Valve Conversion Risks
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Wayne
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Valve Conversion Risks
I play an at least 35 year old Bach 42B that I enjoy very much, but it has that very tight F attachment section. Am I risking the rest of the playing characteristics if I decide to get an open valve conversion done? (Attach a Thayer like valve and wrap section for example.)
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Bonearzt
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Re: Valve Conversion Risks
ANY work done, especially a full valve install & rebuild WILL change how the horn responds.
But along those lines, I've found that rebuilding older Bachs to remove stress in the valve section GREATLY improves the horn! Even without changing the valve.
But along those lines, I've found that rebuilding older Bachs to remove stress in the valve section GREATLY improves the horn! Even without changing the valve.
Eric Edwards
Professional Instrument Repair
972.795.5784
"If you must choose between two evils, choose the one you haven't tried yet."
"Rather fail with honor than succeed by fraud." -Sophocles
Professional Instrument Repair
972.795.5784
"If you must choose between two evils, choose the one you haven't tried yet."
"Rather fail with honor than succeed by fraud." -Sophocles
- Burgerbob
- Posts: 6218
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Re: Valve Conversion Risks
The horn probably won't get worse, FWIW.
Aidan Ritchie, LA area player and teacher
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Kbiggs
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Re: Valve Conversion Risks
+1Bonearzt wrote: Thu Jan 08, 2026 3:31 pm ANY work done, especially a full valve install & rebuild WILL change how the horn responds.
But along those lines, I've found that rebuilding older Bachs to remove stress in the valve section GREATLY improves the horn! Even without changing the valve.
You could also try modifying the valve core—I think it used to be called “boring out.”
Kenneth Biggs
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
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TomInME
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Re: Valve Conversion Risks
There's a better option than boring out now - it's called "3d printing".
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tbonesullivan
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Re: Valve Conversion Risks
opening up the valve ports is a pretty standard mod for the Bach 42B. I believe the gooseneck can also be swapped out, but if you are that far in, might as well just replace the valve with something better.Kbiggs wrote: Thu Jan 08, 2026 4:53 pmYou could also try modifying the valve core—I think it used to be called “boring out.”
David S. - daveyboy37 from TTF
Bach 39, LT36B, 42BOF & 42T, King 2103 / 3b, Kanstul 1570CR & 1588CR, Yamaha YBL-612 RII, YBL-822G & YBL-830, Sterling 1056GHS Euphonium,
Livingston Symphony Orchestra NJ - Trombone
Bach 39, LT36B, 42BOF & 42T, King 2103 / 3b, Kanstul 1570CR & 1588CR, Yamaha YBL-612 RII, YBL-822G & YBL-830, Sterling 1056GHS Euphonium,
Livingston Symphony Orchestra NJ - Trombone
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brassmedic
- Posts: 1399
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Re: Valve Conversion Risks
I put a Thayer valve on my 42B and I would NEVER go back. Just all improvement. It was great before, but outstanding with the Thayer install.
EDIT: It was open wrap originally. What made.it great was not open wrap, but the Thayer install, and a lot of that might have to do with the more open neckpipe.
EDIT: It was open wrap originally. What made.it great was not open wrap, but the Thayer install, and a lot of that might have to do with the more open neckpipe.
Brad Close Brass Instruments - brassmedic.com
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Wayne
- Posts: 76
- Joined: Sat Mar 22, 2025 8:09 am
Re: Valve Conversion Risks
Thanks, now it's down to sourcing parts and finding a tech to do the work in Canada (Toronto area) hopefully. I don't really want to ship my horn cross border. {just the hassle}
- elmsandr
- Posts: 1327
- Joined: Fri Mar 23, 2018 2:43 pm
Re: Valve Conversion Risks
Always risks to cutting into a horn, even if it is just different, that might be a problem for you. That said, I’ve never regretted getting rid of the standard Bach rotor on a 42 for literally anything else, almost no matter how silly. (Even the old Holton Monster valve plays and sounds better in some ways).
Before you buy a Thayer like item; play a couple and see if you like it. I love the blow of a Thayer tenor.. But with even the minor maintenance requirements, I’d rather try a couple of other more improved rotors if I were doing it again.
Cheers,
Andy
Before you buy a Thayer like item; play a couple and see if you like it. I love the blow of a Thayer tenor.. But with even the minor maintenance requirements, I’d rather try a couple of other more improved rotors if I were doing it again.
