Hi, would like to ask what kind of transistor I can use to replace the Toshiba 2SK170BL? I can't find any 2SK170BL over place and thinking to change to other parts that can be replaced the Toshiba 2SK170BL.
2sk170bl are available from Mouser. You can use LSK170BL from Linear Systems, but you'll have to find a distributor in KL. Alternatively, there are a lot of fans of BF862 which is SOT223, but it's easy to find adapters.
Hi, thx for your reply. But I meant maybe newer Transistors (eg. SMD form factor) as the mentioned BF862 ....maybe some superior stuff? the good design seems to be around 15 years old. In the meantime wasn't there any development?
The quickest/easiest answer for the jfets is in post#1 of this thread:
Replacement For Toshiba 2SK170/2SJ74
And this page F-5T V1/2 Transistor Kit – diyAudio Store says:
"The obsolete 2SC4793 and 2SA1837 have been replaced with TIP31 and TIP32 respectively with no difference in performance or package."
Replacement For Toshiba 2SK170/2SJ74
And this page F-5T V1/2 Transistor Kit – diyAudio Store says:
"The obsolete 2SC4793 and 2SA1837 have been replaced with TIP31 and TIP32 respectively with no difference in performance or package."
There are some JFET under production now, J310, CPH3910, NSVJ2394, 2SK3557, there are all cheap and good.
For noise perspective:
J310>CPH3910~NSVJ2394>3557
Although noise might not be important in Hifi field, but thy are still good replacement.
BF862 is great, but EOL. Maybe try some 2SK3557.
<https://www.diyaudio.com/forums/equipment-and-tools/175044-version-1000-low-noise-measurement-amp-ikoflexer-51.html>
I tried 3 types of low noise JFETs, the now extinct BF862 (I have a lifetime stock
) the OnSemi 2SK3557 (also found in the CPH5905 BJT cascode) and the OnSemi CPH3910. All were set to run at 1mA/jfet (8mA total) by adjusting the on board multiturn pot.
- The winner was still the BF862, with 0.44nV/rtHz equivalent input noise.
- There was virtually no difference between the 2SK3557 and the CPH3910, other than some random statistic fluctuation (certainly due the process) at about 0.5nV/rtHz, so a smidge worse than the BF862. This is telling me that the OnSemi devices are sharing the same silicon. The noise performance shows that not everything is lost with the demise of the popular NXP BF862 JFET. For further massive scaling for even lower noise, the OnSemi devices have a major advantage, though: they have Ciss=6pF compared to the 10pF for the BF862.
- All devices delivered a 10Hz equivalent input noise of anywhere between 1.4 and 2.5nV/rtHz, randomly, no correlation with the device type was identified. I suspect one could go lower with sorting the devices for low GR noise, I didn't bother.
For noise perspective:
J310>CPH3910~NSVJ2394>3557
Although noise might not be important in Hifi field, but thy are still good replacement.
BF862 is great, but EOL. Maybe try some 2SK3557.
<https://www.diyaudio.com/forums/equipment-and-tools/175044-version-1000-low-noise-measurement-amp-ikoflexer-51.html>
I tried 3 types of low noise JFETs, the now extinct BF862 (I have a lifetime stock
) the OnSemi 2SK3557 (also found in the CPH5905 BJT cascode) and the OnSemi CPH3910. All were set to run at 1mA/jfet (8mA total) by adjusting the on board multiturn pot.
- The winner was still the BF862, with 0.44nV/rtHz equivalent input noise.
- There was virtually no difference between the 2SK3557 and the CPH3910, other than some random statistic fluctuation (certainly due the process) at about 0.5nV/rtHz, so a smidge worse than the BF862. This is telling me that the OnSemi devices are sharing the same silicon. The noise performance shows that not everything is lost with the demise of the popular NXP BF862 JFET. For further massive scaling for even lower noise, the OnSemi devices have a major advantage, though: they have Ciss=6pF compared to the 10pF for the BF862.
- All devices delivered a 10Hz equivalent input noise of anywhere between 1.4 and 2.5nV/rtHz, randomly, no correlation with the device type was identified. I suspect one could go lower with sorting the devices for low GR noise, I didn't bother.
Attachments
J11x are very low performance cheap switching FETs, in general NO substitute at all for old classic audio or general purpose ones.
That said, they are cheap and plentiful and have *some* uses, I buy them by the 1000 but to use as compressor/limiters in my Guitar/Bass amps and as channel/loop/effects switchers.
There they work well, but for Audio use, only as source followers, where "anything" works.
As Preamps, specially high quality ones? .... fully out of their league.
Pity at least one or two good Audio types were not kept in production 😕
Audient ID22 uses j112 for hi-z(bass or electric guitar) input.So far it proved to be good enough.