For a while now I've been using a pickup on my clarinets. I am dealing with two problems, one is that some effects are louder than others, the other is that some notes are louder than others. The former is much more significant but I pretty much found ways to deal with it. The latter is less significant but a bit more tricky.
In theory I would need an extremely accurate EQ since at first it seemed the problematic notes were very specific, not in areas. I was also sure the problem is the pickup. Some suggested it could be the pickup position, which I considered, but I tried a different position the result is the same. It is also possible that this note and others are just louder on the instrument, but only listening from very close (from the inside in the case of the pickup) makes it obvious. They sound even when just listening or when recording with microphones.
I also considered that it is not the pickup, but the room, speakers, etc. but I remember the same exact note (the most problematic one) being loud in several rooms and types of speakers. But if I use my headphones, there is no problem.
I looked at the db of each note and the "louder" note was actually not louder than a note just one tone under. But the sound was a lot more "bassy" or "boomy". This sounded like the problem to me. I was able to see the actual frequency wave of each note (thanks Pete) and they looked very similar...
So... I still want to see if it's not a crazy coincidence that most of where I played had something that resonated with this note. It is the (concert) C approx 131Hz. In this sample I notice that the note just before it and the couple of notes after it are also a little "boomy", with the C being the worst.
I'm interested if anyone else can listen to this sample and see if it sounds like that to them too. BTW if I listen pretty quietly, there is a lot less of a problem, but it's possible my speakers, audio card, etc. reduce lows at low volume, I don't know. Though I can definitely hear it before it is hurts-my-ears-loud. Maybe my speakers and most others happen to reduce lows around 130Hz, so notes from that area nad above will have a clearer fundamental, and higher notes will reduce "boominess" by simply being higher.
Sorry it is played so fast, maybe I can get a better sample sometimes, but this is what I have now. It is (all described in concert pitch!) G to E. The most problematic when I hear it is C, the 6th note. B, C# and D also have some boominess, but less. All notes from Bb and under don't have it at all. Is that the same for everyone?