Cheers,
Andy
- muschem
- Posts: 335
- Joined: Sun Jan 17, 2021 10:16 am
Re: Valve Conversion Risks
Pete Edwards is doing some very interesting stuff in this area. I understand that Pete can 3D print stainless steel CAIDEX-like valve cores and lap them to fit existing valve casings. A core replacement is a neat and easily reversible modification that doesn't require torch work. Doing a core-only mod is also less costly compared to a full valve replacement, but you won't get the potential benefits of stress-relief and the opportunity to change/improve the gooseneck and other parts, which come along with a good rebuild. Potential benefits either way.TomInME wrote: Thu Jan 08, 2026 5:27 pm There's a better option than boring out now - it's called "3d printing".
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Kbiggs
- Posts: 1708
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Re: Valve Conversion Risks
Thanks for the reminders about Pete Edwards and 3D printing.muschem wrote: Fri Jan 09, 2026 8:06 amPete Edwards is doing some very interesting stuff in this area. I understand that Pete can 3D print stainless steel CAIDEX-like valve cores and lap them to fit existing valve casings. A core replacement is a neat and easily reversible modification that doesn't require torch work. Doing a core-only mod is also less costly compared to a full valve replacement, but you won't get the potential benefits of stress-relief and the opportunity to change/improve the gooseneck and other parts, which come along with a good rebuild. Potential benefits either way.TomInME wrote: Thu Jan 08, 2026 5:27 pm There's a better option than boring out now - it's called "3d printing".
I can also vouch for the benefits of de-stressing and re-assembly of Bach bell sections.
Kenneth Biggs
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
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Boneaphone
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Re: Valve Conversion Risks
I had the original rotor on my 42BO replaced with an Instrument Innovations rotary valve. The difference was profound in a good way.
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GabrielRice
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Re: Valve Conversion Risks
Considering you've been playing that Bach for a long time, I would suggest going ahead with an open wrap conversion but sticking with a rotary valve rather than getting a Thayer. It would still be the same instrument with the Thayer, but it would feel quite a bit bigger all over the range.
For my rare tenor doubling, I have a 42B I bought used, and I compared it to other new and used 42s with various valve configurations. It started as a closed wrap and somebody did a nice open wrap conversion, keeping the original valve. Maybe they opened up the ports, maybe they changed the gooseneck - I don't know. What I know is that it was the best 42 on the wall of that store.
For my rare tenor doubling, I have a 42B I bought used, and I compared it to other new and used 42s with various valve configurations. It started as a closed wrap and somebody did a nice open wrap conversion, keeping the original valve. Maybe they opened up the ports, maybe they changed the gooseneck - I don't know. What I know is that it was the best 42 on the wall of that store.
Gabe Rice
Stephens Brass Instruments Artist
Faculty
Boston University School of Music
Kinhaven Music School Senior Session
Bass Trombonist
Rhode Island Philharmonic Orchestra
Vermont Symphony Orchestra
Stephens Brass Instruments Artist
Faculty
Boston University School of Music
Kinhaven Music School Senior Session
Bass Trombonist
Rhode Island Philharmonic Orchestra
Vermont Symphony Orchestra
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TomInME
- Posts: 293
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Re: Valve Conversion Risks
It's partly "get what you pay for". Spend a few hundred for a drop-in valve core replacement for a better blow, or spend more than a thousand and get the de-stress also. (for a bass, it's more like $500 vs $2,500)
It also depends whether the horn is worth the extra. If it's a little beat-up or the bell just isn't that great, might not be worth it for a full conversion.
A lesser consideration is time. Valve core replacement is pretty quick, the transit time is the biggest component. A rebuild will be somewhere in the week or two range (plus shipping), I think?
For me, with an older Bach that has taken some hits, a full rebuild wasn't worth the $$, but the valve replacements were a huge value considering the performance increase vs the cost. It might have been nice to get another 20% improvement, but not at 400% greater cost.
But if the bell was a real gem and I had the cash, a rebuild could have been worth it.
It also depends whether the horn is worth the extra. If it's a little beat-up or the bell just isn't that great, might not be worth it for a full conversion.
A lesser consideration is time. Valve core replacement is pretty quick, the transit time is the biggest component. A rebuild will be somewhere in the week or two range (plus shipping), I think?
For me, with an older Bach that has taken some hits, a full rebuild wasn't worth the $$, but the valve replacements were a huge value considering the performance increase vs the cost. It might have been nice to get another 20% improvement, but not at 400% greater cost.
But if the bell was a real gem and I had the cash, a rebuild could have been worth it.
