Pianotech

Subject: Bedrocks of Acoustics in Journals

1.  Bedrocks of Acoustics in Journals

Posted 10-18-2017 08:24
What Journal articles are recommended reading that cover all the basics on the behaviour of music wire such as, stiffness,mass, inharmonicity, wave impedance, velocity, etc.?

Thanks in advance


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I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

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2.  RE: Bedrocks of Acoustics in Journals

Posted 10-18-2017 10:58
Edited by Chris Chernobieff 10-18-2017 11:03
Is this right?

Velocity of Sound Wave through Steel Wire.

Example:
440 hz = √ 150 lbs / (.283 lb/in3 / 12 in)
= 6,361 inches per second?

Nope. I forgot to hit the final square root.
Looks like 79.75 inches per second
Is this right?

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I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
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3.  RE: Bedrocks of Acoustics in Journals

Posted 10-18-2017 11:20
So if that's true,

Using the formula for wave impedance:
Z = √ 150 lbs. * .0235 lb/in3

Z = 1.87 inches per second


------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



4.  RE: Bedrocks of Acoustics in Journals

Posted 10-18-2017 12:59
Ok. I’m going to jump in - not having read any of the articles in question - but throwing my elementary understanding of physics in the Ring.

Sound. Through air. Sea level. 761 miles/sec. 30k ft 678 miles /sec. Approx 340 m/sec

That roughly translates to 1000’ /sec. Faster the denser the air

Through water. 1500 Plus meter/sec. A lot faster.

Google says. 5800 meters/sec for stainless steel. Really moving.

I’d have to go back and really refresh my impedance studies for the lambda factor of .230 given by google

Anyway. Denser = faster transmission is my takeaway.

"PTG - Expand your horizon - Share the vision"

George W.R.(Bill) Davis, RPT, SERVP
The Piano Place GA
2315 Rocky Mountain Rd NE
Marietta GA 30066
(770) 778-6881
www.pianoplace.net
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5.  RE: Bedrocks of Acoustics in Journals

Posted 10-18-2017 21:35
I think rather than density George you meant to say stiffness. Youngs modulus is used to figure the speed of transverse waves in taught piano strings.

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Edward McMorrow
Edmonds WA
425-299-3431
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6.  RE: Bedrocks of Acoustics in Journals

Posted 10-19-2017 15:44
What and where were those strings taught, and by whom?

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David Nereson
Registered Piano Technician
Denver CO
303-355-5770
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7.  RE: Bedrocks of Acoustics in Journals

Posted 10-18-2017 22:57
Yes George, you and google are correct on the calculations.

The formula I was playing with was from A.H Benade's book Sound Production in Pianos.  And as Ed (thanks) made me realize, it's the tension formula in disguise. Plus it's missing the diameter!?  Looks like the 79.45 number may have been Hz after all.





------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



8.  RE: Bedrocks of Acoustics in Journals

Posted 10-19-2017 09:29
Left Benade. Looks like Fenner wants me to calculate air.
And learn German
Berechnung der Spannung umsponnener Saiten

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



9.  RE: Bedrocks of Acoustics in Journals

Posted 10-19-2017 09:35
Just found this Gem in the Archives.
As for Klaus Fenner, it is my opinion that he just makes stuff up just to justify his "status"! Not a big fan of the man, in regards to piano design. Pretty much like Charles Fredrick Stein, IMHO!
Regards,
Joe



Joe Garrett, R.P.T. (Oregon)
Captain, Tool Police
Squares R I
Wonder what Joe from Oregon meant?

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



10.  RE: Bedrocks of Acoustics in Journals

Posted 10-19-2017 21:19
Fenner went into detail about calculating the area of a circle. Easier to just get the density (K) of the material then multiply the percent the circle occupies the square, which is 78.5%. The multiplier is .785 (duh).
Using 381 (which is the copper density divisor. e.g.1 divided by .00262 lb/ft3)

so:
381 x .785 = 299


next is the wrap to core ratio.

-chris

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



11.  RE: Bedrocks of Acoustics in Journals

Posted 10-19-2017 22:21
I think you mean miles per hour. 
761 x 5,280 = 4,018,080 ft/hour
4,018,080 / 3,600 seconds in an hour = 1,116.133 feet per second. 

Etc. 

Mark Schecter
 | |   | | |   | |   | | |   | |   | | |_






12.  RE: Bedrocks of Acoustics in Journals

Posted 10-20-2017 10:55
Now Fenner separates into parts the proportion of copper to steel. Then comes up with a new density total (k) to use in the Taylor formula.

