Bb/C 4 Rotary Valve Euphonium

[sugawi]

There’s Bb/C 4 Rotary Valve Euphonium I’ve been looking into but never read good reports about intonation. Someone posted one for sale on eBay stating that intonation is not perfect and included following video which is his own recording:
https://youtu.be/tQd1i74SzdY
I have asked him about it and what slides, key of Bb or C he is using and got his response but not sure I understand everything. I’ll post it here maybe someone can help me explain:
“Use a different bar to sound intonationally pure. The bar for Bb and for C is the same. Changing the build is to change the functionality of the pipe.”
When I asked for clarification I got this response:
“I mean I replace some rotors with others.
For example, the tone C instead of 1 rotor plays it with 4 rotor. No customization.”

Here’s the link to his listing: https://rover.ebay.com/rover/0/0/0?m...2F222906164534
PS: Seems like the same design/manufacturer as offered by Schiller:

[58mark]

those are terrible instruments. I had one for about 10 minutes before I put it back in the box and returned it

[highpitch]

A chunk of garden hose with a funnel and a mouthpiece would sound better...

DG

[sugawi]

Seems like in order to play in tune he had to come up with different fingering system. He writes that to play natural C which normally would be 1st valve he has to use 4th valve and so forth. Description as terrible and garden hose sounds about right. I just surprised that someone with that kind of playing skills would even want to learn new fingering and do a performance like that.