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Old 13th September 2012, 03:39 AM   #5321
Salas is offline Salas  Greece
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Have you got a reliable LTspice model for that Renesas to post?
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Old 13th September 2012, 05:00 AM   #5322
Salas is offline Salas  Greece
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*With that low voltage squeeze, semis Cxxx go up. From 10V Vds to 3.3V Vds the MOSFET triples its Crss for instance, and its a high capacitance one to start with. Try 2.2 Ohm + 3.3uF Zobel. Use a lower capacitance low noise JFET of enough mS like 2SK117 (what is 177?). Priority is about the Zobel.
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Old 14th September 2012, 06:38 AM   #5323
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Quote:
Originally Posted by Salas View Post
*With that low voltage squeeze, semis Cxxx go up. From 10V Vds to 3.3V Vds the MOSFET triples its Crss for instance, and its a high capacitance one to start with. Try 2.2 Ohm + 3.3uF Zobel. Use a lower capacitance low noise JFET of enough mS like 2SK117 (what is 177?). Priority is about the Zobel.
Thanks Salas.
I will try and report later.
Oh, mistyped again, 2SK117 is correct on the schematic.
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Old 14th September 2012, 09:36 AM   #5324
AndrewT is online now AndrewT  Scotland
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post5320.
That extra 0u1F across the CCS.
Does that help or hinder the CCS operation?
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Old 15th September 2012, 12:31 AM   #5325
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post5320.
That extra 0u1F across the CCS.
Does that help or hinder the CCS operation?
In my experiment it helps not to oscillate regulator. I guess that this phenomenon relates some inductance and capacitance between PSU and regulator.

Kon
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Old 17th September 2012, 11:29 AM   #5326
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#5322
I made prototype Reflektor suggested by Salas.
Zobel value is changed from 0.1ohm+20uF to 2.2ohm+(2.2uF+0.47uF+0.47uF).

I use four Reflektors, so I replaced one of them that is connecting SI5317(Jitter Cleaner).
I am not good to explain impression of sound in English, but I say that it becomes more musical than before
Thanks again Salas. Your contribution is great.

Next step I will change three other Reflektors.
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Old 23rd September 2012, 06:59 AM   #5327
Salas is offline Salas  Greece
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Kazuo-san, did you you replace all others by now? A photo of the total project would be nice. Also do you know a store in Japan that we can look for NOS Toshiba, Hitachi, Sanyo semis, Tantalum and YAM resistors, sending few and accepting Paypal?
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Old 26th September 2012, 01:32 AM   #5328
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Originally Posted by Salas View Post
Kazuo-san, did you you replace all others by now? A photo of the total project would be nice. Also do you know a store in Japan that we can look for NOS Toshiba, Hitachi, Sanyo semis, Tantalum and YAM resistors, sending few and accepting Paypal?
I replaced all Reflektors and I got the used oscilloscope Tektronix TDS350 (200MHz, 2ch). I have been evaluating on these few weeks.

Sound becomes changed drastically. Bass and mid are clear, smooth, deep.
But I find one serius problrem. Treble is harsh. Although I changed Zobel C (2.3uF, 3.8uF), no effect. I guess that the cause may be big Cxxx of 2SK2586 in low Vds area as Salas mentioned.
Of course, I have observed that it does not oscillate.

From these result I am convinced that we are going in the right direction, but I must explore other low Cxxx MOS FET. Now I am purchasing some MOS FET from DigiKey.


Salas, I didn't noticed in your PM, sorry to be late.
I am glad you are interested in the items. But I use these in my junk box.

YAM was discontinued long years ago. You can get these in stock from Michael Percy Audio.
2SK2586 can be bought at Chip One Stop www.chp1stop.com
As for the other item, I have no information, unfortunately.
I believe you can find better items than that I use.

Best regard.
Ozawa
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Old 26th September 2012, 02:25 AM   #5329
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Low Vgs Mosfets like the 2SK2586 Renesas you used to go under 5V reg normally have very high transconductance but high capacitance always comes with it. Congrats on getting a good scope, it will prove very valuable. The fact that you saw its stable plus it sounds good on all regions except HF points to suspecting the Mosfet's capacitance, yes.
See another low Vgs Mosfet example (they call them TTL level some times). This is STP55NF06L from ST Micro. Yours is 2V Vgs(th), this one is 1.7V. Looks better for capacitance. Pay special attention to Crss for this application when choosing candidates to test. Maybe you will find more ideal. Thanks for replying about the NOS Japan parts.
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Old 26th September 2012, 03:42 AM   #5330
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Quote:
Originally Posted by Salas View Post
Low Vgs Mosfets like the 2SK2586 Renesas you used to go under 5V reg normally have very high transconductance but high capacitance always comes with it. Congrats on getting a good scope, it will prove very valuable. The fact that you saw its stable plus it sounds good on all regions except HF points to suspecting the Mosfet's capacitance, yes.
See another low Vgs Mosfet example (they call them TTL level some times). This is STP55NF06L from ST Micro. Yours is 2V Vgs(th), this one is 1.7V. Looks better for capacitance. Pay special attention to Crss for this application when choosing candidates to test. Maybe you will find more ideal. Thanks for replying about the NOS Japan parts.
Thanks Salas for good advices.
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