This is a Pass Labs section and I believe comments on Class D should be directed to its section in respect. Class A is class A and I will always favor it over other classes. This is from someone who recently built an amplifier from one of the newer class D boards. And yes class D can and does sound respectable with my old ears. I also have many tube amplifiers along with 6 complete NP clones and I can appreciate the differences of any class of amplification but detailed responses on other classes of amplification should be directed to its proper place.
SIT-1 and similar amps based on "Triody" transfer-curves is an answer to the problem of the asymmetry of sound waves traveling through air and the asymmetry of the normal loudspeakers (especially the Bl asymmetry).
I believe class D can and will be superior to class A. "All" that is needed is much faster switching and a better more powerful DSP-control of the produced wave-form.
Once the switching is in the GHz region class D will have a many order of magnitude higher resolution then class A with the current crop of devices.
With a powerful DSP it should be easy to get any transfer function we want.
I prefer class A today, and will probably keep on prefering class A amps until we get graphene-SITs (which should enable 100 GHz switching), but then again, a graphene-SIT might make a great FIRST WATT SIT-amp....
From Nelson Pass first Zen amp article.
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There are some doubts. Just calculate Amps of gate current for typical gate capacitance...
New type of graphene-based transistor will increase the clock speed of processors
Graphene will revolutionize the semiconductor industry, once we get the hang of building cheap Mosfets in bulk and preferably SITs with it....
Regards,
Johannes
Graphene will revolutionize the semiconductor industry, once we get the hang of building cheap Mosfets in bulk and preferably SITs with it....
Regards,
Johannes
I have never understood the motive for single-ended amplification "because of the single-ended nature of sound propagation".
The asymmetric character of sound will be recorded "asymmetric" as well.
The reproduction chain (amplification; loudspeaker) should not contribute in an "asymmetric" way therefore IMO, so I don't see a task there for single-ended amplification.
With respect to class d: how could a high quality class A or A/B be improved by pulse width modulation of the original signal, using power transistors as switches and apply necessary filtering?
Class d higher efficiency is not so interesting: I just compared a good quality A/B amp (lateral power mosfets) with a "market leading" SMPS powered class d amp. The class d amp produces more heat.
Soundwise, my ears tell me that, especially when listening all day, even the best class d amps introduce some listening fatigue and don't have the high frequency quality of a good class A or A/B amp. They are OK up to MF but, like mentioned by Circlomanen, seem to require higher switching frequencies.
The asymmetric character of sound will be recorded "asymmetric" as well.
The reproduction chain (amplification; loudspeaker) should not contribute in an "asymmetric" way therefore IMO, so I don't see a task there for single-ended amplification.
With respect to class d: how could a high quality class A or A/B be improved by pulse width modulation of the original signal, using power transistors as switches and apply necessary filtering?
Class d higher efficiency is not so interesting: I just compared a good quality A/B amp (lateral power mosfets) with a "market leading" SMPS powered class d amp. The class d amp produces more heat.
Soundwise, my ears tell me that, especially when listening all day, even the best class d amps introduce some listening fatigue and don't have the high frequency quality of a good class A or A/B amp. They are OK up to MF but, like mentioned by Circlomanen, seem to require higher switching frequencies.
Purchasing ready modules is not really my thing on diy, and soldering and or troubleshooting such stuff will probably be outside of the capabilities of most people (including myself)
Perhaps it makes more sense for manufacturers since you basically outsource the biggest part of the product, reducing costs and time to market.
I have owned a pair of belcanto monblocks (ice), briefly auditioned a DSsomething from audio research and used a custom-made class-d integrated amp on my store for some time, but was not impressed by either of them.
Not to mention that the belcantos kept triggering the circuit breakers on my house on startup.
I have no experience with more modern stuff like ncores, but I do not really care for it either.
Perhaps it makes more sense for manufacturers since you basically outsource the biggest part of the product, reducing costs and time to market.
I have owned a pair of belcanto monblocks (ice), briefly auditioned a DSsomething from audio research and used a custom-made class-d integrated amp on my store for some time, but was not impressed by either of them.
Not to mention that the belcantos kept triggering the circuit breakers on my house on startup.
I have no experience with more modern stuff like ncores, but I do not really care for it either.
A Mosfet working linearly does not have an infinite resolution. There is always noise and temperature related variations. A transistor working as a switch bypasses all those imperfections. Once the switching is fast enough to have a higher resolution then the linear transistors (thermal) noise-floor, class D has a greater potential.
