Tubes -vs- Class A SS...the shootout!!!

treitz3

So, I take it that there is no clear definition as to whether an amplifier is or isn't a Class A amplifier, like the definition of pregnant? You are or you aren't...

FTGV

megasat16 wrote: »

But to some, Pure Class A is not about power draw, not about output wave, but about Single Ended Output Stage and nothing else matters.

I seem to recall reading something to that effect,but I'm comfortable with Papa's definition.

dorokusai

treitz3 wrote: »

So, I take it that there is no clear definition as to whether an amplifier is or isn't a Class A amplifier, like the definition of pregnant? You are or you aren't...

Good lord :biggrin:....it's not an easy question since even within Class A, topology can vary drastically from one manufacturer to another.

A Class A amplifier is running high current output at all times, from start to finish of the input signal. They are usually very inefficient because they draw so much power due to running both rails and don't switch like and AB amplifier. The draw more power in order to cover the entire waveform. I'm not sure if that's the scientific answer but its a rough explanation. When I get home, I'll open the book and get something more concrete if it hasn't been hit already.

mhardy6647

My brain is exploding. Class A still has nothing to do with topology (SE vs. PP) and everything to do with bias (operating points of the active device(s)).

http://www.learn-about-electronics.com/amplifier-classifications.html
http://www.smeter.net/amplifiers/classes-of-operation.php
(that latter reference is very clear - it refers to "RF amplifiers"; but one may just substitute "AF" for "RF" when reading the explanations of the amp classes)

Jeepers, folks, there is marketing and there is technology. The intersection of those two sets tends to be rather scant in hifi. The trade-offs as one marches from Class A to AB to B to C is from highest linearity to highest efficiency.

I fall squarely in the camp of "trust" your ears... but I also take a cue from Picasso (who learned the conventions and rules of art before he trampled them all): it's really good to understand the nuts and bolts so as to have context to understand and appreciate the "why" of differences one hears. Besides being more intellectually fulfilling, it can probably reduce investment in things like jars of magic pebbles and Quantum Purifiers for hifi applications.

dorokusai

I mean topology as in the design.....and as far as verbage goes. John Curl's Class A circuit isn't the same as a Nelson Pass circuit....or are we not using the word circuit here? I believe I'm going to Heiney roll and just stick to my own thoughts on audio.

sucks2beme

Class "a" is the resulting output, NOT how you get there.
Yes, some class "a" amps may not sound better.

mhardy6647

dorokusai wrote: »

I mean topology as in the design.....and as far as verbage goes. John Curl's Class A circuit isn't the same as a Nelson Pass circuit....or are we not using the word circuit here? I believe I'm going to Heiney roll and just stick to my own thoughts on audio.

You are a wise man -- wiser than I (which I knew already, but I just wanted to point it out for the masses).

But (better late than never) - I'll just go back to my decidedly single-ended (and thus class A by definition) amps in the living room when I get home...

dorokusai

mhardy6647 wrote: »

You are a wise man -- wiser than I (which I knew already, but I just wanted to point it out for the masses).

But (better late than never) - I'll just go back to my decidedly single-ended (and thus class A by definition) amps in the living room when I get home...

I'm not sure about that Mark and I believe we're simply splitting hairs without ever really getting into what we both know. At least it isn't cables and there would be death threats and hate filled PM's :biggrin:

mhardy6647

I don't post about cables... anywhere!

I do like stuff that sounds good - to me. Oh, and I am a cheapskate when it comes to anything that stands between me and early retirement. Pretty much sums it up.

heiney9

dorokusai wrote: »

I mean topology as in the design.....and as far as verbage goes. John Curl's Class A circuit isn't the same as a Nelson Pass circuit....or are we not using the word circuit here? I believe I'm going to Heiney roll and just stick to my own thoughts on audio.

That's fine.....Tom started another thread and I linked to the 10+ page thread we all had a discussion on not too long ago about class A. I also linked the same articles I've linked numerous times over the past few years from NP's POV. Because 1) they are my most handy bookmarks 2) he has a way of explaining more complicated ideas in a simple easy to follow way and he gives the "why" behind the idea/circuit. That's not to say his is the only way.

For me Pure Class A is pretty cut and dried (it's Single Ended), but there are lots of interpretations by other audio designers and people like us that just love the hobby.

I have yet to hear any other amplifier that "sounds" like a single ended class A amplifier. And, no I haven't listened to every amplifier made. There is something special about a Pure Class A amplifier which I find especially pleasing and intoxicating. The cost, heat and hardware certainly mean they aren't for everyone. And there are numerous rigs they aren't the best choice for such as very, very power hungry speakers or perhaps a huge listening roon or someone who ultimately cares only about reaching ear bleeding spl's. It just works very, very well in my system and the synergy is incredible. I have never needed anything more than the 30wpc it provides and I have yet to really see the limits of the amplifier.........and I've tried.

