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Old 1st September 2011, 07:29 PM   #2611
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Quote:
Originally Posted by Joachim Gerhard View Post
Your squarewave looks good though.
Sorry if I did not pick up this before I am at my Day Job at present.

Tankyou for that it is realy apreciated you are a real gentelman.
All I have is my ears and very litle experience with electronics-

That picture was posted somwhere else and enough to be loughed at and me been slapped around like litle Kid.

IMO Pilgrim Kit is definetley good, and I will give it a go,
still I like to learn things and make stuff the hard way so please carry on with all your hard work.

I think I speak for many here that are folowing what you are doing behind the curtains.
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Old 1st September 2011, 07:33 PM   #2612
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Put information into this world. Siegfried Linkwitz
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Old 1st September 2011, 08:01 PM   #2613
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Joachim Gerhard View Post
It is very simple. One Fet is configured as a grounded gate circuit. That is comparable to a common base stage with a BJT. Fets are self biasing so this simplifies the circuit a lot. biasing a BJT or a conventional MOS is always trouble. The other Fets provides a constant current source. If the Fets are matched in IDss then the potential at the input is zero so no current flows into the cartridge. In fact i measured 30uV but this is low enough. Better matching then i did can improve on that but i found in praxis that even 0.1mV has no effect on the sound i can tell and does not destroy the cartridge at least when it is a Titan i like mine. Most of the current that flows in the Fets also flows in the Battery with the exception of the small current that flows into the 500kOhm resistors. This is a classical case of Kirchhoffs law. The input impedance of that circuit is low because the signal goes into the source of the Fet. It more or less short circuits the cartridge so the movement of the stone in the groove results in a current into the Fet. This current modulates the Gm of the Fet and results in a current over the 470 Ohm resistor that ultimately transfers that current into a voltage. PUHHH
Thank you so much... after all it is not that complicated
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Old 2nd September 2011, 12:39 PM   #2614
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Ricardo, today i will build the other channel of the PEN and try it in my system.
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Old 2nd September 2011, 12:42 PM   #2615
hesener is offline hesener  Germany
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Hi Bksabath, just to let you know that I am a happy user of the Pilgham kit FPS, works beautifully! Here the three little issues I had:
- No bottom labels means it is easy to put in the OPA1632 the wrong way ;-((
- the footprint of the BF246 in the input current sources had D and S reversed
- the jumpers on the input signals (that are used to make the difference between Hi-Z and Low-Z) are quite close to the pins of the input JFETs so it is easy to accidentally short circuit there

Other than that it worked like a breeze. And it sounds fantastic!

just my two cents...
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Old 2nd September 2011, 12:47 PM   #2616
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Thanks Hesener for trouble shooting. I will put this information to Ward Maas. I will talk to Ward if he will solder in the OPA1632 before he delivers the boards. I am very happy that you like the sound.
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Old 3rd September 2011, 12:37 AM   #2617
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Tanks Hesener

I am waiting for Pumpkin and PSM bits and pieces.

I am using a very old Akay SS1 as pre at the moment and IMO I beter waith for Pumpkin before I do same critical listening.

Super Caps will be here in 4 to 5 weeks and was thinking how easy could be for one of those to kill someone...
And old drawings of my MC Phono and LAC charger are in a old/Broken hard drive

So I will have to strip down the lot and redraw and maybe make it beter (I am lerning a lot latley)
So busy busy

It will be a while till I get the Pilgam Kit but preaty shure it will be done.

In the mean time tanks realy realy apreciated
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Old 3rd September 2011, 11:25 AM   #2618
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I hope you find the circuit diagram and can improve it.

Some time ago i published the JLH MC Pre-Pre. It was part of an article about symmetry in Audio in the early 90th i think. This schematic is one of the most simple symmetric schemas one can imagine short of the symmetric version of the PEN or the Hiraga. 20 years later i found a circuit by Samuel Groner that could be the son of those circuits and shows where we stand today. It is basically a symmetric differential input stage plus a second amplification stage and a buffer. It has a positive and negative input and an output so it is a discrete Operational Amplifier.
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Old 3rd September 2011, 11:29 AM   #2619
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Here is the circuit....
Attached Files
File Type: pdf SG pre-pre.pdf (45.8 KB, 156 views)
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Old 3rd September 2011, 02:59 PM   #2620
MiiB is offline MiiB  Denmark
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that one could easily be transformed to a small HiQ poweramp...with laterals as output devices...
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