19 replies to this topic

[T-Bro]

Hey all,

We'll I bit the bullet and have acquired a new sub amp, a Kicker KX600.1 monoblock (oooh baby) birth sheeted to do 750WRMS into a 2 ohm load.

Anyway, this little beast is a Class D amplifier, which appeals to me because its so efficient, with reports from existing users that it runs cool even after extended high volume listening and will not cause extreme dimming of lights etc. Ideal!

But then there is the issue of sound quality. Of course, too late to change the amp now, this is what I want, but I am interested in hearing from people who have ACTUAL AUDITIONING EXPERIENCE as to whether there is an audible loss in definition, clarity, attack, resolution or extension with Class-D sub amps.

i know our forum moderator Critter uses Class-D and has had good results, as have others, yet I read of others elsewhere who don't like the sound.

Ignoring the theory and focusing on actual experience, what are your thoughts on Class-D sound quality?

[Mr_Bob]

i'll take partial responsibility for conning SQ boy into becoming an SPL connoisseur
Critter's setup was certianly smooth and controlled, and there wasn't a lack of low end bass extension.

the extra power to your FS will bring extra attack anyway (or you could go active FS... )
even if the SQ is "worse" in SQ mode i doubt any difference will be audible anyway.

don't forget i'm not far away if you want help/company when installing it. you've got my number

[Sonic Nirvana]

My experience in going from the Kicker ZR amp I used bridged previously to the current JL Class D was in fact a MASSIVE improvement in SQ that defied understanding.
It was hardly the other way around.

Smoother, stronger, much tighter (much) and better detail, attack and extension into very LF.
As well as better efficiency and vastly more flexible.

I wouldn't go any other way without a REALLY strong argument....of course I can only speak to that particular comparison.
But IMO the JL is absolutely viceless. Best product I've ever used.....

[NUTTTR]

Well, i had a class d running my sub, changed to a class a/b more powerful, noticed a big difference, very different sound, changed to class d again (D2!) and noticed a huge difference in Sq, music is quicker, clearer and more defined, so i'd jump on the there's no audiable difference, and if there is, i like it more!
Aaron

[0{noidea}0]

Yes, infact the Class D amp is efficient but u have to forgo some of the SQ.

I have seen a Sound electrical book that actually explain this.

As i have used many amp before i relise that the class a/b amp seem to have deeper and more tighter and faster hit bass compare to the Class D. But what i get from class D amp is that they are Louder, boomier, punchier and seem to have longer kick bass compare to the a/b amp.

That is Xtant X603&PG Ti400.2&Xtant 2100ix,RF800.2 vs X1001&MTX 81000D on the same sub.

But the sould could be affected due to the different built quality of the amp.

[Sonic Nirvana]

There are quite a few different "takes" on how to do Class D, almost as many as there are manufacturers implementing them.

My personal experience with the JL suggests they got it right.....and this is the only Class D I've used.
JL relies on demo-ing their W7's as "the best sub available" with their Class D amps, so that says quite a bit given their attitude to SQ.

[T-Bro]

thanks for your input guys

so far it seems Class-D is indeed comparable in sound quality to Class A/B, as far as sub-bass goes. in those instances where it has been even better, i guess one explanation may be that the improved efficiency of Class-D allows better transient attack through a more even power draw - there is less lag or 'dimming' of the power suppy, and hence more control.

ive heard similar reasoning to yours critter, that the implementation of Class-D is paramount to its performance. here, its the actual switching circuit, and the filters attached to each channel output to remove noise, that play a big part.

the JL you have critter is an exotic and un-usual beast, outputting the same power into any impedance. i actually considered one in my research, but stuck with kicker as ive torture tested their products for a few years now and trust them. (mr bob - we were right, the JL is a class-d, despite what the salesman claimed )

anyway, Class-D would appear to have the potential for greater low end control and transient attack simply based on its efficiency, as cars electrical systems really are quite poor, so the 'stiffer' the amp the more control it maintains. that said, there are lots of Class-A/B amps that are plenty tight and controlled

whoops, got caught on theory and science again....

anyone else with auditioning experience with Class-D?

[0{noidea}0]

Just get a Class T Dammit ....It is more highly efficient than the Class D and also it won't forgo any SQ.

