Talk:Tube sound/Archive 2

message: It seems rather strange that the previous vociferous utterances of the audiophile community have not yet been crystallised into a coherent view of what the audible differences are between valve and transistor amplifiers. Is this because they have difficulty in describing these subtle differences or because in fact there are no differences at all?--Light current 03:18, 21 March 2006 (UTC)
replies: text: There is indeed a difference in sound. The problem is explaining this in words. We don't have many words to describe the characteristics of sounds, we have to use words like 'creamy' and 'crunchy' to describe tube harmonic distortion, which are words to describe texture. Does sound have texture? The 'texture' of sound can only be experienced by you, so you'll have to take the test yourself and see if there is a difference. Otherwise, you have to take everyone's word for it that tube amps sound much 'warmer' and 'creamier' than solid-states. Believe me, for the most part, they do, whatever that means.
Put it in the article! See if it can stand!--Light current 02:09, 25 March 2006 (UTC)
thread_title:  Audible differences 

message: Tended to use the term "Tube" -- Older tubes were sold by several brands under the trademark "Radiotron" (Marconi, GE, RCA)  Rogers used the company name "rogers radio tubes" and I have at least one example where this was molded into the bottom of the base.
cmacd 12:35, 12 May 2006 (UTC)
thread_title:  Canadian English 

message: Perhaps Im being naive here, but I always thought that all active devices had non linear transfer characteristics: some square law, some exponential. Are there any that are truly linear (without NFB) 8-?--Light current 23:22, 1 June 2006 (UTC)
thread_title:  Transfer characteristics of active devices 

message: I found a very interesting reference:
Russell Hamm, "Tubes Versus Transistors - Is There An Audible Difference?", 
Journal of the Audio Engineering Society, May 1973.
It can be found at
It will take a while to digest this. Gerry Ashton 01:10, 3 June 2006 (UTC)
replies: text: Good reference.  This should definitely be in the article. — Omegatron 15:12, 3 June 2006 (UTC)
replies: text: It already is! 8-) . Just a clearer version here--Light current 16:04, 3 June 2006 (UTC)
replies: text:  I know; I just updated it.  It's been there forever.  I mean the information needs to be in the article. — Omegatron 02:06, 4 June 2006 (UTC)

text: Ahh! yes 8-)--Light current 02:30, 4 June 2006 (UTC)

text: This site seems to have some articles about valve sound from a legitimate perspective, too. — Omegatron 04:17, 4 June 2006 (UTC)
replies: text: Yeah looks like a sensible fellow whose stuff can be referenced. I think maybe we need less exposition and more refs? 8-)--Light current 05:38, 4 June 2006 (UTC)
thread_title: Facinating reference

message: Three of the links in the article, in the External Links section, do not work for me:
* PDF Tubes vs. Transistors in Electric Guitar Amps
* Tubes vs. Transistors: Feature Comparison
* Why Tubes?
Does everyone have trouble with these links? Gerry Ashton 00:29, 4 June 2006 (UTC)
replies: text: Yeah. Maybe Milberts server is down!--Light current 01:49, 4 June 2006 (UTC)
thread_title:  Links to milbert.com 

message: I question the article's claim under "Audible Differences" that "it appears that no results from scientifically conducted listening tests are available to confirm or deny the audiophile claims". I think these tests have been done and show that no detectable differences exist when the valve amplifier's distortion is low. For high distortion valve amps the difference is detectable, but only in the same sense as distortion is detectable. Without evidence I suppose this is just hearsay, but it is my recollection.  Nowater57
:Unfortunatley, we cant rely on peoples recollections, but if you can find a ref. then we can put it in--Light current 13:15, 5 June 2006 (UTC)
replies: text:  I also suspect these tests have been done many times.  The aforementioned article (from 1973) says "Previous attempts to measure this difference have always assumed linear operation of the test amplifier. This conventional method of frequency response, distortion, and noise measurement has shown that no significant difference results." — Omegatron 13:30, 5 June 2006 (UTC)

text: Well of course we can reference the published Hamm article (but probably not the unpublished ones) But there doesnt seem to be hard evidence of controlled tests here. We must look elsewhere--Light current 14:17, 5 June 2006 (UTC)
thread_title:  Audible Differences 

