exactly what the topic says

Well I can hit the lowest note possible. triple pedal F. I use a different embouchure though when going lower than the C below the F above the one stated before. How low are you referring too? or what do you have trouble with?

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triple pedal-F is three octaves lower than the one in the staff.

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the lower one in the staff.

What do you mean by "triple pedal F"? It sounds awfully low.

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Just an idea, but you probably shouldn't change your embouchure between ranges because you might come into a situation where you have to jump between them quickly and it could end badly. Though, I don't know where you'd run into something like that.

Most players find it necessary to make some embouchure adjustments over the range - and this is also the case with other brass instruments although the smaller ranges mean that this is less pronouced. Ideally such changes should be small and gradual.

In my experience, pedal notes can't be played - on tubas, horns or trumpets/cornets - with the same embouchure as mid-range or high-notes - in part because a change is necessary in order to play the fundamental for the length of tube ie a pedal note. I don't have the same dynamic range and attack for pedal notes as mid-range notes.

I understand that some players have difficulty descending from the C written below the stave down an octave and most players find descending a further octave challenging. (This requires pedals notes on the Bb side from F downwards and the final C is the first pedal on the F side). I've never found low horn playing difficult regardless of mouthpiece etc although for the very high end of the range I resort to a descant horn as I find this makes it much more secure and easier. I don't know to what extent this is because I developed the low end playing first (contrary to most tutor books).

http://www.youtube.com/watch?v=5XRkCfsiKlY
The lowest note this guy plays here is a triple pedal f (who knows, it might be the same guy that posted saying he could get that low is the the guy in the video!) yeh so anyway if you was wondering what the triple pedal f is, its the last note this guy plays