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Anyone compared high end Class D power amps?

I agree Class D cannot compete within an apples for apples THD+N test.

Example, my A/B amp:
Distortion factor (THD+N, 10 watts @ 4 ohms): 0.0062 %
IM distortions SMPTE (5 watts @ 4 ohms): 0.0075 %
IM distortions CCIF (5 watts @ 4 ohms): 0.0008%
Upper limit frequency (-3dB / 10 W @ 4 ohms): > 185 kHz
Damping factor: 1000 at 100 Hz
Bandwidth: 1 – 500,000 Hz
THD+N:<-90dB
SNR:> 103dB @ 1kHz

ACI-600 Class D amp:
THD+N: <0.01% 1kHz A-Weighted
SNR: >70dB A-Weighted
THD+N: 0.003%, 1kHz
Dynamic Range: 110dB, A-weighted 20Hz-20kHz
Frequency Response: -3 dB 0.5Hz-50kHz, all loads
Damping factor: >500
 
A paper was published in JAES in 1991 (link - the PDF can be viewed) showing the degree of non-flatness in the amplifier - cable - speaker interface for various cables (Kimber types included), amplifiers and loudspeakers.

ABSTRACT
Loudspeaker cables are among the least understood yet mandatory components of an audio system. How cables work and interact with loudspeaker and amplifier is often based more on presumption and speculation than on fact. The literature on loudspeaker cable behavior and effects is minimal. Measurements were made with 12 cables covering a variety of geometries, gauges, and types. The measured data indicate distinct differences among the cables as frequency-dependent impedance, subtle response variations with loudspeakers, and reactance interactions between amplifier, cable, and loudspeaker. In some cases the effects of the amplifier overwhelm the cable's effects. Mathematical models that provide insight into the interaction mechanisms were constructed and compared to the measured data.

A disagreement followed in the pages of Audio magazine between the author (Fred E. Davis) and Edgar Villchur (founder of Acoustic Research) about whether the effects were audible or not. Glossing over the details, Davis thought they could reach to audible levels but Villchur disagreed.

It shows the expected lack of audible differences ie fractions of a dB and at 10-20Khz. As so easily predicted from inductance of cables. I agree with Villchur. And P. J Walker, and D. Self and many others who say they make no difference.

Anyway we are getting off topic and if any subject has done to death already it's this one!

Many such reports exist. They usually show things happening in the MHz range, well above even bats hearing.
 
Cables and cables let open a new page please.
As to Class D (dumb) they sound normally crap having designed a few in the past, best system I have used and heard was the Tripath Hi-Brid Class T but even this had bass pumping and filter problems.
I designed one which runs at 2MHz and has my special Patent design in the PSU which stops Bass Pumping. But it was only low power at 10KW into 1ohm used on a big vibration table.
The odd one I made was with a NE555V and MOSFET outputs clocking along at 100KHz in a loud hailer for the MP's (army).
The output filter designs are nearly always based on standard "T" with no or little thought in the wire used and the type of magnetic material, it seems most are designed around mains filter frequency design, bloody slow.
 
Hi,
No, i have not. What i have tried are cables that are solid core, stranded 42 and 79, and the Van Damme (not QED), and not heard any difference between any of them.

What this shows me is that in general, cables make no difference. Of course, my system may not be resolving enough, or my hearing is sub optimal.

Regards,
Shadders.

Oh dear You mean that I wasted 5 years of my life in R&D at TQ (well I did as it was nicked from me) and in the 1980,s another 4 years. And now with EWA another 4 yrs, thanks mate love you too he he.
Not including the 3 yrs at Catch 22, the company that started TQ (mine)
 
Oh dear You mean that I wasted 5 years of my life in R&D at TQ (well I did as it was nicked from me) and in the 1980,s another 4 years. And now with EWA another 4 yrs, thanks mate love you too he he.
Not including the 3 yrs at Catch 22, the company that started TQ (mine)
Hi,
I would not worry about it, as long as you got paid. :)

Regards,
Shadders.
 
And it was nice, but without knowing the history of past advent who would guess that the press ignore the facts to.
 
Got a bel canto ref 500s this week , my my its sweet !! got loads of prat and transparency but still manages to sound smooth and toe tapping . definately a thumbs up for this icepower amp . [ using a bel canto pre 3 vbs and black ice dac]

P1060998 by https://www.flickr.com/photos/158267783@N02/, on Flickr

P1060997 by https://www.flickr.com/photos/158267783@N02/, on Flickr
nicely built with decent binding posts and solid construction . one reason i like BC stuff is its made to last , some of the bc stuff i owned years ago is still around now
 
I have just finished reading all 15 pages....I'm non the wiser but that's down to me and my lack of understanding of the differences between classes of amps, not the quality of discussion.

