Class A operation is integral to the performance in this case, and it
is worthwhile to explore why. The primary virtue of class A lies in the
smooth characteristics of its operating parameters. The gain transistors
are operated in their linear region only, where the distortions are
limited to smooth, simple forms, unlike the abrupt distortions created
when the transistors in class B output stages switch on and off."
I've built a couple of his DIY Class A projects. They are exceptionally good sounding amps. Why not class A? Cost (especially cost/watt ratio), Heat and nothing else unless you're a greenie. In that case, power consumption.
There is a REAL difference in the functionality of a class A vs anything that has to "turn off" one transistor and "turn on" another one at every wave form. Just considering that it is between difficult to impossible to match those components and operate them outside of their linear reigons. Then you get into negative feedback loops to correct the crossover wave distortion, adding additional complications and additional distortion opportunities. My best example is I've owned a high-end Oddyssey amp that had a billion components in it and costs a ton. My DIY F5 Pass/First Watt amp absolutely blows it out of the water, sound-wise. There are compromises, but I sincerely believe the difference between the functionality of Class A vs class B circuit is obvious and significant.
Broadly speaking, there are often a lot of other design variables between two SS amps beyond just the bias level of the transistors. A lot of the high end Class A amps are designed to have very little feedback, which enhances the high linear accuracy of Class A, but often at the expense of slightly higher noise and lower damping factors. That tends to create a certain sound which I personally feel is a bit closer to the typical tube sound. On the flip side, it is more common for the Class AB amp designers to use some amount of local and global feedback, which "can" marginally impact the linearity, while reducing noise and increasing the damping factors and tightening the bass. In my experience, it is very hard to generalize that Class A sounds better than Class AB since there are a bunch of other design factors that have to be considered. The typical Class A amp may sound different than the typical Class AB amp, but it's not always better...
Class A sound better? No, lots of factors to consider. You have first of all assumed Class A sounds better. Not always true.
Exactly. I own four Class A amps so obviously like what they offer (aside from the heat and the electric bill), but horses for courses - some Class AB amps sound better in some systems. Generalizations like the original posts are meant to stir fuss, not logical response.
I use a Class AB tube amp in my main system as a matter of fact, and I prefer it with those speakers to the 100 lb. + Class A monos I used to use. OTOH I use a stereo Class A amp with some electrostatics and it is a great match. YMMV
Gato Audio, a Swedish company makes AB amps that will compete with almost any class A amp. They now sell factory direct with free shipping. And best of all no sales tax. Steve Guttenberg did a review recently.
It’s not true it’s not that cut and dry many very high quality amps may have the 1st watts say 20:watts in pure class A then switches to class AB. That being said , inside the Quality of the parts have much more to do with the final result of the sound . I owned a Audio store until 09 and Had many parts modded or upgraded,for the vast majority of mfgs use average parts at best . on average 25% or less of the cost actually goes into the electronics,the rest over head and markup. That's how Modwright was able to be so successful by putting in Premium parts in the most critical areas. Companies like Gryphon for example use top of the line puts throughout ,and are exceptional in sound quality. That being said ,not everything is in black and white. As well as the engineering and their design .
We talk, but are we communicating; some people have equipment to hear music, while others have music to hear equipment. Which camp do you fall in?
If one is an obsessive music lover SS preamps never sound quite right, however, obsessive equipment lovers claim tubes give distortion.
I think tubes versus SS is more profound than Class A, AB. Personally, I would not want SS preamp no matter what class or how expensive, SS power amps are OK when necessary. Could not stand ARC preamps that were SS, I don't know if they still make any SS preamps?
While theoretically class A is better, given same quality of parts and craftsmanship, I'm sure there are few people who could pass a blindfold test to distinguish which was which.
I say it again. If they can take it without strain on anything, those same A/B amps will sound even better again if their Class-A bias was turned up full, as you eliminate any xover distortion, as it never goes into Class-B which gives xover distortion no matter how well designed
Why would anyone prefer anything besides Audio Research monoblock tube amps, when they are so awesome? For only $70,000, plus a 5 ton A/C unit to cool it, you could begin building a truly great system. All you need, besides the above, is a $10,000-20,000 preamp, a stupidly expensive source or three, and a room to put it in. Then, you could chase away all of your friends by showing them the intracacies of minute passages of music that really show it off. I prefer the Class A Audire Monarch towers, and a Diffet 5, but settle for a trio of Audire Fortes (Plus two Audire Diffet 3 preamps), and really love my music, even when listening to Jazz 67 on XM, despite its inferior sound. Why would anyone prefer a beautiful Ferrari to a Bugatti, when the latter is faster? Why would anyone prefer a wife of fifty years, when a Russian model is cuter?
