Convert string trigger linkage to direct linkage

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TimBrass
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Location: Nuenen

Convert string trigger linkage to direct linkage

Post by TimBrass » Wed Jul 18, 2018 12:39 am

Hi,

Are there kits to change the linkage on f attachements? change the string to for instance miniball?
shider
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Location: Southern Germany

Re: Convert string trigger linkage to direct linkage

Post by shider » Wed Jul 18, 2018 12:53 am

I don't know of a Kit for private people to buy, but i had my Yamaha 448G converted from string linkage to a minibal-linkage sometime last year and it only const me about 60-80€ (can't recall the exact amount right now). I asked for an estimate up front and the final price was even lower than that.

The tech hat to bend a custom lever in addition to cutting the actual thumb lever because the actuation side (where the linkage attaches to the Valve "shaft") had to be changed. That's because the string was pulling on the Valve to make it turn and the mechanical linkage is now pushing it to make it turn.

I really liked the outcome of it, but i just prefer mechanical linkages to strings.
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TimBrass
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Location: Nuenen

Re: Convert string trigger linkage to direct linkage

Post by TimBrass » Wed Jul 18, 2018 12:58 am

Could you perhaps share some pics of the linkage you have now?
shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Wed Jul 18, 2018 1:27 am

i'm at work right now, but i can try to take and post pictures when i will be at home..
(but that will be in roughly 10 hours from now. )
I also have some pictures from before the conversion.
shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Wed Jul 18, 2018 11:44 pm

These are the pictures before the conversion:
Attachments
20170531_214005.jpg
String linkage
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shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Thu Jul 19, 2018 12:30 am

another picture of the string linkage (since i can't seem to upload more than one picture per post)
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20170531_214008.jpg
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shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Thu Jul 19, 2018 12:32 am

Pictures after the conversion:
1.:
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20180718_210435.jpg
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shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Thu Jul 19, 2018 12:33 am

2.:
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shider
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Re: Convert string trigger linkage to direct linkage

Post by shider » Thu Jul 19, 2018 12:33 am

3.:
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20180718_210456.jpg
20180718_210456.jpg (4.26 MiB) Viewed 279 times
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MoominDave
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Re: Convert string trigger linkage to direct linkage

Post by MoominDave » Thu Jul 19, 2018 6:53 am

The string linkage has some significant advantages over a mechanical one - it's quieter and has fewer moving parts. In various ways it hasn't been bettered as a design.
shider
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Location: Southern Germany

Re: Convert string trigger linkage to direct linkage

Post by shider » Thu Jul 19, 2018 6:59 am

MoominDave wrote:
Thu Jul 19, 2018 6:53 am
The string linkage has some significant advantages over a mechanical one - it's quieter and has fewer moving parts. In various ways it hasn't been bettered as a design.
Totally correct. I didn't want to say that it's absolutely better the way it is now.
It's just my personal preference, i like it better how it is now.

I just wanted to provide some information to Timbrass.
boneagain
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Re: Convert string trigger linkage to direct linkage

Post by boneagain » Thu Jul 19, 2018 7:04 am

Nice pics!

Brings up some important considerations: 1) rotor rest position; 2) rotor rotation direction.

Notice in the photos that the rotor with the miniball rests 90 degrees off from where it did with the string. This means the tech not only replaced the link, but did some "magic" with the shaft so the horn would still rest in Bb. There are a number of ways to accomplish that. The point being, there's more to it than just switching the linkage type.

Also notice, from the photos, that the method used to deal with #1 means that the rotor now turns in the opposite direction. The difference is something you can feel in F-valve slurs. It is caused by the "web" of material between the two sound channels in the rotor core. In one direction this web is passed over the "input" port of the valve. In the other direction it crosses the "output" port. Enough players found that crossing the "input" port degrades valve slurs that Yamaha changed the 2nd valve rotation direction when they made their YBL-830.

The rotation direction change is NOT inherent in the switch between string and minibal. It is a result of choices made in making that change while retaining the rotor rest position.

So, not likely to find a "kit" to make these things happen. As shider noted, and his photos show, the "simple" change involves not just the link, but some kind of work on the trigger AND the actuator and/or the stop plate. Good work for a tech; poor basis for any kind of kit.
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