Grey,
Hear! Hear!
Speaking as a card carrying member of the lunatic fringe,
There is a small difference between lunacy and insanity......
Jam
P.S. I hope I don't get the battery crowd up in arms.
Hear! Hear!
Speaking as a card carrying member of the lunatic fringe,
There is a small difference between lunacy and insanity......
Jam
P.S. I hope I don't get the battery crowd up in arms.
batteries could be used for the A40 inputstage. Then smaller batteries would suffice. The outputstage should care less about a little ripple.
I have just brought to live my Aleph3.
Some question appeared.
There are great differences between current through IRPs - vary from 0.5 to 0.9A. I tried to change the gate resistors (up to 400ohm) without any effect. Is it necessary to set equal current through each end MOSFET? How?
Some question appeared.
There are great differences between current through IRPs - vary from 0.5 to 0.9A. I tried to change the gate resistors (up to 400ohm) without any effect. Is it necessary to set equal current through each end MOSFET? How?
Koy
It seems to me your MOSFETs are unmatched, you should do so inside a corridor of at least 0.1V.
Jens
It seems to me your MOSFETs are unmatched, you should do so inside a corridor of at least 0.1V.
Jens
Jens: These transistors are unmatched. I never believed it to be necessary for output transistors.
Matched output devices are a good idea for any number of reasons. But amongst other things, it will solve the unequal current draw problem.
Grey
Grey
Re: Matched devices
Do you have any idea which values sould be used? Trimpot will be the best solution I think.
Do you have any idea which values sould be used? Trimpot will be the best solution I think.
Source resistors
Typical construction uses .3 to 1 Ohm. Now the Aleph is not a typical amplifier, but increasing the value reduces gain and increases linearity + load sharing (and also the output impedance.
You should be at .47 now. Suggest you try about .7 or even 1 or so as a starting point (R122 etc). You can also solve this problem by duplicating Q104 if you find a way to separate the output transistors.
A "normal" amp would require changes of source resistors both top and bottom. On the Aleph it is only the bottom that needs changing.
Petter
Typical construction uses .3 to 1 Ohm. Now the Aleph is not a typical amplifier, but increasing the value reduces gain and increases linearity + load sharing (and also the output impedance.
You should be at .47 now. Suggest you try about .7 or even 1 or so as a starting point (R122 etc). You can also solve this problem by duplicating Q104 if you find a way to separate the output transistors.
A "normal" amp would require changes of source resistors both top and bottom. On the Aleph it is only the bottom that needs changing.
Petter
Re: how to choose power fets for audio
Petter:Another question - you suggest to change all this resistors (for example from 0.47 to 0.7 or so) or adjust them ( using different values) to the same current through the IRFPs ( ie to change for example to 0.2, 0.47, 0.47 and 0.33 , 0.7, 0.47 - my case)? What is the point of the Q104? Current source too?
Petter:Another question - you suggest to change all this resistors (for example from 0.47 to 0.7 or so) or adjust them ( using different values) to the same current through the IRFPs ( ie to change for example to 0.2, 0.47, 0.47 and 0.33 , 0.7, 0.47 - my case)? What is the point of the Q104? Current source too?
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