RLHofer Posted January 31, 2014 Share Posted January 31, 2014 Noob question..... what IS a "Class A" amplifier? Thanks in advance. Link to comment Share on other sites More sharing options...
SEHpicker Posted January 31, 2014 Share Posted January 31, 2014 Randall Smith explains this very well in this article: Class A amplifier SEHpicker The further a society drifts from truth the more it will hate those who speak it." George Orwell Link to comment Share on other sites More sharing options...
J. Dan Posted January 31, 2014 Share Posted January 31, 2014 That's kind of a long read. The short version is this: a waveform has a + and - half to it. The problem with amplifying it that way, with a bipolar supply, is crossing through zero. You have positive and negative circuits separately amplifying each half, and there's distortion as it switches from plus to minus. Class A uses a DC shift to put the entire waveform into the positive region, amplifies it that way, then uses a coupling capacitor to block that DC. The advantage is lower distortion, the disadvantage is less efficiency. Maximum efficiency is 50%, which means at best! you're drawing 200w of power for a 100w output. Dan Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth. Link to comment Share on other sites More sharing options...
Guitarzan Posted February 1, 2014 Share Posted February 1, 2014 and to add to the confusion a lot of amps are being called class A and they actually are not true class A amps. http://www.soundclick.com/bands/pagemusic.cfm?bandID=193274 rock it, i will Link to comment Share on other sites More sharing options...
Scott Fraser Posted February 1, 2014 Share Posted February 1, 2014 and to add to the confusion a lot of amps are being called class A and they actually are not true class A amps. There is a notion which simply refuses to die that Class A operation equals superior sound. It doesn't, it's just one way to design gain into a circuit. Superior design equals superior sound. Scott Fraser Link to comment Share on other sites More sharing options...
Caevan O’Shite Posted February 2, 2014 Share Posted February 2, 2014 and to add to the confusion a lot of amps are being called class A and they actually are not true class A amps. There is a notion which simply refuses to die that Class A operation equals superior sound. It doesn't, it's just one way to design gain into a circuit. Superior design equals superior sound. Truth. The most important ingredient is ALWAYS the cook. My Fuchs Lucky 7 uses one EL34 output-tube to drive the speaker through its output-transformer; that is an example of true Single-Ended Class A operation. Vox AC30's, which employ a quartet of EL84 output-tubes, are very often referred to as Class A, but are more accurately described as "Class A/B Push-Pull". Ask yourself- What Would Ren and Stimpy Do? ~ Caevan James-Michael Miller-O'Shite ~ _ ___ _ Leprechaun, Esquire _ ___ _ Link to comment Share on other sites More sharing options...
Scott Fraser Posted February 2, 2014 Share Posted February 2, 2014 and to add to the confusion a lot of amps are being called class A and they actually are not true class A amps. There is a notion which simply refuses to die that Class A operation equals superior sound. It doesn't, it's just one way to design gain into a circuit. Superior design equals superior sound. Truth. The most important ingredient is ALWAYS the cook. My Fuchs Lucky 7 uses one EL34 output-tube to drive the speaker through its output-transformer; that is an example of true Single-Ended Class A operation. Vox AC30's, which employ a quartet of EL84 output-tubes, are very often referred to as Class A, but are more accurately described as "Class A/B Push-Pull". And Rupert Neve's circuits, the holy grail of mic preamps, EQs, & mix buss active combining networks, are IIRC mostly Class AB designs. Scott Fraser Link to comment Share on other sites More sharing options...
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