which tube?

[trittya]

With that criteria, I would prefer an EL34/EL84/2A3 based SE amp, even better if class A.

QUOTE
Single-ended topology always operates in Class A
Class A operation can be implemented in a single-ended or push-pull topology
Push-pull topology can be operated in Class A or Class B
Class B operation is only implemented by a push-pull topology
UNQUOTE

A Survey Of Amplifier Types (TAS 217) | The Absolute Sound

Here's what the much acclaimed and widely experienced audio Guru, Mr Thorsten Loesch had to stay in response to the above link on our 950 strong facebook group here
https://www.facebook.com/groups/diy.custom.hifi/
(Copied and pasted for the benefit of all FMs following this thread )

QUOTE
Thorsten Loesch - There are some problems in the definitions
Ignoring SE for the moment (it can only work in Class A) and pure Class B (in some ways it is way worse than class D),the only true choices for high quality amplifiers are Class A or Class A/B.

Given that for example a 50W @ 8 Ohm Class A Amplifier that should drive Speakers down to 2 Ohm in Class A for 50W we would need 3.5A quiescent current, which for 30W rails (50W/8R) would translate into 210W power dissipation, few so-called Class A Amplifiers idle at even a fraction of this and often are rated for more than noted 50W.

So, in reality ALL Push-Pull Solid State Amplifiers (and actually pretty much all Push-Pull Tube Amplifiers meaning most of both genre's) that do not run in pure Class B (for quality audio this basically non) also do not really run in pure Class A but transition from Class A to Class B at some power level into some load.

My own EL34 Push-Pull Amp (custom design) delivers around 25W into matched impedance in Class A and 35W in Class (A)B. This is an extreme example towards a"Class A" Amplifier.

On the opposite side, a china made amplifier advertised as "80W/PC Class A" upon actual investigation is revealed to offer 8W/8Ohm and 4W/4Ohm Class A power the rest is in Class (A)B.

More extreme, a Douglas Self "Blameless" Class AB Amplifier delivers only 0.27W/8Ohm and 0.135W/4Ohm in Class A.

Once the output stage exits true class A operation two things happen.

First, a range of distortion mechanisms usually lumped together as "crossover distortion" start distorting the signal much more than during Class A operation. A competent designer may "hedge" against these using a wide range of techniques.

Secondly,the current draw of the amplifier becomes signal dependent (in Class A this is generally not the case) which causes all sorts of fun and games in the power supplies which again may lead to increased distortion (especially of the "wrong" kind).

So what matters most is not what is claimed, but what really happens.

With an amplifier that offers 80W maximum output and 8W in class A combined with a speaker having an efficiency meaning the amplifier is rarely driven to clipping, this means anything 10dB or more below clipping is class A, usually only short peaks will leave class A, with most of the "average power" of the music being delivered in Class A.

In my books this is "generally good enough" to not notice the excursions into Class B, so such an amplifier delivers the sonic benefits of a Class A Amplifer with music most of the time, without having to burn silly levels of power.

With an Amplifier that delivers 80W before clipping but only 0.27W in Class A and using the same loudspeaker as before the amplifier exist Class A 24dB below clipping, so the transtition happens smack bang in the middle of where most of the interesting stuff in music happens.

So, two amplifiers both actually Class AB played with music will show very different audibility of any Class B artefacts.

Upshot, running amplifiers hot helps, but true Class A may be overrated and using design techniques that remove some of the crossover distortion mechanisms can help to reduce heat waste and deliver as good or even better sound in Class AB with minimal Class A power than Class A monsters with very high Class A power.
UNQUOTE

 

[ranjeetrain]

QUOTE
Single-ended topology always operates in Class A
Class A operation can be implemented in a single-ended or push-pull topology
Push-pull topology can be operated in Class A or Class B
Class B operation is only implemented by a push-pull topology
UNQUOTE

A Survey Of Amplifier Types (TAS 217) | The Absolute Sound

Here's what the much acclaimed and widely experienced audio Guru, Mr Thorsten Loesch had to stay in response to the above link on our 950 strong facebook group here
https://www.facebook.com/groups/diy.custom.hifi/
(Copied and pasted for the benefit of all FMs following this thread )

QUOTE
Thorsten Loesch - There are some problems in the definitions
Ignoring SE for the moment (it can only work in Class A) and pure Class B (in some ways it is way worse than class D),the only true choices for high quality amplifiers are Class A or Class A/B.

