No "AIR" in class D? Yes or No?

My question is based on several listening experiences and wondering how others hear it and maybe I need up to date experience..

6-7 years ago I was travelling around and demo-ing a lot of gear and many set-ups had digital amps connected.. One was NHT-XD one other was 801D with expensive class D..

The Major dissapointment with these system was that the music had no "AIR" which means it was grossly missing HI frequency detail.

Is this still a problem? Or was it never really an issue with some of you? Is there now improvements?

Thanks, Joel
 
My question is based on several listening experiences and wondering how others hear it and maybe I need up to date experience..

6-7 years ago I was travelling around and demo-ing a lot of gear and many set-ups had digital amps connected.. One was NHT-XD one other was 801D with expensive class D..

The Major dissapointment with these system was that the music had no "AIR" which means it was grossly missing HI frequency detail.

Is this still a problem? Or was it never really an issue with some of you? Is there now improvements?

Thanks, Joel

There's lots of air in my class D amplifier. In fact it's how it stays cool...
 

cotdt

Member
2005-10-30 12:57 am
My modded Tripath amp has plenty of air, but my Hypex UcD does not (I call it "polite treble"), even after mods. It really depends on the amp.

You only hear the top end air of instruments on certain tweeters, so most won't be able to hear it anyway. You also need the ability to hear beyond 10kHz, which a lot of people cannot unless a test tone is played very loud.

Even with my Class A SET amp, certain tubes have an excellent airyness with lots of top end detail, while other tubes simply don't.

This applies to Class A SS amps as well. Some do it well, others don't.
 
I have designed class ab and class d amplifiers and have always had trouble telling the difference when listening.

There is a myth going around that all class d is good for is bass.
This really isn't true.

Perhaps early designs were poor but modern designs are very good.

Just because class d amps are cheaper doesn't make them worse.
 

cotdt

Member
2005-10-30 12:57 am
If you have a good tweeter, and you listen for certain things like the decay of cymbals, artificial harmonics played on a guitar, there is a delicate detail that is there with some amps and not there with others. I play musical instruments and I can hear that sparkle.

This effect is also important for spatial information, and is one of the factors in imaging.
 
I have designed class ab and class d amplifiers and have always had trouble telling the difference when listening.

There is a myth going around that all class d is good for is bass.
This really isn't true.

Perhaps early designs were poor but modern designs are very good.

Just because class d amps are cheaper doesn't make them worse.

I find them poor at the frequency extreme, which is bass and lacking Air as described by the OP , i dont get this Class-D is good in bass, i have yet to hear such.

Class-D sound is fast and dynamic, they do tend to capture the pace and impact of live music, but is grainy and dry. Class-a on the other hand is smooth, but lacks the pace of good class-d, but much better air and bass extension, overall more musoical satisfying than class-d.

A/AB is best to me ..... :)

If you have speakers that are a bit dark on the revealing side class-D may just work for you and yes I had a Bel Canto ..........


:wave2s:
 
If you have a good tweeter, and you listen for certain things like the decay of cymbals, artificial harmonics played on a guitar, there is a delicate detail that is there with some amps and not there with others. I play musical instruments and I can hear that sparkle.

This effect is also important for spatial information, and is one of the factors in imaging.

+10
 
There is no general judgement possible.
ClassD is still not a mature technology.
And even in mature fields like classAB amps there remain manufacturers that manage to build poor sounding amps.
Naturally in classD of the year 2013 you will find a lot amps in the market with massive short comings.
One point is of course the often stressed output filter. It can cause to boost or defeat treble depending on the particular values and used speakers.
Besides simple impact on transfer function many outputfilters present high driving impedances to the tweeter.
Furtheron the distortion mechanisms in classD are different from classAB and less expirience exists how specific modulator distortion and/or dead time distortion does sound.
Last but not least the old discussion about feedback and loop structures...
Overall you have good chances to design a class D amp which has strong treble and at the same time sounds muddy or fizzling....

By the end of the day listening to a classD amp before buying it is more important than it was in class AB.

In any case classD has magic for all businessmen.
Except R&D costs classD is by less costly in terms of USD/W.
Especially attractive if you copy a design.
 
One point is of course the often stressed output filter. It can cause to boost or defeat treble depending on the particular values and used speakers.
Besides simple impact on transfer function many outputfilters present high driving impedances to the tweeter.

The output filter is designed to reduce the carrier not the audio signal.
The carrier is many times the max audio signal frequency.
Especially these days where class d carrier frequencies are much higher.