Difference between 2n5457 and 2n5458

[jimbob]

Looking at the data sheet/s they look to be the same yet when I bought them earlier the 2n5458 was more than double the price. Does anyone know of any differences between the two as far as the pedals/effects we make around here?

[George Giblet]

They aren't really the same the data sheet does show differences in Vgs(off) and Idss.

The 2n5457 appear to have a little more gain.

The prices of JFET do vary like that.  IMHO it doesn't follow from a manufacturing/spec point of view but one of popularity at a particular distributor.

[Michael Weidenauer]

A few month ago built the JFet test circuit (I think it's by R.G.), sorted all my JFets in gain groups and color coded them (Tropical Fish Fets - the ultimate Mojo-Boost ).

Most Fets were 2N5457 and 2N5458s and though there was the tendency that the 2N5458s have a higher pinch off voltage and higher Ids-on, but both types were in the same range (Vp from 1.1V to 2.4V).
I couldn't find any 2N5458 with values as high as in the Fairchild data-sheets (most of the Fets were Fairchilds).

The other thing I found out was that all Fets had about the same relation between Vp and Ids-on (i.e a J201 with Vp=1.1V and a 2N5457(or 2N5458 or BF245) with Vp=1.1V also had about the same Ids-on).
There seems to be no big difference between a 2N5458 and a BF245A if have the same Vp (also different brands didn't make much difference).

Build the JFet-Test circuit and choose what you need (in most distortions lower Vp values give more distortion).

[jimbob]

Great info!!

[JDoyle]

http://www.diystompboxes.com/smfforum/index.php?topic=71977.0

Also - If I'm remembering right, J201, 2N5457, and 2N5458 are all from the same process (see above post) - hopefully I will remember to check tonight...