If there is any technicians here yet, I’m wondering what changes are possible to a soundboard to give the tone more bass weight or body. (Less ‘thin’ sounding).
Assuming you can change the soundboard, what can be done?
Would making the ribs wider or taller help? What are the trade offs?
Soundboard design changes to get more ‘body’ to the tone
musicbased A technician who posts on Youtube under Chernobieff Piano has made many videos on soundboard design.
10 days later
This is a great question and the best answer really is - it depends.
There are techniques that can sometimes change the response of the entire instrument, improve elements of the performance, etc. The actual model of piano that we are discussing will dictate possible changes.
Lastly, you specifically asked about a better bass response and suggested a different rib design. Yes, this is a technique that might help. It all depends on the instrument. To me, balance is the key in a small piano. I played a small Chickering worked on by Ed McMorrow that impressed me. His solution included hybrid stringing.
Tell us more about the piano in question. If we can’t help you here, we can certainly direct you to others.
Rich Galassini, Owner
Cunningham PIano Company
Rich-Galassini Thanks so much for the reply.
Yes its a very small piano, the size of the old 132 Wurlitzer or Stohmenger half round shape.
Would love to know more about the hybrid stringing. Hopefully Ed will join here too one day! I’ve always been interested in trying out his pianos. I’ve heard lots of good things about them over the years.
I’m actually going to try using low tensile wire for the bass strings too, it will be my first time using it, but wonder if there is more things to try in terms of stringing.
Which would be better in terms of the ribs? Wider or taller? Do the two independently produce different results? (Wider vs taller). I’m guessing it’s a question of mass vs stiffness. How far can you go before bad things start to happen and what would the be the result of going too far?
I suppose it’s hard to know for sure until the end 
Oh, the physics of it!!...
Back a few decades, when I was privileged to attend a few PTG conventions, I got to sit in on some classes and a few after-class discussions among the likes of Del Fandrich and Ron Nossaman. They had forgotten more than I'll ever know about such things. But I admire those who have followed some of those bunny trails. Unfortunately, I believe Ron passed away a while back, it seems to be happening with some of the great minds.
Rich G, have you gotten into the weeds on soundboard design?
9 months later
Based on my limited knowledge of violin construction, it's going to be a matter of bridge/rib placement more than anything.
In violins, moving the sound post even slightly can change the response quite dramatically and can affect both tone and volume. Since the violin bridge is positioned right in front of the sound post, the two work in harmony to affect the overall tone and playing response. I would suspect that it is similar in pianos only using multiple ribs instead of a sound post.
A guitar maker might have additional insights since guitars have more ribs inside than a violin. There's also going to be a limitation based on the wood thickness/shape/quality of the soundboard. If the tone isn't there, it's not there and you're not going to change that without major surgery and even that's going to be a gamble.