Is single ended Class A better than push-pull?

okhifi · 25th August 2005, 05:43 PM

is single end class a better than push - pull?

(spam site edited out by moderators)

leadbelly · 25th August 2005, 07:15 PM

Is Coke better than Pepsi?

rdf · 25th August 2005, 07:37 PM

Quote:

Originally posted by leadbelly
Is Coke better than Pepsi?

In every way!

Miles Prower · 25th August 2005, 07:39 PM

is single end class a better than push - pull?

That's a big: "It depends".

Push-pull has certain advantages. It eliminates (or nearly so) the DC magnetizing current, and so makes the design and construction of output xfmrs easier. Balanced operation also eliminates (or nearly so) even order harmonics, making for cleaner output.

Unforch, it also removes the second harmonic, which doesn't seem to do much damage to listenability, and may even improve it. The odd-order harmonic content coming from a P-P stage has higher order harmonics (3, 5, 7, 9, etc.) even if the magnitude is lower, these have a greater affect on listenability. Can you control that with feedback? Sure, NBD.

Does it make a difference? Who knows? It all comes down to listenability, and that's strictly a personal preference. Some like P-P cleaned up with feedback; others prefer raw SE, and no feedback. You can fight about that one forever (and they're doing that over in the SS forum.

)

mr mojo · 25th August 2005, 10:18 PM

I agree wholeheartedly about the coke/pepsi thing. In fact, I think a person's previous experiences, state of mind, sobriety level as well as speaker and room interactions will make far more difference than SE or PP.

To add to Miles' post: The center-tapped output xfrmrs of a PP amp, in addition to limiting/cancelling DC current and core saturation (allowing them to be simpler, smaller and cheaper)also cancels out some hum. Feedback in a PP amp will help decrease hum levels even further-with the combined action of the two allowing for less(cheaper) power-supply filtering such as C-R-C rather than using chokes-although there's certainly nothing wrong with using a choke in a PP power supply!

Without the combined action of feedback and center-tapped xfrmrs, hum can be a problem in a SET amp-but can be cured with care.

Best,
mr mojo

EC8010 · 25th August 2005, 10:53 PM

Coke/Pepsi? We are talking about totally artificial hyped-up junk drinks made of water and artificial additives sold at an inflated price and consumed mostly by kids aren't we? Wouldn't a comparison between champagne and cava be more appropriate, or sauternes and graves? Something real... Please?

Johan Potgieter · 26th August 2005, 12:17 AM

I am always intrigued by this argument (was this opened mischievously?). In addition to factors mentioned by Miles and Mr Mojo:

Okhifi did not mention triodes specifically. A pentode will always have substantially more distortion (and very audible) than any p.p. circuit, going into high order harmonics. Then the removal of even order harmonics seems to be a stumbling block for some. One must see that correctly: It is not even harmonics per se that are removed, only even harmonic distortion, i.e. something added by the amplifier that should not have been there in the first place. (There is sometimes a perception that part of the original music is "removed".)

If looked at correctly, I for one cannot see that any circuit causing lower distortion, whatever the content, can be inferior to one causing higher distortion, when the original purpose is to have no distortion - that is not logical. (This with the proviso that one is aware of the listener fatigue caused by severe high order harmonics - I am excluding that for the moment.) Thus if a single ended triode is preferred because it has mainly 2nd harmonic distortion, then use a p.p. triode output stage; it will have even lower distortion, etc. Pentodes generally can be capable of generating some higher order products (they will do more so in single ended) but that depends on the design. However since the days of ultra-linear (rendering largely triode type distortion) I cannot see anyone using straight pentodes any more.

That is it, in a nutshell, for me. . .

arnoldc · 26th August 2005, 12:25 AM

very subjective... depends on whose ears

SY · 26th August 2005, 12:38 AM

Quote:

Originally posted by EC8010
We are talking about totally artificial hyped-up junk drinks made of water and artificial additives sold at an inflated price

SET in a nutshell.

Johan Potgieter · 26th August 2005, 12:46 AM

Dear oh dear SY!

