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Old 16th April 2012, 01:32 PM   #961
generg is offline generg  Germany
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@juanitox

you really mean such a high source resistor of 2k5 -3k? It seems to high to me, or do you mean 2R5 and 3W? I must order such a big cap...

@Zen Mod what a fate......... ! Next life....?

@vdi_nenna it was a pleasure.....!
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Old 16th April 2012, 03:19 PM   #962
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oups sorry , yes between 2.5 3ohm for sure , 15 watt to be between -5 / -4V between gate and source .. Epcos sikorel or Rifa ph200 works well here .. with your 10uf mkp.. for the source res i have put 2x 5ohm 12watts mills
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Old 16th April 2012, 07:25 PM   #963
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Quote:
Originally Posted by juanitox View Post
oups sorry , yes between 2.5 3ohm for sure , 15 watt to be between -5 / -4V between gate and source .. Epcos sikorel or Rifa ph200 works well here .. with your 10uf mkp.. for the source res i have put 2x 5ohm 12watts mills
Juanitox one more question, when I take these source resistor and loose 4-5V for the negative bias, did you keep the 24V supply voltage Mike suggested or did you go for 29V to compensate the loss.......
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Old 16th April 2012, 07:44 PM   #964
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Quote:
Originally Posted by generg View Post
........

@Zen Mod what a fate......... ! Next life....?....
naah

I'm not complaining .....but opposite ....... I'm happy that finished "product" is less important than next prototype

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Old 16th April 2012, 07:59 PM   #965
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yes i keep my 24V power supply so it turns with a 19V at 1.6 amp between drain and source , the 2SK82 run cooler like that but same power as the Res loading version..
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Old 16th April 2012, 09:52 PM   #966
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O.K. I understand, mon ami!

Les condensateurs sont ordonné.........

Encore un autre plaisir...... Je ne peux pas arrêter.....
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Old 17th April 2012, 06:20 AM   #967
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what a chance mon ami! i have finished moding my SIt amp , preamp and source ... what a boring life to have a system working fine ; hoping everyday something burn
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Old 17th April 2012, 09:19 AM   #968
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what a pity that we (sorry) are so stupid....

and have always to wait for Nelson, Mike and Aleksandar....

the three saints (for me).....

besides that I seem to have an build in mechanism the journey goes on, despite the praising words I am writing after finishing one project....
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Old 19th April 2012, 10:23 PM   #969
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Still waiting for the Rifa caps to try juanitox solution

I made some small experiments.....

I tried to get rid of my battery biasing by implementing a 4 Ohm thick film resistor in the negative rail, with the goal to adjust the current through Mikes Semisouth solution to 1,5A. I got by the resisor about 6V available biasing voltage. I took parallel to the resistor the 10k pot and two 15000uF caps Panasonic.

Because I was a bit afraid that it could take a too long time to fill the 30ooouF and to have meanwhile a Poof of the SIT I implemented first time the additional 10k and 220uF in the Semisouth positive biasing branch, I added to my last MU-follower idea I posted some time ago here.

And it works, the current comes a bit later to the full value than the biasing voltage!

Is it correct to see these 4 Ohm resistor in the negative rail as a kind of source resistor but bridged with a cap?
And is it correct that when you need for a 1 Ohm Resistor about 50.000-100000uF I need for 4 ohm only between 15.000 and 30.000uF?
The Semisouth solution B Mike suggested was a bit better in the highs and details and the depletion mode IXYS solution sounded a bit darker, maybe mor bass, less detailed to my ears.

I had more difficulties to dial in to 19V and 1,6A with the self biasing solution D than with the Semisouth solution B.
Because I used my First Watt PSU with two 2,2 Ohm Vishay thickfilm resistor in series I got
the voltage down to about 41V. So 19V at the output node is near to the half of the supply voltage.

And because all went fine I will again start to get a better impression of my MU-follower adjusting.
Once you have the Semisouth solution B from Mike it is very easy to make the small changes to get the MuFollower.
In my last experiments the mufollower sounded a bit to aggressive compared to the pure CCS..... But maybe I was not tricky enough the first time to get the Zen Pot working in the right way.
I will report and of course also report my experience with juanitox modded inductor solution.
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Old 20th April 2012, 09:13 AM   #970
protos is offline protos  Greece
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A simple schematic would help to see what you did.
So you have a proper positive and negative rail on your ps? Or is the negative the bias supply rail ? Is it rated for the power you want?
Is the gate referenced to ground or to the negative rail?
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