What are the advantages to SMD jfets besides avalibility?

[GrooveChampion]

Are they easier to bias?

[nocentelli]

I've heard people say they are more consistent, i.e. pieces from within the same batch are closer in spec to each other than through hole equivalents.

[Pavlos]

I've only had 50 each of the SMD versions of the J201 and 2N5457 from http://www.diyguitarpedals.com.au/shop/ but found they were very consistant specs

MMBFJ201
VP range 0.478 to 0.771
IDSS range 0.25 to 0.62
of those I had identical (To 2 decimal places, 3rd decimal place very closely match) 6 pairs, 3 groups of 3

MMBF5457
VP range 1.231 to 1.47
IDSS range 0.232 to 0.299
of those I had identical (To 2 decimal places, 3rd decimal place very closely match) 7 pairs, 2 groups of 4, 2 groups of 5

[GrooveChampion]

So lets say I want to build a Phase 80, it would be easier with SMD Jfets.

[Pavlos]

Well as long as you get a large enough quantity of a particular type of SMD JFET, the chances of you having very closely matched groups suitable for the likes of a 4 stage phaser is far higher than with the through hole JFET's. So yes it probably would be easier

Other advantages of SMD JFET's is that they are considerably cheaper and more easily sourced than the through hole versions, with far more consistant specs.

Disadvantages are that they are fiddly little blighters (They are tiny) and you need daughter boards (Not expensive) to use them as 1 for 1 replacements of the through hole versions. Doesn't take too much practice to be able to manage it though, just a bit of care and a steady hand if you check out the SMD threads there is a lot of useful information and tips

Personally for JFET's I wouldn't waste time and effort chasing down through hole versions any more, when you can find them the prices are ridiculous and quality is very hit and miss (At best useable, often poor to useless)

[Beaker]

As mentioned, they are much more consistent, due to improved manufacturing and quality control standards. They are also very cheap, which is a big advantage - even when you include the adapter boards.

What this means in practice, is that in a circuit with multiple JFETs, you can buid it fairly safe in the knowledge that you can just take them out the packaging, mount them on the adapter boards and solder them in without any testing or sorting; and that it will work correctly with minimal biasing issues.

Build several identical pedals and they should all sound and behave pretty much the same. Try doing the same thing with random, unsorted through hole JFETs and you will probaly get extremely variable results.

On that score, if you just want to build it, box it and rock it, they are well worth the extra hassle.