Re: short stroke; pros and con(n)s


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Posted by Rob P-M on July 29, 2003 at 21:06:37:

In Reply to: short stroke; pros and con(n)s posted by witboi on July 29, 2003 at 10:38:58:

This has been discussed here before, two or three years ago.

The good part about the Conn short action valves is they're faster than regular pistons, and they don't seem to wear very quickly. I think almost everyone agrees that the valve action on them is outstanding. The short action valves were used on the 20K/24K sousaphone and the 2XJ series of basses (20J, 21J, 22J, 23J, 24J, 25J, 26J, 27J).

The way Conn made them short, was to make the valve ports oval rather than round, making it possible for the holes in the pistons to mate up with the valve ports with a shorter travel or 'stroke'. The jury is out whether there is any negative effect on the air stream from the flattening of the branch tubing as it comes into the valves and through the valves. Some people claim it does, others say no. Some people think these horns are relatively stuffy and less rich sounding than their predecessors with the regular 'long' valves (38K/40K sousaphones, 32J, 34J, 36J recording basses). If I notice any consensus view, its that people would rather have the long valves on the basses, but prefer the short action valves on the sousaphone. Although, in fairness, the only place the short action valves are available is on the 20K sousaphone.

That said, most people think the 20K is the epitome of sousaphone development. Conn certainly thought so. There were a very few 24Ks, a 4 valve version, but they are so rare most people have never seen one. 40Ks, the 4 valve version of the 38K, were more common. The reason is that before WWII, plenty of professionals played sousaphones in dance bands and recording situations, and the professionals often bought 4 valve horns. College and school bands, if they had the money to buy 20Ks/38Ks, simply didn't spend the extra money for a 4th valve. After WWII, professionals rarely bought sousaphones for anything other than marching.

Now, as to why you don't have the short action valves on any other horns, there are a number of reasons:

First, Conn held a patent on them (which was renewed) that prevented anyone else from building them before the '60s, by which time big piston american basses were out of fashion, and German rotary valve horns were the professional standard. Hence, there was not a strong demand to continue the 4 valve versions, and even the 3 valve versions stopped selling well.

Secondly, there is the debate about whether they have any negative effect on sound.

Third, and perhaps most importantly, the short action valves are a bitch to build, and expensive. Not cost effective. Apparently they take a lot of hand work. And there's apparently only one man who can build them - I think the son of the guy who invented them - and he is now very old and arthritic. Matt Walters speculated a few years ago that when the craftsman could no longer make them, they would be gone. I don't know the status now, but there is a long lead time to order a new 20K.

When Macmillan bought Conn in 1969, and moved production to Texas, they threw out lots of tooling and mandrels, apparently including the tooling for the 4 valve short action valvesets and the mandrels for the big Conn tubas and sousaphones.

So, without the demand and without the tooling, the short action valve is history, except on the 20K, where school demand has sustained it over the past 60 years.


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