- harrisonreed
- Posts: 6329
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Re: Valve Conversion Risks
Thayer valves are an aggressive change. They are almost too open on either side of the valve -- your whole horn will play very different, maybe for the better, but it will be like a granny smith apple vs a mango. The throw is forever on those things. That said, the Bach 42 is one of the most restricted, tight trombones ever made, so the Thayer might be the best thing you could do to it, "removing the sock out of the slide crook" so to speak. The one 42 horn that I really dug was actually a 42T. I would have bought it and played it as my main ax if I had been looking for a large bore at the time I tried it.
If you mostly like your 42 already, I'd convert to a bigger modern conventional rotor with the Minick wrap and be done with it. That would be like a Granny Smith Apple vs a Fuji Apple. 99% of people will take the Fuji Apple over the other green waxy thing.
If you mostly like your 42 already, I'd convert to a bigger modern conventional rotor with the Minick wrap and be done with it. That would be like a Granny Smith Apple vs a Fuji Apple. 99% of people will take the Fuji Apple over the other green waxy thing.
- Harrison Reed
Harry's Custom Mouthpieces
Harry's Custom Mouthpieces
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Wayne
- Posts: 76
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Re: Valve Conversion Risks
I get your point and will look at some options. I did play a Thayer on a dual bore (47"/6?") Edwards for about 7 years. I loved that feel but was not going to be playing Bruckner with the NYP any time in my future so it was more horn than I needed. I'd like to get that feel of a horn not making legato or creating an even tone through ranges a chore again.
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slidesix
- Posts: 122
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Re: Valve Conversion Risks
Wayne, I think Harrison might be mentioning a simple conversion, like this with Conn:
Thread (36632) Eastlake Conn 88HO - Successful Instrument Innovations Valve Swap
viewtopic.php?t=36632
Nice isn't it? I think so. (Not my horn, BTW)
I have a Bach A47I. It has a Bach in-house axial valve similar to 42T or 42AF (more like the latter). The Axial isn't the be-all-end-all. I thought it was going to be MORE OPEN than it is. But this is a sample size of 1, to take this with a grain of salt.
Don't get me wrong. I still think it is a fine horn. I wasn't sure what to expect. I am glad I did get to experience an axial. Back in our time when your 42B was new, I think axials or thayers were the rage. Not sure that is still the case since we have other valve options, like rotors that have vastly improved. So don't discount them. With that said, the axial valve isn't bad. It plays fine. The throw is actually shorter and quicker than I was expecting. Nor does it seem to suck-the-air-out-of-me.
Common advice is normally to buy the full horn you like rather than assemble one from parts. I think that advice is gear towards your thread title here. As it down plays the risk. But might cost more. Often modders will mod more than once, making buying a whole complete horn sometimes safer and cheaper in the long run. but given that the 42B has such an undersized valve to begin with, I'm sure the overall risk is likely low.
Just be aware that you might need to mod more than once to find what you ultimately may want. To keep that in mind that this might be a trial-and-error process. Good luck!
Thread (36632) Eastlake Conn 88HO - Successful Instrument Innovations Valve Swap
viewtopic.php?t=36632
Nice isn't it? I think so. (Not my horn, BTW)
I have a Bach A47I. It has a Bach in-house axial valve similar to 42T or 42AF (more like the latter). The Axial isn't the be-all-end-all. I thought it was going to be MORE OPEN than it is. But this is a sample size of 1, to take this with a grain of salt.
Don't get me wrong. I still think it is a fine horn. I wasn't sure what to expect. I am glad I did get to experience an axial. Back in our time when your 42B was new, I think axials or thayers were the rage. Not sure that is still the case since we have other valve options, like rotors that have vastly improved. So don't discount them. With that said, the axial valve isn't bad. It plays fine. The throw is actually shorter and quicker than I was expecting. Nor does it seem to suck-the-air-out-of-me.
Common advice is normally to buy the full horn you like rather than assemble one from parts. I think that advice is gear towards your thread title here. As it down plays the risk. But might cost more. Often modders will mod more than once, making buying a whole complete horn sometimes safer and cheaper in the long run. but given that the 42B has such an undersized valve to begin with, I'm sure the overall risk is likely low.
Just be aware that you might need to mod more than once to find what you ultimately may want. To keep that in mind that this might be a trial-and-error process. Good luck!
Aaron, a hobby player looking to restore and to keep up his chops!
Cleveland, OH area
Cleveland, OH area
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Wayne
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Re: Valve Conversion Risks
What I am most worried about is if the sound would brighten up considerably.
I can't play a small bore below .505 and expect anyone else to stay in the same room as me. The sound just blows apart with any force and gets quite edgy.
My Edwards had a bunch of stuff to keep the sound a bit more controlled: extra long lead pipe, extra big and heavy bell and a different alloy tuning slide.
