TromboneChat

https://www.willson.ch/content/news/das-caidex-ventil

Super interesting. Seeing as Willson's existing ROTAX valve was already one of the smoothest and most well made rotary valves available, it's exciting that they think they've come up with an even better design. I don't suppose anyone's tried one yet, but I'm excited to see how they get used.

Me too! I hope they have the booklet in English, as my German isn't up to schnuffe.

Basically they say the valve has been designed to be even in surface and bore diameter throughout the entire valve and to prevent "pops" when engaging or disengaging the valve.

Rotax were ok... definitely not the best thing out there. There's a reason Edwards dropped them. Interested to see a new valve, though.

Burgerbob wrote: Mon Dec 28, 2020 2:33 pm Rotax were ok... definitely not the best thing out there. There's a reason Edwards dropped them.

What didn't you (or they) like about them? I mean, relative to the other 'improved but normal-ish profile' rotors like the Meinlschmidt OFs or Instrument Innovations...

ithinknot wrote: Mon Dec 28, 2020 2:49 pm

Burgerbob wrote: Mon Dec 28, 2020 2:33 pm Rotax were ok... definitely not the best thing out there. There's a reason Edwards dropped them.

What didn't you (or they) like about them? I mean, relative to the other 'improved but normal-ish profile' rotors like the Meinlschmidt OFs or Instrument Innovations...

I won't say they're bad valves, but they are definitely tighter than most of the other modern offerings. Some serious machining/finishing issues pop up as well- I had a friend with a B502 that had to send his back because they were leaking so badly.

I'm not aware of any chronic manufacturing issues with ROTAX valves, I thought Willson had a really good reputation in that regard? If Edwards installed leaky valves on an instrument that went out the door, surely they are just as much to blame for not catching it as the manufacturer of the valves was. As far as Edwards switching it out for the AR-1, I've seen some posts from CG and ZT about how they believe the AR-1 *plays* better, but never anything about manufacturing quality. I suspect the fact that stuff made in Switzerland is usually really expensive also played some role in the switch. I really like the rotax I have for my Rath R3F, I love the way it plays, it's not fussy at all about just the right oil or getting cleaned frequently; and it's super smooth, light, and airtight.

I heard of more leaky Rotax issues, not just my friend's. I think people have the idea that they are perfect in every way... just wanted to get the information out there. I did like how they played on the T-396, but not any of the Raths or B502s I've used.

SwissTbone wrote: Mon Dec 28, 2020 2:09 pm Basically they say the valve has been designed to be even in surface and bore diameter throughout the entire valve and to prevent "pops" when engaging or disengaging the valve.

Right. I read the site in English and I also sent an email to them asking if they had a booklet in English. I've had historically bad luck with them emailing me back. Or was that Hagmann?

This looks like a similar idea to the Kanstul CR (controlled resistance) valve, although a very different design. I wonder how it responds...

A valve
Like a kidney, might
Be rejected by one body, one perfect set of parts
And hasten death
Yet again might save another, though less well built.
Then again, the best kidney, in the end
All it does is filter a stream
So you can stream
And focus on more human things

I've played dozens of Rath bass trombone rotax valve sections and other custom made instruments with Rotax valves. Never any issues with leaking-ever.

Looks like another greenhoe clone.

I'm curious about their theory that going to an elliptical cross section through the valve eliminates woofiness.

I never heard back from them about a catalog, though it is the holidays.

paulyg wrote: Fri Jan 01, 2021 12:55 pm Looks like another greenhoe clone.

I'm curious about their theory that going to an elliptical cross section through the valve eliminates woofiness.

The original valves aren't woofy.

paulyg wrote: Fri Jan 01, 2021 12:55 pm Looks like another greenhoe clone.

I'm curious about their theory that going to an elliptical cross section through the valve eliminates woofiness.

They don't talk about woofyness in the german article about the valve. Maybe a translation error.

SwissTbone wrote: Sat Jan 02, 2021 6:14 am

paulyg wrote: Fri Jan 01, 2021 12:55 pm Looks like another greenhoe clone.

I'm curious about their theory that going to an elliptical cross section through the valve eliminates woofiness.

They don't talk about woofyness in the german article about the valve. Maybe a translation error.

Yes, I read the translated version of the page.

harrisonreed wrote: Tue Dec 29, 2020 7:35 am A valve
Like a kidney, might
Be rejected by one body, one perfect set of parts
And hasten death
Yet again might save another, though less well built.
Then again, the best kidney, in the end
All it does is filter a stream
So you can stream
And focus on more human things

Cosmic.

I too have never had a problem with any Rotax valve That I have installed or serviced.

The new valve looks interesting, We'll see how it actually works in reality.

