Fitting the Reed to the Mouthpiece - The "Pop" Test

Every once in a while, I find a reference to testing whether the reed and mouthpiece are compatible by using the "pop" test.  That is where the air is sucked out of the mouthpiece, forcing the reed to seal up, and then watching to see how long (or whether), the fit is good enough for the reed to "pop" loose after a period of time.

I'm not a big fan of the test, as I don't believe that it answers all of the issues of whether the reed is compatible with the mouthpiece (or mouthpiece compatible with the reed).  Sometimes an incompatibility can show up as "resistance," which some players prefer.  Sometimes incompatibility shows up as a combination that easily subtones.  Sometimes an incompatibility can manifest as an easier altissimo or effect the intonation of different registers.  

Clearly, "incompatibility" is too strong of an accusation.  How the flex of the reed agrees with the lay of the mouthpiece has both good and bad results, and a simple "pop" test doesn't address all of the variables.  For instance, I've found that when sucking the air out at just the tip, I can usually hear air already leaking in further up the lay towards the ligature.  That generally doesn't matter, as that's where my lips will be when actually playing and my embouchure will take care of any "incompatibility" there.  In fact, not having a perfect match right there probably gives the player more flexibility in using embouchure to control the reed, and thus the complexity of the sound.

The one instrument I have that seems to want a lot of compatibility is my contrabass clarinet.  It could well be that my lack of familiarity with the clarinet, and the difference between the contrabass clarinet and the saxophone embouchure, requires that I have a facing that is smooth and predictable.  For the contrabass, I like the reeds that pass the pop test.  What is a passing grade?  Here's one.  You might need to hit the "full screen" icon at the lower right before you start in order to see the tip clearly. 

I had to work on this reed quite a bit to get it to this point.  I then suck the air out of the mouthpiece (and the "barrel" in this case) and see how it holds.  When it holds the vacuum this long, I know that the low bottom notes can pop out with just a puff of air, changing registers will be more fluid, and the high notes will have more volume.  All of that only happens once the monster and the giant slab of cane is warmed up, of course.