TubeNet

I see why you think compensating, but that would make the 1st valve the master.

I have seen old French and British tubas with the valve loops on the rear (even own such Besson Eb from 1870), but as I see Hirsbrunner they were a German style maker until the design influence from York and British Besson compers. I haven’t noticed them showing French inspiration, even if Switzerland of course is multilingual.

I somehow suspect a Franken-prank going on, as the bell looks like belonging to German style rotary tuba. So I have asked the seller for better photos displaying the airpath fron & back & in details.

Klaus

The photos are horribly bad, which I guess is on purpose. What I see from this bad basis for an evaluation is:

A body from a rotary Hirbrunner.

A valve block from a British 3 valve comper has been placed reversed in respects of front/rear.

The leadpipe goes to the formally 3rd valve, which by relative length of its loop should be the 1st valve.

Klaus

The photos are horribly bad, which I guess is on purpose. What I see from this bad basis for an evaluation is:

A body from a rotary Hirbrunner.

A valve block from a British 3 valve comper has been placed reversed in respects of front/rear.

The leadpipe goes to the formally 3rd valve, which by relative length of its loop should be the 1st valve.

Klaus

I'm sure this horn is 100% original. The Swiss generally don't tinker with their instruments. The date (1913) stamped on the bell looks typical from Sumiswald Hirsbrunners from that era.

I know the seller. It's not on purpose that the pictures are bad, he's just not the best photographer.