I'm placing an order for these this week if anyone wants some.

Let us know how they work!

Amconk wrote: Wed Jan 06, 2021 11:38 pm

harrisonreed wrote: Tue Dec 29, 2020 7:35 am A valve
Like a kidney, might
Be rejected by one body, one perfect set of parts
And hasten death
Yet again might save another, though less well built.
Then again, the best kidney, in the end
All it does is filter a stream
So you can stream
And focus on more human things

Cosmic.

Think he was channeling DJ?

timothy42b wrote: Mon Mar 22, 2021 6:43 am

Amconk wrote: Wed Jan 06, 2021 11:38 pm


Cosmic.

Think he was channeling DJ?

I don’t know, this seemed easier to understand that most of DJs posts!!

LIBrassCo wrote: Mon Mar 22, 2021 5:17 am I'm placing an order for these this week if anyone wants some.

How much are they?

tombone21 wrote: Mon Mar 22, 2021 10:35 am

LIBrassCo wrote: Mon Mar 22, 2021 5:17 am I'm placing an order for these this week if anyone wants some.

How much are they?

They are on the expensive side. I'm not sure Willson would want me tossing their pricing around, but shoot me a message and i will be happy to provide you all the information.

LIBrassCo wrote: Tue Mar 23, 2021 2:52 am

tombone21 wrote: Mon Mar 22, 2021 10:35 am

How much are they?

They are on the expensive side. I'm not sure Willson would want me tossing their pricing around, but shoot me a message and i will be happy to provide you all the information.

Under or over a grand?

skeletal wrote: Thu Apr 15, 2021 1:58 pm Under or over a grand?

Well under $1000, but don't forget they still have to be attached to a valve section first!

Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

patrickosmith wrote: Sat Jun 18, 2022 5:43 am Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

I have a new Caidex rotor for sale that was on a project prototype. Just FYI

I emailed Willson for info on caidex valves as a possible option to replace the valves on my Bach 50B30. They came back with a detailed brochure and pricing.

Per valve

€485 ROTAX valve
€464 CAIDEX valve

BoomtownRath

BoomtownRath wrote: Fri Jun 24, 2022 8:34 am I emailed Willson for info on caidex valves as a possible option to replace the valves on my Bach 50B30. They came back with a detailed brochure and pricing.

Per valve

€485 ROTAX valve
€464 CAIDEX valve

BoomtownRath

Keep in mind that shipping will run you $30-50 USD. I REALLY like my Rotax valve installed on my Bach 42 by Eric Edwards.

BoomtownRath wrote: Fri Jun 24, 2022 8:34 am I emailed Willson for info on caidex valves as a possible option to replace the valves on my Bach 50B30. They came back with a detailed brochure and pricing.

Per valve

€485 ROTAX valve
€464 CAIDEX valve

BoomtownRath

So the newer version is slightly cheaper.

Burgerbob wrote: Mon Dec 28, 2020 2:33 pm Rotax were ok... definitely not the best thing out there. There's a reason Edwards dropped them. Interested to see a new valve, though.

My understanding was that Edwards dropped them because of pricing but I could be wrong.

I love the Rotax on my 79H. At the time of the swap 10 years ago I had $500-550 in the valve shipped directly to me and the cost of the conversion. My next project if I would find one would be an Elkhart 88H with a Rotax conversion. There are cheaper options but I love the feel, response, and sound I get with it.

In 2022, I bought a CAIDEX valve from Willson for X-Wrap and asked a trusted friend to build a valve section for me.
Last week, the CAIDEX valve section for Shires finally arrived from that friend!
I have been playing with this horn for about a week and I really like the valve.
The response is great. There is little difference in resistance when switching with the lever, and the breath can flow without stress in the middle and low register where valve is used a lot. This allows me to play with no worries.

patrickosmith wrote: Sat Jun 18, 2022 5:43 am Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

DON'T DO IT.

blast wrote: Sat Sep 06, 2025 11:33 am

patrickosmith wrote: Sat Jun 18, 2022 5:43 am Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

DON'T DO IT.

I agree - you have a piece of history there! Find a newer instrument with similar specs and an open playing valve to use when you want something more open. Leave the Holton as is - you may find that you drift back to it, and end up selling the new instrument.

Jim Scott

hiktro wrote: Sat Sep 06, 2025 9:06 am Last week, the CAIDEX valve section for Shires finally arrived from that friend!

Wow! That whole setup looks amazing! What's the German bell?

bbocaner wrote: Fri Sep 12, 2025 8:35 am

hiktro wrote: Sat Sep 06, 2025 9:06 am Last week, the CAIDEX valve section for Shires finally arrived from that friend!

Wow! That whole setup looks amazing! What's the German bell?

