Replacement For Toshiba 2SK170/2SJ74


Joined 2010
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K170 / J74 Jfet availability is very spotty. Most, if not all, eBay sellers have fakes.

Linear Systems is trying to make the J74s but their yields are very low, hopefully we'll have a new batch soon and re-stock the store. In the short term, however, we are all waiting.

Every time a new supply seems to be available it's either a false alarm or the people selling get cold feet.

There are some devices that are similar, if not a direct drop-in replacement, but are very nice for audio. Nelson has been talking about using those in new projects.
Can we make this a sticky where Members are reminded regularly where to buy genuine devices?


And request to the store for matched pairs of A and C grade as an alternative since the matched pairs of B grade are quite often in short supply.

Proposal to Mods - please make this Stickiest Sticky

But not in the PASS section.
Maybe in the Solid State? or if it's possible in Amplifiers?
And maybe a sticky back up in the Design and Build - Parts section.


Joined 2010
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indra1 - Linear has very low yields of the J74 is all grades. The store only has matches in B as that's the Idss value that are useful in the Pass circuits. Having matches in different grades would not really help the builders all that much.
Thank you Jim.

However, I found no problem when I tried the GR on an F4, I think experienced builders will find that the A grade can serve well enough for some of the F4, B1R2, M2, F6 and F5 (using Toshiba) builds, off course appropriate resistors have to be adjusted. The C grades are also very usable when cascoded or on lower voltage circuits like the LXmini XO.

Please correct me if I am mistaken.


Joined 2010
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Indra1 -

I agree completely. Where the issue starts is when a novice builder can't find the parts that will just work without any tweaking or subtle changes.

The LXmini XO will most likely be made with different parts... :) but again, you are correct in saying the C (V in Toshiba) would work well.

Niglel -

Are you searching for the straight 240 or the 240PBF? The lead-free is the only one I know that is still in production.
The one and only
Joined 2001
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At the moment, apart from Linear Systems offerings in the DIYaudio store,
this is the most reliable offering I know, a known manufacturer of
our acquaintance who bought tons of these new before they were
discontinued and who does a fussy job of matching them.


punkydawgs on eBay


Toshiba 2SK170 FOUR MATCHED PAIRS (4 pairs) to 0.03mA / 4mV in Temp Control Lab | eBay

Toshiba 2SJ74 + 2SK170 MATCHED PAIR 0.03mA AND 4mV 6.5mA-7.9mA Idss Range | eBay

Toshiba 2SJ74 + 2SK170 MATCHED QUAD to 0.03mA AND 4mV 10.3mA-10.7mA Idss Range | eBay

Toshiba 2SJ74 + 2SK170 MATCHED QUAD to 0.03mA AND 4mV 7.2mA-7.4mA Idss Range | eBay
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