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Simplistic NJFET RIAA
Simplistic NJFET RIAA
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Old 6th December 2017, 08:09 AM   #16891
Salas is offline Salas  Greece
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Simplistic NJFET RIAA
Quote:
Originally Posted by lampes View Post
Very interesting. Have any point to use branded LEDs other than the ones they sell in local shops and more likely are bulk chinese or unkown?
If noise matters in the power supply, how about the quartet D1-D4? Are those more critical to the level of noise?
When not having dedicated noise measurement results there is no way to tell that branded red in general will be quieter than generic.

D1-D4 quartet in the phono circuit are the voltage bias local supply for the common base cascode's top part and its more critical for noise that is why it uses a low noise JFET CCS (Q7) and its also heavily filtered by C8. D1x in the shunt reg can also contribute a little but the whole Vref is heavily filtered again by C1x.
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Old 6th December 2017, 09:02 AM   #16892
lampes is offline lampes  Greece
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Thanks Nick
I 'm going to use 2 pairs of 369s for LOMC (I 'm going to get a Denon DL-301 MKII)
and I have four of them from GB. Two are 10.59 IDSS and two with 10.71 IDSS.
How it's better to install them? one 10.59 paired with a 10.71 to Right channel or both 10.59 to, let say, Right and the 10.71 to Left?
cheers
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Old 6th December 2017, 10:13 AM   #16893
Salas is offline Salas  Greece
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Both same with both same in each channel
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Old 12th December 2017, 09:57 PM   #16894
lampes is offline lampes  Greece
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Thanks Nick
I guess with 369s @10.59 & 10.71mA I will go with a 3.9 R2 & R3
What suggestion you have for loading the 301 MKII? I red about 300-1K is optimal
In any case do we need R1 at 47K and parallel it with a i.e 400-700 ohm resistor or I can go straight with a small dedicated R1 for loading? (I'm not going to use the multiswitch)

Thanks again
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Old 12th December 2017, 10:15 PM   #16895
Salas is offline Salas  Greece
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Yes 3.9 Ohm

You could put 330, 470, 560, 680 on the four way DIP switch and R1 47k at first because it takes time to set a TT for a certain cart to decide in conjunction with the loading. In the end you can remove the DIP or set all positions to OFF and replace R1 with the resistor you listened longer best with. You can also make combinations for intermediate values when having the switch by putting more than one position to ON. Measuring across the input RCA with the DMM (when the phono is powered down and the TT cable is disconnected) you don't need make calculations of what combination load the cart sees.
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Old 21st December 2017, 07:15 PM   #16896
lampes is offline lampes  Greece
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thanks Nick
I wonder if I can keep the board as is without seperating it, Is any problem with it?
Also Can C2x be more that 4.7uF? Is it a gain if I do ,if space allows of course..
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Old 21st December 2017, 09:03 PM   #16897
Salas is offline Salas  Greece
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You can keep them together as long as the two closest sinks are not too hot. Usually they aren't.

No its not a gain because its a part of a tuned Zobel termination for the value it already has.
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Old 22nd December 2017, 08:43 PM   #16898
lampes is offline lampes  Greece
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thanks again Nick
My 117GR are kind of the weak side mostly between 3-4ma so I guess this going with R3x of 9K1 R6x of 22R
I have very few (4-5) of them at 4.5-5mA, I there any need to use those instead of the weak ones and change resistors to 6K2 and 33R respectively?
Do the Q2x Q3x and Q5x have to be close in IDSS?
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Old 22nd December 2017, 11:00 PM   #16899
Salas is offline Salas  Greece
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No need to have the highest Idss samples, you just have to have the right resistors for any available Idss so to reach a usable voltage range.

Q2x Q3x Q5x if having some about close better pair them per position in each channel's reg. They don't need be close Idss across the board.
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Old 1st January 2018, 11:35 PM   #16900
kcdonahue is offline kcdonahue  United States
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Has anyone used a Ortofon Cadenza Black with the FSP yet? I will be helping a friend assemble his soon and was wondering if there was any cartridge loading details I could learn. Cart details below:

Output voltage at 1000 Hz, 5cm/sec. - 0,33 mV
Compliance, dynamic, lateral - 16 Ám/mN
Tracking force range - 2,0-2,5 g (20-25 mN)
Tracking force, recommended - 2,3 g (23 mN)
Internal impedance, DC resistance - 5 Ohm
Recommended load impedance - > 10 Ohm
Cartridge body material - Stainless steel Aluminium

Thanks,

KC
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