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Found this on ebay

http://www.ebay.com/itm/CONN-20K-SATIN- ... 3f4ebbd52f" target="_blank

That "Conn" logo, though.... (4th photo)

Those are definitely real. My undergrad college owns those 20k's with the exact same branding on the bell.

Truly gorgeous horn!

I always thought the valve-stem offset was a clever idea. It should relax the fingers a bit, especially for smaller hands.

Does anyone know how that worked over the long haul? I'm wondering about possible uneven wear.

I have Conn 20K made in about 1957 and its valves work just brilliantly. Cannot hope better. Otherwise the whole horn has gone through numerous repairs during decades.

Thanks for the feedback. Out of curiosity, how do you remove the top cap? Obviously you can't simply unscrew it.

dwerden wrote:Thanks for the feedback. Out of curiosity, how do you remove the top cap? Obviously you can't simply unscrew it.

Dave... the top cap is an assembly of several parts. The only thing that turns is the ring on the outside.

It's a good design and as long as all the parts are all proper the offset of the stem does not cause the pistons to stick as one might think.

Holton also made a short-action valve section in the early 20's that had a radically different design. I have both a Holton SA sousa and a tuba.

Judging from the serial number on this valve section... this horn is from around 1924... same era as the Holton SA horns.

Thanks, Dan. I appreciate the extra insight!

dwerden wrote:Thanks, Dan. I appreciate the extra insight!

I had some more thoughts regarding the mechanics of the Conn SA valves:

With school SA Conns... I rarely see one where the valves are properly aligned. Since the open bugle ports are 'squished', the vertical alignment of the pistons is critical. From the factory the horns had a thick cork spacer (about 1/4", I think) on top of the piston. In many cases I've seen the cork replaced with several felts. Felts don't keep their thickness as well as cork and since the felts are under compression when the pistons are at rest they tend to flatten out resulting in the port alignment suffering.

Also... since the piston diameter on the Conn SA tubas and sousas... they can be prone to being sluggish with certain lubricants since there is so much surface area. The short-action design is nice but I think the larger piston diameter presents sort of a 'trade-off' as far as actual piston speed goes.

I like the SA Conns. It's interesting that they survived over the Holtons. Both the Holton and Conn designs were patented and vastly different. Both were 'outside of the box' in terms of traditional valve making.

The short action valve idea has always been very interesting to me, but it also raises a question:

If the playing qualities of the horn are not compromised by the "squishing" oval design of the short action main ports (and I assume they aren't, due to the long lasting popularity of the design), why is it somehow assumed that playing qualities are compromised by traditionally designed rotary valves (especially 5th valves on piston tubas) or "bumps" inside the piston windways?

(Coincidentally, as a side note, I have definite proof that York changed their valve design at about the same time as, or shortly after, the introduction of the short action valve, quite likely as a result of the short action valve popularity. The stroke became shorter, but at the expense of "bumpless" piston windways.)

roweenie wrote:If the playing qualities of the horn are not compromised by the "squishing" oval design of the short action main ports (and I assume they aren't, due to the long lasting popularity of the design)

I think that assumption might be a stretch. The Conn tubas with short stroke valves sell to a market that isn't super critical about such things - for example, the flat 3rd partial F that I've heard from 20K players and have read also is a problem for the 30J etc. Not saying this problem is caused by the valves (don't know), but there it is, yet they were very popular for a long time. It allowed Conn to use a bigger bore with same stroke, which probably makes up for any compromises, for that market.

Donn wrote:.... It allowed Conn to use a bigger bore with same stroke, which probably makes up for any compromises, for that market.

Well... the Conn short-action sousaphones had the same bore as their 14K sousaphones.

The 20K TUBAS had a larger .770" bore. I need to take a look at the actual area of the K and J ports but I'm guessing that the K 'squished' port area is equal to the .737" diameter of the tuning circuits.

An acoustical engineer might be able to shed some light on the concept of the 'squished' ports and tell us it just doesn't make any difference and it has more to do with the manufacturing. Round stuff is just easier to make.

There was a family of horns at the LA Fiske Museum (I think they have moved to the Phoenix area museum) that had a "venturi" design in the rotor valves. Each pipe was necked down to a significantly smaller valve port, and the expanded after passing through the valve. Even though the exact science of airflow had not been determined at that point, the horns worked well (played sufficiently in tune) and were manufactured for a while. Since they were Over The Shoulder horns, the valve design may have been lost when they became obsolete.

About short valve action vs. "normal" action: My feeling also is that they are not faster - that matter is purely used for advertising purposes. Also I have no any difficulty to play my Eb bass tuba and immediately after that my sousa. My fingers cannot feel any considerably difference to be cared for. Valves are just as fast and accurate with both the horns. But another thing is that playing a short-action sousa feels so good - both ears and fingers !

bloke wrote:In my experience, the valves are no faster with the shorter stoke, because the additional surface area creates additional drag. I'm sure I can feel it. I'm not particularly good at talking myself into perceptions.

(Emphasis added with apologies to Bloke)

+1

Aside from the Holton version of SA valves... there are several other patents on file that never came to fruition. ... including one that has the open bugle split into TWO air paths.

Interesting enough is the fact that many companies ground out patents that they never intended to manufacture just to keep the competition at bay.

David Richoux wrote:There was a family of horns at the LA Fiske Museum (I think they have moved to the Phoenix area museum) that had a "venturi" design in the rotor valves. Each pipe was necked down to a significantly smaller valve port, and the expanded after passing through the valve. Even though the exact science of airflow had not been determined at that point, the horns worked well (played sufficiently in tune) and were manufactured for a while. Since they were Over The Shoulder horns, the valve design may have been lost when they became obsolete.

ALL traditional rotor designs and the Willson Rotax still do this.

The Kanstul is the rare rotor design that doesn't shrink the bore while passing through the valve.