you will only occasionally enter SQ comps and wont be taking it really seriously, then class D maybe better for power and may cost less also. So you get a good enough everyday listening amp that wont set you back a heap and will deliever plenty of power.

By the sounds of everyone else, Class A/B sound better but Class D are more effiencent and cheaper power

not looking for dB's, just more channels to amplify... active front stage.
the digital amp I was looking at would drive the 2 10" woofers as 1x 8 ohms, 350WRMS
the physical size of the amp would mean not having to re-build the boot of the car.
maybe when I'm bored I'll play with this.
until then... whatever

My VOTE for AB too. they sound very different. hollow bass is what you get from class D amp. being A very hardcore SQ sort of person I will never use any class D amp in my setup. no one will deduct your points for using class D amp for sub but the class D amp just don't do the propper job for my ears.

"Typical" D class designs generally have 5-10% THD at big power levels, they get away with being so dirty as it's hard to hear this level of THD on subs. Subs themselves have high distortion.

Newer SQ D class designs are avaialble with much lower THD. Our M1 for example is rated at 1x600Wrms at 0.25%, 1x1300Wrms at 1% THD.

I'm sure if you also look around at other high end D class amps from Alpine, PG etc you'll find that going D class for SQ is a great option.

Phil