...A tuba is the same as a string bass...I learned once. I was playing cello in the pit orchestra for a Musical, it was a community production, although we all did get paid. The Musical was 'Kiss Me Kate'. I was the only cellist, and sat at the back of the pit, and the string bass player was cramped up behind me. It was a long run, 8 weeks, and we all had fun...although I did have ONE REALLY BAD OUT OF TUNE NOTE!...
I flipped off the keyboardest as I cooled down...he was laughing so hard...and so was the Conductor...I didn't flip off the Conductor...A Conductor is the 'Ubar of the Orchestra'. Anyway, the Conductor came to me after the 4th week, and said, "We need a string bass for next week, Harvey has something going on." I was a bit of a 'Concert Promoter' then, and he knew that I knew a lot of musicians. I told him, "No Problemo", I knew 8 string bass players...I was sure one would be available. Well, I was WRONG!
They all had other committments, and the players they suggested also were unavailable. I was miserable...I didn't want to have to call the Conductor and say..."I failed". I then got a BRILLIANT IDEA! I called a tubist I knew, and he said, "Sure". The LOOK on the Conductors face was PRICELESS when he saw a tubist sitting at the string bass seat. I just held up my hands, and whispered..."Best I could do"...
...This was a performance, not a rehearsal...
But, as I knew, it went very well. The tubist fit very well with us, and the performance was nice. The Conductor shook the tubists hands with his...I think the Conductor had had a 'near death' experience. He told the tubist..."You can join us any time." Later, the Conductor told me..."Don't you EVER substitute instruments again without GETTING MY PERMISSION!"
But then he laughed, patted my shoulder, and said..."Good job!"
I still, to this day, think it was a BRILLIANT IDEA!