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Freo-1:I run my amps in triode for the most part, but funny enough, I find some genre's of music actually sounds better in ultra, rock, the blues mostly. Could be the way they were mastered. If I recall correctly, in class a/b, you lose the even harmonics. I would think that the same holds true for switching amps (class d). Does this sound right, or is it possible for class d to produce all the harmonics even though they're switching amps?Jim
Freo-1:Thanks for the clarification. For me it is a personal choice, after hearing it in person. I buy what my ears like and it doesn't matter what class it is. With that said, my ears like tubes, that is not to say that a non-tube amp will capture my attention if it sounds good to my ears.I plan to attend the upcoming show in Newport Beach, CA, no doubt, there will be a bevy of Class D strutting their thing.Jim
Freo-1I was doing some research and came up with this 2009 disertation from the University of Berkley:http://rfic.eecs.berkeley.edu/~niknejad/ee242/pdf/eecs242_class_EF_PAs.pdfOn Page 21 is the following statement regarding class d:Switch capacitance limits efficiency in high frequencyapplications. Maybe this is why I felt a tightness or grain in the high frequencies of the Bel Canto setup that a friend has. I have a Premier (Pioneer) Head Unit in one of my vehicles that is Class D and it sounds amazing in that application and feel no fatigue even on long excursions. However, I'm not doing critical listening while driving. Jim
I am afraid that I am eating my words about Class D amps after reading this review and buying the TBI Millenia. I have a friend that bought one too, and he is as astounded as I am.http://www.tnt-audio.com/ampli/3_mini_amps_e.htmlYou can hear the singers grunt and groan and smack their lips in between their verses, but the amp still retains the magic of any Class A or tube amp that I ever heard. It never becomes sterile or SS sounding. The battery makes it a world class amp, the switching power supply that comes with it just makes it OK. At $500, this is as great a value as the Musical Fidelity A1 Class A integrated ever was. Maybe I should gut the electronics out and put it in a DIY case. I could probably sell it for $1K to the DIY'ers.Tube amps with output tranformers sound very veiled in comparison. I never thought I would like a Class D amp in a million years.
Tom, nice post. Your experience is similar to mine. I was a die hard Class A guy for years - SS and tubes, including OTL's. I tried Class D several years ago and hated them so I refused to try it again until I read about all the buzz on the ClassD SDS kit amps. While the SDS was better than my Class A amps in a couple of areas, it had an over-caffeinated, glassy, unnatural sounding HF so I went back to my Class A's. Then I tried a Hephaestus Class D amp. The Hepha was better overall than the SDS (but then it should be given its price point). It had the tonality of excellent Class A amps and a more natural HF, but was not as resolved and dynamic as top Class A amps. For example, it took only a few seconds to hear that the Clayton M300 Class A's were superior to the Hepha's.Then I bought the NCORE 400's in late January. I know many on AC are tired of the perceived hyping of the Hypex NCOREs... And I get that sentiment, as I have felt the same way with many other products that have been highly touted on this and other forums, only to be sold in droves a year later. And who knows for sure if the NCOREs won't go the same way?All I can say personally is that in my system and to my ears, I prefer the NCOREs to the: (1) last two Class A amps I have owned (Atma-Sphere M60's and Pass Labs XA30.5 and (2) SDS and Hepha Class D's I still own. The NCOREs are more accurate, resolving and musical and they are the only Class D amp I have heard that finally gets the HF right. Will they be everyone's cup of tea? No.
Interesting post. What speakers are you using? I could understand how a higher powered Class D amp would work better on some speakers than a XA 30.5, but for speakers that are moderately efficient, it is more of a challenge. HF is where Class D to me falls short (vocals as well, but less so). Something to consider is what kind of load is presented to the speaker. This link was posted on another forum to discuss this aspect: http://www.audiograph.se/Downloads/PowerCube_12p_brochure_complete.pdf
Freo-1, all of my listening comparisons in the past 2 years have been done on Geddes Abbey 95db efficient 2 way monitors that roll off at about 12db/octave below around 50 hz. I cannot comment on how the NCORE compares to the Class A amps I referenced on other speakers (less efficient or otherwise), although I have read many posts on various forums where comparisons have been made on more demanding speakers such as the Maggies and others.
Unlike most other common class d amps such as the tripath, without post filter feedback, Hypex's UCD as well as ncore have an essentially flat frequency response vs speaker impedance down to less than 2 ohm.....
The NCore circuit contains: 1.A mathematically exact understanding of self-oscillation 2.Improved comparator circuitry insures that actual behaviour matches the theoretical model as closely as possible 3.New gate drive circuitry improves open-loop distortion at moderate signal levels while significantly reducing idle losses 4.A new control loop ups loop gain by 20dB across the full audio range without sacrificing stability Amplifiers using all four of the above will be marketed under the name Ncore. Amplifiers using only the first three will still be sold under the existing UcD brand even though their internals no longer resemble that of the well-known 2001 circuit.
