Just Idss alone is no guarantee for real 2SK170.
You should at least also test the pinch voltage Vp and compare to datasheet.
See :
JFETs: The New Frontier, Part 1 | audioXpress
Fig. 5
Patrick
You should at least also test the pinch voltage Vp and compare to datasheet.
See :
JFETs: The New Frontier, Part 1 | audioXpress
Fig. 5
Patrick
Looks fake to me. The printed '7' diagonal line must be curly. I think punkydawns has some picture of it.
M2X straight out of the box, offers two different options with a factor of 500 lower output impedance than 2SK170/2SJ74. It also provides a third option with 2X higher class A output current and, simultaneously, 4X lower output impedance.
Whether this makes any audible difference, when the amplifier itself uses an $8 iron core transformer for voltage gain, may be a matter of opinion; and may differ from one listener to the next.
Whether this makes any audible difference, when the amplifier itself uses an $8 iron core transformer for voltage gain, may be a matter of opinion; and may differ from one listener to the next.
That typeface looks genuine - pls refer to my post here: My Transistors, original or copy?
Still, as EUVL said, I'd run some more tests...
Still, as EUVL said, I'd run some more tests...
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Got a feeling these K170BL are genuine, those leads are corroded thru long storage, unlike my J74 samples, whose leads are shiny ! Supplier says they got those J74 from Shenzhen China.
Here's some close up shots, will build a simple jig for pinch test next week.
Have a nice weekend guys !
I am afaid they are not. Digit 7 should be curvy.
And see what what genuin seller punkydawgs add to his lots:
https://www.diyaudio.com/forums/attachment.php?attachmentid=743639&stc=1&d=1552827894
Attachments
Ups . I'm afraid about my jfets now. All looks good but they have a little side seam.
I'll add my opinion:
@meanie, what set off alarms for me is the '0' looks too round on your devices. They may be jfets that you can use but they won't necessarily be as low noise as genuine Toshiba. Check the seams (I think only the top seam is applicable) and the indentation on the back but electrical tests will be the real indicator. If these are only for your own use then the only opinion that matters is your own but if you plan to resell these I would not try and represent these as genuine if these were mine.
@darr, based on your pictures, your jfets look real to me or at least they look like the ones I bought 12 years ago
@meanie, what set off alarms for me is the '0' looks too round on your devices. They may be jfets that you can use but they won't necessarily be as low noise as genuine Toshiba. Check the seams (I think only the top seam is applicable) and the indentation on the back but electrical tests will be the real indicator. If these are only for your own use then the only opinion that matters is your own but if you plan to resell these I would not try and represent these as genuine if these were mine.
@darr, based on your pictures, your jfets look real to me or at least they look like the ones I bought 12 years ago
@Twitchie, pls don't get me wrong. I am not trying to be another Jfet seller in this forum.
These pair of jfets are so rare nowadays and i don't mind paying premium for them, but the shipping costs for shipping a weighless envelope is so high that they charged, no offence, but this is what i feel.
So when i stumbled across this local supplier with supposingly NOS, i became excited. And it was timely, as i was starting to collect parts for B1 NuTube preamp. It was thru here that i found out mine may turn out to be fakes too.
Anyway this is getting interesting, from another thread i found out that Marantz used J74/K170 in their HDAM circuit in their CD players in the mid 90's. I do have a CD63SE that i bought while i was a young man then, i will remove the Jfet pair and see how they look like. Will post some pictures to share. Have a nice day ahead !
These pair of jfets are so rare nowadays and i don't mind paying premium for them, but the shipping costs for shipping a weighless envelope is so high that they charged, no offence, but this is what i feel.
So when i stumbled across this local supplier with supposingly NOS, i became excited. And it was timely, as i was starting to collect parts for B1 NuTube preamp. It was thru here that i found out mine may turn out to be fakes too.
Anyway this is getting interesting, from another thread i found out that Marantz used J74/K170 in their HDAM circuit in their CD players in the mid 90's. I do have a CD63SE that i bought while i was a young man then, i will remove the Jfet pair and see how they look like. Will post some pictures to share. Have a nice day ahead !