I have two brass Dixon Trads (not the solid brass), so I decided to try the cavity fill on one of them. This was my first tweaking experiment.
I thought I had some poster putty around here but couldn’t find it, and it’s too cold to go out to Staples to buy some, so I ventured into unknown waters. I used bathroom caulk.
The first thing I have to say is: This is a bad idea. Don’t do it. I knew it was a bad idea before I started but thought I’d try it anyway. And I wasn’t even drinking.
I have a small “patch” tube of white latex caulk, so I thought I could release it straight down into the cavity, no muss, no fuss. This was crazy, of course. The stuff doesn’t come out in a straight line, so although I filled the cavity, I also got caulk everywhere–but none in the windway. I got some around the windway, but none in it.
Well, I chalked, or caulked it off as a learning experience. When the stuff started to get firm in a few minutes, I used a pencil to tamp it properly in the cavity. Then I decided to see what I could do about cleaning the mess I’d made inside the mouthpiece. This took a couple of hours, using carefully cut plastic strips, but little by little I was able to get the stray bits of caulk out. I used one of those ultra-bright LED lights to check inside, and each time I found a bit I’d reach in with the plastic strip and pull it away.
To my astonishment, I eventually got it all out. The surface of the area where the cavity is filled isn’t smooth; it looks like the surface of the moon. But I got the all-important area under and back from the blade nice and clean, and the ramp is impeccable.
So, the cavity is filled with latex caulk that is now firm in its stippled ugliness, should anyone ever peer in there. The sound is…well, it’s what I expected, based on reading this thread. The bottom D and E are stronger than on the other Trad, but the timbre is softer. Having them side by side, the difference is very clear. The bell note on the untweaked Trad has a slightly “dirty” sound; not breathy but not pure either. I’ve never liked that aspect of the Trad. It breaks to high D very easily, although I’ve had these things so long I don’t notice that.
The tweaked Trad breaks to high D less easily and has a slightly breathier timbre. It’s a definite improvement, and the same observations apply to low E. After that, they sound much the same.
Interestingly, filling the cavity makes the Trad sound much like the Hermit Hill brass whistle I recently bought, since one of the main differences between the two is the bottom end. But with the cavity filled, the Trad is now a bit louder at the low end than the HH. Not a big difference though.
In the second octave, I’ve always been able to play the Trad with confidence, and it’s no different with the cavity filled. The second octave is, in my opinion, the best thing about the Dixon Trad.
So, this is an endorsement for doing the cavity tweak on the Dixon Trad, but just don’t do it with bathroom caulk.