Can resistance be heard?

[peterbas]

.

[LeMark]

Sounds like I need to take my York up to Carl and see if there is a reason why it plays a bit stuffy

I'm lucky he's only an hour away from me

[UncleBeer]

OK, yet another somewhat off-topic post. Here are images of an instrument where I measured before- and while I held the spit valve open (aka: a 'leak'). Sure, it's a sledgehammer approach, but I wanted to see what BIAS would make of it. In the first image, you can see the deflection the 'leak' causes, clearly defined by the green line at 110cm from the mouthpiece (red line is normal, with water key closed). The big rise at 520cm is the bell.

1 Wyvern w HB BIAS response, red is normal, green is MTS spit valve open.jpg (174.69 KiB) Viewed 6039 times

And here's how the open spit valve affects intonation (red/blue is normal, yellow/green is valve open).

2 Wyvern w HB BIAS intonation, red and blue are normal, yellow and green with MTS spit valve open.jpg (117.03 KiB) Viewed 6039 times

[matt g]

This is all pretty cool.

[UncleBeer]

This is all pretty cool.

Thanks. Since I didn't get to present at ITEC, I figured I'd 'waste' it on ya'll.

[matt g]

This is all pretty cool.

Thanks. Since I didn't get to present at ITEC, I figured I'd 'waste' it on ya'll.

Be awesome to see this done with various flavors of tubas as well. See how the curves line up and whatnot.

[UncleBeer]

I'm slowly building up a database of BIAS readings of any instruments passing through my shop. As you see, the readings can be dragged over each other for immediate comparison.

[donn]

Do some of the tuba examples run a particularly flat pulse response curve? The variation in response seems to be due to defects - maybe the little bumps we're looking at are solder joints, random gunk, design flaws? I imagine you could use this to find the "good one" off the factory line, or the factory could use it to spot the bad ones.

Or maybe below a threshold, the bumps aren't a defect that would be at all detectable to a player.

[UncleBeer]

Do some of the tuba examples run a particularly flat pulse response curve? The variation in response seems to be due to defects - maybe the little bumps we're looking at are solder joints, random gunk, design flaws? I imagine you could use this to find the "good one" off the factory line, or the factory could use it to spot the bad ones.

Or maybe below a threshold, the bumps aren't a defect that would be at all detectable to a player.

Lots of great info in the BIAS manual, especially starting on p. 100 (top of page says 108 though). A brief excerpt:

With the aid of the impulse response, you can determine imperfections
inside the instrument. Small variation of the order of a 10th of a mm generate "peaks" or noticeable "unevenness" in the curve.
Keep in mind the following "rules"

● A positive peak indicates a position
where a sudden constriction inside the
instrument occurs.

● A negative peak indicates a position
where a sudden expansion inside the instrument occurs and stands as well for
leakiness (e.g. waterkey).

● Each peak features before and afterwards one or more small peaks with opposite direction.

● Nevertheless, the bell of the
instrument always appears as a
strong positive peak! To get the
length of the instrument you have
to measure at the inflection point
at the minimum of the small negative peak before!

● Discontinuities in the cross section with
a distance less than 3-4 cm from each
other cannot be discriminated.

● The first 20-30 cm of the pulse response plot are superimposed by mouthpiece resonances and therefore are not
usfully for detecting imperfections.

● All instruments show more or less small insignificant peaks that are caused by reflections in
the valve area.

● In all trombones, there are generally coarse
imperfections as a result of the slide.

[donn]

OK, but I mean, in practice ... your Wyvern there has significantly higher amplitude reflections going on in the first third of the horn, than the MW. Not good, right? That's why we pay more for an MW?

Could one reason for lack of industry enthusiasm be, they aren't looking forward to seeing a Pulse Response Buyer's Guide to Brass Instruments?

[Mary Ann]

Do some of the tuba examples run a particularly flat pulse response curve? The variation in response seems to be due to defects - maybe the little bumps we're looking at are solder joints, random gunk, design flaws? I imagine you could use this to find the "good one" off the factory line, or the factory could use it to spot the bad ones.

Or maybe below a threshold, the bumps aren't a defect that would be at all detectable to a player.

You're reminding me of what my cryogenics physicist horn playing fiend says about flutes, which is that a concrete flute with the exact same inner dimensions as a zillion dollar platinum flute will play the same, and that the reason expensive flutes are expensive is that the inside is better.

[UncleBeer]

OK, but I mean, in practice ... your Wyvern there has significantly higher amplitude reflections going on in the first third of the horn, than the MW. Not good, right? That's why we pay more for an MW?

I've been in frequent contact with BIAS's developers, and they stress that it's a tool which should be used in conjunction with players' experience. That, of course is the final arbiter of an instrument's success or failure.

[peterbas]

.

[bloke]

something else:

I've learned that we are surprisingly adaptable to "new normal" (assuming others are like me).

When picking up models that I've owned/used in the past - but sold and moved on, at first I'm at "wow stuffy" or "wow, not enough resistance"...but (when I owned one of those) it was just "regular".

That having been said, when my daughter left a Beanie Baby in my F tuba (probably more than thirty years ago) and I was playing a Christmas quintet gig at a church, I was thinking to myself, "d@mn...Either I should get back on a regular practicing regime, or hang this $h!t up."

yes...I played the entire gig with that thing in there...Truth be told (not bragging...just saying...) I managed.

[donn]

OK, but I mean, in practice ... your Wyvern there has significantly higher amplitude reflections going on in the first third of the horn, than the MW. Not good, right? That's why we pay more for an MW?

I've been in frequent contact with BIAS's developers, and they stress that it's a tool which should be used in conjunction with players' experience. That, of course is the final arbiter of an instrument's success or failure.

So it isn't necessarily the case that the Wyvern's relatively large peaks and valleys would translate to any performance issues?

Is amplitude on fixed scale? It looks to me like (with the water key closed) the Wyvern hits magnitude 4, where the MW stays below 2 except where the shelf line drives it up to 4.

[bloke]

re: "why my York tuba plays 'stuffy' "

I've never played an Olds/Reynolds/York .656" bore tuba that (to me) didn't seem to play "stuffy" (nor any 3/4 tuba sporting a similar bore size)...yes, I can certainly adjust, but...

...yet (on the trombone and bass trombone forums) I read their reports of owning those and loving them because they aren't quite "as" wide-open (ie. to them: no resistance) as most all other tubas...

again: a matter of that to which one is accustomed (sort like close-fitting vs. loose-fitting clothing, and all sorts of other things...)

[UncleBeer]

Is amplitude on fixed scale? It looks to me like (with the water key closed) the Wyvern hits magnitude 4, where the MW stays below 2 except where the shelf line drives it up to 4.

The measurement is Pascals per cubic millimeter, so has to do with air pressure levels (compressions & rarefactions caused by sound waves) along the length of the instrument.

[Mary Ann]

I wanna see a chart of a typical rotary F tuba that us weaklings can't get a good low C out of.

[jtm]

Ever tried a miraphone firebird?

[bloke]

I would venture a guess that most people who claim to not be able to play that pitch on an F tuba are actually working too hard, rather than not being strong enough.

Learning to not blow the crap out of it in that range and still getting a loud resonant sound is pretty liberating, because you don't have to shop only for the ones with which you can blow the crap out of that note and it works anyway... most of which feature some pretty serious intonation problems, and please don't try to talk to me about the model you just mentioned, because we're not going to agree.

I'm also not going to link that recording of the Camille Saint-Saens Organ Symphony again. I'm tired of showing how much sound an F tuba can produce on that pitch if someone just feeds the vibration into the instrument, rather than trying to jam it into the instrument.