anyone ever built a clone of the u47 fet?

ive just been glossing through neumann mic schematics, im half having thoughts of trying a clone of the u47 fet. the schem is here:

http://www.neumann.com/?lang=en&id=hist_microphones&cid=u47fet_publications

There are a couple choices of u47 style capsules out there and AMI has a direct replacement for the tranny (anyone else making a similar one?) but i cant seem to find out anything about the actual FET used. i punched the number into google and got nothing. is there a currently manufactured FET that I could use?

any input or other thoughts are definitely welcome...thanks.

A quick way to get out of this if nothing else comes up would be to order it as a spare part from Neumann. It might also be a selected part?

Michael

Try a 2n3819.

[quote author="burdij"]Try a 2n3819.[/quote]
thanks burdij.
i'll be back to bug you guys with more questions about this when i finally get around to doing it...still in the "research" phase.

I looked into it a while back and the the transistor(s) for that were, apparently, made specifically for that mic and have since been discontinued. Maybe you can get a transistor set from Neum@nn?
Ask the Oliver about it.

Don't get hung up of the fet and other transistors.

Neumann used 2n3819s like burdij posted in other microphones like u87s. So that might be a good starting point

Now 3819s have a wide spread of values so maybe breadboard the circuit and plug in different fets that you measured before and see if the voltages match the schematic voltages.

[quote author="Gus"]Don't get hung up of the fet and other transistors.

Neumann used 2n3819s like burdij posted in other microphones like u87s. So that might be a good starting point

Now 3819s have a wide spread of values so maybe breadboard the circuit and plug in different fets that you measured before and see if the voltages match the schematic voltages.[/quote]

thanks for the input gus, nice to hear from a mic master!

cactus, digikey appears to have the bc182b and they have a bc212 (non b, only difference seems to be the current rating). does that make any difference Gus?