JFET shootout

[micolas]

I'm wondering why the J310 Siliconix is never mentioned around here except by me,

Maybe because J310 has Idss in the range of 24...60mA, and for microphones we select specimens with small Idss.

 

[MicUlli]

A lot of jfet suggestions worth a test
At the moment there is no timegap availiable, but i will extend the test list as soon as possible.
BR MicUlli

 

[Wavelength]

If not added I would look at LSK170 and LSK189, 2 of my favs. Both super low noise and both have matched pairs available. The LSK189 is really nice as it has a high bias voltage. I use them in pedals and High End Audio all the time.

 

[Papa Tango Charly]

Sorry, I didn't read this entire thread, but be aware that the currently available 2N3819 FETS from Mouser (Central Semi) have absolutely nothing to do with the original 2N3819. They will not be a drop in replacement for the old ones. They bias completely different. I ran into that with the bansai KM84 kit. Those FETs are trash. Don't use them. I used LS846 instead. Worked great and I would recommend it. It biases close to the original 2N3819.

Great thank for that information. Do you have an supplier, I found this one https://www.digikey.fr/fr/products/detail/linear-integrated-systems-inc/LS846-TO-92-3L-ROHS/14312177. Thank you

 

[McIrish]

I believe I did get them from Digikey.

 

[Papa Tango Charly]

Can i just replace a 2N3819 with a LS846 in a T84 circuit thank you. Have tried a other Fet in this T84 circuit microphone with a 34mm capsule

 

[micolas]

Can i just replace a 2N3819 with a LS846 in a T84 circuit thank you. Have tried a other Fet in this T84 circuit microphone with a 34mm capsule

Yes, LS846 can be used with very good results. Choose it with small Idss.

 

[Papa Tango Charly]

I'm tying to find an IDSS tester / do you any tester that could do the job? I found this on Aliexpress. Thank You

https://fr.aliexpress.com/item/1005...m0dCsrfW&utparam-url=scene:search|query_from:
or

https://fr.aliexpress.com/item/1005...moTDowiR&utparam-url=scene:search|query_from:

 

[Khron]

I'm tying to find an IDSS tester

https://sound-au.com/articles/jfet-design.htm#s2

 

[micolas]

I'm tying to find an IDSS tester / do you any tester that could do the job?

I recommend something more complex, very useful for DIY. Oscilloscope, signal generator, multitester.
I use it everywhere, I am very satisfied with it.

https://a.aliexpress.com/_omLjN3Q

 

[Cqwet Dbdfte]

Right, the dynamic range, including noise floor, is defined by the number of bits in an A/D Converter. (How common are full chain non-digital products?)
Noise is sometimes added on purpose to randomize out unpleasant (monotonic) digital artifacts. Noise is unfortunately a fact of life. If not truly random it is a problem.
Depending on "musical" content (opinions vary) , the final product may often, sadly, be compressed to a limited dynamic range, squashing all intents of low noise.
Vinyl records has more limitations on dynamic range, at both ends, and thus enforces some boundaries on program content, which actually may be a good thing.
A two mike Blumlein or three mike a la RCA living stereo, recorded in a slightly reverberant setting, may be too much of a challenge, and underappreciated and a thing of the past.

 

[abbey road d enfer]

If not added I would look at LSK170 and LSK189, 2 of my favs. Both super low noise and both have matched pairs available.

They have a quite high input capacitance Cgs, about 40pF, which makes them unsuitable for low capacitance capsules.
They also need to operate at significantly higher curret (>2mA) for low noise.

The LSK189 is really nice as it has a high bias voltage. I use them in pedals and High End Audio all the time.

Different applications.

 

[Wavelength]

Great thank for that information. Do you have an supplier, I found this one https://www.digikey.fr/fr/products/detail/linear-integrated-systems-inc/LS846-TO-92-3L-ROHS/14312177. Thank you

I just buy direct from Linear Systems.

 

[Newmarket]

Great thank for that information. Do you have an supplier, I found this one https://www.digikey.fr/fr/products/detail/linear-integrated-systems-inc/LS846-TO-92-3L-ROHS/14312177. Thank you

French dist' for Linear Systems:

France

CATS (Solutec & Microel)​

Email
[email protected]
Phone #
+33-1-69070824 or +33-1-69592150

 

[MicUlli]

Here are some actual measurement results, JFETs at 1mA drain current. Now my favorites are NSVJ3910 and 2SK209..

 

[soliloqueen]

They have a quite high input capacitance Cgs, about 40pF, which makes them unsuitable for low capacitance capsules.
They also need to operate at significantly higher curret (>2mA) for low noise.

Different applications.

The 189 is their process 50 replacement and has the exact same specs as the 3819, including an input capacitance of 4pf. Are you thinking of something else or is there something I don't know

 

[abbey road d enfer]

The 189 is their process 50 replacement and has the exact same specs as the 3819, including an input capacitance of 4pf. Are you thinking of something else or is there something I don't know

Sorry, I confused 189 with 389.

 

[soliloqueen]

Sorry, I confused 189 with 389.

apologies though, i was also wrong in the specifics. the 189 is a single channel version of the 489, which is more of a low impedance version of the 389. it's intended to be a "designer jfet" for low noise impedance conversion. the LS846 is their process 50 replacement. though it is true that both will work in a headamp circuit

 

[abbey road d enfer]

Well, my understanding is the lowest-impedance is the 389, and the 489 is kind of medium impedance, with the typical 2N3819 being high impedance, if I'm allowed this simplification.
It will be interesting to see how the 846 performs as a replacement for 2N3819 in a typical common-source stage..

 

[soliloqueen]

Well, my understanding is the lowest-impedance is the 389, and the 489 is kind of medium impedance, with the typical 2N3819 being high impedance, if I'm allowed this simplification.
It will be interesting to see how the 846 performs as a replacement for 2N3819 in a typical common-source stage..

Sorry it was late. I meant input capacitance, so the reverse of what I said. My brain swapped the words