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Message Forums Car Stereo Message Forums > Amplifiers > Class D or Class A/B for subwoofers
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mtxiznice
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 Class D or Class A/B for subwoofers

Which do members of this forum use on their subwoofers?  Class D or Class A/B amplifiers?  Why?  Is the sound quality better using class A/B better on subs?  Why or why nor?

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New Post 12-23-2008 08:29 PM
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Pioneer~Saturn
Senior Member

 

Well, if youre looking for more power per dollar...class D all the way. But if youre looking for the purest of sound I believe A/B is where it's at

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New Post 12-23-2008 09:42 PM
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1sr
Senior Member

 

Class D, sometimes a/b's aren't as efficient at those power levels.

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New Post 12-23-2008 11:04 PM
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newfosgatesucks
Senior Member

 RE:

quote:
Originally posted on 12-23-2008 by 1sr

Class D, sometimes a/b's aren't as efficient at those power levels.



The a/b's are at their best efficiency at full output.  The d's still win on efficiency though.  Do you want a show-off boom car or a high end sound quality machine?  Do you simply nod or dance to your music or do you actually want to listen to your music? 

It is bizarre noone ever mentions the compromise in Sound quality that class D makes for its added efficiency.  I'd personally reccomend A/B for subs, I believe d sounds harsh on subs and absolutely horrible on mids/midbass.  I have listened to class d, b, a/b, a, t, and so on, and I like A the best, but can't find an old renoir for my components.  So I rely on super low thd a/b's for hi's and lows.  The diff between all the classes is the Greatest when you jump over to class D. 

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New Post 12-26-2008 06:32 AM
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newfosgatesucks
Senior Member

 RE:

quote:
Originally posted on 12-26-2008 by MaximusCarAudio

If I need 500-750rms per sub or 1000-1500 for a single load I always fall back onto a Lanzar Opti 500x2 it is a class ab amp that dose 500rms x2 @ 4 ohms 750rms x2 @2 ohms and 1000rms bridged at 4ohms. I have used them to power single and dual sub boxes and I have also used them to power up a crap load of 6.5" speakers in my rear hatch area on my suv hell I even ran 1 for my front doors and 1 for my rear doors when I custom did them with 8 speakers each.



Those are rugged amps....

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New Post 12-27-2008 09:02 AM
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newfosgatesucks
Senior Member

 RE: RE: RE:

quote:
Originally posted on 12-27-2008 by MaximusCarAudio

A few years back I used 5 of them just for my voice setup and I used 2 of Fusions 4000d amps to power up my 2 DD 9515s That was my fist box that did over a 155 with a tuning of 40hz non wall. Ended up getting louder when I changed the amps to the Z1 amps from DD on same install after. Fusion amps where a let down!



I can imagine how that sounded. 40hz.....that tells me SOMETHING......

  How did the fusions hold up?  Reason I ask is a guy here has the smaller ones, a pair, for cheap, thought I might flip them on ebay or something.  I'd hate to flip them and they not hold up or something...

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New Post 12-27-2008 06:06 PM
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N2Audio
Senior Member

 


"It is bizarre noone ever mentions the compromise in Sound quality that class D makes for its added efficiency. I'd personally reccomend A/B for subs, I believe d sounds harsh on subs and absolutely horrible on mids/midbass."
It's mentioned and debated ALL the time.
Much like the SQ of cheap "measured" watts vs the SQ of expensive "measured" watts -- the scientific/engineer side will almost always argue that our hearing isn't good enough to discern the difference between D and A/B on subs if the test is gain matched/double-blind.
A lot of people disagree with that, most giving anecdotal evidence of how they switched out so and so class D for a so and so class A/b and heard a night and day difference. But there is rarely a case where the comparison is carefully controlled, and it's never double-blind.
I tend to side with the engineers, but I do wonder if a very low damping factor due to driving low impedance loads can be audible with some class D's.

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New Post 12-28-2008 12:02 AM
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newfosgatesucks
Senior Member

 RE:

quote:
Originally posted on 12-28-2008 by N2Audio

"It is bizarre noone ever mentions the compromise in Sound quality that class D makes for its added efficiency. I'd personally reccomend A/B for subs, I believe d sounds harsh on subs and absolutely horrible on mids/midbass."
It's mentioned and debated ALL the time.
Much like the SQ of cheap "measured" watts vs the SQ of expensive "measured" watts -- the scientific/engineer side will almost always argue that our hearing isn't good enough to discern the difference between D and A/B on subs if the test is gain matched/double-blind.
A lot of people disagree with that, most giving anecdotal evidence of how they switched out so and so class D for a so and so class A/b and heard a night and day difference. But there is rarely a case where the comparison is carefully controlled, and it's never double-blind.
I tend to side with the engineers, but I do wonder if a very low damping factor due to driving low impedance loads can be audible with some class D's.


There is going to be a tad diff in damping, but the major factor is distortion.  The intermodulation distortion, is odd-order harmonic, and not typically stated in the speciications of class D products.  The difference in .2 and .15 made sq amps sq at one time.  The .3 most class d's generally produce is actually audible on a similar wattage same vehicle install.  They sound MEANER, and in my opinion it is from the added distortion, which, once again, is not stated by some specs - where ultra hi-end class d's with super low thd actually produce a tad more overall distortion.

