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Great photos, useful commentary.
Thank you.

It's been rumored that cerveny used 795 bore valves on their 835 bore tubas. I've never noticed this, even when using a horoscope aligning valves. Is this a urban myth, or have you even seen it?

Yes, I have seen it and in fact this tuba has that. Measuring across the 3/4 round ports of the rotor, (4 total on each rotor) I got a a measurement of .760"ish. The .770" bore Miraphone rotor was wider. If I had found one of these Cervenys for $1000 or less with trashed valves, I was going to replace them with a true .835" bore valve set. It is possible changing out the valve section may improve intonation but maybe not. Alexander used actually bigger rotors in bore and diameter of the casing (meaning the air had to do less of a bend through the rotor.), but still most Alex 163 CC tubas have that flat D in the middle of the staff. I have the intonation in the "cash register" of my CCB601-4 to the point that I can just put on my big boy pants and plan the thing without getting beat up. I'll put the money saved not buying a new valve set towards a Bermuda Cruise when this Covid-19 Crap is over. Then again, I might still buy a new valve set. We'll see.

BIG QUESTION:
What makes a tuba play stuffy if the smallest opening for air flow throughout the whole thing is the throat of the mouthpiece? If you have played a tuba that you think is "Stuffy" and see no dent that would choke off the air flow to less than the tiny hole at the throat of the mouthpiece, you are either imagining it is stuffy or something other than air flow is causing that sensation. If the later, we are talking about sound waves. Sound waves do indeed create pressure so that is what we are sensing. If a dent, a bore size, or a bend in the tubing/branches causes to much of the sound waves to be reflected back towards the mouthpiece instead of out of the bell, you end up with a "Stuffy" horn. But you do need some feedback to the mouthpiece so you can actually control the horn. If my Cerveny played any more open, I would need to make a tighter leadpipe to add resistance to it.

@Matt Walters, that comment about stuffiness is a great bit of wisdom dropped here in the forum.

A stuffy horn can be so many things that can be rolled up into the category of “non-optimal waveguides”. They could be leaks, globs of solder, crud, or whatever near a node for a certain set of notes.

It’s kinda like in the older hotrod days where a person simply balancing and blueprinting an engine could realize 10-20% more horsepower just from things functioning properly without obstacles.

I’m really enjoying this thread and appreciate your knowledge. Thank you.

matt g wrote:[mention]Matt Walters[/mention], that comment about stuffiness is a great bit of wisdom dropped here in the forum.

A stuffy horn can be so many things that can be rolled up into the category of “non-optimal waveguides”. They could be leaks, globs of solder, crud, or whatever near a node for a certain set of notes.

It’s kinda like in the older hotrod days where a person simply balancing and blueprinting an engine could realize 10-20% more horsepower just from things functioning properly without obstacles.

I’m really enjoying this thread and appreciate your knowledge. Thank you.

It’s not like the engine. In an engine, turbulence is the enemy. For racing at high RPM, maximum flow is the objective. For maximum pulling torque at low RPM, high charge density is the objective and for that you need high velocity through smaller ports. Turbulence limits both flow and velocity, until you get all the way into the combustion chamber, at which point you want even distribution.

It’s more like an impedance problem. Impedance is resistance at specific frequencies. I want to work into enough impedance that the horn doesn’t demand too much from me, but not so much that it damps resonance.

Think of loudspeakers in a stereo. 4-ohm speakers pull more current at a given voltage, and thus require the amplifier to deliver more power, compared to 8-ohm speakers. The lower impedance can be louder, but it can also demand more than the amp can provide, with smoke-releasing results. If the amp is up to it, the results can be nice.

But the location of the impedance matching treatment will affect different frequencies differently, and alter the resonance. That can affect both tone and intonation.

For me, a stuffy tuba is one that doesn’t resonate, and a tuba with too little impedance demands too much signal. I’ve played tubas that seemed to suck the air out of me. I once heard the statement that the first 2165, unlike the CSO York, was not designed to make the most of what the player offered it, but rather to make the most of what Warren Deck could offer it. That captures my thinking about too little impedance.

