Talk:Amplifier

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Amplification is a basic process sometimes seen in nature, and often used in processes which involve a signal which must be made stronger.

Removed. According to basic process, saying that amplification is a basic process is to say it is "a phenomenon which is one of the elemental building blocks of reality". I don't believe there is any significant body of human thought that makes this claim. Furthermore, it seems to border on meaninglessness, unless someone cares to flesh this claim out. For example, is amplification more or less "elemental" than, say, light, or souls, or cultures, or "the market", or fundamental particles? Whether you take amplification to be "fundamental" seems to depend entirely on the question one is asking, or the area one is investigating. Why do we need to claim amplification is elemental in general? --Ryguasu 08:35 Nov 12, 2002 (UTC)

An amplifier is a device which changes a small movement into a larger movement. But this also defines transformers as well as SImple Machines, and these are not amplifiers. An amplifier amplifies, i.e. there is energy-gain.--Wjbeaty 05:43, Mar 31, 2005 (UTC)

Though you always should mention where the extra energy is coming from, or risk both confusing newcomers and inspiring crackpots. - Omegatron July 9, 2005 19:18 (UTC)

Contents

[edit] who invented the amplifier

Perhaps Thomas Edison? The Carbon microphone is an amplifier. Edison even built amplifiers for long distance phone lines by connecting a loudspeaker to a carbon microphone and battery. But I don't know if there were earlier amps before this. See: [1] --Wjbeaty 05:43, Mar 31, 2005 (UTC)

Microphones are really transducers, which convert energy in one form (mechanical air pressure) into another form (electrical signals).

[edit] Complete Rewrite

This page is not really satisfactory as it is with lots of imprecision, errors and just lack of theme. I propose to rewrite.

Any suggestios/comments? Al212.74.96.201 03:58, 1 August 2005 (UTC)

I looked at this article again. I think the basic concept of an amplifier has to be layed out first. And lets not throw these big words around like "transfer function." I never met a tekky that could explain anything. I think when you know something you forget that other people don't know it. Let's go a little slower. Maybe we should be starting out with the idea that an electronic amplifier works by controling a large source of electrical power with a small one. To make this useful to people who know little about electricity, we can use the hydrolic analogy. The voltage is the pressure and the current is the amount of fluid that flows along. The British even call their vacuume tubes "valves". Then we could define power as having both current and voltage. Indeed voltage times current equals power, in watts. I'm surprised that no electrical people have looked at this. This article could turn out very nicely if given some help. Hey the guy down on "class of amp" has it right. Just go to electronic amplifier.69.122.62.231 (talk) 17:59, 15 February 2008 (UTC)

Lots of articles, not just this one, that have to do with electrical concepts are full of half truths, sometimes non-truths.
I think it is because they are written by enthusiasts, but not by actual specialists who have studied these topics and have contributed to the discipline.
You've said that on a few pages, but haven't given any examples. — Omegatron 19:35, 5 November 2006 (UTC)
I agree. This page suffers from a distinct lack of organization and an occasional lack of knowledge on the subject matter. I think the first sentence of the article sums up my point. I vote for a complete rewrite. Snottywong 16:55, 28 April 2007 (UTC)

[edit] transistor amplifier

Should we create an article for the different types of transistor amplifiers? We already have common base, common collector, differential amplifier, long-tailed pair, cascode and so on. Would be helpful to tie them all together. — Omegatron 18:07, 24 October 2005 (UTC)

I was thinking a nav box type thing would be handy. Three columns: FET, BJT, tube; three 'common-'s per column; and topologies along the bottom. Such a box could become bloated, though. - mako 07:27, 25 October 2005 (UTC)
Oh. I made it the other day. See Common_base#See_also. — Omegatron 12:27, 26 September 2006 (UTC)

[edit] External Links are Bad

This page explains about basic amplifier, but unneccesarily links to some 60w amplifier circuits. External links are not required for this page.

[edit] Class of amp

While it may not be written clearly it looks OK in terms of electronics design. I would suggest that as a external definative reference you use the first few chapters of the radio communication handbook published by the RSGB. This book is aimed at the radio electronics community but the ideas apply to audio equipment. I think that this page should be rewritten as an audio amp page, as it concentrates on audio equipment very much with the exclusion of things such as radio amps.

You may wish to read the page at Electronic amplifier which I suspect has been created and worked on by a different group of people who have not had much to do with this page.

Cadmium 16:41, 28 December 2005 (UTC)

[edit] Merge with electronic amplifier

This entry should be merged with electronic amplifier. In particular, the discussion of amplifier classes and efficiency is not clear on this page. This could be eliminated from this page, since there is a good discussion of amplifier classes under the electronic amplifier entry.

