Time to buy a class D amp?

You say you hear somethings not quite right in the upper-mids and highs, and phase shift going on in those areas. Could you, respectfully, enlighten me as to what you are hearing?

Not just me, unless you’ve been hiding under a rock, it a common complaint.

What I hear from that technology, is dependent on where the "output filter is set" to filter out the switching noise.

1:Too high and it lets through too much switching noise but with reduced phase shift into the audio band, this to me sound hard and bright on music.

2:To low and it roll off the highs and causes too much phase shift into the audio band, but it filters out more of the switching frequency, this to me sound soft and opaque in the highs, and not involving in the mids, but at least it’s not hard.

Nuforce with their many different 9 models tried different versions V1 V2 V3 in them, of the above output filter that were retrofit-able for customer that had issues with the sound.
One of those version filters that was set way too high actually caused bluing of the Wilson Watt Puppy tweeter voice coil with HF switching noise (that only twoleftears dog can hear), didn’t stop them working just blue’d the voice coil with "undetectable to us" switching noise that was let through to them slowing cooking them over time. Naturally the diaphragms had to be replaced, he got rid of those amps.

I know from your past posts you are not a fan of class D.

BTW, Incorrect I’m not a fan of it’s two Achilles Heels, dead time and switching frequency. And I have said many times I’ll be the first to get one when they don’t have these problems and are a module I can buy an throw in a box like they do now with the old technology, but say they "modify it" so they can charge $$$$$ for, if you look at a $10k Contiuum Class-D, it has a $100  class-D module in it (modified of course), the same module is used in the $500 Red Dragon S500 class-D, this is not uncommon.

Cheers George

Actually thanks to twoleftears ’s dog, this would be a great way for Class-D owners if they have a young’ish dog to tell if their output filter is set too high or too low, as they will be one the other, or combo of both, eek!

Just watch to see if they react when in the same room when you turn on and wait for the delay to switch on your class-D amp/s.
I would say if you get no reaction you’ll have the "set too low filter" and you have a Class-D that is not hard or bright at all, but I bet it’s number 2: of the above.
If they run out of the room or react you know it’s the high filter number 1: above.

From Texas Instruments on output filters of Class-D amps that are set too high corner frequency.
"A concern with the switching waveform being dissipated in the speaker is that it may cause damage to the speaker"
This is what happened to my mates Wilson 8’s above, as Wilson does not use a Zoble Filters on this tweeter and I think all their speakers.

Cheers George

Something's wrong when I agree with George. He is right.

Hello George
You seem to know a lot about technical issues about class D Amps (I dont), but in my case I dont feel any of the problems you have mentioned above, if I understand you correctly. 

When I listen to music at low levels at night (everybody is sleeping), I dont feel the mids or the highs rolled off or not involving at all. In fact, as the AC Power is cleaner and the ambience noise is lower, I experiment the best of the music as it gets much more involving, smoother, with more dynamics, detail, better tone and with an incredible soundstage.

Also, when I listen loud (I try not to do it often for my earing safety), I dont feel the sound harsh.

On the other hand, I've listened to multi thousand dollars systems (+120k), much more expensive than mine, and I've found them harsher and with more digital flavour than mine. And those systems had class A or A/B amps.

In fact, I've had class A valve amps that didnt sound as smooth and grainless as my class D amp, at all. 

I dont want to start an endless and pointless discussion, but my experience doesnt follow your theory. I guess there must be exceptions. 

My amp is a Nord Acoustics NC500DM with Rev D boards and Sparkos Op Amps. My preamp is the Audio-gd Master 1 and my DAC is the Audio-gd R8. I feed the DAC with the SOtM SMS-200 Ultra Neo going through the Gustard U16 USB to I2S converter. My speakers are the Q Acoustics Concept 500 floorstanders. 

georgehifi:
"What I hear from that technology, is dependent on where the "output filter is set" to filter out the switching noise.

1:Too high and it lets through too much switching noise but with reduced phase shift into the audio band, this to me sound hard and bright on music.

2:Too low and it roll off the highs and causes too much phase shift into the audio band, but it filters out more of the switching frequency, this to me sound soft and opaque in the highs, and not involving in the mids, but at least it’s not hard."

     Wow George, you finally responded to how your theorized and supposed class D deficiencies are manifested audibly. I’ve been requesting this info from you for what seems like years with no responses. What gives?

     I understand your position is not to utilize a class D amp until you deem it to be technically perfect and that’s your choice. However, to me and I believe to the majority of other class D amp adopters, making the perfect the enemy of the extremely good makes little sense.
     I’ll use logic to explain my perspective. Even if your theories about the deficiencies of most current class D amps are correct, that the current carrier switching frequency needs to be raised to the 1.5mHz range and the current output filters removing the carrier frequency are inadequate, they are meaningless to all individuals that do not perceive your claimed audible effects of the music sounding hard, bright, soft and opaque in the highs and not involving in the mids. Since I perceive none of these effects in my system using numerous class D amps, by your own definition your claimed class D deficiencies don’t exist in my system.
     I believe this is also true for all individuals who do not hear the audible qualities you detail in your above descriptions labelled as 1 and 2. Our combination of perceptions represent all of our realities.
     However, I'm still willing to keep an open mind and will listen to any class D amp you deem to be perfected in the future just in case your claims are actually valid and I can perceive the audible results. 


Tim