But turbulence in the right place damps the bottom octave more than the overtones, and a given signal will present more harmonic content. If it damps the bottom octaves (plural) too much, the instrument fights the low frequencies and becomes stuffy. Turbulence in the right place nudges the resonance on certain notes, but in the wrong place may nudge them in the wrong direction.

The magic instruments find the balance.

Rick “living in the frequency domain” Denney

I would love to be able to look at a brass instrument's taper, internal volume, and the locations of bends and be able to identify where resistance probably needed to be added or removed to strike that balance.

And so would a lot of major companies, heh, heh…

@Rick Denney you're in the weeds.

The point about balancing and blueprinting an engine is that you simply stop the engine from fighting itself to simply turnover. I’m not talking about polishing ports and valves and managing exhaust flow for optimal waste discharge and how that’s possibly somewhat analogous to the optimal mode structure of a brass pipe as a waveguide. Because it isn’t.

Next time, take the word “kinda” at face value.

ETA: :-)

Some fixing up of internals and cleaning up some of the inconsistencies that come out of whatever factory can make a big difference. That’s it.

Miraphone’s most recent .835” bore rotors are pretty sweet because they appear to be 186 rotor bodies that are cut out to the larger bore, thus quite lightweight and fast.
…but any (standard design) rotary valve converts the bore from a circle to a D shape, so every single one features a pinched bore...and any rotor body that is less than two times the bore in diameter (which is most all rotor bodies) can’t possibly accommodate the bore of the instrument in its ports. Finally, those rotor bodies that feature round holes are pitched even more in their bore, and are even heavier - because of the added material around the circumference of them.
Something else to consider is that we almost blow no air into/through our tubas. Indeed, the way that we play is to close our mouths off and force air between our lips so that our lips vibrate at pitches sympathetic to the length of the air columns that are in our instruments...and - whether our instruments have tight bends or gradual bands – our instruments (provided they are not leaky) have very defined lengths of air columns. The fact that we slowly replace the air - that is vibrating in our instruments - is completely incidental.
... Of course, Matt knows all of this, but a few others might not.

matt g wrote:[mention]Rick Denney[/mention] you're in the weeds.

The point about balancing and blueprinting an engine is that you simply stop the engine from fighting itself to simply turnover. I’m not talking about polishing ports and valves and managing exhaust flow for optimal waste discharge and how that’s possibly somewhat analogous to the optimal mode structure of a brass pipe as a waveguide. Because it isn’t.

Next time, take the word “kinda” at face value.

ETA: :-)

Some fixing up of internals and cleaning up some of the inconsistencies that come out of whatever factory can make a big difference. That’s it.

But you wrote that a few posts after Matt W. made the point that some turbulence is necessary. You don’t think that an engine analogy wouldn’t lead some to conclude that all internal smoothing is desirable, even after the expert suggested that too much internal smoothing is undesirable?

An engine is an air pump. A tuba is an air resonator. What fights an air pump might be necessary for resonance, and resonance itself might fight an air pump.

Rick “all models are false, even if some are useful” Denney

bloke wrote: ↑Sun Oct 18, 2020 8:32 pm …but any (standard design) rotary valve converts the bore from a circle to a D shape, so every single one features a pinched bore...

When I was at Miraphone they told me (and showed me) that the knuckles between the valves on the 497 were angular (as opposed to rond, like a macaroni elbow). So when the air left the valve it hits two "sharp" angles before it entires the next valve. Their reason for doing this was that it played better. Good reason.

Now I wish I could add a hypothesis as to what the angles in fact do.
But I can't.
So I won't.

Great post. Thanks Matt for taking the time to walk us by the hand through your work. And thanks to the others for their educated responses.

I don't work on my own tubas, so I find it very important to know the science and craftsmanship that make the tuba tick (if only to better evaluate what a repairman does to my own horns).

LeMark wrote: ↑Sun Oct 18, 2020 7:10 am even when using a horoscope aligning valves.

