I'm fairly new too, and I have similar experiences. I find that the force I exert on producing the note affects the note I get, and I think more force produces a higher pitch, but then softening the force brings the note down to the one I wanted. Try to go from the low pitch up to a high pitch, just to understand what I am talking about, and then practice softening the production of the notes, (I think called the attack).
Having said that, I am new to sax, just a couple of months, and I could be very wrong.
I hope this comes across OK.
Assuming your set up is OK (Sax in good order, reed and mouthpiece manageable and in good order).
There are many things that can effect producing a note that you will one day get right and just take it for granted.
How's your embouchure?
Not too tight, your jaw/lips will soon ache.
Not too loose, you'll leak air and probably slobber the sides of the mouthpiece.
Bottom lip should be over your bottom teeth and allow the reed to rest gently on it.
Top teeth should not bite the mouthpiece, though this seems to be less important as many good players have gouged the beak of the mouthpiece over time.
All in all as a beginner you will tire quickly but each time you pick up the sax, think comfortable embouchure.
There are many good explanations of correct breathing and air support and Pete explains it on the main site.
In short, you need support/control from your diaphragm to release a full body of air consistently.
Make sure you can achieve the two points above by being in a comfortable standing position. You can sit down but to start with, as you absorb the benefit of good embouchure and breathing, it seems easier to think about and monitor from a standing position in my opinion.
They are the basics.
When you learned to ride a bike, what stopped you wobbling about and finding good balance is probably hard to describe...but you did it right? so have confidence, its a matter of time.
Hi guys, all that Saxlicker has said above is quite correct, basically your muscle memory will improve the more you play, your lips (embouchure) will gain strength and help to support these notes.
A good thing to practice is playing "long tones" simply take a nice deep breath and play a note. Play one that you find easy and hold that note for as long as you feel comfortable. Push the air out slowly using you diaphragm and support the airstream in this way. All the time that your playing it, listen to it carefully, hold it steady and don't let it waver. This will help to build you embouchure quickly and will cure your problem (I hope)
i think most beginners have experianced this...i know i certainly did and posted a very similar question on the old forum...all i can say is IT WILL get better the more you practice. I cant remember which member gave me this advice but it certainly worked for me ( after a while) but basically you have to try to visulaise trying to `Blow the high notes and Breathe the low notes`...if you try it it sort of gets you to open up your throat a bit and the low notes just come. But like i said earlier i think its a common beginners problem which will almost certainly disappear with time.
Good luck...dont give up