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I've seen some posts on this but haven't found any answers.

Has anyone added a yfb-621 5th rotor to a ycb621?

If so, did you cut the stock c mouthpipe or use the f mouthpipe?

Was there any difficulties found with pitch after the conversion?

Any other thoughts, concerns, or parts for sale?

I will be doing the work my self as I own/operate a repair shop outside of Chicago, but I thought I would check on input from others that perhaps have done this or tried one that has had this done to before dropping the cash and my time.

I've been primarily an orchestral player that is starting to do more quintet work and need something WAY smaller, but I also need to have access to the full pedal range and this horn has no false tones. Yes, I have an F, I've tried it but the sound is still too big for what I'm looking for.

Thanks in advance for the help

Yeah, I've gone through the Yamaha parts website and see the options... I'm a bit surprised at how much the F mouthpipe assy is... Makes me wonder if the rotor comes with it compared to what it costs to get a C mouthpipe that I can cut up and if it doesn't work out, oh well I put the stock part back. I'm also curious if they have different tapers.

I will.

I'll say the pitch is not high on the C.

My thought process is in line... Just bummed on the price for the f mouthpipe... It's super high... Even at dealer cost. True, if it works out I have a great little horn to use and the benefit of the added resale value. I would also guess the tapers are different... Guess I can grab the calipers and find out if it's straight near the end or not.

I've know of two people to do this, and the horns were great. Both at Bowling Green in the 90's....

Any chance you can get in touch with them and ask what mouthpipe they used?

OK so I had a YFB-621 at the shop today and the mouthpipe outer diameter right before the ferrule for the rotor is measuring .060" small than the YCB-621 at the same distance from the receiver.

Elephant, you're correct, the F leadpipe is smaller. I get approximately an inch shorter after accounting for the length of the rotor than the C leadpipe.

Now I'm not sure what to do... why the heck would Yamaha make the C mouthpipe larger than the F mouthpipe? The ferrule into the pistons does seem to be a similar outer diameter and the main slides are identical.

I'm considering moving back to the "cut the C mouthpipe" idea. I'm a little concerned about the rotor being a smaller diameter than the leadpipe. I suppose I could always make a spacer if I have to account for extra room under the ferrule. Any thoughts? Any spare parts lying around that you wanna sell me?

Thanks for the input. I know there's people who have done this. I'd really really like to hear from someone that has already played this guessing game.

There is a picture at this link of Tom McCaslin's custom Yamaha 621 C with the changes. There was also one of those "Jim Self" model Yamaha's for sale not too long ago as well that I couldn't find. Hope this helps.

viewtopic.php?t=71596&p=583104

Maybe this set up would be a good option for you.

https://wessex-tubas.com/collections/tu ... agey-te465" target="_blank" target="_blank

Not to hijack this thread, but I'm not interested in the 5th valve for my 621CC. I would be interested, however, in the larger bell. How can I get one??

Well... It continues...

Sam- thanks for the idea, I don't think it's going to work for my situation. I will be standing and playing this horn and I think the 5th valve tubing will get in my way. Otherwise I think it could work. There's also the possibility of putting it in far side of the tuning slide but I will be flying with this horn and that could cause case issues.

I think mouthpipe is best option... Might be going with generic allied pipe. Another thought someone presented is if I want to consider a larger valve/tubing than .689 for the valve. Geez... Get closer with one answer and more questions come up. Turns out the bore of the mouthpipe where it connects to the valve set is larger than the valveset bore...

Actually I appreciate that info. I haven't done much with the allied pipes as most I've done I've been able to get parts from the manufacturer. Of course, I've done plenty of French horn pipes with the allied generic pipe.

I'm waiting to hear back from Craig about what one was used on the Getzen G50.

I've also got a call in to Wayne at yamaha to see if he can offer any insight from their end... I'm not expecting much but never hurts to ask.