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L'Amp: A simple SIT Amp
L'Amp: A simple SIT Amp
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Old 9th July 2018, 08:31 PM   #2941
sontero is offline sontero  Italy
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Quote:
Originally Posted by Michael Rothacher View Post
I wouldn't recommend the MoFo circuit for a SIT. Some other follower, perhaps. But If I had some 2SK180's lying around, I use them in a CS amp.
Ok not mofo scheme for sk180
which means "CS amp" Mr.Rothacher
I hate abbreviations.....

Ps: maybe I understood
does it mean common source?

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Old 9th July 2018, 09:23 PM   #2942
Michael Rothacher is offline Michael Rothacher  United States
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L'Amp: A simple SIT Amp
Common Source. Output taken from the Drain, has gain e.g. L'Amp.
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Old 17th August 2018, 06:02 PM   #2943
plasnu is offline plasnu  United States
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Originally Posted by Michael Rothacher View Post
I wouldn't recommend the MoFo circuit for a SIT. Some other follower, perhaps. But If I had some 2SK180's lying around, I use them in a CS amp.
Hi MR,

Why would you not recommend MoFo SIT? I wonder if any technical reasons.

The prototype schematic of FW SIT-3 was CCS loaded common drain SIT, but NP has later replaced it with DEFiSIT.

I have tried choke loaded Sony VFT L'amp with both common source and common drain (MoFo like?), and I noticed the difference in sound signature between them, probably not only due to the obvious difference in damping factor.
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Old 17th August 2018, 06:45 PM   #2944
Michael Rothacher is offline Michael Rothacher  United States
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L'Amp: A simple SIT Amp
MoFo benefits greatly from the high Drain resistance of the MOSFET in terms of output impedance and noise.

The Sony SITs don't offer much in the transconductance department and you wind up needing some gain in the front just to get unity. That's not to say NP might not have other ideas. I'm sure he does.
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Old 17th August 2018, 07:37 PM   #2945
Soundhappy is offline Soundhappy  France
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One more question to Mr Rothacher please
Ok Sony Vfet's have too little gain but is doable MoFo Sit with higher transductance Tokin's
like 2SK180 or THF-51 and big 2.5A ~ 3.5A rated choke ? Kind regards
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Old 17th August 2018, 08:00 PM   #2946
Michael Rothacher is offline Michael Rothacher  United States
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Not so much with the inductor load, IMO.

Try NP's original SIT-3 if you want a SIT follower.
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Old 17th August 2018, 08:15 PM   #2947
Soundhappy is offline Soundhappy  France
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Noted Thanks Michael
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Old 17th August 2018, 09:26 PM   #2948
plasnu is offline plasnu  United States
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Quote:
Originally Posted by Michael Rothacher View Post
MoFo benefits greatly from the high Drain resistance of the MOSFET in terms of output impedance and noise.

The Sony SITs don't offer much in the transconductance department and you wind up needing some gain in the front just to get unity. That's not to say NP might not have other ideas. I'm sure he does.
I see.

Do you think if any advantage to use SIT instead of MOSFET for follower amp?
Someone told me that the curves of MOSFET in MoFo are "already more ‘triodey’ than a triode.”.
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Old 20th August 2018, 08:22 PM   #2949
Rodeodave is offline Rodeodave  Austria
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L'Amp: A simple SIT Amp
I'm currently gathering parts for a L'Amp build. I'm going for the twin bulb version with a regulated adjustable supply based on the Zen v3 (cap multiplier). I'd like to generate the negative bias from the main transformer, like the schematic that popped up in post #1953 L'Amp: A simple SIT Amp Is there any further information on where that circuit originated from, and more importantly, if it actually works?
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Old 20th August 2018, 08:29 PM   #2950
Michael Rothacher is offline Michael Rothacher  United States
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L'Amp: A simple SIT Amp
NP posted that.
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