My buddy has Klipschorn corner speakers. He runs them with CJ premier mono block tube amps. So tonight I brought over an old class A stereo amp my partner put together with some old parts we had laying around. 1.5wpc 45 tube pure class A. Needless to day the Class A walked all over the CJs. It was not even close - better everything including more bass and deeper bass output from 1.5 watts. Music just poured out of the system, tone and space was killer, wide open musical sound. So dynamic and delicate at the same time. I may have to get some horn speakers now!
Orpheus10, I would say that tube phono stage is most important. SS class A line level preamp and class A power amp can be quite acceptable, at least. Most people, if not all, do prefer class A amps and integrated amps from the same company, be it Accuphase or Luxman or Pass.
One has to take the time ( as little as absolutely necessary) to pause and reflect on the reality that written or spoken opinions are largely driven by the insatiable need to be acknowledged.
As someone who earned a living as an electronics technician, I am qualified to state what is "theoretically" better. While Class A is theoretically better, you need the hearing of a good hound dog to tell the difference between AB and A; maybe some young people got it, but I'm very doubtful about old folks.
What some old folks got is "deep pockets": deep enough to entertain their fantasies.
If I was rich, I would still have high quality AB, because I'm certain I can not hear the difference, so why pay so much just to heat the house.
Dan D’Agostino's son Bret certainly agreed with your premise & his co. Bully Sound still has their site up even after his demise so presumably they're some kind of going concern > https://bscaudio.com/Pages/aboutHistory.php
Inna, some people can hear better than others in regard to Class A.
In regard to SS versus tubes, some people are music lovers, and some people are equipment lovers.
When I had an audiophile music loving friend, we swore by our "0 distortion" SS gear. I requested a CJ preamp to audition at my home, and invited my friend over for his evaluation.
The CJ was a loaner and produced apparent distortion, but even through this distortion, we both agreed that the music sounded better. Neither one of us has ever considered SS preamps, since.
However, an SS power amp simply reproduces the signal of the preamp; consequently, a high quality SS power amp is acceptable.
While I don't feel strongly enough about class A vs AB to become a television evangelist so I could spend a few billion to hire the Islamic State tosteal for me a Tzar Bomba to use against people using AB amps, I make my own class A tube amps because they are simpler to build and you can for a few hundred dollars buy parts as good or better that what you get if you spend five figures on a high end tube amp. I like my Magnepan speakers so I solve the sensitivity issue by using radio station transmitter tubes. If I use 45s by themselves I have to use sensitive speakers.But I have heard some fine sounding AB amps too.
... as already noted, because it does not always sound better. I can easily design a horrendous class-A amplifier. Design is everything. All the practical benefits are noted as well, but i can further assure you that the cost (transformer, devices, heat sinks, etc.) of a pure class-A amp consumes resources that could be better spent on sound quality elsewhere.
I can design a horrendous class whatever amp too. That's not the point. No, design is a lot but it is not everything. There are limits of what is possible. Orpheus10, there are great SS preamps, they are expensive and one can probably do better with tubes for the same or less but I don't know it. Boulder, Gryphon, D'Agostino, Soulution, Accuphase etc.
Yet another fine example of a tempest in a teacup.
Hey, y'all. Let's visit each others' homes and argue about the color selections of wall paint, furnishings, each others' shoes....
...that dumb aze Porsche vs. a nice Cadillac SUV.....with all the options...
The latter strikes me as the most blatant offering of a pointless ego toy that will NEVER see muddy roads....perhaps a deep puddle @ the mall....the bumpy RR Xing that gets 'tippy-toed' over...
Strange noboby is complaining about weight and dimensions of class A serious equipment. I just gave away two clones of class A Pass Labs and I'm looking for a good traditional A/B amplifier, because I'm tired of turning on two blocks each time, having double waste of space (one block on floor and the other in the rack), having to move 38kg (83lbs) for each operation on every block for cables, cleaning floors, etc.
The difference in sound is evident, as well as the inconvenience. Just my experience.
Clearly, there are lovely examples of amps of all description. That said, I still occasionally hear old low watt Levinsen and Krell class A devices which move me to tears. There is something there. Options exist at my house but a Pass XA-30.5 remains an object of my most ardent affection.
The most difficult thing to discern is who listens to equipment, and who listens to music?
Ages ago when there were stereo stores all over the place, I fell in love with new speakers everyday. It's for certain I was an equipment lover then, but that's before I got into "The high end". My favorite tuner was "Sansui", it had a most beguiling sound that was quite soothing, and many people still prefer them to more accurate tuners.
My favorite speaker was first JBL, and next it was the Amazing Carver Speakers; https://www.stereophile.com/floorloudspeakers/290carver/index.html The music had an other worldly quality; "ephemeral", I guess would be the one word description, but at one time I liked "reverb" in my car, that made your automobile sound like you were in a cave.
When I got into the high end, I finally discovered how good the music sounded unadorned without any tricks. Since most speakers have some kind of "sound", I had mine custom built to have no sound of their own, but to deliver the music, the same as a Class A amplifier delivers it to them; without anything added or subtracted from the music, only what the artist wanted you to hear, his music, with each and every individual nuance.
