Originally Posted by zoky2 View Post
apexaudio,
I replaced 6k8 resistor with 12k and still no change . Something other must be wrong
Regards
zoky2
XRKaudio wrote:
Did you ever resolve the lack of bias issue?
Yes, I was resolve bias issue,but I can t remember how exactly I do this.
It was something with 100k trimers T1 and T3 and some voltage across them.
Sorry ,I can t remember anything else.
Regards
zoky2
yes i tried these changes.
FFT looks a bit weird but this is a FFT-setup problem i think.
I added cap multiplier ( power supply )
and want to see hat happens and what is the difference
and use a cap multiplier instead of diode + 10Ohm
i will understand the functionality of current feedback amplifiers ...
FFT looks a bit weird but this is a FFT-setup problem i think.
I added cap multiplier ( power supply )
and want to see hat happens and what is the difference
and use a cap multiplier instead of diode + 10Ohm
i will understand the functionality of current feedback amplifiers ...
Perhaps you should try the Thiago layout with all corrections and built in cap Mx?
Schematic:
Gerbers:
https://www.diyaudio.com/forums/attachments/solid-state/621480d1497647661-cfh7-amp-cfh9cx-zip
Schematic:
Gerbers:
https://www.diyaudio.com/forums/attachments/solid-state/621480d1497647661-cfh7-amp-cfh9cx-zip
Last edited:
Hi Saddevil,
I took your LTSpice file and modified the FFT analysis part to use V(out) label. Changed the gate snubbers from 22 ohm to 220ohm. Otherwise the schematic is the same.
It runs fine and a nice performance: at 72Wrms (68Vpp) into 8ohms has
predicted 0.00123% THD and nice harmonic profile. Dominant third order and
descending higher orders. This will only be true if parts are matched but in reality, MOSFETs and other parts are not matched above and below so THD will be a bit higher and distortion profile may end up being dominant 2nd order (a good thing).
Here is predicted FFT:
Revised .ASC file attached.
I took your LTSpice file and modified the FFT analysis part to use V(out) label. Changed the gate snubbers from 22 ohm to 220ohm. Otherwise the schematic is the same.
It runs fine and a nice performance: at 72Wrms (68Vpp) into 8ohms has
predicted 0.00123% THD and nice harmonic profile. Dominant third order and
descending higher orders. This will only be true if parts are matched but in reality, MOSFETs and other parts are not matched above and below so THD will be a bit higher and distortion profile may end up being dominant 2nd order (a good thing).
Here is predicted FFT:
Revised .ASC file attached.
Attachments
Last edited:
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