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General Asylum General audio topics that don't fit into specific categories. |
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General Asylum General audio topics that don't fit into specific categories. |
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In Reply to: Re: wrong posted by Story on June 20, 2005 at 08:42:28:
Sorry to butt in here, but SE will make sure that you are thoroughly confused, if I don't.
Technically triodes have a form of feedback, because the output current current is changed by the output voltage. With pentodes, ideal bipolar transistors or fets, this is not true, and they are free of this 'feedback' mechanism.
Actually, triodes are probably the most linear device available. This is because the change in output conductance that occurs with changes with the output voltage at the plate of the tube, tends to cancel the rising transconductance (input voltage to output current) to linearise (make equal) the spacing BETWEEN the lines as seen on a curve tracer, (see previous article cited on tubes).
This effect can also happen with fets and bipolar transistors, and is more tricky to implement. For example it is possible to cancel the 2'nd harmonic in a single fet or bipolar transistor without any push-pull action by careful selection of device, load resistance and operating point. For further explanation, contact Bascom King, who showed me this over 30 years ago.
In any case, triodes are generally the most linear devices, and the first watt is the most important one, in any amplifer. Why? Because that is where we normally operate when listening to music. Higher powers are usually reserved for special effects, like cannons, explosions or very loud rock.
If you are in doubt, just put a simple AC voltmeter across one of your loudspeakers and not its average output. Then convert what you find to watts. You might be surprised.
However, IF you want significantly higher levels, to create explosions, or to impress your friends, you will find that it takes lots of watts, and that is one reason why we usually make much larger amps, the minimum usually being 100W.
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Follow Ups
- Re: wrong - john curl 11:31:31 06/20/05 (1)
- thanks - Story 12:02:18 06/20/05 (0)
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