Some question for hard to obtain j-fet/mosfet

[aht]

I'm cloning legendary high-end preamp from Threshold in model Fet-10 HL.

It's use dual j-fet 2N5566, diode protect mosfet 3N172, PN4250A, MPSA42 / 92.

3N172 is very hard to obtain more than other number. How can I use hexfet IRF...XXX... or other mosfet/hexfet instead it ?

I use 2SK289 instead 2N5566 on original PCB it's work


Need a quickly reply
AHT

 

[aht]

ooops...

I use 2SK389 instead 2N5566 on original PCB it's work.

Now designing a PCB. It's coming soon.

 

[Nelson Pass]

3N172 OR 3N173 are difficult to obtain anymore, although
I have a few. You can try a Zetex ZVP3310 as a replacement.

Availability of the 2N4250 should be OK, otherwise you can
substitute any high gain (>400) low noise PNP, and the
MPSA42 / 92 are generic in this circuit.

 

[steenoe]

Now designing a PCB. It's coming soon.

Sorry to ask, but are you gonna make those available to DIY members?
Legendary?
I have memories about the Threshold 400A and the 4000 back in the late 197x'es. That was the times! The amps mentioned was just about the highest regarded, at that time You should hear those connected to a pair of JBL 4330 studio monitors!!!!
Wauw, as far as I remember I am still suffering

Steen.

 

[aht]

Heaven of DIY

Thanks for your reply Mr.Nelson Pass

Now I use ZVP3310 instead 3N172 it's OK but I feel some difference after increase a gain it's too much more than original...( I think) maybe it's the effect of 2SK389 which I instead of 2N5566

Today I try to reduce a gain and make a PCB I like your GOLDPLATE PCB it's look so beautiful now I'll modify to single layer for a low cost PCB.

I'm to be convince about this product model very much.
It's use J-FET circuitary which best of the world



regard
AHT

 

[Nelson Pass]

You can try various Source resistance values for the ZVP3310
to lower the gain.

In my experience, there isn't a huge difference between the
2N5566 and the 2SK389.

 

[aht]

Mosfet again...

Could I use IRF9610 instead 3N172 ?
Why does THRESHOLD use 3N172 not ZVP3310 ? (or zetex there isn't this product ?)

Is the FET-10HL or FET-10E who newer version ?

Thank you very much
AHT