What should I use instead of J201s

[GGBB]

Hi, I want to build some pedals and they all require J201 J-FETs, which are not easy to get. I googled it and there are a lot of replacements like the 2n5458, the 2n5457 and others. Some say they work fine, others say they cant be used as replacement because it will sound totally different ? Is there any FET, which is easy to get an can be used as direct replacement ?

I was in the same situation with J201s and 2N5457s (BSIAB2, Orange Squeezer, May Queen) so I looked at a fair number of JFETs and compared VGS(off) and IDSS values.  Nothing seems to come close.  I don't know if other parameters matter - I suppose they do but perhaps substitutes are fine in that regard.  In my EA Tremolo which calls for a J201 or a 2N5457, I used an MPF102 without any issues even though their respective values aren't that close.  But as others have said, it might not be easy to substitute in certain circuits.  I finally bit the bullet and bought a bunch from Small Bear.

[Texandub]

Ok, which are the important parameters ? I only worked with FETs as switches before, but never as amplifieres.

I've only worked with FETs as amplifiers, never as switches 

Here's the datasheet for the J201:
http://www.fairchildsemi.com/ds/MM/MMBFJ201.pdf

Aside from absolute maximum ratings (although I've never encountered a FET that couldn't handle 9v stompbox conditions), the main parameters relevant to common-source JFET amplifiers are the Gate-Source cutoff voltage (sometimes called the pinch-off voltage), notated as VGS_(off), and the saturated drain current, notated as I_DSS.  I'm not sure how true this is for JFET amplification in general, but the rule of thumb I go by is the lower the VGS_(off), the more gain you can wring out of it.  Both of these parameters affect the input dynamic range, meaning how hot a signal it can amplify without clipping; again this may be subject to biasing method you're using. 

When working with JFETs I usually keep ROG's Fetzer Valve notes up on my screen and use it as a reference for biasing, but while it's a great article, it really only applies to the biasing method they use so sometimes I just have to figure it out.

[merlinb]

The J113 comes close to the J201, with Vgs(off) = -0.5 to -3V, and Idss = 2mA. It's also quieter.
The BF245A seems to be readily available sthis side of the pond, and is vaguely similar, though the characteristic spread is wider.