Contrastique Posted March 21, 2008 Report Share Posted March 21, 2008 I posted this on head-fi a while back and thought it might be interesting reposting it here for the ones who haven't seen it and just to post something interesting... I already forgot what was in it so I'll have to reread again I guess, it's very long: "Audio Power Amplifier Fundamentals Introduction The term amplifier is very generic. In general, the purpose of an amplifier is to take an input signal and make it stronger (or in more technically correct terms, increase its amplitude). Amplifiers find application in all kinds of electronic devices designed to perform any number of functions. There are many different types of amplifiers, each with a specific purpose in mind. For example, a radio transmitter uses an RF Amplifier (RF stands for Radio Frequency); such an amplifier is designed to amplify a signal so that it may drive an antenna. This article will focus on audio power amplifiers. Audio power amplifiers are those amplifiers which are designed to drive loudspeakers. Specifically, this discussion will focus on audio power amplifiers intended for DJ and sound reinforcement use. Much of the material presented also applies to amplifiers intended for home stereo system use. Basics The purpose of a power amplifier, in very simple terms, is to take a signal from a source device (in a DJ system the signal typically comes from a preamplifier or signal processor) and make it suitable for driving a loudspeaker. Ideally, the ONLY thing different between the input signal and the output signal is the strength of the signal. In mathematical terms, if the input signal is denoted as S, the output of a perfect amplifier is X*S, where X is a constant (a fixed number). The "*" symbol means Quote Link to comment Share on other sites More sharing options...
Dusty Chalk Posted March 21, 2008 Report Share Posted March 21, 2008 First of all, thanks. I'm cutting and pasting it, will read it later. So...where'd it come from, did you write all that? Oh, and hey, it looks like it got cut off at the end. Quote Link to comment Share on other sites More sharing options...
Contrastique Posted March 21, 2008 Author Report Share Posted March 21, 2008 First of all, thanks. I'm cutting and pasting it, will read it later. So...where'd it come from, did you write all that? Oh, and hey, it looks like it got cut off at the end. Sorry, have to dissapoint you here...I'm not that knowlegable to come up with that myself, google is my friend I got it from here: http://www.rocketroberts.com/techart/amp.htm There's more on the site if you're interested. What I posted is the intire article about that except for the outro. Quote Link to comment Share on other sites More sharing options...
JBLoudG20 Posted March 21, 2008 Report Share Posted March 21, 2008 Indra Quote Link to comment Share on other sites More sharing options...
aerius Posted March 22, 2008 Report Share Posted March 22, 2008 Indra You're just doing that 'cause you want to get in her pants. Quote Link to comment Share on other sites More sharing options...
JBLoudG20 Posted March 22, 2008 Report Share Posted March 22, 2008 You're just doing that 'cause you want to get in her pants. We already had this discussion in another thread. Try to keep up. Quote Link to comment Share on other sites More sharing options...
Smeggy Posted March 22, 2008 Report Share Posted March 22, 2008 We already had this discussion in another thread. Try to keep up. Besides, JBL probably wouldn't fit in her pants. Though I'm sure they'd make a nice hat. Quote Link to comment Share on other sites More sharing options...
Contrastique Posted March 22, 2008 Author Report Share Posted March 22, 2008 Ow jeezz, here we go again.....you're not all 15 yr olds, right??? Quote Link to comment Share on other sites More sharing options...
Fungi Posted March 22, 2008 Report Share Posted March 22, 2008 20, I think that's close enough to 15. Quote Link to comment Share on other sites More sharing options...
deepak Posted March 22, 2008 Report Share Posted March 22, 2008 On the plus side aerius gets straight to the point, unlike some of the creepy posts I read at Headfi people hitting on you (fifty plus year old men). Quote Link to comment Share on other sites More sharing options...
Dusty Chalk Posted March 22, 2008 Report Share Posted March 22, 2008 Young/cute/female == 50 year old man posting on the internet. Quote Link to comment Share on other sites More sharing options...
