No "AIR" in class D? Yes or No? - Page 2 - diyAudio
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Class D Switching Power Amplifiers and Power D/A conversion

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Old 6th February 2013, 09:26 PM   #11
cotdt is offline cotdt  United States
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Sure I agree about the bass, but this thread doesn't talk about bass. It takes about upper treble detail (the air effect).
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Old 6th February 2013, 09:28 PM   #12
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Originally Posted by cotdt View Post
Sure I agree about the bass, but this thread doesn't talk about bass. It takes about upper treble detail (the air effect).
I have had no trouble with treble on my amps.

So long as the output filter doesn't break too early then treble should be fine.
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Old 6th February 2013, 09:36 PM   #13
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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.
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Old 6th February 2013, 09:36 PM   #14
a.wayne is offline a.wayne  United States
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Originally Posted by nigelwright7557 View Post
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 ..........


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Old 6th February 2013, 09:38 PM   #15
a.wayne is offline a.wayne  United States
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Originally Posted by cotdt View Post
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
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Old 7th February 2013, 12:50 AM   #16
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I'll have to check out class D again sometime.. Problem is Stereo shops just connect a pile of popular name brand components together.. Their goal is to sell by name alone..
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Old 7th February 2013, 07:32 PM   #17
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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.
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Old 7th February 2013, 09:16 PM   #18
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Originally Posted by ChocoHolic View Post

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.
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Old 7th February 2013, 10:19 PM   #19
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Did you never calculate or simulate the transfer function typical output filters?
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Old 7th February 2013, 10:31 PM   #20
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If you use a higher frequency carrier then the problem disappears.
This means the breakpoint of the filter can be higher.
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