Exactly. The required jFET must suit the duty.
It's not a guessing and hope for the best game.
What voltage will the diff pair actually see? We can use the same ones in Tube amps - so hundreds of volts.
-Chris
-Chris
What?, across the the Jfets?
Normally I hold the voltage down to 7 VDC - ish. Cascode those so you can reach your supplies.
-Chris
Normally I hold the voltage down to 7 VDC - ish. Cascode those so you can reach your supplies.
-Chris
Cascoded, And look this is with 25mA standby current, will be better with 75mA.
The bias setting gives 2V-to-4 bias but the simulator is not right about this because it gives that 25mA with 4V bias, this is not normal.
The offset is very good 11mV.
I have old russian jfets, will test with them -> кп103к
The bias setting gives 2V-to-4 bias but the simulator is not right about this because it gives that 25mA with 4V bias, this is not normal.
The offset is very good 11mV.
I have old russian jfets, will test with them -> кп103к
Attachments
Last edited:
Another mosfet54 open end poisoned question to lure forum members into an endless and inconclusive thread.
Details are vague on purpose so answers can be dodged or ignored and instead ask new ones which may or may not be related to the original one.
Details are vague on purpose so answers can be dodged or ignored and instead ask new ones which may or may not be related to the original one.
Keep up the dumb threads and even the mods will get sick of the nonsense.
Most of your choices are for obsolete parts and for folk who are yet to buy, it means for the prime types, they will be getting substitutes, fakes or sorting rejects with useless parameters. Even if they buy large quantities in order to get a few matched pairs for an LTP, any benefits will be diminished by the performance being too far from optimum.
Diyaudio store sells these, LSK170 and LSJ74, to avoid the major problem of thru-hole JFET obsolescence and meaningless polls about cheap unqualified products that are still sold by online stores: Transistors – diyAudio Store (BETA)
They're not cheap but at least they will be genuine, true to the datasheets and the opinions of pro. members may be considered valid. A serious poll should include them with an explanatory note about the high likelihood of fakes in currently available JFET supplies, whether members realise it or not.
Most of your choices are for obsolete parts and for folk who are yet to buy, it means for the prime types, they will be getting substitutes, fakes or sorting rejects with useless parameters. Even if they buy large quantities in order to get a few matched pairs for an LTP, any benefits will be diminished by the performance being too far from optimum.
Diyaudio store sells these, LSK170 and LSJ74, to avoid the major problem of thru-hole JFET obsolescence and meaningless polls about cheap unqualified products that are still sold by online stores: Transistors – diyAudio Store (BETA)
They're not cheap but at least they will be genuine, true to the datasheets and the opinions of pro. members may be considered valid. A serious poll should include them with an explanatory note about the high likelihood of fakes in currently available JFET supplies, whether members realise it or not.
Yes, I think he is testing you if you know anything about audio 😀
BTW, some people ask, what is so special about the vintage 2n5565 used in the Goldmund Mimesis? Well, I think if you know the answer, you know a lot of things about subjectivity of sound in amplifying devices.
And here I pick the 2N5566 (for normal LTP implementation) 😉
Hi Jay,
Oh, good grief! Me?
In that case, Linear Systems has a nice replacement for that, and it is something I have worked with, but in instrumentation, not audio. But it ain't on the allowed list above. Anyone who knows me also knows I prefer J-Fets for the diff pair in an amplifier. So no surprises there.
Oh, good grief! Me?
In that case, Linear Systems has a nice replacement for that, and it is something I have worked with, but in instrumentation, not audio. But it ain't on the allowed list above. Anyone who knows me also knows I prefer J-Fets for the diff pair in an amplifier. So no surprises there.
Hehehe... No 😉 What is the new replacement? The Vishay in the list (2N4416) doesn't look too bad either if applicable in the circuit (looks like current production?).
Last edited:
Hi Jay,
I'm sorry, I thought I listed that.
LSU401. It's available in TO-71, TO-78, PDIP and surface mount. If you're really brave, you can get these as die. How's that for surface mount?
Linear Systems is a real hero for many of us.
-Chris
I'm sorry, I thought I listed that.
LSU401. It's available in TO-71, TO-78, PDIP and surface mount. If you're really brave, you can get these as die. How's that for surface mount?
Linear Systems is a real hero for many of us.
-Chris
Hmmm... I don't know how I can source modern parts through import. Can you just go to a website and purchase one or two items using credit card??
PS: Before anybody comment on the Vishay 2N4416, I guess it's trans-conductance is too low to be usable...
Last edited:
- Status
- Not open for further replies.