Bandwidth Limitations Of Class D Amps??


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Audiogon member Kijanki said :
Some people argue that class D, as good as it is for the money, cannot really compete with best traditional SS amp. I can see that, especially with still limited bandwidth...
What are the bandwidth limitations of class D amps, and is it audible?
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128x128mitch4t
" But to be honest, I only have about $65k-$70k in my system, I don't have a high-end system."

That's funny!

If Class D amps are even in the discussion for a system in this price range, high end or not, I would say that's another good indicator that they have arrived.

FWIW I have ~$10K invested in my main system, and slightly less in other gear I use concurrently in various rooms. Most people I know would probably label it "high end" if they cared. That is what I payed, not retail, but I am very value conscience and have bought a lot but not all of my current stuff used or discounted via vendor trade-in programs, etc. I will say I think I know and like quality sound when I hear it and leave it at that without getting into details of what that means to me. My Class D amps list for $6K new, FWIW and represent my single biggest monetary investment in my system, though my speakers would list for about the same amount..
At the NY Audio show recently, a few rooms had very high end class D amps that were superb. Other than a no-limit budget and ability to use a crane to move class A amps, my experience has been where top class D amps are just as good as some very expensive class a/b amps i have used.

they also work better if you want to go "digital" straight from DAC to amp with passive pre-amp
To echo Lapentas comments, I have reasons to believe that the stereotypical artifacts at the outer ends of the audible bandwitdh that were frequently associated with a number of older class D amps may not be necessarily reflected in recent designs based on much evolved power conversion modules, like the Ncore NC1200 by Hypex.

Case in point is the Merrill Veritas monoblock that I have just reviewed for Positive Feedback on issue No. 68:

http://positive-feedback.com/Issue68/merrill_audio.htm

Once the amps were properly broken in with 1,000 hours of active operations, I did not detect any musical bandwidth limitations, nor any stereotypical class D artifacts with Veritas.

Of course, there are other amps based on Ncore technology (such as Mola-mola Kaluga and ATSAH by Acoustic Imagery) , and other new class D modules other than the Ncore family (such as the Pascal modules). The examination of more examples of new class D amps should confirm or disprove my hypothesis of class D designs having now grown up into general musical adulthood.

G.

Class D amplifiers do require low pass filters to remove out of band power supply switching noise from passing to the speakers. This is also true of AB amplifiers leveraging high speed switching power supplies such as class H amplifiers (Emotiva and Outlaw for examples). Whether the filtering and related phase shifting is audible is a separate matter, likely depending on the listeners age and hearing loss that is inevitable with age and high sound pressure level damage to our hearing.