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Just an aside, the patented slides Couturier made were conical on the INSIDE. The OUTSIDES were cylindrical,
The outsides were dual bore, but reversed. In first position the trombone was ALL conical bore.
Extending the slide added a cylindric percentage, but the bore was always increasing.

windshieldbug wrote: ↑Wed Oct 25, 2023 12:37 pm Just an aside, the patented slides Couturier made were conical on the INSIDE. The OUTSIDES were cylindrical,
The outsides were dual bore, but reversed. In first position the trombone was ALL conical bore.
Extending the slide added a cylindric percentage, but the bore was always increasing.

That was my guess as well. Although i haven't thought how to test it, as it likely is very gradual, and it might be possible the inside of the outer slide is conical as well, just still within the tolerances of sliding, with some grease on it, and a good sock what seals the air well?

But yeah, i haven't thought how to measure or verify these speculations, and i also got shown a later era Couturier French Horn with slides, so they did find a way to make slides not effect the sound so much? Or maybe just determined it wasn't worth the trouble?

Anyway, still curious.

The outer slides were cylindrical, only the inners were conical.
And after Lyon &Healy bought Couturier they went to dual-bore valve slides as a cost savings.

Bump on behalf of the conically curious.

Likewise, although i'm not holding out hope for a BBb tuba. I would try to follow up on a helicon though, if any were out there.

MiBrassFS wrote: ↑Mon Nov 04, 2024 7:57 am https://www.ebay.com/itm/335653712778

4878 puts it late 1919 or 1920 per the serial number list on hornicopia. Have yet to hear back from seller to confirm there is a piston in the second valve.

Pretty safe assumption that this is an Eb.

(Hornicopia has 2 pics, and mistakenly says the BBb is an Eb, but they are obvious which is which)

Hope this sings again!