In what case can we go for open loop, and when should we use feedback? - Page 3 - diyAudio
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Old 19th October 2004, 05:51 PM   #21
Bricolo is offline Bricolo  France
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Do someone have an example schematic for an open loop gain cell?
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Old 19th October 2004, 06:07 PM   #22
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Quote:
Do someone have an example schematic for an open loop gain cell?
i would expect there are some in the pearl, BZLS, SOZ and other articles at passdiy.
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Old 19th October 2004, 06:32 PM   #23
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Or simply a BOZ? (I don't need balanced in and out)
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Old 19th October 2004, 07:28 PM   #24
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Default Re: In what case can we go for open loop, and when should we use feedback?

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Originally posted by Bricolo
In what case can we go for open loop.............
In linear audio amps? NEVER!
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Old 19th October 2004, 07:32 PM   #25
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nonlinear gainstage
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File Type: gif jfet gain.gif (6.8 KB, 113 views)
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Old 19th October 2004, 09:01 PM   #26
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Quote:
Originally posted by till
nonlinear gainstage

I just simulated the "input stage" with 1 fet
why is it so unlinear?
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Old 19th October 2004, 09:19 PM   #27
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i simulated it as drawn, and it looks pretty linear.

the title was aimed on the ot posting above.
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Old 19th October 2004, 09:45 PM   #28
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Quote:
Originally posted by till
i simulated it as drawn, and it looks pretty linear.

the title was aimed on the ot posting above.


That's odd.
I use simetrix too, and simulated your schematic (the whole schematic)

Placing a probe on the output, a transient analysis gives 0.04% distortion
same analysis, but the probe at the output of the fets: 5% distortion!
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Old 19th October 2004, 09:55 PM   #29
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i have some miracolouse effects with the simetrix spice THD analizer also. I think we need to build some and measure THD with spectralab or so.

for small input signals ans much gain:
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Old 19th October 2004, 09:58 PM   #30
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can 10V RMS be considered as small signal?
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