Just like a true 32 bit 10 GHz sampling-frequency digital sound-stream would have a much higher resolution then any analog recording equipment known to man, a fast enough class D amp should beat any analog amplifier in measured data.
It's not a good argument for single-ended amplifiers, more of a rationale as to
why 2nd harmonic is less problematic.
I expect to be safely out of the picture by then.
At the same time, you have to remember that this is the entertainment
business, not dialysis. The argument about accuracy and efficiency can
be applied to to photography over painting. Easier and better photographic
equipment does not injure the market for painting supplies.
I would not be surprised by future Class D amplifiers having the software
to emulate single-ended Class A. After all, what do SITs do but conveniently
emulate triodes?
Yes, also part of the "entertainment business" is differentiation.
It's hard for a brand to stand out in the class a/b market segment. It may be easier for a brand to compete against other class D amps than it is within all the amps that are A/B. Some goes for class A.
Also, it's much easier to make what I call a "lifestyle" amp (smaller/cool looking/lots of tech) in class D than it is A/B or A.
I have not heard any hi-end class D. My only experience is with Tripath which I think is inferior to Class A but better than some similar powered class a/b amps.
But I have an open mind. Whatever works. Even if that's class D.
What is clear to me is that those inventing new technologies or topologies or what have you really are not interested in hi-end audio. Efficiency, size, etc. are what they are going for. Any great leaps forward in audio quality will be coincidental or trickle-down technology coming out of the need for smaller, more efficient technology or from technology designed for non-audio use.
And Nelson has already done some of that.
It's hard for a brand to stand out in the class a/b market segment. It may be easier for a brand to compete against other class D amps than it is within all the amps that are A/B. Some goes for class A.
Also, it's much easier to make what I call a "lifestyle" amp (smaller/cool looking/lots of tech) in class D than it is A/B or A.
I have not heard any hi-end class D. My only experience is with Tripath which I think is inferior to Class A but better than some similar powered class a/b amps.
But I have an open mind. Whatever works. Even if that's class D.
What is clear to me is that those inventing new technologies or topologies or what have you really are not interested in hi-end audio. Efficiency, size, etc. are what they are going for. Any great leaps forward in audio quality will be coincidental or trickle-down technology coming out of the need for smaller, more efficient technology or from technology designed for non-audio use.
And Nelson has already done some of that.
I would not be surprised by future Class D amplifiers having the software
to emulate single-ended Class A. After all, what do SITs do but conveniently
emulate triodes?
Guitar amps are doing this already, with results ranging from awesome to laughable. This does not mean that good studios are going to stop using Marshal amps.
On the practical side, at least for now, it seems that we are exchanging a set of problems for a different one.
wakoo ggetzoff is having perfect moto :
if not Boeing , I'm not going
("If it's not Boeing I'm not going")
.
if not Boeing , I'm not going
("If it's not Boeing I'm not going")
.
Never have warmed too much to class D - too close to what I do for a living to offer respite from it....
I expect to be safely out of the picture by then.
At the same time, you have to remember that this is the entertainment
business, not dialysis. The argument about accuracy and efficiency can
be applied to to photography over painting. Easier and better photographic
equipment does not injure the market for painting supplies.
I would not be surprised by future Class D amplifiers having the software
to emulate single-ended Class A. After all, what do SITs do but conveniently
emulate triodes?
Ever think about playing around with some triodes/pentodes in your well proven designs? Just for fun?
Can't speak for mr. pass, but he did say once.. even recently that one of the best amps he ever heard was an el34 SE. But like he said, and I believe this empirically as well, it's all just entertainment. All this stuff is like arguing who's the best guitar player ever. If you like that guy (or girl), listen to him.
I couldn't agree more with you. Now, I myself am a guitar player perhaps 25 years now. You can emulate the sound of a les paul and marshall head, but you can't emulate the physics of it. When done well, in person.. it can't be faked because it involves a specific stress of parts. These Class A amps involve a specific stress of parts of particular operating points, and if done well (by Mr. Pass or whomever) they probably have a slant toward a type/level of distortion that balances a few logistical hurdles. That's what separates me from NP.. he knows how to tune something. I just enjoy it like anybody else; this flogging of parts. I dare say, he's not emulating anything but himself. That's pretty organic.
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