Posted by turd on June 09, 2002 at 00:59:10:
In Reply to: Re: Re: Re: Cerveny C Tuba posted by Doug on June 09, 2002 at 00:38:35:
The current and old Amati/Sear/Ziess/you-name-it Czech standard 4/4 rotary model has a .795" bore.
I haven't looked in quite a while, but for years and years the manufacturer simply used the .795" bore rotors and casings on the .835" (again, I'm not sure if I have the "Kaiser" bore size exactly right) bore tubas by brazing "Kaiser" bore knuckles on to the standard bore rotor casings.
As to problems...I have found these tubas to certainly have their fair share. I'm not sure if the pinched bore in the rotors is a contributing factor. Beyond taste (which pitches happen to play out-of-tune, tone quality, response, etc.), the most disturbing thing to me about many of the large Czech tubas is their signature "death rattle". That is, when I try to play FFF low pitches on these tubas, the sound starts and stops and starts and stops and starts and stops (very fast), etc. I could blame it on "me", except for the fact that it only happens when I try to play big Czech tubas very loud in the low range.
Jay B. apparently believed that the mis-matched rotors were the main problem on these tubas, as he paid someone to do the very risky and tedious job of grinding material out of each rotor body to open the rotor bore scoops to approximately the correct size.