I recently (15 months now) began playing euphonium after 50 years of contrabass tuba. Upper range has been an uphill battle (pun inevitable), but coming along. My low range constantly increases. This morning I was able to hit C1-- yes, 5 ledger lines below the bass staff. I am curious: what is the low-range limit of a compensating euphonium? If Bb1 is the fundamental, I would assume a seventh below that is "it," yes?