IS IT THE WATER KEY?
Now after all the modifications, the "E" in the middle of the staff went from 40 cents flat to only 15-20 cents flat. For some reason the 1st valve "D" in the same harmonic stayed 40 cents flat.

The theory about Amado, Saturn and Pollard Water Keys is; they rest directly on the crook eliminating the chamber the water key NIPPLE creates. There is a simple way to find out if the answer is NO or MAYBE to the question of will removing/replacing the water key help my tuba.
Pop the water key open while playing your trouble note. If you can't tell that you even popped it open, a water key change will not help that note. If on the other hand you pop the water key open on your bad note, air comes gushing out and the note goes away, you have a nodal or anti-nodal happening at that point. Maybe getting rid of the deep nipple will help you because something acoustically is happening at that point.

On this Cerveny CCB601-4, the "E" in the staff is one such note. Strangely, the 1st valve "D" on that harmonic plays the same even if the water key is open. If both responded to the water key being open, I would have already changed the water key. On a big bulky tuba, it's nice having a water key with a long lever that is easy to reach, so for now I will leave the factory water key on it. I can always change it later.

Holy crap that's an out of tune D. I would be using 4th valve full time on that horn

In my 601, the low C is about 20 cents flat, and the Bb in the staff is about 20 cents sharp. Never been happy with the 2-4 fingerings. For those notes mentioned, I added a tuning slide stick.

Ed Jones just bought a 601 that was probably the most in tune 601 I have ever played, same vintage as yours. It's funny how inconsistent they are.

pjv wrote: ↑Mon Oct 19, 2020 3:07 am

bloke wrote: ↑Sun Oct 18, 2020 8:32 pm …but any (standard design) rotary valve converts the bore from a circle to a D shape, so every single one features a pinched bore...

When I was at Miraphone they told me (and showed me) that the knuckles between the valves on the 497 were angular (as opposed to rond, like a macaroni elbow). So when the air left the valve it hits two "sharp" angles before it entires the next valve. Their reason for doing this was that it played better. Good reason.

Now I wish I could add a hypothesis as to what the angles in fact do.
But I can't.
So I won't.

Great post. Thanks Matt for taking the time to walk us by the hand through your work. And thanks to the others for their educated responses.

I don't work on my own tubas, so I find it very important to know the science and craftsmanship that make the tuba tick (if only to better evaluate what a repairman does to my own horns).

My small point is that - over the years (as just one example: once *square-corners-in-the-air-column Vienna valves were mostly abandoned) many design considerations (with brass instruments) have been based on "flow"...and there is very little "flow". It would be interesting, though, if designers could ACTUALLY figure out ways (other than increasing the ease of "flow") to improve the quality (aesthetic beauty) of the sonic vibrations.
When this actually DOES happen (ie. the vast majority of listeners agree that the SOUND has been improved, by some design change), I believe (mostly...rather than scientific theories and laws being applied) it is due to trial and error. Indeed...with one stalwart model of Miraphone tuba, there are quite a few who prefer the characteristic type of resonance (with a smaller bell, and preceding other changes - some of which I doubt would offer any sonic affects) that older versions offered...whereby newer ones are often toughed as "really great instruments for budding students", yet brought-back-to-specs older ones are those sought out by working professionals.
_____________________________________
*yet - when we hear magnificent horn players in Austria play beautiful solos on horns outfitted with Vienna valves, we never say to ourselves, "yeah...that's pretty good, but just imagine how much better it would be WERE IT that the player were playing a horn that had no square corners in its air columns"

...so BACK to Matt's magnificent Cerveny project, please...

Matt Walters wrote: ↑Sun Oct 18, 2020 9:17 amBIG QUESTION:
What makes a tuba play stuffy if the smallest opening for air flow throughout the whole thing is the throat of the mouthpiece? If you have played a tuba that you think is "Stuffy" and see no dent that would choke off the air flow to less than the tiny hole at the throat of the mouthpiece, you are either imagining it is stuffy or something other than air flow is causing that sensation. If the later, we are talking about sound waves. Sound waves do indeed create pressure so that is what we are sensing. If a dent, a bore size, or a bend in the tubing/branches causes to much of the sound waves to be reflected back towards the mouthpiece instead of out of the bell, you end up with a "Stuffy" horn. But you do need some feedback to the mouthpiece so you can actually control the horn. If my Cerveny played any more open, I would need to make a tighter leadpipe to add resistance to it.

