Asymmetrical Upper Bow on 1292

[Bill Troiano]

Does anyone know the reasoning behind the asymmetrical upper bow design on the 1292? I've owned mine for about a year and I never even noticed this until someone pointed it out to me. The 1291 and 1293 seem to have regular, symmetrical upper bows (like all other tubas that I know of). There must a reason why this was done on the 1292. Thanks!

[Musical_Eagle]

The Miraphone 1291 has the same asymmetrical upper as the 1292 as well and I think the case is the same for the 1293 but not sure 100%.

[Dan Schultz]

Does anyone know the reasoning behind the asymmetrical upper bow design on the 1292? I've owned mine for about a year and I never even noticed this until someone pointed it out to me. The 1291 and 1293 seem to have regular, symmetrical upper bows (like all other tubas that I know of). There must a reason why this was done on the 1292. Thanks!

Please explain what you are speaking of. And... as some others have said... is it also true with the 1291BBb?

[Dan Schultz]

The Miraphone 1291 has the same asymmetrical upper as the 1292 as well and I think the case is the same for the 1293 but not sure 100%.

LV... this is the post I was alluding to.

[Musical_Eagle]

The Miraphone 1291 has the same asymmetrical upper as the 1292 as well and I think the case is the same for the 1293 but not sure 100%.

LV... this is the post I was alluding to.

Sorry for the lack of clarity. I should have been more clear and said 1291 CC. Sorry for the confusion.

[Dan Schultz]

The Miraphone 1291 has the same asymmetrical upper as the 1292 as well and I think the case is the same for the 1293 but not sure 100%.

LV... this is the post I was alluding to.

Sorry for the lack of clarity. I should have been more clear and said 1291 CC. Sorry for the confusion.

AHA. Thanks!

[aqualung]

"Old World Craftmanship". They are bent around an asymmetrical tree trunk in the back yard of the factory.

[Bill Troiano]

Here's a picture of the back of my 1292 CC. Yeah, I know. It needs a cleaning. My wife, who is not a musician, offered a very logical answer as to why the upper bow is shaped as it is. She said it's because it is so tall, this way it's easier to get your hand through to move the slides. So, there's a microbiologist's (retired) answer. However, the branch right under the top one is also shaped the same way. You can't see that from the picture. Sorry about the sideways picture. If somebody knows how to rotate it, feel free.

[soyezu]

Rotated for your viewing pleasure...

[joh_tuba]

I've always suspected that there is a nodal point at those points in the upper bow.

Miraphone is attempting to recreate a more 'American' style of horn in the 129X CC series. That style of horn always has weird intonation AND disproportionately large upper bows.

My theory: rather than shrink those bows to a sensible proportion relative to the rest of the bugle(and lose some of the "American-ness" they are using asymmetric bows to move the nodal points for better intonation.

Maybe I'm wrong. I find the asymmetric bows and the overly large bell VERY ugly to look at. In addition, if you spend much time studying how these horns are braced together you'll find lots of things that are very 'odd'. I consider it one of the most aesthetically displeasing tubas ever made.. they play 'fine'.. but it looks terrible. Perhaps that opinion is wrong too.

FWIW

[Dan Schultz]

From an engineer's perspective.... I recall having some of those "Oh ****!" moments. It could simply be a matter of OK.... how to we get from here to there and add a couple of inches to make it in tune at the same time.

[bort]

Having owned a 1291 for several years, I have to say that design feature is nearly unnoticeable. Bill's picture seems to accentuate it far more than it appears in real life. It's also not a very flattering picture, and the 1291 doesn't exactly have the best looking back to begin with. Meh.

Is the asymmetry related to the taper? Or are we really looking at one side of the top bow is higher than the other.

[imperialbari]

The asymmetrical top bow hits the bell at a point where its diameter is smaller. Which in turn means the secondary bottom bow can be of a wider diameter than would have been possible with a symmetrical top bow.

Klaus

[PaulMaybery]

Roger Lewis (then at WWBW) once explained to me several years ago that that particular design technology does come from organ building, especially when longer pipes needed to be folded. Belief from organ acousticians is that it (the asymetrical bend) somewhat enhances the depth of sound of the fundamental. In the context of a tuba, it is intended to help a 4/4 horn respond a bit more like a 5/4 or 6/4.

I'm sure Roger could explain it more clearly and with a few more interesting details.

[iiipopes]

Looks to me like the bend was started early to stay out of the way of the bell taper, and then the curve and taper adjusted for the outside bend of the bow accordingly, as if it were modified from an earlier model or prototype.

[imperialbari]

A symmetrical bow would have taken the 2nd vertical tubing and the secondary bottom bow further away from the main plane of this tuba, if that secondary bottom bow should keep its present radius.

[Dan Schultz]

Looks to me like the bend was started early to stay out of the way of the bell taper, and then the curve and taper adjusted for the outside bend of the bow accordingly, as if it were modified from an earlier model or prototype.

+1. My sentiments exactly. Those so-called 'nodal points' are moving targets, anyway.

[Matt Walters]

The asymmetrical bow is to change acoustics. Someone who has more time on their hands can dig into finding the paper on acoustics about this. The "Slokar" trombones used this in the main tuning slide starting 15 maybe 20 years ago. Their propaganda stated " Reduction of disturbance echoes". This also reminds me of some performance exhaust systems. The great Walter Lawson once told me "you have to have Irregularities in the taper or the response will be dull." He then showed me where in the French Horn branch he had a sudden flair.

[Bill Troiano]

Thanks for all of the responses, everyone. Good to hear from you, Matt.

Sooooo, does the 1291CC and 1293CC also have this asymmetrical upper bow? And, the BB's do not?

[Musical_Eagle]

Thanks for all of the responses, everyone. Good to hear from you, Matt.

Sooooo, does the 1291CC and 1293CC also have this asymmetrical upper bow? And, the BB's do not?

Yes, the 1291 CC and the 1293 CC have the asymmetrical bow. And the BBb tubas do not have this asymmetrical bow.

Hope this helps