I have several Soundtraxx-equipped engines, and I have noticed that some are louder than others. They're all basically the same decoder, installed in similar Atlas engines, all using 1/2" round speakers with enclosures. I have found that sometimes subtle changes can make a big difference in the sound, like having a decoder face up instead of down or moving it to a different part of the engine. I even had one diesel where I found that some sound was "leaking" out the open cab windows. When I installed glazing and sealed them up, the sound was all focused down out of the engine body and sounded much better.
I've found a bigger speaker can generate more sound, so maybe try a bigger speaker - if you're using a round speaker, see if you can fit an oval shaped one in, or a larger round one by tipping it on it's side etc.
From your description of the speaker mounting, I'd say the sound has no escape path from inside the shell.
Did you properly isolate the back of the speaker so it doesn't cancel out the front waves?
In other words, is the front of your speaker exposed to the outside, and the rear of your speaker pointing towards an enclosed/sealed container?
A larger capcitor will do nothing for sound on the tsunami. That's the keep alive capacitor. It will however give you less stalls & hiccups at lower speeds. Try equalizing out (lowering) the bass below 300 Hz.
On the older DSD/LC series the capacitor acted as a hi-pass filter. (Meaning it would filter out bass signals, so that amplifiers output energy wasn't wasted on producing sound the speaker couldn't handle)
The frequency cut off point is defined by the forumula:
Where R = 8 Ohms and C = Capacitance.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
I have done a dozen Soundtraxx installations, in various locos. Most work quite well. One however, in an SD60 seems to have very low volume. I have programmed all the CVs to max, but the volume is still too low. I am running out of ideas.
Tonys says to use the largest capacitor you can fit into the loco. Soundtraxx always includes a small 33mfd capacitor with the decoder. Can I get more volume if I use a larger capacitor?
I may also try a different speaker, to see if it is defective. Thanks for any help.