Agree about the new classes section. There should just be a paragraph about electronic amplifiers in here with a {{main}} link to electronic amplifier. — Omegatron 22:48, 11 January 2006 (UTC)

[edit] Rewrite.....

I personally feel that the quality of the article is very poor......i vote to rewrite the article...... and there is no need to merge the classification of amplifiers with electronic amplifiers...

Jayant, 17 Years, India|(Talk) 05:51, 16 January 2006 (UTC)

[edit] Hub Page

I intend to make this into a hub page with all different sorts of amplifer being breifly described then linked to their own main pages.--Light current 01:23, 29 January 2006 (UTC)

Started tidy up. and transformation to hub page.--Light current 01:31, 29 January 2006 (UTC)

LC, the discussion is a bit too audio-centric. The audio amplifier page could use some content. - mako 02:31, 30 January 2006 (UTC)


[edit] Cut from page

Harmonic distortion is fairly easy to measure. The amplifier output is connected to a spectrum analyzer (a device which graphs frequency against amplitude). A pure tone -- typically a sinusoidal signal at 1 kHz -- is then applied to the amplifier input. The largest signal on your analyzer should be the input signal at 1 kHz. You will sometimes see humps at even intervals along the graph at multiples of that base signal. These are the harmonics. The total harmonic distortion (THD) is the sum of these components relative to the signal. --Light current 11:48, 23 May 2006 (UTC)

[edit] Information about high power microwave valves

I added information about the continuing advantages of microwave high power valve over semiconductor in the Valve amplifier section. I also added a Reference section and cleaned up the See also secton.Gerry Ashton 18:59, 4 June 2006 (UTC)

Thats good. 8-) But have you considered adding the info to Valve amplifier instead or in addition? PS dont forget to sign your posts!--Light current 18:26, 4 June 2006 (UTC)


[edit] Someone clean "linearity" up please

The last paragraph there? I don't even know where to begin.

KjellElec means:

Linearity as such is easily defined, see Wiki. But this statement from the article is a horror and needs to be dealt with in detail or removed:

"Because tubes are significantly more linear than transistors, tube amplifiers do not need as much global negative feedback to achieve acceptable linearity."

Does he compare triodes, tetrodes or pentodes to bipolar, Jfet or Mosfet transistors, and are they low-power types or not? Does he compare components or practical circuits? Tube audio power amps must normally use output transformers, whose wild phase excursions at high frequencies forbid hard overall global feedback in order to stay stable. Thus tube power amps are _forced_ to use a limited amount of global feedback.

End of KjellElec meaning

[edit] Carbon mic amplifiers

http://en.wikipedia.org/w/index.php?title=Carbon_microphone&action=edit&section=2 --Light current 19:23, 31 December 2006 (UTC)

[edit] Removed text

I removed the following text from the article for the reason that it is mostly unsubstantiated opinion:

In the earlier years of audio, vacuum tubes filled the active device role. Valve amplifiers are widely, but not always correctly, associated with the valve sound. Some claim this sound has more to do with the circuit topology and circuit design of the amplifier, than to the use of valves rather than transistors as the active gain devices. However, this reasoning is not entirely correct. Because tubes are significantly more linear than transistors, tube amplifiers do not need as much global negative feedback to achieve acceptable linearity. While large amounts of global negative feedback are effective for reducing total harmonic distortion (THD) at low frequencies, feedback has downsides such as reduced stability, reduced slew rate, reduced bandwidth, increased high-order distortion[citation needed], and artifacts such as asymmetrical slewing[citation needed]. In most commercial designs, little attention is paid to these problems, and designers simply attempt to achieve the lowest possible THD.

Alfred Centauri 17:56, 24 April 2007 (UTC)

[edit] Metadyne, Magnicon and Magnavolt

I accept the reason given for the removal of the reference to the BBC article on Metadyne but is this a reason for removing the words Metadyne, Magnicon and Magnavolt as well? If so, shouldn't we remove Rototrol too? Biscuittin 11:28, 18 May 2007 (UTC)

If you have a reliable source for Metadyne, Magnicon and Magnavolt, go ahead and add them back (but trademarks might not be important enough to include, if they are trademarks). As for Rototrol, from looking at http://siris-libraries.si.edu/ipac20/ipac.jsp?uri=full=3100001~!219875!0#focus it seems to be a trademark of Westinghouse; perhaps it should be removed. --Gerry Ashton 15:06, 18 May 2007 (UTC)

[edit] Definition of amplifier and gain

The current definition of amplifier from this article is: any device that uses a small amount of energy to control a larger amount of energy. I think "amount of energy" should be replaced by "signal" to be more general. Also the definition of "gain" in this article should be similarly generalized. Any comments about this? Roger 15:47, 24 May 2007 (UTC)

