The Mannheim clarinet is one of the Chinese made clarinets that are now flooding the US market.
This clarinet seems identical to
This one came in for repair to the local store.
Serial: NC 3417xx
The key work is made of soft metal. A student who plays one of these should take careful note of the keys while assembling and disassembling.
Testing using Portnoy BP02 mouthpiece and Legere 4 reed.
Summary of the intonation: The intonation is quite good. The main problem will be the fiercely sharp chalumeau register. This clarinet will also seem quite flat in the upper register when compared to other instruments, and especially other clarinets. This is because nearly all other instruments play sharp in the upper register.
I don't recommend these Chinese brands for any level of player. They will have zero resale value. They will quickly need repair, but some shops will not service them.
The springs of this instrument seem to be rather flimsy.
A bigger problem is that there is plastic flashing that was left over from the molding process on the lower edge of tone holes. This will make a big difference in intonation.
Update: Today, when working on a Lauren clarinet that must have been made by the same maker, I found that this is not flashing left over from molding. The joint is made without the tone holes, and the tone holes are inserts that are glued in. I just tried to fix a Lauren where the tone hole inserts had come out. The band director tried to glue them in, but didn't get them inserted far enough down. The result is that the horn is unplayable because it leaks in the cracks between the inserts and the hole. I am recommending they use this horn for a lamp.
The side keys are modeled after Vito/Leblanc, with four posts for the four keys.
I wonder if this is the same factory that makes the Ridenour in China. Clearly they have some good plans and dimensions. The key weaknesses seem to be