I've played Bb Soprano clarinet for around 2 years, and about 10 months ago I decided to flesh out. Learned Soprano Sax, got a Tenor, and just today I've recieved a Bass clarinet. I purchased some Vandoren Standard 3 1/2's (on Soprano I play Vandoren 56 5's) to start off, and immediately started noticing major problems .

From Eb3 to G4 produce decently, although a little airy. Ab4 to Bb4 produce perfectly. B4 - E5 are slightly difficult to produce and are extremely airy, and F5 - C6 are EXTREMELY difficult to produce, and when they do it's so airy, it's hardly musical. C#6 on up are alright although, again, airy. I am thinking there must be quite a few air leaks, but before dropping the money on repairs, I want to make sure I'm not doing anything wrong.

Are there any embouchure changes needed when moving from Soprano to Bass?

<Added>

Just to add to this... I've been playing now for a good few hours or so, and the problem seems to be slightly self alleviating... Eb3 - F#5 now produce just fine, although it starts to get a bit airy in the higher parts of that, and G5 up is playable, however difficult production and very airy tone quality. I'm hoping the problem will do itself away if I just keep playing but I would still like to know what's happening.

Here's what my chromatic scale, E3 to C6 sounds like. (Still working on getting Eb6 in there :) ).

http://www.thesaladcaper.com/stuff/bass_e3_to_c6.mp3

i dont play the bass, from listening to the scale, it sounds like like the reed is the problem. try playing with a different reed, or a softer one.

i sometimes get those problems with the Bb soprano, and its usually the reed. i would also check that all the keys move freely and that all the springs are attached and working properly, as it may not be sealing properly, making it harder for you.
good luck, i hope it works

From the sound of your scale, I would reccomend trying a softer reed. When I first switched from soprano to bass, I had been using a 3 on soprano and moved down to a two, because that was what my director gave me, then moved up gradually to 2.5 and now play on a 3 (4 years later, mind you) Just becuase you use a ridiculously hard() reed on soprano doesnt neccesarily mean that's what you'll want to use on bass.
Try eitehr a softer reed, or moistening it a lot before you play. you may just need to break it in, new reeds can be beastly on bass clarinet.

It doesn't sound too much like the horn itself is having problems, fortunately. Be nice to the thing and maybe it'l stay that way, bass clarinets get out of ajustment so annoyingly easily.

embouchure-wise, if it seems to you like it might be the problem, play around, and try loosening and tightening on different ranges. The embouchure is slightly different than on soprano, but it tends to come with time, and is harder to describe. still keep your corners tight and your chin flat, though!
btw, USE LOTS OF AIR. this is a neccesary part of getting a good full sound on the bass clarinet.

good luck! let us know if you have success!