message: Good paper on ear 'self distortion' etc.--Light current 15:24, 5 June 2006 (UTC)
thread_title:  Psychoacoustics 

message: Audio valves typically have only modest gain. This makes it possible to design very simple valve circuits that rely on this inherent open-loop linearity and have little, or no negative feedback, and thus have very simple distortion spectra.
:Less NFB = nicer sounding distortion?--SlipperyHippo 00:09, 9 April 2007 (UTC)
replies: text: I think its obvious that the author does not like NFB, and thinks it degrades the sound! most of the other statements  ::seem to follow from this belief.--SlipperyHippo 17:14, 9 April 2007 (UTC)

text: Tend to agree ATM --SlipperyHippo 01:03, 10 April 2007 (UTC)
thread_title:  (2) 

message: It is relevant at this point to note that the class A differential stage draws almost constant current regardless of the signal. The rail pull down is thus constant. This stage has a very high "commmon mode rejection ratio" and good regulation becomes unimportant.
::This semms to be saying that because Class A diff stages draw a constant current from the supply rail under all signal ::conditions, you dont need to regulate the rail voltage (which BTW would harm the sound because the 'regulator' is in ::the signal path)--SlipperyHippo 17:19, 9 April 2007 (UTC)
replies: text: Thinking!--SlipperyHippo 01:03, 10 April 2007 (UTC)

text: No not quite all! You could have a bridged amplifier  where each half is class AB. This could be said to be a differential 'stage'.--SlipperyHippo 23:32, 10 April 2007 (UTC)

text: Class A made up of 2 class (A)B stages. Yes, I suppose--SlipperyHippo 12:41, 11 April 2007 (UTC)

text: But there again, if you want 360 deg angle of flow (conduction angle), in the end everything has to simulate class A doesnt it?--SlipperyHippo 13:31, 11 April 2007 (UTC)
thread_title:  (4) 

message: The above simple analysis only applies to single tone continuous sine waves. Real world music contains transients and many tines at once. When multiple tones are present, if the amplifiers transfer function is not perfectly flat (which it never is in the real world), intermodulation products will also be generated (these typically being harmonic to the original tones involved.
::The author seems to be confusing transfer function with non linearity as far as I can see.
::--SlipperyHippo 17:19, 9 April 2007 (UTC)
replies: text:  Something that is non-linear will have a non-linear transfer function.  Transfer functions are almost always assumed to be linear so you can do LTI stuff, but they aren't linear in real life, and obviously aren't assumed to be when you're talking about non-linearities.  See Talk:Transfer_function#LTI_systems_only.3F from a long time ago. — Omegatron 19:36, 9 April 2007 (UTC)
replies: text: Depends what you mean by TF--SlipperyHippo 01:03, 10 April 2007 (UTC)

text: agreed--SlipperyHippo 01:03, 10 April 2007 (UTC)

text: I admit dont understand electronics to the same depth as you, but what about Af corresponding to an integrator in the time domain? why would that be nonlinear?  --SlipperyHippo 01:03, 10 April 2007 (UTC)

text: No I dont quite see yet. Youre saying a diffr is linear and an intgerator is non linear? Yes?
--SlipperyHippo 01:24, 10 April 2007 (UTC)

text: Sorry I was thinking of the bode plot (in dB) of an intergrator. On a linear scale, the TF of an integrator is of course non linear. TF of a differentiator is linear--SlipperyHippo 10:16, 10 April 2007 (UTC)
thread_title:  (5) 

message: Is the following an admission by audiophiles that its ok to mess with the recorded signal by adding their own favored brand of distortion by means of a (valve) amplifier of their choice?
However at the upper end our audio systems (so called "high end" or "audiophile" systems) it is recognised that "accuracy" is not something that can be simply described by eg a wide quoted frequency response and a low measured distortion level (THD) - the music also has to sound "natural", and in fact "musical", rather than eg "sterile".
 
All real world designs distort to some degree, and designers seek a compromise in the nature of the distortion their design produces, that "sounds good", rather than simply measures well. In the high end world audiophiles will typically pay greater regard to how it sounds than to how it measures, to the point of just not caring about measured distortion levels at all.
--SlipperyHippo 15:02, 11 April 2007 (UTC)
thread_title:  Audiophile admission?