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mr2racer 17th April 2012 12:50 AM

SE distortion
 
Why is single ended distortion so high? In looking at tube data it seems SE distortion specs for tubes is much higher than for push pull. If that is the case why would anyone build an SE amp in the first place? Is it mostly 2nd order?

Wavebourn 17th April 2012 01:00 AM

Because no distortions born equal. If you in order to remove distortions that are measurable but less audible add distortions that are more audible you actually add more distortions, no matter what your measurements suggest. Also, when distortions go down when sounds decay it is natural and much less audible than when distortions go up when sounds decay. Strictly speaking, you want cleaner sound, not cleaner picture on the screen, because this pictures not so well corellate.

Why it so? Because everything in the Nature that conducts, reflects, generate sounds, is non-linear. But sounds that you hear in the nature do not sound distorted. But electronic additions different from what your ears and brain expect to hear draw attention and sound as distortions, while distortions of SE amp are almost ignored by ears and brain.

mr2racer 17th April 2012 01:55 AM

Wavebourn,

So what you are saying is its distortion that can be measured you just don't hear it as distortion?

Wavebourn 17th April 2012 02:09 AM

It is not like black and white. Any distortions are distortions.

I am just saying that some distortions sound more as distortions than other distortions. Like, 1 grain of salt and 1 grain of cyanide in a glass of water tastes differently, even if 1 grain of salt is easier measured by sensitive ohmmeter. Or, a glass cleaned by acetone looks cleaner than cleaned by water, but in which glass a water tastes better? The same with electronics: means to remove "visible" distortions often add distortions that are more audible, even though they are less visible. Second tube in push-pull adds audible distortions, but decreases visible distortions.

Push pull is very good approach when you want more output power loosing less for heating the air. Like, I can easily get 100W of clean power from a pair of GU-50 tubes. To get such power from tubes in SE will be quite problematic.

Pano 17th April 2012 02:17 AM

Quote:

Originally Posted by mr2racer (Post 2988210)
Is it mostly 2nd order?

It doesn't have to be. A good design will have a harmonic spectrum that falls off evenly. 2nd, 3rd, 4th, 5th, 6th, etc.

Quote:

Originally Posted by mr2racer (Post 2988261)
So what you are saying is its distortion that can be measured you just don't hear it as distortion?

Indeed. There is research going back to the 1930s (at least) that shows the masking properties of harmonics. If they fall off in a certain way, at certain levels, you don't hear them. I.E., you can't tell them from a pure sine.

scott17 17th April 2012 02:32 AM

Quote:

Originally Posted by Wavebourn (Post 2988221)
Because everything in the Nature that conducts, reflects, generate sounds, is non-linear. But sounds that you hear in the nature do not sound distorted.

+100

DualTriode 17th April 2012 04:47 AM

Because we can!
 
Quote:

Originally Posted by mr2racer (Post 2988210)
Why is single ended distortion so high? In looking at tube data it seems SE distortion specs for tubes is much higher than for push pull. If that is the case why would anyone build an SE amp in the first place? Is it mostly 2nd order?

Why would any one build any kind of tube amplifier at all? Go buy 500 watts of Solid State amplifier for less than a 5 watt 300B if that is your thing. (I must confess)

Back in the early days, think 45, 2A3 and 300B, gain and watts were precious. Two or 3 watts at 5% was heaven, to some it still is. Pentodes, Push Pull and Ultra-Linier feedback came along came along and added greater efficiency and less total distortion. This was heaven and to some it still is.

Now some build hybrid tube / solid-state riaa preamplifiers with vanishing distortion. Why do this if you can get less distortion with $10.00 dollars of op-amps?

We do this human dance with technology, because we can and we like it.

It is all just for fun!

DT

bobrown14 20th April 2012 12:28 AM

Quote:

Originally Posted by Pano (Post 2988281)
It doesn't have to be. A good design will have a harmonic spectrum that falls off evenly. 2nd, 3rd, 4th, 5th, 6th, etc.


Indeed. There is research going back to the 1930s (at least) that shows the masking properties of harmonics. If they fall off in a certain way, at certain levels, you don't hear them. I.E., you can't tell them from a pure sine.

It's your brain that is configured to ignore them. Your ears and your brain cavity create a type of distortion, your brain is tuned to ignore these distortions and if your amp creates these similar distortions they will be ignored by your brain as well. SE amps tend to create distortions that are similar to the natural distortions your ear creates which your brain likes because the brain will ignore/filter them out. My interpretation of a lot of reading regarding NFB and why it all works when on paper it should not. my .02

Cheers,
Bob

mr2racer 20th April 2012 02:04 AM

Hey DualTriode,
I have an SP3A that I rebuilt with Curcio's mods. A pair of Dynaco MarkVI's that I completely rebuilt that with the recent addition of some Mundorf Silver in Oil coupling caps are really starting to sound good. (12Au7 front end KT88 outputs.) I built an 8b from scratch last year. A pair of Mark III's from scratch. I'm almost done with an SCA35 rebuild. And on deck a set of Sansui/Tango EL84 transformers, A 6V6 Magnavox, a pair of Acrosound TO 300's, I just sold a point to point 6922 Aikido. And I'm waiting for Antek to get a AN-0209 so I can start Artur Loesch's 6922 preamp.

I LOVE tubes. Sunday I bought an old Zenith EL84 SE amp to see what they're all about. I don't even like using voltage regulators!

popilin 4th May 2012 03:38 AM

Quote:

Originally Posted by Wavebourn (Post 2988221)
Because everything in the Nature that conducts, reflects, generate sounds, is non-linear. But sounds that you hear in the nature do not sound distorted.

Very true, even poetic, Chapeau !


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