[Walkinshaw]

Dependant if the class D amp offers stiffer internal capacitance, more power and a higher dampening factor than your origional bridged 2ch you may find that subbass SQ may be better.

[LongWay]

the few things I've noticed between A/B and D amps:

*Lower damping factor on the Class D amps
*Higher THD- especialy the shredder- car audio mag tested it at 7.89%- good god!

The only real good thing those dirty amps are good for...is to get loud! But thats what they were designed for...SPL

I'll stick with my A/B amps

[Bassaholic]

Quote

Originally posted by LongWay:

*Lower damping factor on the Class D amps
*Higher THD- especialy the shredder- car audio mag tested it at 7.89%- good god!

Dude, ANY amplifier can be overdriven into producing 8%+ distortion.. When the D2 isn't being overdriven, the THD will be under about 1%

As far as damping factor goes, 99% of car audio amplifiers have a damping factor that is significantly high enough that it will not be audible..

[ May 03, 2003, 03:01: Message edited by: Bassaholic ]

[Anonymous]

I have used both a regular class A/B Amplifier and two different Class D Amplifiers.

I have found that their is a distinct different in sound, the class A/B to me gave me more of that warm/fuzzy feeling. However the class D did go harder easier.

As to differentiating SQ, well i dont think its possible, I think they both have there benefits, both have their disadvantages and it is not a case of one being better than other.

I initially used a 1507, from an SQ prospective it was fantastic, was very natural right through the spectrum and played effortlessly. Then I 'downgraded' to an M500. I found the bass attack was a little cleaner and more precise however this could be put down to the amazing control/processing on this amplifier.

I now am using a pair of 900.1's (Phoenix Gold). THese will go hard no matter what your playing, are amazingly flexible in their task and have fantastic clarity. However the cone control doesnt seem quite as good to me. however with the change of subs at same time it is hard to tell :/

In the end though I think they are both great designs, the differences are only as recognisable as audiable differences between brands.

[T-Bro]

8% THD for the D2? phwoah!!!!!! well i think Class D averages around 1% THD anyway, which is quite a bit higher than Class A/B on average/ but the reality is, humans struggle to hear anything less than 3% THD anyway.

in addition, even at 1% THD, your sub box creates more distortion than the amp, making it a pretty moot point anyway.

also, think about Tube Amplifiers. regarded many audiophiles as a better sounding amp design than transistor designs. HOWEVER, valves feature alot more distortion (pretty terrible on paper from what ive been told) - yet, people love their warm and natural sound.

the more i research, the more i think that Class D is just fine for sub-bass SQ, so long as your going with a reputable design from a good manufacturer, and running it sensibly, its all dependent on how it fits into your overall system. sub choice and box construction would appear to be alot more important.

BTW, i heard a Rockford Fosgate 1500BD in a mates car, which i believe is a Class D, what a MONSTER of an amp, so much power! seemed to maintain good control of the sub when pushed hard. he also reports that it barely gets warm even after hard use - a good thing given the poor ventilation amps receive in a boot.

[DG Phil]

A few points to consider.

1. 99% of people can't pick 1% distortion, let alone 5% distortion, I have a test CD that enlightens quite a few people at times!

2. Subs have a high inherent distortion built in because of the high moving mass and long cone excursions

3. A lot of people mistake a power increase for an SQ increase.

Don’t ever reject a sub amp because the catalogue says 0.05% and it’s competitor says 0.04%, that’s my point here.

It's virtually impossible to compare two amps unless you have them wired up in the same car and can switch from one to the other instantly. Further, the gains must be matched precisely.

I've generally found most of the better D class amps sound OK, the Signat Ts seem to be a little better again. But none of the Ds I've used can match a very nice AB, we recently put a pair of Boston GT28 (1250Wrms at 2 ohms mono) into our Civic. I've never heard the subs sound as good and it still makes well over 155! We've had MTX 1000Ds, 81000Ds, Signats, Audisons etc etc in that car, so impressing me was no mean feat. The new Boston amps are worth a listen imo.

Phil

[Bassaholic]

Quote

Originally posted by Incar Phil:

3. A lot of people mistake a power increase for an SQ increase.

Or for that matter, sometimes a power decrease - as the amount of sub bass will be more level with the front speakers..