Orange squeezer,heartthrob How critical are the transitors specs?

[biggy boy]

I'm working on populating two circuit boards right now and realize I don't have any of the spec-ed transistors that are called for in these to builds.
How critical are these exact transistors?
Can another transistor with the same hFE and a voltage rating capable of handling the supply voltage, be used.
For example Hearthrob Tremolo calls for 2N5088.
Can I use BC547C or a BC549C which have an hFE approximately the same and the voltage rating is adequate?
The BC547C is also a low noise transistor hFE = 420-800
2N5088 = 300-900

Thanks
Glen

[R.G.]

For the vast majority of applications, any small signal NPN will do. Keen's Second Law is "When in doubt, use a 2N5088", but you could also put many other type numbers in there.

On the orange squeezer, though, you're in a world of hurt. Those are JFETs and NPNs won't sub in there at all. Well, OK, they will sub in there, but it won't work right.   

[biggy boy]

On the orange squeezer, though, you're in a world of hurt. Those are JFETs and NPNs won't sub in there at all. Well, OK, they will sub in there, but it won't work right.   

LOL ya forgot to talk about the Orange squeezer and what Jfets I could use.
" you're in a world of hurt. Those are JFETs and NPNs won't sub " I was reading about that last night.
When I googgled  2N5457 Keen's rules was one of the search results that came up, good info!
Well I've decided to go to the suppliers tomorrow and pick up some of the 2N5457.
So I guess you can't recommend a replacement for the 2N5457, in-case they don't have them?
Oh and then there is the JRC4558 that I don't have, for that I was planning on using an TL072 or an JRC 8011?

Glen

[arawn]

for the orange squeezer you can safely use either a J201 or an MPF 102 in exchange for the 5457. Also a tlo 82 will work but with reduced output or if you can get your hands on a rc 4560 it is a lower noise version of the 4558

[biggy boy]

for the orange squeezer you can safely use either a J201 or an MPF 102 in exchange for the 5457. Also a tlo 82 will work but with reduced output or if you can get your hands on a rc 4560 it is a lower noise version of the 4558

Thanks
That's great info.
I ended up ordering 3 RC4558  on EBay will get them in a week
But still need the trannies. I'm going to have to make a trip to the suppliers this week. I don't seem to have any of the suggested 5457 replacements.
I have on hand TL072, TL082, LM358N, TLO272acp, IL4218 and 24LC168

I find it funny how I can have close to 1000 components, yet I never seem to have enough parts to make a project.