Hi all,
Just curious as to what available (as in, lots of stock at RS, E14, Digikey, etc) fets or mosfets are you guys using in your small signal audio designs? Be it buffers, phono pre's, regular pre's, you know, the lot.
I'm not looking for superexpensive vibranium made devices, just your usual runofthemill "hey this works pretty good for me" components.
Cheers,
Alberto
Just curious as to what available (as in, lots of stock at RS, E14, Digikey, etc) fets or mosfets are you guys using in your small signal audio designs? Be it buffers, phono pre's, regular pre's, you know, the lot.
I'm not looking for superexpensive vibranium made devices, just your usual runofthemill "hey this works pretty good for me" components.
Cheers,
Alberto
The DN2540 is one of my favorites to play with.
https://www.mouser.com/datasheet/2/268/DN2540%20B060313-965103.pdf
It's a depletion mode N-MOSFET, kind of a rare beast. Capable of quite good linearity if you cascode it and run at around 10mA with a source resistor, and handles high voltages. Also good if you need a high voltage current source.
https://www.mouser.com/datasheet/2/268/DN2540%20B060313-965103.pdf
It's a depletion mode N-MOSFET, kind of a rare beast. Capable of quite good linearity if you cascode it and run at around 10mA with a source resistor, and handles high voltages. Also good if you need a high voltage current source.
Toshiba has a very nice range of lower voltage MOSFETs with excellent characteristics (in particular gm) - here's one example I've used quite a few of so far :
SSM3J327R,LF Toshiba | Mouser
Mouser's currently out of stock, expecting a delivery next month.
SSM3J327R,LF Toshiba | Mouser
Mouser's currently out of stock, expecting a delivery next month.
IRF610 has been a favorite since the dawn of internet and PassLabs...
My understanding is the capacitances associated with semiconductors is nonlinear. That is it changes depending on voltage. So I always look for devices with minimum capacitance. Of course the effect does depend on which situation the FET is being used, follower, gain stage, etc.
But I may be wrong and select out of the wrong criteria...
My other understanding regarding MOSFETs of today is they are exclusively made for switching duties. Up untill a decade ago I believe they still made FETs for linear duties. This effects their durability more than linearity I think.
But also the packaging is getting less and less diy friendly. Leads have inductance, and in switching duties any and all inductance is bad.
It would be interesting to make a jig where different MOSFETs can be plugged in/out in a moment, and measure each's distortion, bandwidth, noise, gain, etc.
I've got some FDT86256 but havent had time to try them yet.
My understanding is the capacitances associated with semiconductors is nonlinear. That is it changes depending on voltage. So I always look for devices with minimum capacitance. Of course the effect does depend on which situation the FET is being used, follower, gain stage, etc.
But I may be wrong and select out of the wrong criteria...
My other understanding regarding MOSFETs of today is they are exclusively made for switching duties. Up untill a decade ago I believe they still made FETs for linear duties. This effects their durability more than linearity I think.
But also the packaging is getting less and less diy friendly. Leads have inductance, and in switching duties any and all inductance is bad.
It would be interesting to make a jig where different MOSFETs can be plugged in/out in a moment, and measure each's distortion, bandwidth, noise, gain, etc.
I've got some FDT86256 but havent had time to try them yet.
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