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Old 5th December 2006, 02:05 AM   #1
Ipanema is offline Ipanema  Malaysia
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Default PMBFJ620 dual Jfet

Is this any good for LTP input stage or as a replacement for the favourite 2SK386?

http://pdf1.alldatasheet.com/datashe.../PMBFJ620.html
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Old 5th December 2006, 11:32 AM   #2
Ipanema is offline Ipanema  Malaysia
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anyone have ever use this care to comment? It's difficult for me to source 2Sk386 in my place.

Thanks.
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Old 5th December 2006, 05:36 PM   #3
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Quote:
Originally posted by Ipanema
anyone have ever use this care to comment? It's difficult for me to source 2Sk386 in my place.

Thanks.

compare S of both.....
in which construction you need them?
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Old 7th December 2006, 01:45 AM   #4
Ipanema is offline Ipanema  Malaysia
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Hi,

I'm planning to use it in the front end like this :
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Old 7th December 2006, 01:49 AM   #5
Ipanema is offline Ipanema  Malaysia
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Hi,

I'm planning to use it in the folded cascode front end like this. What's your opinion on this Jfet pair? Or can you recommend other easier avalaible jfet pair?

Thanks.
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File Type: jpg folded_cascode.jpg (55.0 KB, 241 views)
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Old 7th December 2006, 02:10 AM   #6
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without looking at exact schmtc with all values ,including voltage-it's hard to say..........besides-is it 2SK369 originally in schmtc?
with S of 40mA/V it's pretty hard to find adequate replacement type...even 2SK389 have just half of that.....


mebbe two 2SK389,but they are also hard to find......

seems that your philips part is somewhere around 15mA/V.....so maybe one case (two in parallel) instead one half of 369.........

give us schmtc (if it's too large to post here , mail it to me (chokyATneobee.net) and I'll shrink it for here or host it for some time


EDIT:


OK google is our friend

http://home.no.net/andiha/articles/audio/claclassa.htm


there is all info you need
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Old 7th December 2006, 05:19 AM   #7
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Does paralleling more fet provides any disadvantage besides the advantage of increases transcoductance and lowering the input loise level?

FYI, I do not have the final design yet. Just something playing in my mind to use differential Jfet folded cascode front end and single ended class A MOSFET source follower. The objective is to eliminate miller compensation caps by having only single stage high gain folded cascode. Do you think this configuration will produce nice sound?
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