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-   -   MEMDIST POWER AMP + JC + TMC - help to set up (http://www.diyaudio.com/forums/solid-state/181813-memdist-power-amp-jc-tmc-help-set-up.html)

padamiecki 25th January 2011 09:25 AM

MEMDIST POWER AMP + JC + TMC - help to set up
 
1 Attachment(s)
Hi,
I was hot after reading about headamp from peufeu Memory Distortion Philosophies - Part 8 : More tests
and wanted to build higher power version for LS driving.
Please look at the schematic,
I added JC-like coupling within the mirror and VAS
then I wanted use TMC like gnfb correction like Edmond Stuart proposed http://www.diyaudio.com/forums/solid...dback-336.html
and got this.
Please help to adjust the values/other parameters to obtain the amp possible for working,
I believe that the combination of memdist/TMC correction might give something better that "Lavardin" sound.

Additional explain: I hate global nfb :t_ache: and believe that that solution in most cases spoils the sound,
however
with you help
will this be good sounding?:hug:

padamiecki 28th January 2011 10:07 AM

3 Attachment(s)
ok
here are initial settings
and sim results

padamiecki 28th January 2011 10:10 AM

1 Attachment(s)
and here clipping
Seems that bad 2nd and 3rd harmonics are from the mistakes in the design.
Please advice how to set it more symmetric?

padamiecki 28th January 2011 12:56 PM

simplified version
 
3 Attachment(s)
...
again
not too good...
:bawling:

padamiecki 31st January 2011 08:23 AM

it looks like input tripple clips the signal at 4V.
it is linear but clips...
how to improve its headroom?

WuYit 31st January 2011 09:03 AM

Hi,
maybe you should pay a visit to: http://www.diyaudio.com/forums/solid...d-cascode.html
That`s a much better topology despite some flaws.

padamiecki 7th December 2011 12:31 PM

3 Attachment(s)
Hi
after some time I designed something like this.
As input fet I am going to use BF245B but did not have the models.
The design seems to be a bit from the oscillations
please suggest how to make it more stable.

padamiecki 7th December 2011 12:34 PM

1 Attachment(s)
and asc file for ltspice

padamiecki 10th January 2014 09:38 AM

rewarming memdist power
 
5 Attachment(s)
Hi
after some play with LTSpice I found that this time it is working.
Close to full power has very low thd and nice descending harmonics distribution @~110mA idle.
The circuit has the potential, maybe I will build it someday:rolleyes: = needs 2SK170 or other 50V DC device instead of BF245B which is only up to 30V (only for simulations).
TMC nice lowered the thd.
asc file attached for play & fun:wave:


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