I agree completely. "Stuffiness" is a function of the nodes and antinodes being damped and/or reflected improperly, whether through restrictions in the valve or tubing, or improperly placed braces, dents, etc. These same discontinuities can also affect tuning "bending" where the antinodes are rather than where they should be.

It is Interesting how various oversized tubas’ 5th partials behave.
Some of them sag with less cylindrical tubing added, and some of them sag with more cylindrical tubing.
My kaiser baritone behaves like the tuba you’re working on. The open D is fine, the second valve D-flat is barely flat, but the C and B-natural sag quite a bit (asking for alternates). Elkhart Conn 4/4 sousaphones (14K, 36K) also behave in this way.
In contrast, I have a Kaiser B-flat tuba with very flat open D, a very flat 2nd valve D flat, and a very nicely in-tune 1st valve C and a very nicely in-tune B-natural.

Holy crap that's an out of tune D.

.
Yes it is, but here is the crazy thing. All the other notes I need are within plus or minus 10 cents with the 1st valve slide pulled out 2 inches and left there. The Bb's and F's played first plus the A's and E's played 1&2, don't need any slide movement.
It's time to keep playing it for a month and then reevaluate if I want to make further changes.

Sounds like my Holton 345 *and* my Alexander 163. I played both as three-valved horns and adjusted the 1st slides as would a trumpeter, using the 4th valves only where needed.

The "miracle" of the Alex was that none of the longer alternate combos blew or sounded different than the open horn (even above the staff), and the 40¢ flat bottom line G was dead-on played 13 with the 1st out where it normally was for most notes. All Ds were played 13 and were stable and in-tune, and the 4th line F was also very in-tune with 1st in that position.

I have owned a number of tubas with much better intonation that were also much harder to play with fine intonation. Despite their much more accurate scales, they were more difficult to steer and manipulate to play killer chords with the trombones. That Alex was a *lot* 0f physical work to play well, but it made very good sense once you figured it out, and it was super easy to steer with alternates or the lip.

Some older horns, while wild to learn, worked just fine after some time in the woodshed. A lot of modern horns are impossible to correct adequately, regardless of how hard you work at it.

The most disconcerting flaw I see a lot on newer horns is a 23 overtone series that is impossible to play well without moving the 3rd slide in or out by two inches as you pass through every other partial. Horns like this are the ones I sell first. I would rather have out of tune open notes that are predictable and lippable than a 23 series that is wonky. On horns like that it seems that the Eb below the staff is miles sharp, and to correct is ruins all of the Ab octaves. (I am sorry, but I am talking about CC tubas, specifically but I ought to be speaking in terms of partials since these issues are common to tubas of all keys.)

Different strokes, as they say. Some people value one thing while others value something else entirely.

I’ve noticed that Cerveny has standard in all of their models the long tuning slide on the 3rd valve. (I remember switching it out with the 4th on an Arion once because the 4th was too short)
And I always wonder why.
Is this to allow the player to opt out for an old style 3rd valve tuning with the slide way out, making it a minor 3rd (instead of the usual Major 2nd)?

The 3rd circuit normally drops the pitch by a minor 3rd; the 1st circuit is normally a major 2nd (or whole step). So your question generates from me a big "Huh?"

Did you mean a 3rd valve that could be tuned from a normal minor 3rd to a major 3rd (like 23 would normally net — two whole steps)? I have only ever heard of *very* old tubas using that system. I have heard of more recent valve interval systems whereby the 4th circuit is cut to drop the pitch by a major 3rd.

Forgive me if I am missing something, here. It is early and I have not yet had my "fix" of liquid caffeine.

I've often had that thought myself