Given that for example a 50W @ 8 Ohm Class A Amplifier that should drive Speakers down to 2 Ohm in Class A for 50W we would need 3.5A quiescent current, which for 30W rails (50W/8R) would translate into 210W power dissipation, few so-called Class A Amplifiers idle at even a fraction of this and often are rated for more than noted 50W.

So, in reality ALL Push-Pull Solid State Amplifiers (and actually pretty much all Push-Pull Tube Amplifiers meaning most of both genre's) that do not run in pure Class B (for quality audio this basically non) also do not really run in pure Class A but transition from Class A to Class B at some power level into some load.

My own EL34 Push-Pull Amp (custom design) delivers around 25W into matched impedance in Class A and 35W in Class (A)B. This is an extreme example towards a"Class A" Amplifier.

On the opposite side, a china made amplifier advertised as "80W/PC Class A" upon actual investigation is revealed to offer 8W/8Ohm and 4W/4Ohm Class A power the rest is in Class (A)B.

More extreme, a Douglas Self "Blameless" Class AB Amplifier delivers only 0.27W/8Ohm and 0.135W/4Ohm in Class A.

Once the output stage exits true class A operation two things happen.

First, a range of distortion mechanisms usually lumped together as "crossover distortion" start distorting the signal much more than during Class A operation. A competent designer may "hedge" against these using a wide range of techniques.

Secondly,the current draw of the amplifier becomes signal dependent (in Class A this is generally not the case) which causes all sorts of fun and games in the power supplies which again may lead to increased distortion (especially of the "wrong" kind).

So what matters most is not what is claimed, but what really happens.

With an amplifier that offers 80W maximum output and 8W in class A combined with a speaker having an efficiency meaning the amplifier is rarely driven to clipping, this means anything 10dB or more below clipping is class A, usually only short peaks will leave class A, with most of the "average power" of the music being delivered in Class A.

In my books this is "generally good enough" to not notice the excursions into Class B, so such an amplifier delivers the sonic benefits of a Class A Amplifer with music most of the time, without having to burn silly levels of power.

With an Amplifier that delivers 80W before clipping but only 0.27W in Class A and using the same loudspeaker as before the amplifier exist Class A 24dB below clipping, so the transtition happens smack bang in the middle of where most of the interesting stuff in music happens.

So, two amplifiers both actually Class AB played with music will show very different audibility of any Class B artefacts.

Upshot, running amplifiers hot helps, but true Class A may be overrated and using design techniques that remove some of the crossover distortion mechanisms can help to reduce heat waste and deliver as good or even better sound in Class AB with minimal Class A power than Class A monsters with very high Class A power.
UNQUOTE

:lol:

I can understand the itch to make that post. Specially because it was said on a 950 strong fb group More specially if it comes from a person who barely two weeks ago said "I also understand that a reasonably powered Class A SET" :clapping:

Full post here.

By the way, I don't see how that rant against class A is useful to the OP's question - "which tube".

 

[trittya]

:lol:

I can understand the itch to make that post. Specially because it was said on a 950 strong fb group More specially if it comes from a person who barely two weeks ago said "I also understand that a reasonably powered Class A SET" :clapping:

Full post here.

By the way, I don't see how that rant against class A is useful to the OP's question - "which tube".

:lol:Good one, Ranjeet. Nice try.
The fact of the matter is that I am no Guru and have limited knowledge, so I did say that in a query because I didn't know it then. Not that I know much now or have ever claimed to . . . .
Nevertheless, whatever little commonsense I have does lead me to infer that, more often than not, it is always worth its while to read the succeeding line which, in this case, clearly states that "Class A operation can be implemented in a single-ended or push-pull topology". Surely beats having a "foot-sandwich" in ones mouth, but then thats just me, eh? I actually tend to stink between the toes due to perspiration.