Contrastique Posted March 22, 2008 Author Report Share Posted March 22, 2008 Young/cute/female == 50 year old man posting on the internet. Yeah, let's keep it on that Anybody maybe something to say about the article itself besides the chattering....? Quote Link to comment Share on other sites More sharing options...
Pars Posted March 22, 2008 Report Share Posted March 22, 2008 Yeah, the basic article is fine. I don't see anything that I would consider to inaccurate as far as it goes. It is meant to be an entry level overview of amplifier concepts, and as such is fine. Quote Link to comment Share on other sites More sharing options...
Spiug31 Posted March 22, 2008 Report Share Posted March 22, 2008 Anybody maybe something to say about the article itself besides the chattering....? It's to long for me to hear just now but seems intresting, thanks for the link to the original text. Quote Link to comment Share on other sites More sharing options...
ron mexico Posted March 22, 2008 Report Share Posted March 22, 2008 A technical question from the technically ignorant - The article states: "If you have ever looked at a spec sheet for a decent quality amplifier, you probably noticed that the power output of an amplifier is higher when the load impedance (number of ohms) is lower. Important: a load with a low number of ohms is a more difficult load than one with a higher number of ohms! That is, a 4 ohm speaker is harder for an amplifier to drive than an 8 ohm speaker." My question relates to the impedance ratings of headphones. The 300 ohm Sennheiser is harder to drive than the 32 ohm Grado, correct? This is the opposite to what is stated in the article about speaker loads. Can someone explain? Quote Link to comment Share on other sites More sharing options...
grawk Posted March 22, 2008 Report Share Posted March 22, 2008 The senn is easier to drive, it just doesn't get as loud. That's easy. A technical question from the technically ignorant - The article states: "If you have ever looked at a spec sheet for a decent quality amplifier, you probably noticed that the power output of an amplifier is higher when the load impedance (number of ohms) is lower. Important: a load with a low number of ohms is a more difficult load than one with a higher number of ohms! That is, a 4 ohm speaker is harder for an amplifier to drive than an 8 ohm speaker." My question relates to the impedance ratings of headphones. The 300 ohm Sennheiser is harder to drive than the 32 ohm Grado, correct. Seems the opposite to what is stated in the article about speaker loads. Can someone explain? Quote Link to comment Share on other sites More sharing options...
Pars Posted March 22, 2008 Report Share Posted March 22, 2008 The Senn requires more voltage swing to drive, but less current. A home power amp has no problem with voltage swing... driving adequate current for the 4 ohm and 2 ohm (and possibly 1 or less) ohm loads is more of a problem. Conversely, in headphone amps, particularly portable ones powered by 9V batteries, the voltage swing is usually harder to achieve than the current levels necessary to drive Grados. A technical question from the technically ignorant - The article states: "If you have ever looked at a spec sheet for a decent quality amplifier, you probably noticed that the power output of an amplifier is higher when the load impedance (number of ohms) is lower. Important: a load with a low number of ohms is a more difficult load than one with a higher number of ohms! That is, a 4 ohm speaker is harder for an amplifier to drive than an 8 ohm speaker." My question relates to the impedance ratings of headphones. The 300 ohm Sennheiser is harder to drive than the 32 ohm Grado, correct? This is the opposite to what is stated in the article about speaker loads. Can someone explain? Quote Link to comment Share on other sites More sharing options...
Vortex Posted March 22, 2008 Report Share Posted March 22, 2008 An accessible entry level read which might be very helpful for non-electronics skilled people to get a little insight in amplifier concepts. Goed gedaan, Contrastique! Quote Link to comment Share on other sites More sharing options...
jp11801 Posted March 23, 2008 Report Share Posted March 23, 2008 Nice read should be required reading for people who are interested in amps prior to asking questions, good for speaker and headphone people alike. Quote Link to comment Share on other sites More sharing options...
F1GTR Posted March 25, 2008 Report Share Posted March 25, 2008 On the plus side aerius gets straight to the point, unlike some of the creepy posts I read at Headfi people hitting on you (fifty plus year old men). Sovkiller is such a mack daddy pimp player extrordinaire. Quote Link to comment Share on other sites More sharing options...
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