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Class D really not so great

L

L. Larabee

Active Member
Here is a recent review of a class d amplifier considered to have excellent performance by everyone involved at the site. As you can see, the specs are not as good as your average class a/b amp from 1985 and, in fact, so horrible that Thd at 20khz is not even shown because it would look very much like that of a well designed tube amp at an estimated level of -60db or 0.1%.

How can anyone consider this sota when something like this graph is staring you in the face.



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The thing about Class D is that some of the highest-performance units are boxes holding Hypex or Purifi all-in-one boards, yet are often VERY expensive IMO. The very-affordable ChiFi boxes are often chip-amp based and decent but tend to be lower power. I'm an old guy and used to standard-sized Class AB boxes and feel like I can get a great example with a healthy 100W/8Ohms for under $1000, less if buying used.

All of this is to say that except for uses that require small boxes in tight spaces, I am much more likely to stick with Class AB than D.
 
Haven't we beaten the whole the whole thing about numbers not being the only arbiter of what sounds good to death by now?

If not, can we? I swear this sort of thing comes up on a regular basis and it always turns into a dozen pages of numbers matter vs numbers don't matter at all vs only some numbers matter.
 
As a gigging musician that made the move from old solid state and tube amplifiers, I can say with confidence that for "professional sound systems", class D is the ONLY practical option. The reason? Weight. And the difference is HUGE. It's like looking at specs and saying that an incandescent light bulb is better than an LED bulb. Swell. I've replace every single incandescent in my home and shop with LED. Every. Single. One. The longivity and power savings are HUGE.

I have a Crown class D amp for my bass rig and a bigger Crown class D for my PA. The weight difference is a game changer.

And as someone noted, in the real world, 16k hz is really the maximum most of us care about.

All my future amps (assuming I'll ever need any more) will be class D, until they come up with something better.
 
gadget73 said:
Haven't we beaten the whole the whole thing about numbers not being the only arbiter of what sounds good to death by now?

If not, can we? I swear this sort of thing comes up on a regular basis and it always turns into a dozen pages of numbers matter vs numbers don't matter at all vs only some numbers matter.
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So, which do you think sounds better, vinyl or CD? :rflmao:
 
L. Larabee said:
Here is a recent review of a class d amplifier considered to have excellent performance by everyone involved at the site. As you can see, the specs are not as good as your average class a/b amp from 1985 and, in fact, so horrible that Thd at 20khz is not even shown because it would look very much like that of a well designed tube amp at an estimated level of -60db or 0.1%.

How can anyone consider this sota when something like this graph is staring you in the face.



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Click to expand...

Well, since we don't know what this mystery amp is, how do we know it's considered SOTA?
 
What everyone is saying is true and perfectly fine with me. The point I make is the factually horrible objective performance vs the cherry picked and optimized 'feature' spec lauded as being the most important on that site.

it's a new Boxem Arthur amp (says on the graph)
 
Currently (see what I did there) I'm using a Crown Class D amp.
Thank goodness my hearing falls off above around 10 or 12 Khz.
I guess that keeps me from hearing how crappy it is. Even when I use an eq would it still sound crappy if I couldn't hear it?
Oh wait, I am using an EQ. But my wires didn't cost thousands of dollars, so I guess that keeps me from hearing how crappy the class d amp sounds.
 
To the OP,

While I can see your point about Class D, I also notice you're a fairly recent member, and might not realize that the folks bristling at your premise have chewed this particular bone down to dust.

If it sounds good, it sounds good. If it measures poorly and sounds good, who cares?

Stick around long enough, and I surely hope you do, you'll see others point of view, especially what my man @RobRoy said about being a gigging musician. I've done that myself, and Class D is a godsend for us who tote our own gear.

My Threshold 400a has....get ready.....ONE PERCENT THD at its limits. And she sings sweetly. My point is, measurements are a guide, not an absolute.
 
onwardjames said:
To the OP,

While I can see your point about Class D, I also notice you're a fairly recent member, and might not realize that the folks bristling at your premise have chewed this particular bone down to dust.

If it sounds good, it sounds good. If it measures poorly and sounds good, who cares?

Stick around long enough, and I surely hope you do, you'll see others point of view, especially what my man @RobRoy said about being a gigging musician. I've done that myself, and Class D is a godsend for us who tote our own gear.

My Threshold 400a has....get ready.....ONE PERCENT THD at its limits. And she sings sweetly. My point is, measurements are a guide, not an absolute.
Click to expand...
Not to mention that Threshold is one heavy beast, I’ll warrant. And my Antares is within a whisker of 100 lbs. If I had to tote it around? Class D indeed, no question. But I don’t.
 
goodolpg said:
Currently (see what I did there) I'm using a Crown Class D amp.
Thank goodness my hearing falls off above around 10 or 12 Khz.
I guess that keeps me from hearing how crappy it is. Even when I use an eq would it still sound crappy if I couldn't hear it?
Oh wait, I am using an EQ. But my wires didn't cost thousands of dollars, so I guess that keeps me from hearing how crappy the class d amp sounds.
Click to expand...

I've got some Crown XLS amps and they have good distortion specs similar to typical AB amps.

I have seen class D amps that have 10 or more % distortion at the advertised output. I think those are the sort of amps the OP is talking about rather than the Crowns or the higher end stuff.
 
RobRoy said:
As a gigging musician that made the move from old solid state and tube amplifiers, I can say with confidence that for "professional sound systems", class D is the ONLY practical option. The reason? Weight. And the difference is HUGE. It's like looking at specs and saying that an incandescent light bulb is better than an LED bulb. Swell. I've replace every single incandescent in my home and shop with LED. Every. Single. One. The longivity and power savings are HUGE.

I have a Crown class D amp for my bass rig and a bigger Crown class D for my PA. The weight difference is a game changer.

And as someone noted, in the real world, 16k hz is really the maximum most of us care about.

All my future amps (assuming I'll ever need any more) will be class D, until they come up with something better.
Click to expand...
I was given three of the Crown CDi-1000 amps. They sound pretty damn good and are so much easier to lug around. These are 275w into 8 ohms, 500w into 4 ohms and can be bridged. I can grab one with one hand. On the other end, I have a couple 125w tube mono blocks that weigh in at around 38lbs each! The Crown CDi specs are pretty good also.
 
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