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Old 20th June 2008, 11:20 PM   #51
Vix is offline Vix  Yugoslavia
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Or, can it be something like "Buffer for Blues", but, instead of the resistor (R 19) it uses a Jfet current source?
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Old 21st June 2008, 12:41 AM   #52
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Quote:
Like this ?
No Erno, not like that.
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Old 24th June 2008, 09:26 AM   #53
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Question transistors

Hi Nelson,
Did you used in B1 buffor pre following transistors : 2SK170 and 2SJ74 ?
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Old 24th June 2008, 07:22 PM   #54
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Default Re: transistors

Quote:
Originally posted by Krzysztof
Hi Nelson,
Did you used in B1 buffor pre following transistors : 2SK170 and 2SJ74 ?
I refer you to posts 45, 46, and 47

The devices are either 2SK170 or 2SK370
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Old 24th June 2008, 08:22 PM   #55
mlloyd1 is offline mlloyd1  United States
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for folks that want to read about design of the jfet single ended buffer, i wanted to share again this article from dennis feucht.

i first saw this circuit in the early 70's (yes, i am an old phart :-) ) in some old (even back then) national semiconductor datasheets showing test circuits for some of their parts.

i don't have access to an audio precision (maybe mr. pass can share some data at some point), but you can get pretty good performance from this circuit using some cheaper, easier-to-get jfets like the 2N5484, etc. so, save your 2SKxxx for your phono preamps.


enjoy!
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Old 24th June 2008, 11:36 PM   #56
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Quote:
Originally posted by mlloyd1
for folks that want to read about design of the jfet single ended buffer, i wanted to share again this article from dennis feucht.

i first saw this circuit in the early 70's (yes, i am an old phart :-) ) in some old (even back then) national semiconductor datasheets showing test circuits for some of their parts.

i don't have access to an audio precision (maybe mr. pass can share some data at some point), but you can get pretty good performance from this circuit using some cheaper, easier-to-get jfets like the 2N5484, etc. so, save your 2SKxxx for your phono preamps.
An oldie but a goodie. I dropped the Source resistors on mine.

I don't have 2N5484 distortion curves, but the 2SK170 is pretty
spectacular, and the LSK170 is available and cheap enough.

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Old 25th June 2008, 10:01 PM   #57
Vix is offline Vix  Yugoslavia
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Quote:
Originally posted by Nelson Pass


...but the 2SK170 is pretty spectacular...


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Old 26th June 2008, 03:05 AM   #58
mlloyd1 is offline mlloyd1  United States
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agreed!

also, oddly enough, the 2SK369 is still around and relatively cheap as well.

Quote:
Originally posted by Nelson Pass
... but the 2SK170 is pretty spectacular
mlloyd1
(who is hiding his 2SK146 and 2SJ73 stash from the wife for fear that she will sell them on ebay! )
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Old 27th June 2008, 01:01 PM   #59
arupg is offline arupg  Latvia
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Love the knobs on the Front panel - a reminder from the Theshold days.....
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Old 27th June 2008, 06:48 PM   #60
mlloyd1 is offline mlloyd1  United States
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nelson:

anything you can share at this point on the differences in the distortion spectra for these buffers built with or without source resistors?

the answer "be patient and wait for my article" is a valid response.



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