I am going to sit this one out as every other time this subject has come up I've made my POV known and I was even sent a PM once and asked to give it a rest not all that long ago. It seems some don't enjoy my passion for this subject.

H9

H9

dorokusai

H9 - I know what you mean and knew that everything existed here already...let alone recently. I wondered why Treitz posted it at all but figured he had a reason and just added a couple comments, of which he probably doesn't care about anyways.

Do you guys have any other books that you've read concerning amplifier design and the like, that I may want to pick up?

heiney9

treitz3 wrote: »

So, I take it that there is no clear definition as to whether an amplifier is or isn't a Class A amplifier, like the definition of pregnant? You are or you aren't...

For me there is, atleast for the term Pure Class A; it's Single Ended.

H9

FTGV

mhardy6647 wrote: »

My brain is exploding. Class A still has nothing to do with topology (SE vs. PP) and everything to do with bias (operating points of the active device(s)).

Game, set, match.

FTGV

dorokusai wrote: »

Do you guys have any other books that you've read concerning amplifier design and the like, that I may want to pick up?

Bob Cordell and Doug Self both have excellent books regarding amplifier design.

heiney9

mhardy6647 wrote: »

My brain is exploding. Class A still has nothing to do with topology (SE vs. PP) and everything to do with bias (operating points of the active device(s)

.

But it's still A/B unless the power devices never turn off. Splitting hairs I known, but it's mostly because the claim and phrase Class A has been so abused by marketing departments that the term is watered down and used for everything under the sun.

Pure Class A is singled ended, end of story in my eyes. Everything else is A/B.

H9

mhardy6647

heiney9 wrote: »

But it's still A/B unless the power devices never turn off. Splitting hairs I known, but it's mostly because the claim and phrase Class A has been so abused by marketing departments that the term is watered down and used for everything under the sun.

Pure Class A is singled ended, end of story in my eyes. Everything else is A/B.

H9

We're in total agreement about the marketing part, my friend.
(as well as about the devices never turning off in true class A)

disneyjoe7

I feel by design PP are AB class, and can't be A class.

FTGV

disneyjoe7 wrote: »

I feel by design PP are AB class, and can't be A class.

I disagree, the amount of bias is what differentiates between A or A/B in a PP design.

heiney9

And to add another twist, single ended class A sounds quite a bit different than high bias class A or push/pull class A as some would call it. Notice I carefully said different and not better or worse. That's for the listener to decide.

H9

megasat16

mhardy6647 wrote: »

We're in total agreement about the marketing part, my friend.
(as well as about the devices never turning off in true class A)

hehe...

Brock, I know you are not wrong but your view of Class A is incomplete. It's missing a hole in the middle.

May be...just may be, your Papa Pass can fill you in about PP Class A

heiney9

megasat16 wrote: »

hehe...

May be...just may be, your Papa Pass can fill you in about PP Class A

James, I'm fully aware of the X and XA series and in the words of "papa" the hybrid topology of marrying the original Aleph (single ended Class A) topology w/ the super symmetry (push/pull) of the X series.

H9

megasat16

heiney9 wrote: »

And to add another twist, single ended class A sounds quite a bit different than high bias class A or push/pull class A as some would call it. Notice I carefully said different and not better or worse. That's for the listener to decide.

H9

Frankly, High Biased Class AB is a later development. There is something called Push Pull Class A using output transformer in the earlier design that doesn't involve with the high biasing Class AB design. It's already biased for SE design and use the output transformer to sums the output. It increase efficiency of SE design.

It's very much the same to PP Tube Ultralinear amplifiers. In the case of transistors amplifiers, the output devices conducts all 360 degrees of the waveform and there is no crossover distortion to occur.

And the sound of SE vs. PP Class A amplifiers, you got to be kidding me. The sound of an amp is not based on what class or topology it uses, it's based on how well it's made.

FTGV

heiney9 wrote: »

And to add another twist, single ended class A sounds quite a bit different than high bias class A or push/pull class A as some would call it.

H9

Potentially,but it could also be said not all SE designs will sound a like.Lots of variables .

heiney9

megasat16 wrote: »

And the sound of SE vs. PP Class A amplifiers, you got to be kidding me. The sound of an amp is not based on what class or topology it uses, it's based on how well it's made.

Wow!!! I completely disagree!! Each topology sounds completely different.

