Interesting fault

[Dibbs]

In all my years I've never come across this fault before.

The multiphonic low E here.  I've never heard anything like it before.  I'm not growling or anything like that.

https://app.box.com/s/xktd221m8drawbv5mvtz2pc7hnu35vby

I've fixed it now but let's see if anyone can guess what the cause was.

[Dibbs]

Clue:  It only happens playing loudly.

[jdbassplayer]

Seems like a spring issue. One of your keys is opening slightly when you play causing the fluttering sound. Most likely this would be the F#/C# key but could be any key held down under spring tension. Try pushing the pad cup down somehow while playing and see if it goes away.

-Jdbassplayer

[Dibbs]

Dead right Jared.

It was a weak spring on the Ab/Eb key.  It was originally too strong and I'd been trying to lighten it but I overdid it and this happened.  I've never come across anything like it before.  It only affected the low E.  Every other note was fine.

[LarryS]

A bit of sympathetic vibration. Would be neat if all the notes sounded like that 😉

[Dibbs]

A bit of sympathetic vibration. Would be neat if all the notes sounded like that 😉

A barrel with a membrane in it like a kazoo might be interesting.  The Chinese dizi flute has that sort of arrangement.

[modernicus]

I've had this exact problem before.

[Windsong]

Jd--that was my assumption, too.  Failing that, I would have guessed a torn fish skin on a pad, that was not completely disengaging from the tone hole whilst lifted.
Thanks for sharing that, Dibbs.  I love puzzlers.