While I mentioned Class A because it is "Theoretically perfect", I can not audibly distinguish it from AB.
One of the problems of differentiating music lovers from equipment lovers, is that equipment lovers will almost never come clean and admit it (maybe they don't know themselves) consequently, right or wrong, I discern who is an equipment lover, and who is a music lover. This is very important when reading Posts.
I like equipment that gives me good sound, other than that I only like tape decks. I don't think that liking good sound and liking good music are always in conflict. They can be but not necessarily so. Old Levinson ML-2 class A amp is a dream piece.
"I don't think that liking good sound and liking good music are always in conflict."
Agreed
I average approx. 4 hours a day of listening to music through my system when life is "normal" for me. I have not been able to do that for the last couple months due to other priorities, but plan on getting back to it again soon. My amp is an AB (Magnus Audio MA400) & I love it. I've had class A's, other AB's, Triodes, Pentodes, SET's (both tube & SS), & class D. They all sound different & have their plus & minus's. This one connects best with me & my system.
Inna, I believe you to be quite sincere in your threads and posts which is why I'm responding now.
Whether it's class AB or A, or tubes or SS; the purpose of the equipment is to reproduce "music". As I previously stated, utilizing high quality parts, one would need the hearing of an "Irish Wolfhound" to tell the difference between A and AB. If you have it, fine, maybe it's worth the additional expense; I don't.
The reason for this post is to separate equipment lovers from music lovers. First, in order to qualify for that distinction, (The ability to separate the two) one must be an Audiophile with at least 30 years of experience, and I'll explain why that's necessary.
In the beginning, we started with our favorite music on the radio. And then we advanced to our own fundamental rigs. They were SS rigs because tubes were too expensive. Those who are still into SS are there because they simply followed along that path to better SS without comparing that to tubes. Or, they decided tubes create distortion.
If you compare the reproduction of a 1K hertz tone, using SS and tubes; SS would win, but that's not music. Music has a certain "Essence" that can only be reproduced by tubes. People who are exclusively into SS are not even aware of that "Essence"; that's because they're not true music lovers. They buy music to hear their equipment, while music lovers buy equipment to hear their music.
Clarification on the above post; SS is OK for power amps; that's because tube power is very expensive when one needs a high powered amp, but tubes are still the ultimate. Here again is the question; can one actually hear "the ultimate".
The Plinius amps of yesteryear allowed users to utilize an A or A/B button on the front of the amplifier to allow for Class A critical listening. The amp generally sounded its best in Class A, but A/B was very close.
I don't know if the current generation of Plinius amps allow for such user friendly options.
Lower power consumption with most A/B amplifier designs. They tend to be popular in devices like DACs. Due to the nature of the Class A topology, they are very inefficient with electricity and typically generate a lot of heat. My Class A systems can only be run once or twice a week...otherwise my power bill will go up!
Class A has a conduction angle of 360 degrees, whereas A/B is less.
In theory, this should translate to a more controlled and linear amplification of the signal. In most cases, Class A amps have more of a "grip" on the signal and can be "straight wires with gain." Everyone hear probably knows what I mean (see what I did with that spelling mistake) lol
yep. So class A is superior if it is designed well without compromises.
Orpheus10, I don't have such a hearing as you imply, but my ear is quite sensitive to some aspects of a sound. Let's not transform this thread into tubes/transistors debate. Sure, ultimately tubes rule. That's what we are trying to talk about - designs without compromises or almost without compromises. Heat, space, cost, look - this is all BS, just certain side effects. Done right it should always be full Class A design. And since Class A requires high level power supply, that's an additional advantage, that's where it all starts - with a power supply.
Anyone in the NYC area - Northern NJ area who would like to hear the differences, send me a PM. I would be more than happy to show you differences in equipment - Class A tube, Class A SS, Hybrid amplifiers, Direct Heated Triode components, etc. I'll even supply the pizza. Bring your amp if you like!
@audioman58That being said , inside the Quality of the parts have much more to do with the final result of the sound.
I would have normally agreed with your statement but last night hearing an OK to good parts preamp it was so close in sound to the better parts model we build I began to wonder if paying for custom transformers, resistors, capacitors, separate chassis, etc. was worth it. So close it was confusing to us and made me think that we have now come full circle. Still point-to-point wired and good parts but so close.
https://youtu.be/abdmZbQPQtY This guy has a very good channel, in one of the videos he talks about amp design and how many watts we really need, just bare in mind he is talking about European midsize room not US cathedrals 😜 I must say I totally agree with his viewpoint, when ever I go over 80db it starts to get seriously loud and often uncomfortable very soon. Anyway, I thought his views on the matter would interest most audiophiles, also he has a very good way of presenting his views. Enjoy!
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