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Old 13th March 2010, 12:30 AM   #1021
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Default Joachim

Hi Allen,

Joachim and I have more or less the same illness.
We just don't know when to stop and actually if it wasn't for our partners, we would stay awake the whole day just for audio purposes.

Joachim, don't listen to Allen, listen to me GO TO BED


Tjuus,


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Old 13th March 2010, 06:24 PM   #1022
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I slept well, thank you very much.
I put more thought into the BJT INA.
The current sourced caskode did not work so well with BJT´s so i simplified a bit.
They are now fed by a capacitance multiplier and the feedback goes directly from the collectors.
Circuits like that proved to work in designs by Douglas Self and Burkhard Vogel but they used them unbalanced.
Idle current in my design is adjutable for minimum DC offset and optimisation for an MC with higher impedance like the Denons and Clearaudios.
When i use 4 x 4 input transistors and reduce the feedback resistor to 1 Ohm i could get 0.3nV/qHz in a balanced design.
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Old 14th March 2010, 01:25 AM   #1023
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i promissed some photos.
I have build a lot of stuff where i only posted the schematic.
I changed now from building in the small metall boxes to groudplane construction.
I use a double sided board so in a double mono construction i have 4 groundplanes and i use a metal box under that for a 5th groundplane. I place connections of the groundplanes at strategic positions. I also earth the planes at one point with a 6.8uF cap to wall outlet earth.
I have a cable with two wires from the tonearm and one shield that is connected together at the tonearm side. That way i can try balanced and unbalanced.
Attached Images
File Type: jpg Rosi with 75usec RIAA.jpg (83.3 KB, 348 views)
File Type: jpg Balanced In - Unbalanced Out Buffer.jpg (108.1 KB, 330 views)
File Type: jpg MPP High Z Capacitive RIAA.jpg (105.5 KB, 326 views)
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Old 14th March 2010, 01:28 AM   #1024
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Here is some more
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File Type: jpg Earting Cap.jpg (142.1 KB, 320 views)
File Type: jpg JG Headphone Amp as Preamp.jpg (91.0 KB, 304 views)
File Type: jpg Balanced INA, left Fet, right BJT.jpg (100.9 KB, 182 views)
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Old 14th March 2010, 01:32 AM   #1025
Salas is offline Salas  Greece
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Dead bug P2P = hardcore DIY. I like!
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Old 14th March 2010, 01:35 AM   #1026
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P.S. Batteries...I don't like! Where are dead bug inferno hot Mosfets on wildly oscillating shunts?
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Old 14th March 2010, 01:35 AM   #1027
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It performs great and can easily being changed.
Look at the third picture on the right, last post. Left is the FET INA and right is the BJT INA.
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Old 14th March 2010, 01:38 AM   #1028
Salas is offline Salas  Greece
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Very good. But can you write a service manual?
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Old 14th March 2010, 01:40 AM   #1029
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i started to build the Shunts. The cabinets arived and i bought BHC Slit Foil caps instead of Sikorel. I worked a lot with Dennis Morcroft of DNM. the invertor and always wanted to try them. Mosfet are also on the way and i build most of the small parts.
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File Type: jpg Pre Regulator Box.jpg (80.8 KB, 194 views)
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Old 14th March 2010, 01:41 AM   #1030
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I see 1837s and Polystyrenes here and there. I will try COG-NPO for RIAA filter caps soon. Did you ever try any? Nice tiny for dead bug.
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