2Sj109's available on Ebay for 7.80 a pop.

[dodo]

Mr Blues
I advise you to make some small experiment , build the Borbely jig for jfet matching and measure the Vgs parameter of your sj74 for different Id (f.e. 2mA 4mA , 6 mA )
After that you will know what Mr EUVL is talking about

sj109 data sheet says the maximum Vgs difference between two jfets in single device (the same die ) is 20mA
Only with curve tracer measurements you can get better matching pairs , but this will not solve problems caused by the thermal drift

 

[steenoe]

One can go nutz and make matching a science or a goal in itself, but is it necessary for audio use? I was under the impression that audio circuits are not the most critical circuits in the world.

 

[dodo]

One can go nutz and make matching a science or a goal in itself, but is it necessary for audio use? I was under the impression that audio circuits are not the most critical circuits in the world.

well it's a matter of circuit , where you would like to place the jfets f.e.
take a look
Distortion in JFET input stage circuits

point 5

 

[steenoe]

well it's a matter of circuit , where you would like to place the jfets f.e.
take a look
Distortion in JFET input stage circuits

point 5

Thanks for the link. Those are interesting investigations.

 

[AndrewT]

I have a very small stock of 2sk389 and 2sj109.
I'm going to do some measuring soon.

 

[ggetzoff]

I did find new ones for $20 bucks here.....

Digitron solve sourcing challenges for parts like -- hard to find, long lead time, obsolete components and ICs.

They have a $100 min. order, which won't be hard to reach at these prices!!!

 

[StevenOH]

And this is what some places advertise as 2SJ109.

 

[ggetzoff]

nice...

 

[spurlte]

Transistors

I have a very small stock of 2sk389 and 2sj109.
I'm going to do some measuring soon.

Andrew. I know it's a few years ago for this thread, but would you have available a pair, each, of 2sk389 BL/2sj1209 BL. BL because John Curl suggested over V. But I understand one can't be picky these days for either V or BL. David P.S. I tried to send this message over PM but your are full and cannot accept PMs until you remove some messages.

 

[AndrewT]

I see the cheapest Ebay price is now over £20 each
Maybe if I still haven't used them in another 3years, the price might be right. I only have 4.

 

[kasey197]

Andrew. I know it's a few years ago for this thread, but would you have available a pair, each, of 2sk389 BL/2sj1209 BL. BL because John Curl suggested over V. But I understand one can't be picky these days for either V or BL. David P.S. I tried to send this message over PM but your are full and cannot accept PMs until you remove some messages.

This chap has some v grades on the swap meet forum.http://www.diyaudio.com/forums/swap-meet/227509-fs-toshiba-2sj109-v-dual-jfets.html?highlight=2sj109

If you have your heart set on BL and cant get them, drop me a pm, a local shop has them (originals) at about $7-8 iirc. Ill try n help if I can.

 

[Nelson Pass]

I see the cheapest Ebay price is now over £20 each

MuuuHahahahahahahaaaaaa.......

I'm Rich!

So long, suckers!!

 

[EUVL]

You are rich anyhow.


Patrick