I've lost count how many times this question keeps getting asked.
PLEASE USE THESE DEVICES
Linear Systems Matched LSJ74/LSK170 JFET pairs (Grade B) – diyAudio Store
J74/J74 Stereo Differential Kit – diyAudio Store
Linear Systems LSK170 Ultra Low Noise Single N-Channel JFET (8 Pieces) – diyAudio Store
Linear Systems LSJ74 Ultra Low Noise Single P-Channel JFET (8 Pieces) – diyAudio Store
PLEASE USE THESE DEVICES
Linear Systems Matched LSJ74/LSK170 JFET pairs (Grade B) – diyAudio Store
J74/J74 Stereo Differential Kit – diyAudio Store
Linear Systems LSK170 Ultra Low Noise Single N-Channel JFET (8 Pieces) – diyAudio Store
Linear Systems LSJ74 Ultra Low Noise Single P-Channel JFET (8 Pieces) – diyAudio Store
+1
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.
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.
If you visit Akizuki Denshi and search for P-channel junction JFETs, you can find the 2SJ498-C which is being made by Isahaya Denshi. The package is TO-92S (a short TO-92).
A few of these in parallel can be an adequate 2SJ74 substitute.
??????/?e?d?s/Pch????^FET ?H???d?q??? ?d?q???i ?l?b?g???
hth
A few of these in parallel can be an adequate 2SJ74 substitute.
??????/?e?d?s/Pch????^FET ?H???d?q??? ?d?q???i ?l?b?g???
hth
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.
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.
Understood. Same problem with matched pairs of other grades?...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. ...
Can we make this a sticky where Members are reminded regularly where to buy genuine devices?
+1
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.
But not in the PASS section.Proposal to Mods - please make this Stickiest Sticky
Please.....
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.
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.
New designs should be moving over to vertical mosfets.
I certainly cant tell the difference in sound having built loads of each type, vertical and lateral.
Having said that the popular irfp240/9240 are now hard to get.
But there are other options.
I certainly cant tell the difference in sound having built loads of each type, vertical and lateral.
Having said that the popular irfp240/9240 are now hard to get.
But there are other options.
Having said that the popular irfp240/9240 are now hard to get.
They can still be found through the big houses easily. That said, everything though-hole is rapidly going away. Which is a bit of a challenge in the long term.
IRFP240/9240
RS no longer do them.
Farnell were out of stock but I checked again today and they are back in stock.
I have noticed through hole components dwindling slowly.
RS no longer do them.
Farnell were out of stock but I checked again today and they are back in stock.
I have noticed through hole components dwindling slowly.
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.
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.
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.
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.
Farnell, Rapid, mouser and digikey all have stock of irfp240
RS has the irfp9240 in stock.
I wonder if you have been searching for irf240?
RS has the irfp9240 in stock.
I wonder if you have been searching for irf240?
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Thank you. What a relief to know.... The LXmini XO will most likely be made with different parts... 🙂 ...
I agree. Seeing the LXmini+sub crossover with what appeared to be eighteen (18!) pair of K170/J74 during the BAF17 presentation gave me a momentary heart attack. 😱
Luckily there's a different solution that works very well.
Luckily there's a different solution that works very well.
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.
Seller:
punkydawgs on eBay
Listings:
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
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.
Seller:
punkydawgs on eBay
Listings:
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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