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In the trhread about source follower I showed part of amp's schematic and got lot of questions in e-mail and in private messages.
A first, what means inaudible? For me, it means distortions are not unexpected. For example, if a cat barks everybody will see the fact, even being scared. If a dog barks, few people will pay attention.
The same, if distortions increase when the sound fades out (guitar strings, reverberation), and spector of them is wide, it is well audible.
But if level of distortions decrease with fading and order of harmonics became lower and lower we don't pay attention: it is natural, ordinary, "clean".
Here is the example of mentioned in that thread amplifier, this version is designed to drive headphones. In SPICE simulator the amp gives 8V PP on 32 Ohm load with 0.02 percent of 2'nd order harmonics, higher order harmonics nearly don't exist. In reality, it sounds very clean and natural, as if just an amplifying wire is connected between a player and headphones.
Feel free to build it for personal usage, no usage of output stage for profit without my permissions!
It contains in this particular case paralleled source and emitter follower (emitter follower is degraded - one part of error correction), loaded by a voltage to current convertor. Iddle current is half of maximal peak current for given load, this is another part of error correction. Bottom right transistor (Q5) with diode and resistor in base is a current mirror implementation. R1: set 4V on output (Vpp-Vgs)/2, R7 - to set iddle current.
Anatoliy
A first, what means inaudible? For me, it means distortions are not unexpected. For example, if a cat barks everybody will see the fact, even being scared. If a dog barks, few people will pay attention.
The same, if distortions increase when the sound fades out (guitar strings, reverberation), and spector of them is wide, it is well audible.
But if level of distortions decrease with fading and order of harmonics became lower and lower we don't pay attention: it is natural, ordinary, "clean".
Here is the example of mentioned in that thread amplifier, this version is designed to drive headphones. In SPICE simulator the amp gives 8V PP on 32 Ohm load with 0.02 percent of 2'nd order harmonics, higher order harmonics nearly don't exist. In reality, it sounds very clean and natural, as if just an amplifying wire is connected between a player and headphones.
Feel free to build it for personal usage, no usage of output stage for profit without my permissions!
It contains in this particular case paralleled source and emitter follower (emitter follower is degraded - one part of error correction), loaded by a voltage to current convertor. Iddle current is half of maximal peak current for given load, this is another part of error correction. Bottom right transistor (Q5) with diode and resistor in base is a current mirror implementation. R1: set 4V on output (Vpp-Vgs)/2, R7 - to set iddle current.
Anatoliy