NOW you are going to get an earfull! (But I will remember this retort - quite relevant.)

Johan

25th August 2005, 07:15 PM	#2
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Is Coke better than Pepsi? __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

25th August 2005, 07:39 PM	#4
Miles Prower diyAudio Member Join Date: May 2005 Location: USA Blog Entries: 2	is single end class a better than push - pull? That's a big: "It depends". Push-pull has certain advantages. It eliminates (or nearly so) the DC magnetizing current, and so makes the design and construction of output xfmrs easier. Balanced operation also eliminates (or nearly so) even order harmonics, making for cleaner output. Unforch, it also removes the second harmonic, which doesn't seem to do much damage to listenability, and may even improve it. The odd-order harmonic content coming from a P-P stage has higher order harmonics (3, 5, 7, 9, etc.) even if the magnitude is lower, these have a greater affect on listenability. Can you control that with feedback? Sure, NBD. Does it make a difference? Who knows? It all comes down to listenability, and that's strictly a personal preference. Some like P-P cleaned up with feedback; others prefer raw SE, and no feedback. You can fight about that one forever (and they're doing that over in the SS forum. ) __________________ There are no foxes in atheistholes www.dolphin-hsl.com

25th August 2005, 10:53 PM	#6
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	No, no tolerance whatsoever... Coke/Pepsi? We are talking about totally artificial hyped-up junk drinks made of water and artificial additives sold at an inflated price and consumed mostly by kids aren't we? Wouldn't a comparison between champagne and cava be more appropriate, or sauternes and graves? Something real... Please? __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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25th August 2005, 10:18 PM	#5
mr mojo diyAudio Member Join Date: Jun 2005 Location: Iowa	I agree wholeheartedly about the coke/pepsi thing. In fact, I think a person's previous experiences, state of mind, sobriety level as well as speaker and room interactions will make far more difference than SE or PP. To add to Miles' post: The center-tapped output xfrmrs of a PP amp, in addition to limiting/cancelling DC current and core saturation (allowing them to be simpler, smaller and cheaper)also cancels out some hum. Feedback in a PP amp will help decrease hum levels even further-with the combined action of the two allowing for less(cheaper) power-supply filtering such as C-R-C rather than using chokes-although there's certainly nothing wrong with using a choke in a PP power supply! Without the combined action of feedback and center-tapped xfrmrs, hum can be a problem in a SET amp-but can be cured with care. Best, mr mojo

26th August 2005, 12:17 AM	#7
Johan Potgieter diyAudio Member Join Date: May 2005 Location: Pretoria, South Africa	I am always intrigued by this argument (was this opened mischievously?). In addition to factors mentioned by Miles and Mr Mojo: Okhifi did not mention triodes specifically. A pentode will always have substantially more distortion (and very audible) than any p.p. circuit, going into high order harmonics. Then the removal of even order harmonics seems to be a stumbling block for some. One must see that correctly: It is not even harmonics per se that are removed, only even harmonic distortion, i.e. something added by the amplifier that should not have been there in the first place. (There is sometimes a perception that part of the original music is "removed".) If looked at correctly, I for one cannot see that any circuit causing lower distortion, whatever the content, can be inferior to one causing higher distortion, when the original purpose is to have no distortion - that is not logical. (This with the proviso that one is aware of the listener fatigue caused by severe high order harmonics - I am excluding that for the moment.) Thus if a single ended triode is preferred because it has mainly 2nd harmonic distortion, then use a p.p. triode output stage; it will have even lower distortion, etc. Pentodes generally can be capable of generating some higher order products (they will do more so in single ended) but that depends on the design. However since the days of ultra-linear (rendering largely triode type distortion) I cannot see anyone using straight pentodes any more. That is it, in a nutshell, for me. . .

26th August 2005, 12:25 AM	#8
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	very subjective... depends on whose ears

26th August 2005, 12:46 AM	#10
Johan Potgieter diyAudio Member Join Date: May 2005 Location: Pretoria, South Africa	Dear oh dear SY! NOW you are going to get an earfull! (But I will remember this retort - quite relevant.) Johan

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