I have quite a binary question having just got myself a lovely set of Dynaudio Special Fortys, which I am running off an Exposure 3010S2. That amp sounds 'ok' but I'm considering whether or not to buy something more powerful and was considering one of the Nord amps which I believe are class D. Would I be likely to experience an improvement or degradation in sound quality if I changed and what, if any, advantages would that give me?

Thanks.
 
I have just finished reading all 15 pages....I'm non the wiser but that's down to me and my lack of understanding of the differences between classes of amps, not the quality of discussion.

I have quite a binary question having just got myself a lovely set of Dynaudio Special Fortys, which I am running off an Exposure 3010S2. That amp sounds 'ok' but I'm considering whether or not to buy something more powerful and was considering one of the Nord amps which I believe are class D. Would I be likely to experience an improvement or degradation in sound quality if I changed and what, if any, advantages would that give me?

Thanks.

The most obvious difference will be power. As an example, the Nord One NC500DM is 400WPC at 8 ohms, compared to the 110WPC from your Exposure. The Nord is a bit cheaper. Whether that extra power will actually make a difference to your system is another matter.
 
The only way to find out is to try one !! I am certain these little Ghent audio monoblocks would impress with the special 40
 
yes , thats the hard part . occasionally second hand ones come up. there may be folks nearby to come and try with your speakers . whereabouts in uk are you?. next on my list to try is the highly rated PSaudio m700 mono`s .these are about 2550 for two

https://www.mcru.co.uk/product/ps-audio-stellar-m700-stereo-power-amplifiers-pair/



I have yet to try a hypex unit , only ever had icepower units and considering these Ghent audio ones can be made at fairly low cost by anyone competent in diy electronics

https://theartofsound.net/forum/showthread.php?66306-B-amp-O-Icepower-50ASX2-monoblocks
 
from the m700 review [ of which there are a lot !!! ]

Although PS Audio's Stellar M700 monoblock power amplifier ($2998/pair) is a brand-new design from a team led by engineer Darren Myers, it draws on the company's extensive experience with class-D amplification. Sam Tellig and Kalman Rubinson reviewed PSA's HCA-2 power amp in, respectively, the October and December 2002 issues, and I reviewed their GCC-100 integrated amp in January 2006. The Stellar M700's input stage is the latest version of PS Audio's Gain Cell, which they describe as a "proprietary, fully differential, zero feedback, discrete, class-A MOSFET circuit.

In the Stellar M700, the Gain Cell drives a 700ASC class-D power module from the Danish company ICEpower. I asked Paul McGowan, CEO of PS Audio, why they chose this module rather than, say, one from Hypex, another class-D specialist. He said that they spent a lot of time listening to modules from various manufacturers, and the 700ASC was the one whose sound quality most closely matched that of the Gain Cell.

https://www.stereophile.com/content/ps-audio-stellar-m700-monoblock-power-amplifier
 
I have just finished reading all 15 pages....I'm non the wiser but that's down to me and my lack of understanding of the differences between classes of amps, not the quality of discussion.

I have quite a binary question having just got myself a lovely set of Dynaudio Special Fortys, which I am running off an Exposure 3010S2. That amp sounds 'ok' but I'm considering whether or not to buy something more powerful and was considering one of the Nord amps which I believe are class D. Would I be likely to experience an improvement or degradation in sound quality if I changed and what, if any, advantages would that give me?

Thanks.
By more powerful, do you want a more 'powerful' sound to come from the speakers (at normal listening), or more headroom needed (big space to fill at volume or whatever)?

I think the latter is where class D can really come in.

If the former, just some experience: I replaced a Nord NC 252 (basic NCore sans input buffers) with a Quad power amp. Both had tonnes of headroom for my set-up, but the Quad brought considerably more weight and body to the sound in normal listening. ie less oomph on paper but more powerful-sounding.

Both smooth and extended, just a sense of more matter-of-fact starkness with the Nord.

Could see the appeal of both depending on set up and tastes.
 
The headroom aspect of Class D...the argument seems to hold some logic that Class D "stop" at the at their max power whereas A/B etc can manage peaks better. ie Class D amp won't be able to manage very short duration peaks vs a A/B, is this correct tech gurus? I can't say I notice this issue but I don't drive my Class D amps hard, so I wouldn't...
 


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