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Old 30th October 2012, 07:08 AM   #5521
Salas is offline Salas  Greece
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Quote:
Originally Posted by Kazuo Ozawa View Post
After long journey I reached the goal to serch for Zobel of Reflektor +3.3V.
The story is following.(Of course no oscillation on all cases)...
Cheers for giving the subjective feedback.
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Old 30th October 2012, 07:52 AM   #5522
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Hey you know SAPPORO Beer! I love it.
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Old 30th October 2012, 09:54 AM   #5523
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The Zobel damps the resonance/ringing if a fast transient unsettles the quiescent operation.
The resistor in the Zobel is what "damps" the resonance.
The capacitor is there to prevent the resistor burning out, due to excessive dissipation.

What you should have done was to experiment with changing the resistor value, while monitoring the rail during impulse activation. Once the resistor value is found you can then make the capacitor smaller until it begins to interfere with the damping, then go back up a value or two.

Kaz,
you mucked about with the capacitor until your hearing told you something was changed. Not at all what is required to optimally damp a resonant system.
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Old 30th October 2012, 04:26 PM   #5524
Salas is offline Salas  Greece
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Quote:
Originally Posted by Kazuo Ozawa View Post

4) 0R47+0.44uF(0.22u//0.22u)
Become great deep sound, no more harsh.
I also guess that it is very good for 1R0+0.47u as Salas recommends.

On this experiment I found a few principles about Zobel.
1 Zobel is strongly related to quality of sound.
2 If Zobel is not been optimized, sound become harsh or dim.
3 The optimal value is between the narrower area than I expected.

Next step, I build Reflektor +1.2V. If I get good result, will report.

Best regard
On the simulator your choice looks well damped and extended for OLG. I could not get exact STP model, still with an alike but less for gfs and more for Crss Fairchild the output impedance for DVCC 1R5 R1 is 2.4mOhm flat for double the audio band and it only climbs to 3mOhm lazily at 80kHz. 1R+0.47u shows the same for Zo, bit better phase theoretically, but not sure without exact model, near prediction to yours indeed. Bottom line is, very good technically for no extra error amp stage and no buffer stage, a mirror does all that, very elegant.

1.2V will challenge the threshold...

Quote:
Originally Posted by Kazuo Ozawa View Post
Hey you know SAPPORO Beer! I love it.
Used to drink it where I could see it, pure taste, best can ever, could not squash, Rowland amps look like that beer can.

Sapporo Beer Commercial - Legendary Biru - YouTube
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Old 31st October 2012, 01:14 AM   #5525
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Default Reflektor +1.2V

Quote:
Originally Posted by Salas View Post
1.2V will challenge the threshold...
Yes, there are two big walls of threshold, namely, Vgs and Vbe.
I have already built prototype, and running well with constant resistor load.

PS
SAPPORO BEER and Rowland amps.. woom, very impressed.
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Old 1st November 2012, 01:53 AM   #5526
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Default Reflektor +1.2V

With joy I would like to announce that Reflektor +1.2V has come out.
Two big walls of threshold are overcome. Though I have no confidence to call this circuit pure Reflektor.

Last night I replaced old MOSFET source follower regulator, that is simple no-NFB type, with new Reflektor in my Sabre DAC. The sound has changed dramatically far beyond my expectations. Quoting Michael Elliott's words, "this one left us with dropped jaws". It is my impression.

Zobel is same as Reflerktor +3.3V, I have no need to change.
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Old 1st November 2012, 02:07 AM   #5527
Salas is offline Salas  Greece
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You doubled circuitry the other way around to give it several Vbe threshold. Excellent solution, if it MUST be 1.2V and Reflektor. More circuitry but what the heck, still a Reflektor! Congratulations. MOSFET is not still the logic level STP?
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Old 1st November 2012, 03:07 AM   #5528
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Thanks Salas. I am encouraged.

Shunt MOSFET is Vishay's SI3460DDV which I happened to find via search engine. I think it has good spec regarding to low Cxxx, high gfs and very low Vgs. For TSOP-6 package, need surface mount adapter.
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Old 1st November 2012, 03:14 AM   #5529
Salas is offline Salas  Greece
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For that purpose OK but to generally sink it, plus the dioded 4401s dissipation roof, small current stuff. How hot is it now for how much current you spare through it?
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Old 1st November 2012, 12:41 PM   #5530
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Interesting stuff Kazuo! Thank you for sharing your adapted design! Itís very interesting and helpful to be able to make 5V and below Reflektors. I am going to try the version with STP55NF06L for a 5.25V supply (Buffalo 3 DAC).
Sabre DACS can sound fantastic with the right power supplies. The sound is really as good as power supplies go. With this DAC you (even) get rewarded for every subtle change you make in your power supply.

Peter
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