Best low noise regulator?

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ikoflexer said:
jwb, in these tests, were you using the exact circuit from post 214? It is important if we compare, to compare apples with apples.

OK, here's the exact circuit I'm testing.
 

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ikoflexer said:
I can confirm that pulling out J1 is detrimental; I left R5 in because I never got the time to experiment with it, but pulling it out probably will not affect much. However, I cannot say I've tried it.

It just helps a wee bit, especially with grounding. You can pull R5 off without any penalty.
 
But if you were really worried about that you could put a resistor and a capacitor on the emitter of the NPN and raise the Vds across the FET. Then you would not need to worry about the pinch-off voltage.

Actually I think that's a good idea, because then you have a way to trim the output voltage. 200R in parallel with 3800u would give you about 3V across the FET without sacrificing low-frequency performance.
 
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jwb said:
But if you were really worried about that you could put a resistor and a capacitor on the emitter of the NPN and raise the Vds across the FET. Then you would not need to worry about the pinch-off voltage.

Actually I think that's a good idea, because then you have a way to trim the output voltage. 200R in parallel with 3800u would give you about 3V across the FET without sacrificing low-frequency performance.

The way it was I was naturally worried about pinch off. It got it designed under a minimal component idea and to recycle spare 2SKs remaining from the RIAA circuit matching process. This is a nice idea to lift the emitter. 2 more passive components, no big deal. How is the transient performance with the large cap and resistor lifting the emitter? How much ESR did you simulate for it?
 
I just measured the output impedance with a sine wave load of 9mA RMS on top of a DC load of 65mA. Output impedance was below 10mOhms from 20 to 40k. Anything lower is below my ability to measure.

Didn't simulate it, and when I built it I used an ordinary NHG capacitor (standard ESR).

If you're just rolling in K170s, mail them to me :) I only have 13 left.
 

iko

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jwb, this latest moddification degrades regulation both in simulation and in the real circuit. Perhaps someone can confirm either case. I have applied the modification you suggested to the circuit salas presented earlier, and not to your 12V circuit (I don't have those parts on hand); at the moment my interest is in a higher regulated voltage (24-25V).
 
ikoflexer said:
jwb, this latest moddification degrades regulation both in simulation and in the real circuit. Perhaps someone can confirm either case. I have applied the modification you suggested to the circuit salas presented earlier, and not to your 12V circuit (I don't have those parts on hand); at the moment my interest is in a higher regulated voltage (24-25V).

Define "regulation"? Output transient response or something?
 
Here's the simulator output for ripple rejection. The grounded emitter (original) on the top, the AC emitter lift (current) on the bottom. I agree that the simulator makes it look worse, but on the bench it measures better.
 

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iko

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jwb said:
Here's the simulator output for ripple rejection. The grounded emitter (original) on the top, the AC emitter lift (current) on the bottom. I agree that the simulator makes it look worse, but on the bench it measures better.

Any chance of showing the ripple rejection output with R3 (from post 241) replaced by a 2sk170 ccs?
 
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