Silenced Fred Posted February 14, 2010 Share Posted February 14, 2010 Now that I have your attention... What is the difference in class mean for amplifiers? (ie Class A, Class A/B, Class D, etc.) I have always wondered and never gotten a straight answer. As far as I know, and have been told, Class A is "more true tube tone" Link to comment Share on other sites More sharing options...
SweetMarie Posted February 14, 2010 Share Posted February 14, 2010 The plate voltage on a true Class A amp never passes through zero...the power tubes are continuously powered. An example would be a Fender Champ 600... Class A/B amps have power tubes in push-pull pairs. The plate voltages pass through zero because the tubes cycle "on" and "off" alternately. Pretty much any amp with tubes in pairs is an A/B, although many amps will run in either mode (Epiphone Blues Custom for instance). A lot of people think Vox AC30 amps are Class A - technically they are not. Link to comment Share on other sites More sharing options...
mcmurray Posted February 14, 2010 Share Posted February 14, 2010 It's not specific to tube amps. It basically describes the mode of operation of the output devices in an electronic amplifier. For class A, the output device is on all the time and amplifies the whole signal. For class B, the output devices take turns; Class AB is a mixture of the A and B, i.e. each output device amplifies more than 50% of the signal. Class C is relevant to RF designs only, and Class D uses PWM for amplification. Contrary to popular opinion, the 'class' of amplifier has nothing do do with the quality of sound. Yes they'll sound different, but none is 'better' than the other. Also I might add that Class A can really only be used for low wattage amplifiers. Once you're past a certain power rating, Class B or AB is your only choice. For hifi applications, Class A can be desirable. Because there is no mixing of signals from each device, there is zero intermodulation distortion. Link to comment Share on other sites More sharing options...
Silenced Fred Posted February 14, 2010 Author Share Posted February 14, 2010 Thanks mcmurray, that helps a lot. I kinda made that connection, that only low power amps could be all class A, but wanted to ask. Thanks everybody Link to comment Share on other sites More sharing options...
jefleppard Posted February 14, 2010 Share Posted February 14, 2010 great lesson. thanks. Link to comment Share on other sites More sharing options...
deepblue Posted February 14, 2010 Share Posted February 14, 2010 I always wondered about A/B amps myself, and do you know what? Even though it was explained I still havent got a clue! lol Link to comment Share on other sites More sharing options...
mcmurray Posted February 14, 2010 Share Posted February 14, 2010 lol Link to comment Share on other sites More sharing options...
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