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I've noticed that nowadays, virtually ALL .748/19mm piston valve horns (either German, Chinese, or whatever) feature a .787/20mm bore 4th valve.

Is this a relatively new phenomenon? Every 4 valve "vintage" horn I've ever seen, owned, or played did not have this (the 4th valve was also .750) and truth be told, it never was an issue for me, not one bit.

Did the CSO York(s) feature this? Does this account for the practice, or is it new science based on empirical evidence? I was in the same room with one, but didn't have my calipers with me at the time......

Inquiring minds want to know....

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disclaimer: My legitimate research is equivalent to the amount that warmists have done on man-made climate change.[/quote]

It is called man-made carbon dioxide....duh....

bloke wrote:M My legitimate research is equivalent to the amount that warmists have done on man-made climate change.

DANGER DANGER. pointless debate looming.

Hup

bisontuba wrote: It is called man-made carbon dioxide....duh....

Warning too late.

Hup

Larger bore tubing offers less resistance. Since the 4th valve circuit is typically the longest, and adding length adds resistance, it makes a bit of sense. Perhaps it is an attempt to obtain a slightly less stuffy low range?

pittbassdaddy wrote:Larger bore tubing offers less resistance.

The theory of it is well understood, and I suppose that could be used as a reason for its use.

roweenie wrote:Every 4 valve "vintage" horn I've ever seen, owned, or played did not have this (the 4th valve was also .750) and truth be told, it never was an issue for me, not one bit.

I didn't know the 345 had this feature too - the ones I've seen didn't.

True, my experience is limited to BBb horns - I've never had an issue with "stuffy" low registers.

That particular valveset was "tubed" from scratch, so it wasn't possible to check that.

FWIW, the knuckles coming off of the 4th valve were .750.

Yes, but this larger bore is now not limited to 6/4 horns - ALL of them have it, defacto.

Has it come to the point that the larger bore in the 4th valve is expected?

bloke wrote:My SUSPICION (??) is that it's generally humbug, if not generally detrimental.

I'm beginning to think you're not alone in this.

The discussion so far is oversimplified. Nobody has commented on static wave theory: compressions, rarefactions, nodes, and anti-nodes. Larger diameter tubing, by itself, does not help the performance; nor does a same bore as the rest of the valve block, by itself, hinder the performance of a tuba, as velocity of the air stream is not an issue as are the four items mentioned. You can have larger diameter tubing, but if the circuit is not routed correctly for the bends and bows, and/or if the braces are improperly placed, the nodes and anti-nodes will be interfered with and the tone of notes played 4th valve will be stuffy, no matter how large the bore. The King 1251/2341 and the Miraphone 186/7/8 have 4th valves of the same diameter tubing, properly designed and executed, with no detriment to tone or response.

It really isn't new to vary bore size. The pre-1900 Cerveny BBb I once had had graduated bores through the four valves.

Ken Herrick wrote:It really isn't new to vary bore size. The pre-1900 Cerveny BBb I once had had graduated bores through the four valves.

As did all the Couturier horns...

bloke wrote:not testable...
Therefore any theories or opinions will remain pure conjecture.

Well, it may be testable, but who wants to unsolder a perfectly good 4th valve with its circuit and encounter unnecessarily the risks of reassembly involved, if the person involved is not in the R&D department of a brass musical instrument factory?

This may be something to propose to the good folks at Wessex, as they are very careful and thorough in their R&D when developing a new model. For example, they completely re-engineered the 4th valve circuit of their 4-front-valve compensating euph after player trials and feedback.

bloke wrote:

iiipopes wrote:

bloke wrote:not testable...
Therefore any theories or opinions will remain pure conjecture.

Well, it may be testable, but who wants to unsolder a perfectly good 4th valve with its circuit and encounter unnecessarily the risks of reassembly involved, if the person involved is not in the R&D department of a brass musical instrument factory?

This may be something to propose to the good folks at Wessex, as they are very careful and thorough in their R&D when developing a new model. For example, they completely re-engineered the 4th valve circuit of their 4-front-valve compensating euph after player trials and feedback.

It's not testable - not even subjectively (via gathering of opinions, which are not scientific), because the larger-bore and smaller-bore circuits could not be instantaneous interchanged on the same instrument...and (even if two same-model instruments were built with two different 4th-circuit bore sizes) - as many of us have experienced - two same-model instruments (with all of the same bore sizes and all of the same everything) can play differently - certainly differently in the "low range".

Re-read my post. I didn't say it was testable, I said it may be testable. The mechanical logistics, for example, a quick-release valve set, Jupiter style, might work, or something else, or it might not. From a conventional unsolder-resolder perspective, I agree with your view that it is not. That is why I suggested this may be an R&D project for a manufacturer.

Ok, all things being equal, let's explore the actual ($) value of a larger bore 4th valve - - - -

Is this now expected by prospective buyers? Would a uniform bore through all 4 valves be a "deal-breaker" for some? (I suspect for some it might be preferred?)

(And, before someone says it, I'll add that I understand that, in the "real world", how the horn plays, of course, is most important - however, sometimes perception is just as important, if not sometimes more important...)

I've got a few BB flat 6/4 "lap sousaphones" that have exceptional "low ranges", and they all sport a .748/19mm/.750 bore 4th valve (and an .807/20.5mm bore 5th).

My rephrased "value" question is referring to marketability.

I read on the internet that F tubas with all five valves stepped a mm larger than the previous one are always best. ;P

roweenie wrote:I didn't know the 345 had this feature too - the ones I've seen didn't.

True, my experience is limited to BBb horns - I've never had an issue with "stuffy" low registers.

FWIW - my 1966 345 BBb has a much larger bore in the 4th valve. I could pull out the calipers and measure, I suppose, but for now, I do know that the 4th valve tuning slide will swallow the other 3, and is too large to inadvertently insert into the other slides' places.

It does have the common 6/4 Holton tendency to require embouchure adjustments when working your way on down to the basement, but once you 'get it', the resulting output is impressive, so it's a trade-off, I guess.