Then averages the values??
Looks like there is a big chart on the next page.

-chris

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



13.  RE: Bedrocks of Acoustics in Journals

Posted 10-21-2017 15:40
Well I think i'm done with Fenner. Just too outdated. Looks like his method depends on a special proprietary scale. And there was none with my copy.
So just a little bummed when I came to this paragraph.

Well it looks like i'll be looking at a S. Fairchild Journal article from 7/1961 next.

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



14.  RE: Bedrocks of Acoustics in Journals

Posted 10-21-2017 22:36
Well the Fairchild formulas are not too bad. He admits they're loosely based on Roberts, Sanderson. Maybe someone can share how he differs from them? And perhaps how Fairchild arrives at the 644164 constant?

I'm not a fan of the Note/6 method (which is useful on a calculator i suppose) but I prefer to use and be able to manipulate frequency.
I do like the (1+B) idea tho.




------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



15.  RE: Bedrocks of Acoustics in Journals

Posted 10-22-2017 11:57
Looking at the Dave Roberts Tension formula, from the well written journal articles 'The Calculating Technician' of 79-80. Although, they are becoming outdated due to the advancement of computers since they were written. But one point of contention is the mixture of units. Correct me if I am wrong, but,  K seems to be based on inches. And A seems to be based on the metric system. Plus there never was any explanation as to how those constants are arrived at - pi, acc/gravity, density, etc.  that I could find.


Next i'll be looking at the 1998 Brown articles and the following reaction articles by Fandrich, Sanderson, Tremaine Parsons, and Garrett.

How about those Bedrocks?!

-chris

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



16.  RE: Bedrocks of Acoustics in Journals

Posted 10-22-2017 22:42
Just read Harry Conklins jr's article called "Thoughts on thoughts". January 1999
Sooo good. Insightful!!
Really tore apart the Brown article piece by piece. His longitudinal mode listening and testing was cool.  His chart showed an amazing amount of data he used for his decision process of designing string scales was impressive.
He put a lot of emphasis on impedance [ Z=n * (T*M).05 ] and pointed out that this was not even considered by Brown.
His fictional story at the end was hilarious too. Here's a snippet.



------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



17.  RE: Bedrocks of Acoustics in Journals

Posted 10-23-2017 11:22
Any mathematicians out there?

Playing with this reverse tension formula of Steve Fairchild's this morning.


In the article, the example given, core diameter is .061, length is 79.5", and the target Tension is 356Lbs. The formula is suppose to calculate the desired O.D.  of .189, but i think there is a typo in the formula.

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



18.  RE: Bedrocks of Acoustics in Journals

Posted 10-24-2017 10:33
A little playing around on the Fairchild reverse formula. I believe instead of 0.5 it should be 0.483, then I was getting the same numbers as he was.

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



19.  RE: Bedrocks of Acoustics in Journals

Posted 10-26-2017 12:25
Edited by Chris Chernobieff 10-26-2017 12:26
Studying all those article sure was beneficial.
Great resources. Here's what I learned.

First, base all future changes on your ear. That's the foundation! I'm fortunate in that I am very familiar with this weber grand and its acoustical weaknesses. Which if I didn't play the piano daily, I would not have picked up those nuances. So it was only in a confirmation capacity that the scaling software shows it's value.

Tension is to adjust for core transition smoothness.
Breaking percent is to adjust winding transition smoothness.
Inharmonicity is to refine and compromise between the two.
Impedance is the road map.







-chris

------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



20.  RE: Bedrocks of Acoustics in Journals

Posted 11-07-2017 09:03
Ah, Found it!



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I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------



21.  RE: Bedrocks of Acoustics in Journals

Posted 22 days ago
Studied over the Article "A Question of Rib Dimension" by Nick Gravagne. January 1990

Horrible! Leaves more questions than it answers.
Frankly, I blame this article for keeping me misinformed about the relationships ribs have to each other and the panel.
Mr. Gravagne sure spent a lot of time on Aggregate cross section differences, but never figured out or let alone shared how to arrive at that aggregate cross section. That's crucial to know when evaluation a rib scale and determining the spacial relationships to the case.

What fools everybody (Nick Included) is the shape of the piano and the different lengths of ribs created. Study a square soundboard first, and then all the math comes together.
-chris
#caveman





------------------------------
I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?

chernobieffpiano.com
865-986-7720
------------------------------