This bell is a Thein bell with a lightweight screw bell ring, weighing approximately 30 grams.

patrickosmith wrote: Sat Jun 18, 2022 5:43 am Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

Before you chop up this instrument, contact Pete Edwards to see if he can fashion a "CAIDEX-like" (i.e. strongly vented lipped-tube constant-area intact-duct) rotor for the original Holton casing. The constant-area intact ducts have a varying aspect-ratio "round-cornered rectangle" (instead of elliptical) cross section that varies continuously throughout the rotor, circular at both inlet and outlet, then "more rectangular" in the mid section to compensate exactly for where they are "squeezed" radially by the compact casing so that the cross-sectional area remains constant throughout. Pete's rotors are 3D-printed slightly oversized (in a wax-like substance) that is then used to make a cast (in stainless steel) in a lost-wax process. Pete then precisely machines them and laps them into the casing. This can be done in order to upgrade any kind of traditional rotary valve, provided the casing is in excellent condition—without removing it from the attachment.

The picture shows the principle of the constant-area unsymmetrical rounded-rectangle geometry and a typical lipped-tube intact-duct rotor constructed with this continuously varying cross-section, maintaining constant cross-sectional area throughout the compact valve. Since there is absolutely no "non-functional" mass, the moment of inertia is greatly reduced, resulting in a very fast and light direct action.




.

where did u get the screw bell ring?

hiktro wrote: Fri Sep 12, 2025 9:13 am

bbocaner wrote: Fri Sep 12, 2025 8:35 am

Wow! That whole setup looks amazing! What's the German bell?

This bell is a Thein bell with a lightweight screw bell ring, weighing approximately 30 grams.

john14u wrote: Fri Nov 21, 2025 4:07 pm where did u get the screw bell ring?

hiktro wrote: Fri Sep 12, 2025 9:13 am

This bell is a Thein bell with a lightweight screw bell ring, weighing approximately 30 grams.

https://glanztb.thebase.in/categories/6535731
In addition to the screw bell rings for Bach, Yamaha, and Courtois featured in the web shop, they should be able to make screw bell rings for Shires, Rath, Edwards, Thein, and others.

Sesquitone wrote: Sat Sep 13, 2025 9:35 am

patrickosmith wrote: Sat Jun 18, 2022 5:43 am Are there any updates to the choice between
Rotax vs. Caidex rotary valve. I'm planning to convert Crisafulli's Holton to an open wrap and in the process I will replace the 1950 vintage Holton rotor as well.

Before you chop up this instrument, contact Pete Edwards to see if he can fashion a "CAIDEX-like" (i.e. strongly vented lipped-tube constant-area intact-duct) rotor for the original Holton casing. The constant-area intact ducts have a varying aspect-ratio "round-cornered rectangle" (instead of elliptical) cross section that varies continuously throughout the rotor, circular at both inlet and outlet, then "more rectangular" in the mid section to compensate exactly for where they are "squeezed" radially by the compact casing so that the cross-sectional area remains constant throughout. Pete's rotors are 3D-printed slightly oversized (in a wax-like substance) that is then used to make a cast (in stainless steel) in a lost-wax process. Pete then precisely machines them and laps them into the casing. This can be done in order to upgrade any kind of traditional rotary valve, provided the casing is in excellent condition—without removing it from the attachment.

The picture shows the principle of the constant-area unsymmetrical rounded-rectangle geometry and a typical lipped-tube intact-duct rotor constructed with this continuously varying cross-section, maintaining constant cross-sectional area throughout the compact valve. Since there is absolutely no "non-functional" mass, the moment of inertia is greatly reduced, resulting in a very fast and light direct action.




.

Does this Pete Edwards have a web page ? Very interesting!

Burgerbob wrote: Mon Dec 28, 2020 2:33 pm Rotax were ok... definitely not the best thing out there. There's a reason Edwards dropped them. Interested to see a new valve, though.

Interesting that you have such a low opinion of the Rotax. The most likely reason for Edwards dropping Rotax̌ will be financial...historically that's been the case, going right back to Bach buying Meinelschmit ? valves in the thirties...they were dirt cheap.
Rotax are some of the better rotors... they may well be better than the Caidex. Smoke and mirrors. I was not keen on the Shires skeletonised rotors, which looked like the Caidex.

I'm am huge fan of the Rotax. I loved them on my Edwards bass and Bach 42B. I feel imagine it was a financial decision also. Why outsource when you can make a product of comparable quality and efficiency in-house? It makes good business sense. I never got to try the AR valve on bass, but the Rotax was rather sufficient for my needs and taste.

jjenkins wrote: Fri Nov 28, 2025 3:34 pm I'm am huge fan of the Rotax. I loved them on my Edwards bass and Bach 42B.

