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Old 6th June 2007, 05:48 AM   #11
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Hi Twitchie,

I look forward to your completion and impressions. I'm sure I won't get to it for quite some time. Amongst the majority of the company on DIYA I'm a hopeless newb but I think you may want to make room on the board for 10uf film caps. I'm thinking that with so few parts - selection may be more important.

Please free to tell me I'm wrong and I'll happily crawl back into my hole
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Old 6th June 2007, 07:34 AM   #12
Manu is offline Manu  Europe
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The 170' are BL I suppose?
Manu
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Old 6th June 2007, 07:50 AM   #13
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by Babowana




You just got a great gift from Papa. Congratulations!
I already got Babo Zen that was much bigger than a small gift.
I wonder what Choky would get . . . ^^.


Papa already promised to me one X1000 case ,complete with hsinks
( that dreky box will be probably good enough for my next phono preamp), randomly throttle filled with small/medium/big jfet/mosfet goodies ;

he sez-because weight is slightly under 100 killos ,he will pay for shipping.......there is no need that I worry about trivia like this ........



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Old 6th June 2007, 09:01 AM   #14
Vix is offline Vix  Yugoslavia
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Default Re: Pass 2SK170 BOZ

Quote:
Originally posted by lineup

shouldnt those resistor values be adjusted a little bit?
I mean the Drain resistor, 2k2 and Source resistor, 10 Ohm.

If am not mistaken, it should be possible to increase the source resistor to get a lower gain. But I am not sure how this would affect the operating area of the Jfet.

Second, is it possible to operate this one from a higher supply voltage (60 v)? I see that 2sk170 max. voltage is 40v...

What if we increase the supply voltage to 60v, Drain and load resistors to 3,9 K and the source resistor to 33 ohms?
I know these are basic questions, but....


Quote:
Originally posted by Babowana




You just got a great gift from Papa. Congratulations!
I already got Babo Zen that was much bigger than a small gift.
I wonder what Choky would get . . . ^^.


Diamonds are small.



Vix
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Old 6th June 2007, 09:13 AM   #15
cviller is offline cviller  Denmark
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Quote:
Originally posted by Nelson Pass
Maybe you would like to try this first.


How did you know I needed that exact circuit for my lunch-box project???

That saves me a lot of time! Thanks!
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Old 6th June 2007, 09:35 AM   #16
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Quote:
Originally posted by Zen Mod


Papa already promised to me one X1000 case ,complete with hsinks


Very good Choky . . . ^^~


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Old 6th June 2007, 09:39 AM   #17
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Default Re: Re: Pass 2SK170 BOZ

Quote:
Originally posted by Vix


Diamonds are small.


Yea . . . thanks for reminding me of it ^^

Oh, I forgot that Blues also got a special F4 front end from Papa ^^


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Old 6th June 2007, 09:40 AM   #18
lineup is offline lineup  Sweden
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Default Re: my first layout

Quote:
Originally posted by twitchie

I know this one is simple enough that most people will try it P2P, but I figured this would be a good lesson in Eagle for me.

Anyway, I'm going to etch this and try it out with a regulated (LM317T) psu ... wish me luck, and any recommendations or comments are welcome.

Thanks to NP (Papa) for this

It's not labelled, but input is at the top (L&R) and output is at bottom. Large middle hole is +35V and large bottom hole is GND.

Here is a PNG image of your PCB suggestion.
I wonder if not The Master had intended source resistor = 100 Ohm
... what I can estimate, using my head only,
this would render a Lineamp with a Gain of like x5 - x7.

10 Ohm here, seems too little,
when the total Drain Lood impedance is like 1000 Ohm.

Gain is set by: 1000/(source resistor) x k
....where k maybe is something like 0.5-0.8

Let's see what comments Nelson himself has to give
( next time he can spare some time for www.diyAudio.com )
before we start decide for our Final Version.
Anyway, one resistor or two are easy to exchange ..
and for these circuits, will hardly be much smoke


Regards
lineup
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Old 6th June 2007, 10:26 AM   #19
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Default Re: Re: Pass 2SK170 BOZ

Quote:
Originally posted by mpmarino




Should we have a groupbuy on the perfboard ?

LOL
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Old 6th June 2007, 10:56 AM   #20
lineup is offline lineup  Sweden
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Quote:
Originally posted by Manu

The 170' are BL I suppose?
Manu

Manu
I dont know if I have 2SK170BL spice model, but I think ....

I know I have 2SK170GR spice models. They are the ones easy-to-find.
And this is the variant of 2SK170 I can easily buy in my country.

This evening I will set up Nelson's circuit in my Electronics WorkBench, EWB MultiSim.
I will post in this thread my findings:
- regarding my optimal values of drain & source resistors.
In Nelson's schematic those are:
- 2k2 coming from power supply
- 10 Ohm ... attached to ground, 0 Volt

I will also present a fourier analys: Level of 2nd 3rd 4th harmonics.
For one rudimentary No-feedback JFET circuit, like this one,
we can expect some 2nd harmonics and considerably less 3rd harmonics

Regards
lineup

=================================
APPENDIX, software used:
EWB MultiSim for FREE download:
MultiSim Download
There is also a free evaluation version from EWB website!
www.electronicsworkbench.com
But this eval. vers. has a almost no audio transistors in spice library.
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