Date: 2021-08-12 20:58
I had a similar issue when I was playing Yamaha CSGs. It has a different bore than your CSVR, but the low A was also quite sharp. I found the problem could be made better or worse by certain mouthpieces, but off the top of my head, I couldn't tell you what mouthpiece made it better.
In either case, my main fix for the note was "shading" it. To do this, you take your 3rd finger on your right hand, straighten it out against the roller (I believe that's the name for the long metal tube that allows the keys to move in unison) and vary its proximity to the tone hole. Just to clarify, you aren't actually covering the tone hole, but your finger does get pretty close. Experiment moving it closer and farther away to find the distance that allows you to play the note in tune. This method allows for a wide degree of intonation fluctuation and requires some practice, but it's adaptable to pretty much any chord when playing with others.
The alternative for people who want more consistent, reproducible results without needing to practice it quite so intensively, is to experiment with your pinky keys. Trying adding different pinky keys to your low A, (generally the F#/C# key is a good place to start) and see if that brings your pitch sufficiently down.
Both of these options will change the timbre of the note, but I think its a worthwhile trade to be able to play it in tune! I hope my descriptions make sense, let me know if they don't!
Post Edited (2021-08-12 20:59)