dual N Channel Jfet

eapavant · 22nd May 2006, 09:09 PM

Has anyone used something like this for a differential front end? Any reason why this part would not be ideal?

jrdmedford · 23rd May 2006, 12:44 AM

http://www.linearsystems.com/

This firm is located in California. They are now producing under
license the Toshiba 2SK389. These are dual matched JFETs
but much higher gfs than the U401s, this means much lower noise.

In addition, this firm is also making the 2SK170, which is a high gfs single JFET found alot in MC phono stages and what not.

As far as I know, the only other producer of these devices in
North America is InterFET (Texas) - but they will only sell minimum
200 ct orders. Linear will do samples as well as smaller qtys.
You can request up to 5 ct as samples too which is nice.

Another part out there is the 2N5566. However, the 2SK389
outguns that as well as your U401.

-- Jim

tINY · 8th February 2008, 07:10 AM

I'll hijack this thread, since I don't appear to be able to start my own:

I'm building a phantom powered impedance converter (instrument input to XLR balanced) and settled on a JFET buffer design similar to what used to get put on FET probes for scopes.

Now I am finding that the Dual Matched JFETs are not readily available. Is there a good source for these things, or is it time to redesign using MOSFETs?

There seem to be a lot of dual N-channel MOSFETs out there....

-tINY

23rd May 2006, 12:44 AM	#2
jrdmedford diyAudio Member Join Date: Mar 2004 Location: Medford, MA	a little better http://www.linearsystems.com/ This firm is located in California. They are now producing under license the Toshiba 2SK389. These are dual matched JFETs but much higher gfs than the U401s, this means much lower noise. In addition, this firm is also making the 2SK170, which is a high gfs single JFET found alot in MC phono stages and what not. As far as I know, the only other producer of these devices in North America is InterFET (Texas) - but they will only sell minimum 200 ct orders. Linear will do samples as well as smaller qtys. You can request up to 5 ct as samples too which is nice. Another part out there is the 2N5566. However, the 2SK389 outguns that as well as your U401. -- Jim

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8th February 2008, 07:10 AM	#3
tINY diyAudio Member Join Date: Jun 2007	I'll hijack this thread, since I don't appear to be able to start my own: I'm building a phantom powered impedance converter (instrument input to XLR balanced) and settled on a JFET buffer design similar to what used to get put on FET probes for scopes. Now I am finding that the Dual Matched JFETs are not readily available. Is there a good source for these things, or is it time to redesign using MOSFETs? There seem to be a lot of dual N-channel MOSFETs out there.... -tINY

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