I think "power" is better than "signal". Some people may feel "signal" implies communications, and amplifiers are not confined to communication applications. Also, "power" is closer to the physical phenomena that occur in an amplifier than "signal". Finally, gain is usually defined as the ratio of the output power to the input power, so sticking with power will allow a more concise definition of gain. --Gerry Ashton 17:03, 24 May 2007 (UTC)
But the output power can be smaller than the input power (like in a voltage amplifier), so it may not be a small power controlling a larger one. Also there are different types of power gain (transducer, available, etc.) that would need to be mentioned, so it may not be more concise. I think signal is better, because it can mean an energy, power, voltage or current signal. Roger 17:14, 24 May 2007 (UTC)
This article is not confined to electrical amplifiers, so the input and output could be even more general than the examples mentioned by Roger: light, fluid flow or pressure come to mind. A power gain could be computed for any of these. An advantage of using the word "power" would be to eliminate certain quantities that, strictly speaking, cannot serve as input to an amplifier (energy, for example). --Gerry Ashton 17:33, 24 May 2007 (UTC)
Thats true, but a voltage amplifier, for example, could have a power gain of zero or infinity, so it may not always be best to think in terms of power gain. Usually "amplifier" means "electronic amplifier" so I still think signal is a better word. Other non-electrical amplifiers could also be mentioned. Roger 17:58, 24 May 2007 (UTC)
A transformer can increase voltage, but not power, so it is not an amplifier. Also there is nothing wrong with an amplifier having a power gain less than one. No real device has infinite power gain, which is another argument in favor of using the word "power"; it is intuitively obvious that no device can output infintite power. --Gerry Ashton 18:52, 24 May 2007 (UTC)
My point is its misleading to ONLY think in terms of power gain. A voltage amplifier and a simple resistive divider can both have the same power gain, but obviously they are different. And yes, real devices won't have infinite gain , but a MOSFET CS amplifier can have an enormous power gain, but very little voltage gain for example. Roger 19:02, 24 May 2007 (UTC)
I don't have any more arguments to make; I just want to say that I still think "power" is a better word than "signal" and if I don't make any further posts, it means I maintain my opposition to changing the word. --Gerry Ashton 20:08, 24 May 2007 (UTC)

[edit] Carbon amps

I think these could do with their own article. There are bits of info on carbon amps dotted about in different categories, but no carbon amp article. Alas no time today. Tabby 16:42, 3 December 2007 (UTC)

[edit] Rototrol

A Rototrol isn't an amplifier.[2]. It's a motor-driven power regulator for balancing currents in 3-phase systems. It belongs to the family of big adjustable inductive components used in power distribution. So I removed Rototrol from the amplifier article. --John Nagle (talk) 17:30, 15 December 2007 (UTC)

It looks like the term "Rototrol" has been used for two different devices. The reference above to an adjustable inductive regulator is from a 1994 publication. But US patent 2470672 , "Rototrol scheme", from 1949 shows a field-modulated generator like a Ward Leonard control. This is probably too much information for the Amplifier article; it belongs somewhere else, under "obsolete rotating electrical machinery" or something like that. I've been putting in a few lines on each obscure amplifier type, but avoiding too much detail. --John Nagle (talk) 18:34, 20 December 2007 (UTC)

[edit] This article should be distinguished clearly from "Electronic Amplifiers"

There is massive identity crisis here: this article should be restricted to discussion of ampifliers in general, and properties common to all amplifiers, and not contain undue detail about e.g. power amplifiers. Its scope should be ALL amplifiers. Brews ohare (talk) 17:55, 9 January 2008 (UTC)

I have moved the Power Amp Classes to "Electronic Amplifiers" and combined it with the already existing extensive discussion there. However, it would be desirable to put it all into a Power Amp article. Brews ohare (talk) 18:37, 9 January 2008 (UTC)
Moved classification scheme to discussion of that name in "Electronic amplifiers" Brews ohare (talk) 19:09, 9 January 2008 (UTC)
This entire article contains so many weak sections that it makes one weep. Brews ohare (talk) 00:22, 10 January 2008 (UTC)

[edit] this article lacks car audio/home entertainment information

definitely lacks in this category. I would like to see amplifier class, types of connectors, RMS ratings, number of channels, etc. It only briefly touches on "Efficiency" and never stating why it is more efficient or what each class does and how it works. 12.215.147.98 (talk) 04:41, 21 January 2008 (UTC)X

For class definition, have a look on Electronic amplifier. Yves-Laurent (talk) 07:08, 21 January 2008 (UTC)

[edit] Could use some pics

Right now the article looks like a wall of text. Some pics would really help to break the monotony. —Preceding unsigned comment added by 72.186.242.122 (talk) 03:47, 5 June 2008 (UTC)