TubeNet

I was using my electronic tuner today. I just got a contact mic to hook up to it. Mostly, I've seen brass players clipping it to the bell. I decided to try other locations to see if it made any difference. It did. I got sharper readings (c. 20 cents) on the bell than I did clipping it to the leadpipe just beyond the mouthpiece. I also clipped it various other places-wherever it fit- and got differences from one spot to another. I checked to make sure it was solidly in contact wherever I clipped it. I tried to be as consistent as possible with attack and volume at each location. My questions are: Have others experienced this and is there a reason why this happens?

This would be more convincing if you used two identical tuners at the same time (one on the bell and the other on the leadpipe) and had two observers recording their readings.

Better yet, clip two microphones onto the tuba and make a digital recording with them. Look at the waveforms with any sound-editing software, and play the two tracks back through a pair of stereo speakers. If there really is a pitch discrepancy as you describe they you will hear beats.

I have not found any strange behavior like that with my Korg.

I've tried attaching my Korg or Shar tuner at either at the bell or down lower near the tuning slide and the pitch reading is always the same on my euph. I find using a tuner this way though is only good when rehearsing alone. In any group setting, we need to move the pitch around for 'just intonation' depending where we are in the chord.