No replacement for 2SJ74.
So you need to design round it, like in the Wayne line stage.
Patrick
So you need to design round it, like in the Wayne line stage.
Patrick
Bob Cordell has quite a few paragraphs and schematics of using n-channel JFETs with bipolars to arrive at the same (or better) conclusion. In any event, his book: "Designing Audio Power Amplifiers" deserves a place on your bookshelf.
J113 and k170 have different pinout
any idea what jfet are chinese 'experts' relabeling as K170?
to frozenpod1 #504
Hello frozenpod1,
the datsheet from LinearSystems for the LSJ74 doesn't show a value for max. D-S-voltage. 😕
Greets
Dirk
Hello frozenpod1,
the datsheet from LinearSystems for the LSJ74 doesn't show a value for max. D-S-voltage. 😕
Greets
Dirk
to frozenpod1 #504
I run a quartett of LinearSystems LSK170 / LSJ74 complementary pairs in one
of my BA-3 poweramps (frontend) at a rail voltage of +- 34.5 volts (with a little extra heatsink - selfmde for TO-92) for 2 years now. With no problems. They run at a temperature around 35-40 C (temperature).
So they seem to be very robust / tough.
Greets
Dirk
I run a quartett of LinearSystems LSK170 / LSJ74 complementary pairs in one
of my BA-3 poweramps (frontend) at a rail voltage of +- 34.5 volts (with a little extra heatsink - selfmde for TO-92) for 2 years now. With no problems. They run at a temperature around 35-40 C (temperature).
So they seem to be very robust / tough.
Greets
Dirk
No value for max DS because usually G is lower than both (for a N-JFET).
So rated voltage of 25V also applies to D-S.
I hope you have installed speaker protection. 😉
Patrick
So rated voltage of 25V also applies to D-S.
I hope you have installed speaker protection. 😉
Patrick
Yes, we are well advised to stay below the 24 V - rails - 'border'.
Hot-rodding can be dangerous.....🙄
Greets
Dirk
Hot-rodding can be dangerous.....🙄
Greets
Dirk
I ask as the original Toshiba 2SJ74 would break down a touch over 40V and I always assumed the datasheet had a typo given the matching 2SK170 was 40V rated.
Precision. In my experience, the part-to-part conformity of the Toshiba
parts has always been excellent.
What we really need here is that Eff-ing price slasher guy
who'd slash the price of the cars during the "Creature Feature" breaks.
We need the price slasher to help us regular folk so we can buy some of these
devices.
As that's not likely to happen I take solace--drinking to my
Harvey Wallbanger posters as I shudder in fear at the thought that
the "Creature of the Dark Lagoon" may infact have been reel.
Cheers
who'd slash the price of the cars during the "Creature Feature" breaks.
We need the price slasher to help us regular folk so we can buy some of these
devices.
As that's not likely to happen I take solace--drinking to my
Harvey Wallbanger posters as I shudder in fear at the thought that
the "Creature of the Dark Lagoon" may infact have been reel.
Cheers
NAC Semi seems to be the distributor of all manner of Linearsystems JFETs including LSK170/LSJ74, LSK389 etc. I just received from them a bunch of surface mount devices. Prices -- well that's what makes markets.
Many here have already published circuits which, instead of 2SK170/2SJ74, make use of JFETs readily available.
Be it 2SK209, 2SK2145, J113, ..... etc.
True that they are not direct replacements.
And they are not 1:1 comparable in performance.
But anyone can still build very nice sounding amplifiers with a limited budget.
The UDNeSS, for example, uses 4x 2SK209GR and 2x FQA9P25.
The JFET costs less than 40 cents a piece; the MOSFET less than 2 USD each.
There is no reason to complain if you do not want to pay for those unobtaniums.
But of course there are good reasons why they cost what they do.
A matter of supply and demand.
Cheers,
Patrick
Be it 2SK209, 2SK2145, J113, ..... etc.
True that they are not direct replacements.
And they are not 1:1 comparable in performance.
But anyone can still build very nice sounding amplifiers with a limited budget.
The UDNeSS, for example, uses 4x 2SK209GR and 2x FQA9P25.
The JFET costs less than 40 cents a piece; the MOSFET less than 2 USD each.
There is no reason to complain if you do not want to pay for those unobtaniums.
But of course there are good reasons why they cost what they do.
A matter of supply and demand.
Cheers,
Patrick