I played an 88H before the 42 and my control in louder playing changed greatly for the better when I moved to the Bach.
I don't need the trigger a lot, but when I do, it such a drag to not be able to make it sound like the rest of the horn. I don't know if fixing the trigger sound would be worth creating a horn that rips apart on me at high volume.
I can't play a small bore below .505 and expect anyone else to stay in the same room as me. The sound just blows apart with any force and gets quite edgy.
My Edwards had a bunch of stuff to keep the sound a bit more controlled: extra long lead pipe, extra big and heavy bell and a different alloy tuning slide.
I played an 88H before the 42 and my control in louder playing changed greatly for the better when I moved to the Bach.
I don't need the trigger a lot, but when I do, it such a drag to not be able to make it sound like the rest of the horn. I don't know if fixing the trigger sound would be worth creating a horn that rips apart on me at high volume.
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Kbiggs
- Posts: 1708
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Re: Valve Conversion Risks
There are aftermarket components that can provide a similar effect to a 42B that you had for your Edwards. However…
Sometimes a horn that plays differently is an opportunity to learn how to play differently.
If your Edwards was designed to keep your sound controlled at loud volumes, and if your experience with a Conn was that it was difficult to control in louder volumes, then perhaps an adjustment to the way you play in louder volumes could help.
Do you notice any changes to your embouchure as you increase volume? What is your soft playing like?
Sometimes a horn that plays differently is an opportunity to learn how to play differently.
If your Edwards was designed to keep your sound controlled at loud volumes, and if your experience with a Conn was that it was difficult to control in louder volumes, then perhaps an adjustment to the way you play in louder volumes could help.
Do you notice any changes to your embouchure as you increase volume? What is your soft playing like?
Kenneth Biggs
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
I have known a great many troubles, but most of them have never happened.
—Mark Twain (attributed)
- Sesquitone
- Posts: 274
- Joined: Mon Apr 25, 2022 12:26 pm
Re: Valve Conversion Risks
Before you do anything "drastic" and irreversible—like boring out the typically undersized Bach valve or a full conversion to another type of valve, you might try a simple "fix" of the well-known "very tight F attachment" problem. See if you can borrow (from a colleague or nearby music store) a Bach 50 bass-trombone hand-slide, and try that on your 42. Unless your valve is misaligned (or damaged), that will convert your Bach 42B into a good approximation of the Jay Friedman "Chicago" style Bach tenor. If that helps (a lot), you might consider investing in a Bach HS6262LT slide, or (even better, in my estimation) an HS4762LT dual-bore slide. [Or other equivalent slides, like Edwards, that are compatible with your Bach slide receiver.]Wayne wrote: Wed Jan 07, 2026 8:09 am I play an at least 35 year old Bach 42B that I enjoy very much, but it has that very tight F attachment section. Am I risking the rest of the playing characteristics if I decide to get an open valve conversion done? (Attach a Thayer like valve and wrap section for example.)
Why would this simple fix "work"? On the standard 42B, when the valve is engaged, the sound-path sees a sudden increase in bore size between the slide and attachment, and then a sudden decrease again between the attachment and the beginning of the gooseneck. This tends to distort the second and third attachment harmonics, lowering the second and raising the third: F2 (stuffy) and C3 (uncentered), respectively, in first position. And it can also affect higher harmonics, causing poor tone quality and unreliable attack response. With the matched bore, the attachment is simply an extension of the cylindrical slide bore near the location of the slide-receiver, before the gradual expansion through the gooseneck into the bell. This maintains the natural distribution of all harmonics.
Once the matched-bore slide is affixed, tune the attachment to match the pitch of F3 in first position with and without the valve engaged. The F2 will be clear and well in tune. The C3 will be quite stable. Sub-tenor notes will blend seamlessly down towards pedals.
That should make a big improvement to all attachment notes—without significantly affecting the slide-alone upper register (Mr Friedman praises the "open feel" throughout all registers). You might still need a better valve. Some of the newer (modular) Bach 42 attachments actually use a (slightly modified) Conn 88H valve: the rotors are identical (interchangeable), the only differences are in the knuckle geometry.
.
- dukesboneman
- Posts: 921
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Re: Valve Conversion Risks
I had my valve removed on my 42BO and had the Olsen Rotary valve from Instrument Innovations put on.
Best thing I could have done for the horn. Plays fantastic and the "F" side is now just as open as the open horn
Best thing I could have done for the horn. Plays fantastic and the "F" side is now just as open as the open horn
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hornbuilder
- Posts: 1331
- Joined: Wed May 02, 2018 9:20 pm
Re: Valve Conversion Risks
Something that has not been mentioned, is the factory gooseneck on the Bach 42. It is just as much of a choke point as the factory rotor valve, being "considerably" undersized for a horn of that size slide bore.
