[Agent27]

But shouldn't an alto mouthpiece by itself play A concert?

 

[Agent27]

Yes, when somebody brings up the "mouthpiece exercise" and says "play an A on the mouthpiece", they mean to play a concert (piano) A and not an A on the saxophone.

You can go here and get a concert A.

http://www.onlinetuningfork.com/

For a longer sustaining note (and accordingly more annoying), click here:
http://www.saxlessons.com/Sine440.ram

I actually think this last one is a tad flat.

 

[Agent27]

Yeah, but those pitches refer to concert pitch. An alto mouthpiece should blow a concert A, a tenor mouthpiece should blow a concert G. He didn't make that distinction but he should have.

And yes a Concert A = F# on alto sax.