Simplistic NJFET RIAA - Page 735 - diyAudio
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Old 1st March 2012, 03:13 PM   #7341
vgeorge is offline vgeorge  Greece
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I mean percentage deviation from nominal value(+-%), not resolution. Look at his manual or specifications.
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Old 1st March 2012, 04:00 PM   #7342
Salas is offline Salas  Greece
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Quote:
Originally Posted by DARIO1997 View Post
Hi Salas,

i have built your phono stage to fet. For the riaa i have used:
Resistor metal film 1% 47K,
Resistor metal film 1% 6.8K,
N2 Cap 47n + 1.5n to 5% (i measured 46500),
N3 Cap 15n + 330p + 100p (i measured 15300).
This value are correctly for accurate riaa?

Many thanks
If those values are close to real, they are fine. Waiting for pictures of finalized build.
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Old 2nd March 2012, 07:46 AM   #7343
atupi is offline atupi  Romania
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Why my shunt output voltage is not steady and it going up in the first few minutes after start ? Is that normal ?

Last edited by atupi; 2nd March 2012 at 07:53 AM.
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Old 2nd March 2012, 08:41 AM   #7344
Salas is offline Salas  Greece
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Yes, its the Tc of its K170. A bit more than others because GR. Set it for after say half an hour.
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Old 2nd March 2012, 06:03 PM   #7345
Marinos is offline Marinos  Greece
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Since I didn't catch up the latest BIB GB I'm proceeding with Shunt 1.0.5 from pdf P2P.
Here is my PRELIMIARY layout... (Don't use it without care !!!)
Board will be mounted vertically with Q1&4 bolted to case bottom.
The only thing that bothers me is that C4 is too close to Q4 (heat..) or it shouldn't.
Comments please
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Old 2nd March 2012, 06:28 PM   #7346
Salas is offline Salas  Greece
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Use 105 C part, mount it underneath board if you got space to stick out the other way, or mount the MOSFETS parallel like in power amps or many DCB1.
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Old 3rd March 2012, 01:30 AM   #7347
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Hi
could I use smaller coupling cap for C7 (V1102F0), it is looking into R8=1M parallel to 47k on the input of my line preamp (grid to ground). I think 0.47uF will give me around 7.5 Hz corner freq. which should be low enough.
Cheers
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Old 3rd March 2012, 01:48 AM   #7348
Salas is offline Salas  Greece
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Give it 1uF because C3 does some pre roll off between stages, and 0.47u cuts too early in that situation.
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Old 3rd March 2012, 01:49 AM   #7349
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OK, thank you.
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Old 3rd March 2012, 01:51 AM   #7350
Salas is offline Salas  Greece
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If you make any, don't forget to show it and discuss it here. See ya.
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