Djeez, this dual jfet has 0.3 nV/sqrt(Hz) at 100 Hz. Great for a MC amp isn’t it:
http://www.interfet.com/pdf/DS_IF3602.pdf at
http://www.interfet.com/
Only problem is minimum order is $500
Cheers 😉
http://www.interfet.com/pdf/DS_IF3602.pdf at
http://www.interfet.com/
Only problem is minimum order is $500
Cheers 😉
...and it has a gm of 750 !!! This would be really worth a try!?
input capacitance is not low. Doesn't it count?
Someone found a source for purchasing say 20 items or so?
Rüdiger
input capacitance is not low. Doesn't it count?
Someone found a source for purchasing say 20 items or so?
Rüdiger
GM=750mS=0.75
Other potential problem is low power dissipation of 300mW for entire device.
Petter
Other potential problem is low power dissipation of 300mW for entire device.
Petter
Petter said:
Do you usually need more for typical low-noise applications
like MC input stages? Seems quite sufficient IMHO.
Sorry, this definitly can't be true. You'll end up with a damper instead with an amplifier...
Rüdiger
Hi,
A Gm of 750 mS looks a bit high indeed. Here is a bit more about the chip:
http://www.interfet.com/pdf/P_NJ3600L.pdf
No need to e-mail Interfet, they simply will give you not more info than what is on the WEB-site.
Note that this is simply a very large area jfet-chip that acts like many smaller jfet-chips in parallel. The large input capacitance is not an issue IMHO regarding the 50-100 ohms resistance involved with MC amps.
I got this hint from an old colleague at the University of Delft. For that 500 bucks you get app 25 fets. It is excluding VAT and duties. Interfet does not keep them them in stock, they produce on order. He measured a real 0.7 nV/sqrt(Hz) at 10 Hz and room temperature. He has still a lot in his drawer but refuses to sell me a pair
At the moment I use the 2SK389’s but these become rare and expensive nowadays. Also these are not well tailored to low source resistances regarding noise.
Cheers 😉
A Gm of 750 mS looks a bit high indeed. Here is a bit more about the chip:
http://www.interfet.com/pdf/P_NJ3600L.pdf
No need to e-mail Interfet, they simply will give you not more info than what is on the WEB-site.
Note that this is simply a very large area jfet-chip that acts like many smaller jfet-chips in parallel. The large input capacitance is not an issue IMHO regarding the 50-100 ohms resistance involved with MC amps.
I got this hint from an old colleague at the University of Delft. For that 500 bucks you get app 25 fets. It is excluding VAT and duties. Interfet does not keep them them in stock, they produce on order. He measured a real 0.7 nV/sqrt(Hz) at 10 Hz and room temperature. He has still a lot in his drawer but refuses to sell me a pair
At the moment I use the 2SK389’s but these become rare and expensive nowadays. Also these are not well tailored to low source resistances regarding noise.
Cheers 😉
At that price it is a theoretical discussion at all...
There seem to be just a few fets suitable for audio (that are obtainable), if one searches the archives here.
Rüdiger
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