My design objective with the (all-caps) CAIDEX was to create a valve that was as close as possible to a continuation of the attachment tubing—similar to the objectives of the Thayer, Hagmann and other, more bulky designs—but contained within a very compact standard rotary casing such as that used for the Rotax, which has an inside diameter at midline of 28.25 mm. Basically: two curved tubes each turning the sound-path through 90º—attached to bearing components. Allowing for the thickness of the tubing, this means that a bore size larger than 13.1 mm inside diameter will suffer some radial ‘squeezing’ as it passes through the mid-section of the valve. The cross-section cannot remain circular. If we want to maintain a constant cross-sectional area, we need to adjust its shape continuously.
The area of an ellipse is proportional to the product of its minor and major axes; if they’re equal, it’s a circle. So an elliptical cross-section that is circular at inlet and outlet but varies so that the major axis is ‘stretched’ to compensate to keep the area exactly constant as the minor axis gets ‘squeezed’ will do the job. You need some ‘lips’ around the inlets and outlets to assure a good seal. Depending on the lip width, this geometry has the concomitant advantage of providing ample venting during transition—an optimal width totally eliminates ‘transition pop’. Ideally, these lipped-tubes are then attached to bearing components to create the rotor, with minimal addition mass—thereby minimizing rotational inertia.
So, how to construct such a design with precise dimensions? I experimented a lot with 3D printing. A ‘wax’ model of the rotor is printed (with slightly oversized exterior dimensions). This is then used in a ‘lost-wax’ casting process to produce the metal rotor, which is then machined to give precise external diameters to match the casing and bearings—into which it is then lapped. [In fact, I used this method to produce rotors for prototypes of my ULTRA valve. René Hagmann did the machining. And these turned out very nicely.] The alternative is CNC machining of a solid block of brass, and we ultimately chose this for the CAIDEX. The first picture shows the resulting CAIDEX rotor.
The second and third pictures show, respectively, the sound-paths and cross-sectional areas through a standard butterfly rotary valve. You’ll note a lot of ‘sharp corners’ and ‘discontinuities’, as well as oddly shaped and ‘squeezed’ cross-sections. The fourth and fifth pictures show the corresponding sound-paths and cross-sectional shapes for a 15.2 mm CAIDEX valve. The cross-sectional area is constant. This is a large-bore bass-trombone valve in the same compact (28.25 mm ‘Rotax’) casing. You can see the ‘axial bulging’ in mid-section. The last picture shows an engineering drawing for this 15.2 mm rotor, emphasizing the need for close tolerances.
The CAIDEX valve has a couple of other ‘bells-and-whistles’: (i) individually adjustable bumper stops for precise alignment—eliminating cut-and-try (and start-over if you over-cut) methods. And (ii) a ‘see-through’ end cap for checking precise alignment, since even a slight misalignment (of any valve) can create discontinuities in the sound-path that can distort tone quality and produce unreliable attack response.


.

Custom built CAIDEX valve section paired with an O’Malley gold brass bell, fresh out of Todd Clontz’ shop in Baltimore. Holy smokes this valve is the best rotor I’ve ever played, and I think I’ve tried them all on the current market.

The CAIDEX builds look amazing!!! I am thinking of ordering one of these valves to put on my Bach 36B. Could I get one configured to fit neatly into the original closed wrap? Or should I just do a new wrap?

Also I never had a problem with the Rotax valve ever. I owned an R4F with the first Rotax valve they put on there for about eight years. I barely oiled that thing it was awesome. If this is an UPGRADE I am interested!

RJMason wrote: Fri Dec 05, 2025 7:48 am The CAIDEX builds look amazing!!! I am thinking of ordering one of these valves to put on my Bach 36B. Could I get one configured to fit neatly into the original closed wrap? Or should I just do a new wrap?

Also I never had a problem with the Rotax valve ever. I owned an R4F with the first Rotax valve they put on there for about eight years. I barely oiled that thing it was awesome. If this is an UPGRADE I am interested!

The CAIDEX uses the same casing barrel as the Rotax (with different end caps: see-through and adjustable stops). The rotor is indeed an UPGRADE. The knuckle geometry can be ordered to align smoothly with almost any wrap (with pictures and dimensions sent to Willson). The nominal tenor bore for CAIDEX is (currently) only available in 14.3 mm—this might be a bit too large for your 36B unless you're using a larger (perhaps dual-bore) hand-slide. [What is the bore of your attachment tubing?] However, since you're in Los Angeles, the main problem would be the current (Hello, Supreme Court) large tariff imposed on imports from Switzerland, with the import duty (that you pay) drastically increasing the US price over the European price (of everything!).