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Replacement For Toshiba 2SK170/2SJ74
Replacement For Toshiba 2SK170/2SJ74
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Old 24th September 2018, 04:48 PM   #221
Mayank is offline Mayank  United States
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I just saw that BDent has Toshiba 2SK170BL's in stock @ $2.69 each for 10 units.

Do they look genuine? I've bought from them several years ago, but wanted to know if someone has made a purchase recently? I'm in the process of building an ACA.

Thanks
Mayank
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Old 24th September 2018, 04:54 PM   #222
6L6 is offline 6L6  United States
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Replacement For Toshiba 2SK170/2SJ74
I bought from them a few years ago. The parts were fine.
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Old 24th September 2018, 05:02 PM   #223
Mayank is offline Mayank  United States
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Quote:
Originally Posted by 6L6 View Post
I bought from them a few years ago. The parts were fine.
Thank you.

Just placing an order

Rgds
Mayank
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Old 27th September 2018, 01:57 PM   #224
Extreme_Boky is offline Extreme_Boky
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LSK389B/LSJ689 seem okay; probably not easy to match k to j, though. However, an LSJ689 seems perfect for Aleph J

Last edited by Extreme_Boky; 27th September 2018 at 01:59 PM.
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Old 1st October 2018, 07:14 AM   #225
astromo is offline astromo  Australia
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Quote:
Originally Posted by EUVL View Post
> GR is fine for buffers.

Depends on what load and what max. output current you want to deliver.
If you can cherry pick 6mA Idss from GR then it is indeed not far from BL.
But then for buffer you can also use a pair of 2SK369V.




Patrick

To repeat back for confirmation, so I take it that for a 2SJ74 and referring to its datasheet:
http://www.mouser.com/ds/2/408/6903-18063.pdf
that with the following specs:

Quote:
IDSS classification GR: −2.6~−6.5 mA, BL: −6.0~−12 mA, V: −10~−20 mA
then a GR at an IDSS of 6 - 6.5 mA will be functionally equal to a BL of the same Idss performance?


Or is there some nuance in the numbers somewhere else on the datasheet that I'm not appreciating as being critical / important?



Sounds like I can make a GR work. The pairs I'm looking at are advertised with an IDSS of 6.2 - 6.4 mA and a match to 0.05 mA. They're destined for an Aleph J build.


In the first instance, I'm just after reassurance that I haven't blown my dough.


In the same vein, and from the perspective of expanding my understanding, the LS gear offered by the diyAudio Store:
Linear Systems LSJ74 Ultra Low Noise Single P-Channel JFET (8 Pieces) – diyAudio Store
uses "Grade" to differentiate the transistor classification, so:
LS A Grade ~ Toshiba GR
LS B Grade ~ Toshiba BL
LS C Grade ~ Toshiba V
The store's prices increase from C to A, so A grade appears to be the "best" if price is a metric but from what I've read here "A Grade" or Class GR is not the most useful or "as easily usable with minimal mucking about" for the Pass amp family. Just seems counter-intuitive at first glance to those at the start of the journey like me.


With any replies, please go easy on me. I've just built a pair of ACAs, so even though I might have kicked off the trainer wheels I'm still a bit wobbly.
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Old 1st October 2018, 10:10 AM   #226
EUVL is offline EUVL  Europe
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Perhaps some references would be of help :

JFETs: The New Frontier, Part 1 | audioXpress
JFETs: The New Frontier, Part 2 | audioXpress


Patrick
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Old 2nd October 2018, 01:00 PM   #227
astromo is offline astromo  Australia
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Quote:
Originally Posted by EUVL View Post

Thanks for the links to the Borbely papers. I need to give them a solid second read.


However at this stage, I can't see that I'll have an issue with the plan I've got in place to apply the Toshiba 2SJ74 GRs to an Aleph J build. That said, I will be looking hard for the part where Borbely explains why this classification is worth a little bit extra over (say) the BLs. From a first read, I didn't pick that up.
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Old 2nd October 2018, 01:23 PM   #228
kstagger is offline kstagger  United States
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Quote:
Originally Posted by Mayank View Post
I just saw that BDent has Toshiba 2SK170BL's in stock @ $2.69 each for 10 units.

Do they look genuine? I've bought from them several years ago, but wanted to know if someone has made a purchase recently? I'm in the process of building an ACA.

Thanks
Mayank
I went to BDent and bought two pairs of 2SK170/2SJ74s for a future M2 build. They "look" real to me but I haven't done any measuring yet.
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Old 2nd October 2018, 10:44 PM   #229
Extreme_Boky is offline Extreme_Boky
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An LSJ689 seems perfect for Aleph J; no matching required, 1/5th capacitance.... around $10 a pop (which is 2 X 2SJ74)
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Old 3rd October 2018, 12:00 AM   #230
6L6 is offline 6L6  United States
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Replacement For Toshiba 2SK170/2SJ74
Kstagger - “matched” K170/J74 from b&d are not measured, just one of each from the same grade. Just FYI.
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