Low noise Dual JFET, anyone know of any

jaialrai · 29th July 2011, 12:11 PM

Hi All, Ive been using the Linear Systems LSK 389A dual JFET for a while, it works brillinatly in my low noise audio amp.

Unfortunately I have just been informed that they are having problems fabricating all but the LSK389C version which will draw much more current in my design.

Does anyone know of any other low noise dual jfets that are comparable?

AndrewT · 29th July 2011, 12:31 PM

2sk389, but you will have to pay to buy some after a long search for the little available stock.

If I wait long enough, my small stock might make a millionaire of me

MRupp · 30th July 2011, 11:44 AM

Somewhat lower transconductance, and common source. If you can live with that - and actually find a seller, Toshiba 2SK2145 might fit your bill: MOSFETs Products - Toshiba America Electronic Components, Inc.

EUVL · 30th July 2011, 12:06 PM

2x Toshiba 2SK170 with matched Idss and thermally coupled.

The next best thing to 2SK389 / 2SJ109 ?

Patrick

jackinnj · 30th July 2011, 01:14 PM

Mouser has 2SK170GR in stock -- these have Idss of 2.6 to 6.5mA -- if you purchase about 20 you should get several matches +/- 0.2mA. The distribution of parts isn't "normal" and seems to "mode" around 4 to 5 mA. What you don't use as matched can be used for CCS. Let me know if you have a problem.

jaialrai · 30th July 2011, 05:01 PM

Thanks for the suggestions, Unfortunately I cannot afford the time to perform such a select on test procedure (to match IDSS) though with over 100 audio channels. The Toshiba part would be usefull if the two source terminals were seperate, but as they are, it would require a major redesign to use it.

Does nobody make discreet dual JFET's anymore?

Conrad Hoffman · 30th July 2011, 05:24 PM

IMO, you're lucky to find discrete anything anymore. A few years ago we were warned that discrete parts, especially leaded ones, were simply going away. It hasn't happened, but I find the specialty parts are getting tough to find. Also, the actual stock on the shelves at places like Digikey seems to be less than it used to be.

You may well have to make the time to match some parts.

theAnonymous1 · 30th July 2011, 05:43 PM

Quote:

Originally Posted by AndrewT

2sk389, but you will have to pay to buy some after a long search for the little available stock.

If I wait long enough, my small stock might make a millionaire of me

What's a good price for the 2SK389? I know a parts supplier that has some stock of these. Maybe I can join that millionaires club with you.

gmphadte · 3rd August 2011, 04:28 AM

Try ebay. U may find matched pairs of 2sk170

Gajanan Phadte

tommy1000 · 3rd August 2011, 06:38 AM

Found this source for the LSK 389A dual JFET: N-Channel: SMSLSK389A LOW NOISE MONOLITHIC DUAL N-CHANNEL JFET same as Linear Integrated Systems LSK389A, Linear Integrated Systems LSK389A TO71 manufactured by Semiconix Semiconductor - Gold chip technology for known good N-Channel die, N-Channel fl
However they have a minimum order of 550 USD.

29th July 2011, 12:11 PM	#1
jaialrai diyAudio Member Join Date: May 2010	Low noise Dual JFET, anyone know of any Hi All, Ive been using the Linear Systems LSK 389A dual JFET for a while, it works brillinatly in my low noise audio amp. Unfortunately I have just been informed that they are having problems fabricating all but the LSK389C version which will draw much more current in my design. Does anyone know of any other low noise dual jfets that are comparable?

29th July 2011, 12:31 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	2sk389, but you will have to pay to buy some after a long search for the little available stock. If I wait long enough, my small stock might make a millionaire of me __________________ regards Andrew T.

30th July 2011, 11:44 AM	#3
MRupp diyAudio Member Join Date: Dec 2003 Location: Frankfurt area	Somewhat lower transconductance, and common source. If you can live with that - and actually find a seller, Toshiba 2SK2145 might fit your bill: MOSFETs Products - Toshiba America Electronic Components, Inc. __________________ Martin Rupp

30th July 2011, 05:24 PM	#7
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	IMO, you're lucky to find discrete anything anymore. A few years ago we were warned that discrete parts, especially leaded ones, were simply going away. It hasn't happened, but I find the specialty parts are getting tough to find. Also, the actual stock on the shelves at places like Digikey seems to be less than it used to be. You may well have to make the time to match some parts. __________________ I used to be an audiophool like you but then I took an arrow to the knee.

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30th July 2011, 12:06 PM	#4
EUVL diyAudio Member Join Date: Oct 2003	2x Toshiba 2SK170 with matched Idss and thermally coupled. The next best thing to 2SK389 / 2SJ109 ? Patrick

30th July 2011, 01:14 PM	#5
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Mouser has 2SK170GR in stock -- these have Idss of 2.6 to 6.5mA -- if you purchase about 20 you should get several matches +/- 0.2mA. The distribution of parts isn't "normal" and seems to "mode" around 4 to 5 mA. What you don't use as matched can be used for CCS. Let me know if you have a problem.

30th July 2011, 05:01 PM	#6
jaialrai diyAudio Member Join Date: May 2010	Thanks for the suggestions, Unfortunately I cannot afford the time to perform such a select on test procedure (to match IDSS) though with over 100 audio channels. The Toshiba part would be usefull if the two source terminals were seperate, but as they are, it would require a major redesign to use it. Does nobody make discreet dual JFET's anymore?

3rd August 2011, 04:28 AM	#9
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	Try ebay. U may find matched pairs of 2sk170 Gajanan Phadte

3rd August 2011, 06:38 AM	#10
tommy1000 diyAudio Member Join Date: Mar 2008	Found this source for the LSK 389A dual JFET: N-Channel: SMSLSK389A LOW NOISE MONOLITHIC DUAL N-CHANNEL JFET same as Linear Integrated Systems LSK389A, Linear Integrated Systems LSK389A TO71 manufactured by Semiconix Semiconductor - Gold chip technology for known good N-Channel die, N-Channel fl However they have a minimum order of 550 USD.

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