Dear friends,
i have posted one amp design with new type of VAS. PLS review it and help me to finalize the design. I know you masters will have some thing to say.🙂
i have posted one amp design with new type of VAS. PLS review it and help me to finalize the design. I know you masters will have some thing to say.🙂
Great to see guys actively engaged in amplifiers,
Trying new stuff and getting personal experience.
Keep it up,
At least you not content like some to just build proven designs.
I hope yout get this one finalised and built up.
Trying new stuff and getting personal experience.
Keep it up,
At least you not content like some to just build proven designs.
I hope yout get this one finalised and built up.
Well, yes the smoke will get in someone's eyes but that CFP arrangement is fairly common where the emitter resistor is shoved in the collector lead instead. We had a popular DIY class A stage like that. It gave no problems.....No emitter resistors in the drivers or outputs
Normally I would expect the emitters of Q1 and Q3 to be connected to the other sides of the resistors, such that you get a local feedback loop that stabilises the bias current.
What's the idea behind the rather unusual connection of Q2 and Q4?
Finally, I think most BC547's and BC557's should be replaced with BC546's and BC556's, respectively, otherwise you will exceed their voltage limits in the signal peaks.
Putting the 'emitter' resistor in the collector lead will simply reduce peak output, won't it? In a proper CFP output the resistor is an important part of the crossover handover, but not here.
I understand that there actually are a few adjustments to make. The general plan is there but according to mr. Self's slender volume, current edition p150; the links between the driver emitters and the output should be deleted, each emitter tied to ground with around 100R, then another 10R taken again from each emitter to the corresponding output collector. This forms a potential divider to force close to unity gain. If you prefer mr Slone's book, there's a version there too.
edit:Surprise, Bob Cordell also uses this general form to illustrate the CFP stage
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I only have an older version of Self's book. The 'CFP with gain' was used 40 years ago in the famous (in the UK) PW Texan amp - the output stage had a voltage gain of around 10. Since then it seems to have been frowned on. A gain of about 1.1 seems more reasonable.
Dear friends,
i have posted one amp design with new type of VAS. PLS review it and help me to finalize the design. I know you masters will have some thing to say.🙂
You can play with LTspice file here...😀
Bootstrapping is likely to be counterproductive if you already have a current source. Likewise, a resistor in series with a current source makes little sense.
2N2955 is not a 2N3055 complementary (MJ and TIP types are).
Your bias/output circuit is odd. You're aware that you'll lose a bunch of current gain in Q2/Q4, right?
Finally, I'd say you're either going to see generous amounts of crossover distortion or bad thermal stability.
2N2955 is not a 2N3055 complementary (MJ and TIP types are).
Your bias/output circuit is odd. You're aware that you'll lose a bunch of current gain in Q2/Q4, right?
Finally, I'd say you're either going to see generous amounts of crossover distortion or bad thermal stability.
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