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Easiest Bb/G mod
Posted: Sun May 10, 2026 12:23 am
by dewque
I've been thinking a tenor with a G valve would be pretty cool. Problem is I live somewhere where custom work isn't common, which means conjuring up bespoke valve tubing is not realistic. What's the easiest way for a tech to build a G valve?
The base horn will be a ysl-823, probably not a first choice for this mod, but I'm no pro so am free to do whatever bad descisions I want
I think maybe cutting down an open wrap for a transplant would be best, but that might not leave a lot (if at all) of tuning slide left. Anyone have any experience on this?
Re: Easiest Bb/G mod
Posted: Sun May 10, 2026 9:22 am
by MichaelMedrick
Hello!
I had this done on the Bach 36/42 design. Many of the parts are the same after the slide connector. Eric Edwards cut down an open Wrap f section to g. Additionally, an normal F attachment tuning slide works and gives you the option of an F attachment.
Re: Easiest Bb/G mod
Posted: Sun May 10, 2026 11:09 am
by Sesquitone
dewque wrote: Sun May 10, 2026 12:23 am
I've been thinking a tenor with a G valve would be pretty cool. Problem is I live somewhere where custom work isn't common, which means conjuring up bespoke valve tubing is not realistic. What's the easiest way for a tech to build a G valve?
The base horn will be a ysl-823, probably not a first choice for this mod, but I'm no pro so am free to do whatever bad descisions I want
I think maybe cutting down an open wrap for a transplant would be best, but that might not leave a lot (if at all) of tuning slide left. Anyone have any experience on this?
Chopping down an OPEN wrap from F to G is a relatively straightforward job—for a brass tech (not a DIY project). The same tuning-slide crook (appropriately shortened) can be used. For a compact wrap, it would be a little more complicated. The following
sketches show the difference. [Lengths not to scale.] And, yes, the minor-third attachment is indeed "pretty cool"—for a number of reasons. The main advantage being the availability of up to
sixteen attachment alternates (with the same sound-path length as their slide-alone counterparts) in the otherwise awkward low-tenor register (mainly within the bass clef)—as compared with only
four attachment alternates available with the P4 attachment. The minor-third attachment alternates are easily learned because they have the same nominal slide positions as the same notes one or two octaves higher in the facile register above the bass clef. The G attachment is not designed to extend the sub-tenor range down to connect to pedals—although you do get a couple of extra notes: Eb2 and D2 (and their pedals).
.
Re: Easiest Bb/G mod
Posted: Sun May 10, 2026 1:06 pm
by Sesquitone
dewque wrote: Sun May 10, 2026 12:23 am
I've been thinking a tenor with a G valve would be pretty cool.
And, after you get the G attachment installed, try this warmup, played with a "light-swing" feel. From the first D3 to the Bb4 should be played molto-legato in one breath, entirely by lip slurs. Similarly, down the Bb major arpeggio. This is possible because every successive note is on is
different (slide-alone or attachment) harmonic. Very cool!
.
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 5:20 am
by dewque
MichaelMedrick wrote: Sun May 10, 2026 9:22 am
Hello!
I had this done on the Bach 36/42 design. Many of the parts are the same after the slide connector. Eric Edwards cut down an open Wrap f section to g. Additionally, an normal F attachment tuning slide works and gives you the option of an F attachment.
That's nice, I'm mostly worried about the S bend taking up too much length, which are a lot shorter on a Bach.
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 5:22 am
by dewque
Sesquitone wrote: Sun May 10, 2026 11:09 am
Chopping down an OPEN wrap from F to G is a relatively straightforward job—for a brass tech (not a DIY project).
Your pictures look like the S bend goes straight into the tuning slide. Will the ferrules also need cutting to have a sensible amount of tuning left?
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 6:50 am
by Sesquitone
dewque wrote: Mon May 11, 2026 5:22 am
Your pictures look like the S bend goes straight into the tuning slide. Will the ferrules also need cutting to have a sensible amount of tuning left?
Yes, this is the trickiest part of cutting down an original equipment wrap. Both arms of the tuning crook will need some customising. The short arm will probably limit the tuning pull to about 10 mm; this should be enough—if the attachment is very precisely tuned to G in the first place. A fully customised wrap will allow a (slightly) longer pull, as seen in the photo below (of a Conn 88H converted to Bb/G). Ideally, it should be tuned so as not to require any pull at all.
`
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 11:17 am
by hyperbolica
I might be wrong about this, maybe I'm misremembering something, but I think a 3b with 2 slides in the F attachment can be fairly easily cut to G. Might this also apply to a 4b with a similar wrap?
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 12:09 pm
by elmsandr
hyperbolica wrote: Mon May 11, 2026 11:17 am
I might be wrong about this, maybe I'm misremembering something, but I think a 3b with 2 slides in the F attachment can be fairly easily cut to G. Might this also apply to a 4b with a similar wrap?
Yup. Some of the versions with two identical crooks. Short answer just swap them. But you have to remove the brace that is in the way.
To the OP: Cut a length of string, one ~37 inches. That’s your F attachment. Cut another at about 20”. That’s your G. Temporarily tape it to the tube to figure out where you want it. To be and if you need to shorten any sections.
Cheers,
Andy
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 12:56 pm
by brassmedic
Maybe use the smaller radius crook and reverse the direction of the S bend. That would take up less length and allow for more ability to pull the slide. Or don't use the S bend at all and substitute a smaller radius bend for the other port. Lots of parts to work with since the stock configuration is a double wrap. I'm sure a good tech could figure out a way to do it.
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 5:14 pm
by MichaelMedrick
Sesquitone wrote: Mon May 11, 2026 6:50 am
dewque wrote: Mon May 11, 2026 5:22 am
Your pictures look like the S bend goes straight into the tuning slide. Will the ferrules also need cutting to have a sensible amount of tuning left?
Yes, this is the trickiest part of cutting down an original equipment wrap. Both arms of the tuning crook will need some customising. The short arm will probably limit the tuning pull to about 10 mm; this should be enough—if the attachment is very precisely tuned to G in the first place. A fully customised wrap will allow a (slightly) longer pull, as seen in the photo below (of a Conn 88H converted to Bb/G). Ideally, it should be tuned so as not to require any pull at all.
`Nice!!!!
Re: Easiest Bb/G mod
Posted: Mon May 11, 2026 6:36 pm
by dewque
brassmedic wrote: Mon May 11, 2026 12:56 pm
Maybe use the smaller radius crook and reverse the direction of the S bend. That would take up less length and allow for more ability to pull the slide. Or don't use the S bend at all and substitute a smaller radius bend for the other port. Lots of parts to work with since the stock configuration is a double wrap. I'm sure a good tech could figure out a way to do it.
Didn't think about this at all, thanks!