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.
Thanks eddyvb,
Will research more into this topic, best bet is to use it on my upcoming M2X.
I will built one channel with LS74/170 pair from the DiyAudio Store, the other with this (possible fakes) and compare.
Hope i don't blow up anything seriously.
Will research more into this topic, best bet is to use it on my upcoming M2X.
I will built one channel with LS74/170 pair from the DiyAudio Store, the other with this (possible fakes) and compare.
Hope i don't blow up anything seriously.
For applications like M2X, 2SK369V is a better device.
Lower output impedance, and higher Class A output current.
I am sure Nic would be happy to supply you with matched ones.
You may even find them in SGP locally.
Patrick
Lower output impedance, and higher Class A output current.
I am sure Nic would be happy to supply you with matched ones.
You may even find them in SGP locally.
Patrick
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
@carsten.witt
Yeah. While i search how to add attachement was too late. 😀
Still did it in a strage way.
Yeah. While i search how to add attachement was too late. 😀
Still did it in a strage way.
Double is better, think we should post this on all new page or asked the admins to add this to the first post?
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
Yes Darr, what I see in your pictures looks like Toshiba JFETs all right.
I was also irritated when I read the sides should be seamless. In fact it is just very thin and only barely visible. With the fingertips you can probably not feel it. At least I can’t [emoji106]
I was also irritated when I read the sides should be seamless. In fact it is just very thin and only barely visible. With the fingertips you can probably not feel it. At least I can’t [emoji106]
I can feel it more with fingernail than with fingertip🙂 I'm glad that purchase is successful and I have finished searching for jfets. Only once I got fake. Thanks for all
@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 !