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Simplistic NJFET RIAA
Simplistic NJFET RIAA
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Old 20th September 2012, 10:08 PM   #8041
Joachim Gerhard is offline Joachim Gerhard  Germany
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You will find other gems in this volume. Buy it although it is expensive. This guy reduces the problems to the max although i do not particular like his slide presentation style.
This seems to be the slides he projects in his lectures.
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Old 20th September 2012, 10:10 PM   #8042
Joachim Gerhard is offline Joachim Gerhard  Germany
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Yes, reducing the gain to x1 gives a follower !
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Old 20th September 2012, 10:11 PM   #8043
Joachim Gerhard is offline Joachim Gerhard  Germany
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If the ( voltage ) gain is exactly x1 we have a distortion less follower.
Yes, the old one made it super simple. We are too clever to understand nature.
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Old 20th September 2012, 10:13 PM   #8044
Salas is offline Salas  Greece
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Simplistic NJFET RIAA
There is still gmRDS that keeps perfection at bay.
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Old 20th September 2012, 10:44 PM   #8045
Joachim Gerhard is offline Joachim Gerhard  Germany
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If we take psycho acoustics into account your direct couple B1 is damned good and i trust that simpler is better provided that distortion is under the audible threshold. We try to make a better one in another thread that will be opened but it is not that simple any more.
Making the current gain amplifying device into fooling to not see any variable is the goal.
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Old 29th September 2012, 04:53 PM   #8046
RCruz is offline RCruz  Switzerland
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Simplistic NJFET RIAA
Hi Salas

I am now preparing myself to build the V12R shunts for the cascoded simplistic.
As I will need 35V, and using 56kr for R11 (The voltage setting resistor in the V12R) I will need to set the k170 uder it to produce around 0.34mA.

But I have been looking at the 2SK170 datasheet and it seems that working at such a lo current the jfet might produce audible noise.

Reducing R11 to 30k the current goes up to 1.15mA and that improves the noise fugure but I know that reducing R11 also produces more Zo at very low frequencies...

I would really apreciate your comments regarding my assumptions.
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Old 29th September 2012, 07:59 PM   #8047
RCruz is offline RCruz  Switzerland
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Simplistic NJFET RIAA
PS:
My most recent Simplistic build.... a real contender.... Bass is now up to the bjt specimen I have been playing with, but stage size, mids and trebble are incomparable.

I am getting experienced.
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Old 29th September 2012, 09:57 PM   #8048
Salas is offline Salas  Greece
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Quote:
Originally Posted by RCruz View Post
Hi Salas

I would really apreciate your comments regarding my assumptions.
Look to the right hand diagram, Rg (trimmer) is on your side. You can use 27K Vref there even. Increasing the ref filtering cap is the main weapon against 1/f noise in general but with the quality components I see in your pic above it can be costly. Luckily rumble filtering response shape suppresses subsonic 1/f also.

P.S. Which gain setting is the one in the pic and what you cooked better components wise?
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Old 29th September 2012, 10:51 PM   #8049
Bksabath is offline Bksabath  United Kingdom
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Quote:
Originally Posted by RCruz View Post
PS:
My most recent Simplistic build.... a real contender.... Bass is now up to the bjt specimen I have been playing with, but stage size, mids and trebble are incomparable.

I am getting experienced.
That looks realy good altrought expensive must be 300 in Caps ?

Parts boom and sonic signature of components would be realy apreciated.

Me was thinking about choosing 3 or 4 records and cooment on those ...
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Old 30th September 2012, 09:37 AM   #8050
RCruz is offline RCruz  Switzerland
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Initialy I just swaped the output caps. I had 4u7 obbligatos and now I have those uge Clarity. I imediately noticed a uge increase in high freq definition, stage size and extension.

Then I swaped the Mundorf MKP in the output zobel of the V12R by the obbligatos and everything became more refined. Finally I bypassed those obbligatos in the zobel with 15p SM and bingo.... Super sweet with just a little bit of high freq sparkle.

As a bonus, bass became more detailed letting us hear lower freq info that was buried before.

Total cost of the upgrade was around 100euros (the cost of the clarity caps)

I will listen to some records and let you know my subjective opinion bksabath.

This build has 48dB at 28V. It was already so good I believed it could stand this cap upgrade. Now it is really incredible.
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Last edited by RCruz; 30th September 2012 at 09:40 AM.
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