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Old 7th December 2018, 02:35 PM   #941
alexberg is offline alexberg
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Knowing the headroom you may clip at the input not clipping amplifier itself. Is it production type design? Especially if this does not damage amp.
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Old 8th December 2018, 05:55 PM   #942
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by alexberg View Post
Knowing the headroom you may clip at the input not clipping amplifier itself. Is it production type design? Especially if this does not damage amp.
Cheers
It is the output who does clip, and as a result the feedback does try error correction, so VAS is also distorted.

I have not very much open loop, however I use two cascodes, who does the job well. I do however ask myself of this is a good idea to drive the mosftes gate capacitance because cascodes are high impedance who needs a soruce follower, I have that as extra into the circlotron itselfs as a IRF 610, but means twice the voltage before idle gets up.

also the drive needs higher output, but the bridge do put that in half.

I see that the autobias needs always a sudden idle current, when not the system does not start because reference voltage stays higher.

So I'm look at a way to get it right, it is possible to start with 1 amp idle, everything above the idle I want is oke, so when I do 500 ma amp needs to start with 600ma as a example, or invert things but I do not now if that works.

I have no plans for commercialize this design, I do think about class D design, it is better and better with the new parts. and I have some done.

regards
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Old Yesterday, 02:11 PM   #943
kees52 is offline kees52  Netherlands
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I have a question what proberly already is answered by alex, I get high distortion in the long tail pair or differential input stage, and very low at the output, but this can mean sound will be not that good, I presume there are here amp designers who can tell me if this is maybe because of current feedback, a current source below the input stage can help however current feedback then give for shure errors.

twh pics one the output probe and one the input stage who has jfets and cascoded with a mosfet.

thanks for help.
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Old Yesterday, 02:30 PM   #944
kees52 is offline kees52  Netherlands
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Voltage feedback now but still, low output distortion, but quite high at long tail pair stage.
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