    Watt vs watt, at any given volume and similar setup, no, a pyle watt and a macrom watt are the same.  It is the distortion content that our ears hear, and it is that same distortion that allows blown subs and crudded out mids/hi's......

 

    If the distortion is absolutely not there, then try a class D on some mids like a set of focals or dynaudios or MB's and I tend to think the difference will be clearer...Or dirtier, actually....

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New Post 12-28-2008 07:34 AM
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newfosgatesucks
Senior Member

 yeah, and...

Also, dont think for a second tht manufacturers dont fudge thd just as much as wattage either.   Aside from distortion content, a watt is a watt is a watt on the same class amplifier, some makes and designs of each class have their own sound, due to which part of the wave gets reproduced - its minute, barely audible, and most dont care.  We are talking minute, but with the added distortion in some models, it increases to clearly audible. 

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New Post 12-28-2008 08:26 PM
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N2Audio
Senior Member

 

when people start talking about hearing fractions of a percent of THD I stop listening, or in this case, reading.

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New Post 12-28-2008 11:57 PM
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newfosgatesucks
Senior Member

 RE:

quote:
Originally posted on 12-28-2008 by N2Audio

when people start talking about hearing fractions of a percent of THD I stop listening, or in this case, reading.



Go google richard clark challenge and see for yourself. 

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New Post 12-29-2008 01:40 AM
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N2Audio
Senior Member

 

LOL

what's that going to get me??

I've been reading his stuff since I registered at Carsound 1/01.

He is one of the many respected engineers involved in the audio industry that will tell you if you think you can hear .15 or .2 or .3 % THD you're dreaming.  Even picking it out on a tone would be next to impossible...with music, not a chance.

So, like I said, if .3% thd is the reason why you think class D's sound different than a/b's I will take that to mean there IS no difference.

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New Post 12-29-2008 12:04 PM
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mhubbard
Member

 Class D or Class A/B for subwoofers

I don't know if it relies only on THD.  There are other factors.  With mono amps driving the ohm loads down to 1 ohm is not good for SQ.  There will be a difference especially when listening to an amp that is bridged mono at 4 ohms.

Not to also mention that driving a mono block amp down to 1 ohm also brings down efficiency close to that of class A/B amps which is around 68%. Stephen Mantz told me that class D amps are not that efficent at low levels and are not much better than class A/B amps. The differences in sound between class A/B and class D may not always be due to THD levels also. There are other factors which are unknown to us.

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New Post 12-29-2008 12:37 PM
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N2Audio
Senior Member

 


"I don't know if it relies only on THD. There are other factors. With mono amps driving the ohm loads down to 1 ohm is not good for SQ. There will be a difference especially when listening to an amp that is bridged mono at 4 ohms."


You're defining damping factor. As I mentioned above I would think that would contribute much more to audibility than a few tenths of a percent of THD which might not be present anyway.

"Not to also mention that driving a mono block amp down to 1 ohm also brings down efficiency close to that of class A/B amps which is around 68%. Stephen Mantz told me that class D amps are not that efficent at low levels and are not much better than class A/B amps."


Strange -
I have nothing agiainst Mr. Mantz, that is for sure. I have two of his amps in my trunk and don't plan on ever getting rid of them. However, there are countless magazine/online tech reviews that will clearly show otherwise. I'm sure there are those that don't do so well, but for example - I have a pdf saved of the Opti6000D review from Performance Auto and Sound. It's probably not a stretch to call this a budget amp by most enthusiasts standards. It was 74% at full 2 ohm power (3617w).
At one time I had a similar report on the 2000D which measured at 84% doing 1900w at 1/2 ohm.

Besides, the real advantage of a class D is that their efficiency doesn't fall on its face below rated output. A class D that is 70% at full output is going to be close to 70% in the 30-50% output range whereas EVERY class A/B will fade to 30-35%.
THAT is where efficiency really comes into play.

Steven has always seemed to have something against class D amps. There wasa big blow up a while back on the Minilith because a lot of his customers had issues with them driving 1 ohm laods. I don't think he would build them at all if they weren't so popular right now, but he, like any manufacturer, wants to make money so he has to build what's selling.

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New Post 12-29-2008 03:21 PM
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mhubbard
Member

 

I agree with you on that N2Audio.  BTW my other name is mtziznice but I am using this one for here on in since I use ZED and not MTX.  It's funny that you mention class D with Steven Mantz because his new amps coming out are a 2 channel class D and a 4 channel class D which is capable of being used as a 2 channel or being driven mono.  It's odd that his minilith amps can't drive 1 ohm because his Opti 1000.1D have the same issues.

Anyway, I agree with you about class A/B but cannot dispute the sound advantage of class A/B over class D.  However when listening to rap and a lot of the heavy bass music it isn't easy to distinguish the differences.  When listening to real music such as R&B, classical, jazz or reggae then the differences are very obvious.

 

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New Post 12-29-2008 04:57 PM
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