


The 1st valve slides are the same diameter. The first valve slide on the holton actually fits in the mienl weston set with no finagling.




The valve section and tubing on all three is very similar with some mild changes in third and fourth routing to accommodate the main body.arpthark wrote: Sun May 28, 2023 10:11 am Besides them having similar model numbers and the later Big Valve block, I've never thought the 2145/55/65 had too much in common. Correct me if I am wrong.
Is the 4th valve on the MW set not larger than the other three? would it not have the same problem/feature/bug?LargeTuba wrote: Sun May 28, 2023 8:39 am I’m replacing the entire valve section on my holton. On the holton the 4th valve bore is 0.830” but the port exiting the valve is 0.750, which I believe leads to some response issues. Neither are for sale for the time being.
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The MW bore is 19mm (0.748”) for 1-3 and 20mm (0.787”) for 4. This Holton set seems to be a massive dilation of the tubing with little/no change in porting.cjk wrote: Tue May 30, 2023 2:27 pmIs the 4th valve on the MW set not larger than the other three? would it not have the same problem/feature/bug?LargeTuba wrote: Sun May 28, 2023 8:39 am I’m replacing the entire valve section on my holton. On the holton the 4th valve bore is 0.830” but the port exiting the valve is 0.750, which I believe leads to some response issues. Neither are for sale for the time being.
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matt g wrote: Tue May 30, 2023 4:48 pmThe MW bore is 19mm (0.748”) for 1-3 and 20mm (0.787”) for 4. This Holton set seems to be a massive dilation of the tubing with little/no change in porting.cjk wrote: Tue May 30, 2023 2:27 pmIs the 4th valve on the MW set not larger than the other three? would it not have the same problem/feature/bug?LargeTuba wrote: Sun May 28, 2023 8:39 am I’m replacing the entire valve section on my holton. On the holton the 4th valve bore is 0.830” but the port exiting the valve is 0.750, which I believe leads to some response issues. Neither are for sale for the time being.
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That makes sense, particularly considering that removal/rebuilding/reinstallation is no longer c. $700, but (probably) two-and-a-half times that amount (just as with the daily necessities which we must continue to purchase have mostly increased in cost/price by roughly the same percentage).LargeTuba wrote: Sat Jun 03, 2023 7:02 pm @bloke the point of this is to add more resistance in the 4th valve, I’m bumping down the bore nearly 1.5mm. I’m also eliminating lots of straight tubing in the bugle, and I’ll have a smaller main tuning slide. Again, putting more resistance in the bugle.
The original Holton valves need to be replaced. So at minimum this is still an upgrade.