Matthew Walker
Owner/Craftsman, M&W Custom Trombones, LLC, Jackson, Wisconsin.
Former Bass Trombonist, Opera Australia, 1991-2006
Owner/Craftsman, M&W Custom Trombones, LLC, Jackson, Wisconsin.
Former Bass Trombonist, Opera Australia, 1991-2006
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Floridatrombonekenneth
- Posts: 150
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Re: Valve Conversion Risks
Curious for myself, but I feel like this question also fits on this topic. Has anyone replaced the 42 valve section with a 50 single valve section. I often see post 50B single valve sections come up on here and other sites. Assuming you were also able to replace parts required to make the tuning slide and neck-pipe compatible etc.
Also to the OP, replacing the neck pipe and having someone bore out the valve core makes a huge difference. Including a link to Dana Hofer's website. He did the work on my Trombone and also explains the process. https://www.danahoferbrassrepair.com/services/trombone
Also to the OP, replacing the neck pipe and having someone bore out the valve core makes a huge difference. Including a link to Dana Hofer's website. He did the work on my Trombone and also explains the process. https://www.danahoferbrassrepair.com/services/trombone
- BrianJohnston
- Posts: 1057
- Joined: Sat Jul 11, 2020 7:49 pm
Re: Valve Conversion Risks
Ken, I believe the Dallas Symphony tenor trombones have Bach 42s with 50 valves. Someone correct me if that info is wrong, but listen to them to see what you think.
Faculty - Mount Royal University
Civic Orchestra of Chicago Alum 2019-2021
Bach Brass Artist
Civic Orchestra of Chicago Alum 2019-2021
Bach Brass Artist
- elmsandr
- Posts: 1327
- Joined: Fri Mar 23, 2018 2:43 pm
Re: Valve Conversion Risks
Valves, or valve sections? I’ve not seen anybody play a 42 with .593 tubing in the valve section, unless you count a Bach 45…
But the valve swap? Yeah, that used to happen a bunch before the improved rotors came out. I tacked one together like that for a little bit, but I preferred my Thayer.
Cheers,
Andy
But the valve swap? Yeah, that used to happen a bunch before the improved rotors came out. I tacked one together like that for a little bit, but I preferred my Thayer.
Cheers,
Andy
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Wayne
- Posts: 76
- Joined: Sat Mar 22, 2025 8:09 am
Re: Valve Conversion Risks
For convenience, cost and choice of regular or axial flow I’m zeroing in on getting an Olsen (Instrument Innovations) valve. Bach will sell a valve section for over $2000 USD. Innovations can get me a valve and new linkage parts for under $1000 CAD. I’ve seen a few good reviews on these valves. Would anyone else here make this choice? Again the goal is to make the low end trigger notes easier to play and overall make the horn a little more free blowing.
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Gfunk
- Posts: 142
- Joined: Mon Jan 10, 2022 9:56 pm
Re: Valve Conversion Risks
I know people that have done the Instrument Inovations rotor on a 42 and have great things to say. Especially for the price.Wayne wrote: Thu Mar 19, 2026 8:24 am For convenience, cost and choice of regular or axial flow I’m zeroing in on getting an Olsen (Instrument Innovations) valve. Bach will sell a valve section for over $2000 USD. Innovations can get me a valve and new linkage parts for under $1000 CAD. I’ve seen a few good reviews on these valves. Would anyone else here make this choice? Again the goal is to make the low end trigger notes easier to play and overall make the horn a little more free blowing.
I’m having a conversion done on my Corp 42 with a Rotax at the moment. I’ll update here when I get the horn back. But, my reason with the Rotax vs the Olsen rotor was that the character of the horn was great and I wanted to minimize the change in overall compression of the horn. Some of the magic lies in the balance of all the parts and I don’t want to throw that off. My goal is to modernize a bit, but not change to a big large “orchestral” trombone. So, a Rotax valve and custom neckpipe was the route I went. After I found a solder blob down the neckpipe I decided to have the tech rebuild the whole bell section too.
I also considered replacing the valve core or boring it out and calling it a day. But, I needed the tuning slide cut and I decided with so much of the horn apart I’d just go all the way with a rebuild. And the neckpipe is 36 sized, so it’s not doing any favors for the open/modernness of the horn.
I’ve played some 42s with thayers and oversized rotors, but they all lose some of the character that makes a great 42 so great IMO. Of course, YMMV