It doesnt take knowledge of intricate Rocket Science nuances to conclude that all single-ended amplifiers are Class A but all Class A amplifiers are not single ended. (If nothing else, I am utterly sanguine that youll readily concur when I say that, If it did involve the aforesaid intricacies, I wouldnt have been able to arrive at such conclusion in the first place, :lol: that too, by myself, sans assistance.) Now, that clearly implies that it was incumbent of me to mention that I wanted to ask about Class A SET and NOT Class A Push-Pull. Or am I still missing something here?
Having read up a mite, I just wanted to share that because I saw a friend making the same slip, that is all there was to it, no more no less. If you notice, I had made it a point to remove your name from the quote, thereby suggesting that it wasn't aimed at any individual, least of all a friend who happens to be a member of that very FB group. In fact, I had posted my "find" on that group a while before I read your post and as you are a valued member there, you may like to ascertain that if you still have the inclination. I only hope like hell you haven't taken offense, man. My sincere apologies if my post made you uncomfortable in the least.

Now, coming to the next part ie about the itch. Well, I fail to understand how being part of a 950 strong group could lead to a scratchy epidermis. :lol:Again, I am no dermatologist, maybe thats why I failed to fathom that. However, I must share with you that since it appeared to be quite a coincidence-in-context, Id reckoned that it might be a good idea to share something that an eminent and venerable DIY Pro-Audio enthusiast like Mr Loesch had said elsewhere(it may as well have been a forum of which I am not a member).
Why do I have the lurking notion that there is an attempt to make me feel that maybe I was wrong in having done so?
Look, man, all I can do is assure you that I derived no pleasure out of that post other than that of sharing it with fellow FMs. The rest is up to you, my friend. I can't possibly hope to shove and thrust my assurances down the gullet. Having said so, need I tell you that well both feel better if you believe me.
Now, next but by no means least, about the rant part. Id be cheating you if I didnt convey that I am rather underwhelmed at your choice of that particular word in the context under mention, my friend. I am sure you can do (a little) better than that, in view of the years that that man has walked the Earth, if not much else. :indifferent14:
This, in wake of the fact that some of the better English dictionaries have this to tell us about that word rant.
- "to speak or shout at length in an angry, impassioned way"
- "to utter in a bombastic declamatory fashion"
- "to complain or talk loudly and angrily for a long time, sometimes saying unreasonable things"
- "to talk in a noisy, excited, or declamatory manner"
- "to scold vehemently"
- "shout and complain angrily and at length"

Pragmatically speaking, had it come from someone held any lower in esteem than I hold you in, it wouldnt have made me wonder the way it just did. For want of a better choice, here I am, constrained to presume that whoever/whatever made you feel one had an itch also led to choice of the word rant used for Mr Loesch. I daresay that for once I am glad hes not here to read this. You might say you couldnt care less and then again, for want of better choice, Id have to agree with you. No sweat on that either. Fine with me. :thumbsup: But I daresay that that I didn't catch him taking sides or being parochial about topologies, as you shall see for yourself, if you give it another 'deliberately cool' perusal.

In conclusion and in response to your query/comment about the relevance of that rant with the OPs thread topic/query, I do earnestly hope youll agree with me when I say that its usually a chosen amplifier topology that leads to choice/selection of tube(s) and not vice versa.

Ranjeet Bhai, I meant no malice and never will. Nor am I, even remotely inclined to lock horns with you or with anyone else, for that matter. I am well and truly sorry if my post upset you. Maybe its high time I did some introspection and soul-searching, earnestly attempting to search new meaning and/or connotation for the word share. I promise to try hard, if not succeed.

I am not here to rattle my sabre, my friend, rest assured, for, I don't even want to carry one. I do believe that nor are you inclined to. I have no reason at all to believe otherwise and Id rather it remains that way. It helps. Hard feelings just make it 'harder' . . . .
I have merely made a genuine attempt to appeal to your sensibilities. Do let me know if I've said wrong, maybe I need to be flogged for that. If that doesn't appeal, there's always the Guillotine, if not a firing squad. :indifferent14:

Wishing you and all your loved ones a merry Christmas. May the Almighty bestow you and them with His choicest blessings in that, all you enjoy much good health, cheer, happiness and prosperity, always and forever.

Hope to catch up with you next time you are in Delhi/India. Do ping me well in time so that I can plan to move accordingly.

Warmest regards

PS - Just wanted to enhance your feel-good-factor by "sharing" that the group is about 1015 strong now. Not bad, eh? Thanks for being part of it.

 

[ranjeetrain]

Look Trittya, tone down. Since you look up dictionaries reading others' post, do the same reading your own post. Your post contains a lot of offensive expressions and tangents, avoid that.

Since your post (and any subsequent replies) are not relevant to this thread I will reply you over PM.

Regards.