I agree with starting with how well it's made. I guess my reference point is from a single designer (NP) and how he has all types of different topologies using a few different types gain devices and they all have their own distinct sound signature.

Current source, voltage source, Jfets, MosFets, transformer coupled, single ended, super symmetry, Stasis and they all sound the same????? What did he waste his time making so many different types of amps available if all he had to do was make sure they were all well made?

So in your eyes the X series amp will sound exactly the same as the XA series amp and First Watt amps even though the topologies are different enough?

H9

megasat16

heiney9 wrote: »

Wow!!! I completely disagree!! Each topology sounds completely different.

I agree with starting with how well it's made. I guess my reference point is from a single designer (NP) and how he has all types of different topologies using a few different types gain devices and they all have their own distinct sound signature.

Current source, voltage source, Jfets, Mosfest, output transformers, single ended, super symmetry and they all sound the same. What did he waste his time making so many different types of amps available if all he had to do was make sure they were all well made?

So in your eyes the X series amp will sound exactly the same as the XA series amp even though the topologies are different?

Coz Mr. Pass is not the only one who made amps. There are lots of competitors out there using Class AB topology that sounds as good as any Class A topology. Mr. Pass Love KISS and lots of his design are based on the good solid Engineering. But the Engineering doesn't stop there.

As for the sound comparison between X and XA, I don't know about the later X.5 series sound. But as I stated in CP long ago, a friend of mine sold XA30.5 and bought X600.5 or something. He said he is very happy with the bigger power. I haven't been to his place since he bought the X.5 amps since he lived about 400 miles near from me.

Brock, I have amps I can put up against any NP SE Class A amps at my disposal. If we live closer, we can make a shootout sometimes.

P.S. One other reason it came to my thought is that very fundamental again. Not everyone likes the same taste in sound. What is special to you with Class A amp may be nothing special at all to another person.

heiney9

megasat16 wrote: »

Coz Mr. Pass is not the only one who made amps. There are lots of competitors out there using Class AB topology that sounds as good as any Class A topology. Mr. Pass Love KISS and lots of his design are based on the good solid Engineering. But the Engineering doesn't stop there.

As for the sound comparison between X and XA, I don't know about the later X.5 series sound. But as I stated in CP long ago, a friend of mine sold XA30.5 and bought X600.5 or something. He said he is very happy with the bigger power. I haven't been to his place since he bought the X.5 amps since he lived about 400 miles near from me.

Brock, I have amps I can put up against any NP SE Class A amps at my disposal. If we live closer, we can make a shootout sometimes.

P.S. One other reason it came to my thought is that very fundamental again. Not everyone likes the same taste in sound. What is special to you with Class A amp may be nothing special at all to another person.

It's not about shootouts or what I think is better. I cannot believe as much as you and Fred have been around this stuff that you can make a blanket statement that topologies don;t matter only how well it's built. That's ridiculous.

Written words in a few paragraphs never can take the place of a good face to face discussion over a few ice cold beers so as I stated before I am sitting this one out. Way to many assumptions are added by the readers in threads like these (myself included).

I would appreciate an answer as to why all of NP's designs using various topologies sound different if topology has nothing to do with the way something sounds. I guess he just wasted the 30 years of his life when all he had to do was make sure things were well built then all his amps would sound the same.

H9

FTGV

heiney9 wrote: »

So in your eyes the X series amp will sound exactly the same as the XA series amp and First Watt amps even though the topologies are different enough?

H9

The X and XA share the same basic super sym. circuit topology but I would expect some SQ differences because of the way in which they are biased.

heiney9

megasat16 wrote: »

P.S. One other reason it came to my thought is that very fundamental again. Not everyone likes the same taste in sound. What is special to you with Class A amp may be nothing special at all to another person.

Never said we all had to have the same taste, I said there are difference's in sound and they can be based on topology chosen. I didn;t mean to imply that was the SINGULAR thing.

You guys read way too much into posts sometimes.

H9

FTGV

heiney9 wrote: »

It's not about shootouts or what I think is better. I cannot believe as much as you and Fred have been around this stuff that you can make a blanket statement that topologies don;t matter only how well it's built.

Whoa chief where did I say that?As for blanket statements I believe I have pointed out your doing such on a few occasions.

heiney9

FTGV wrote: »

The X and XA share the same basic super sym. circuit topology but I would expect some SQ differences because of the way in which they are biased.

James, What about the First Watt stuff? You don't consider using Jfets or transformer coupled outputs a different topology?

You said above as long as it's well made topologies don't influence sound. Perhaps we define the word "topology" differently. I tend to define it very narrowly. If you define it very broadly then there's where our disconnect is.

H9

P.s. I edited to read James rather than Fred...........my mistake