<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <title>RE: 2:1, 4:2, 6:3 octaves</title> <meta http-equiv="Content-Type" content="text/html; charset=windows-1252" /> </head> <body> <p>Ah, the mysteries.</p> <p>Generally speaking, the 4:2 is preferred in the middle of the piano at about F3 up into the 5th octave. The reasons are: The fourth and second partials tend to be strong in this range and to beat unnicely if not closely matched. Likewise for the 6:3 from about E3 down into the bass (farther on small pianos, changing to 8:4 and even 10:5 on big pianos, i.e., long bass strings and big soundboards.</p> <p>There are no hard and fast rules applying to all pianos! In many (most) cases, your temperament octaves must be slightly (SLIGHTLY) wide to make a good temperament. Widening the 4:2 starts to infringe on the 6:3 width ...</p> <p>The octave tests give you some information that will help you determine two things, purity/width of the octave, i.e., beat rate, if any, and that your octave is pure or wide (it must never be narrow). <br /></p> <p>Use the 3rd-10th test on the 4:2. If tuning the top note, say F4 to your F3, tune it pure then a noodge more wide. The beat rate difference should be no more than the beat of a durn clean fifth, i.e., 1/2 bps or less. While learning, it can help to test your octaves with ghosting: In our example silently hold down F3 and F4 and whack the 4:2 key, i.e., F5. You should hear something between pure and a very slow roll. If you are unsure that your octave is wide, tune a 4th or 5th inside it. In the F3-F4 example, tune either A#3 or C4. Use the 3rd-6th test on the 4th and the 6th-10th test on the corresponding fifth. You MUST end up with a wide fourth (6th faster than 3rd) AND a narrow fifth (6th faster than tenth). If you have a nice, quiet octave, a 4th beating 1 bps or so and a very lazy fifth, then you have three notes that are tuned purty accurately--in relation to each other, that is.</p> <p>6:3 octave, use the m3rd-M6th test. If they beat exactly the same, you have an exact 6:3 octave. The reference note for ghosting is one octave + a fifth above the higher note of your octave. This is the 6th partial of the lower note and 3rd partial of the upper note. Remember that the minor 3rd is a narrow interval so, for example, if the octave is too narrow, the m3rd will beat faster than the M6th and vice-versa if it is too wide.</p> <p>There is so much more, including using the m3rd-M6th test for a stretched 4:2, that we are only just beginning.</p> <p>Treble tuning ... someone else, please. The 2:1 is not that tough and is required for octave 7 of the tuning test, but between the 4:2 mid-range and the last octave (or to the top in the real world, if it sounds right, you should be looking for 4:1 double octaves which are, among other things, good candidates for ghosting, at lease up through the fifth octave. Here you will need to learn the 10th-17th test and the 3rd-17th test. Mostly to ensure that the octaves are a little wide, never narrow, then sound quality and double octaves will help you nail the 4:1.</p> <p></p> <p>S'Late, bye ...</p> <p>Alan Barnard<br />Salem, MO<br /><br /></p> <div style="padding-right: 5px; padding-left: 5px; padding-bottom: 5px; border-left: #000000 3px solid; padding-top: 5px"> <hr />Original message<br />From: "Matthew Todd" <toddpianoworks@yahoo.com></toddpianoworks@yahoo.com><br />To: pianotech@ptg.org<br />Received: 8/21/2007 10:11:26 PM<br />Subject: 2:1, 4:2, 6:3 octaves<br /><br /> <div align="left">I have been really, really studying tonight.</div> <div></div> <div>Can someone please explain the system they use to tune 2:1, 4:2 and 6:3 octaves.  I am so close to grasping this concept, but I think I need another tech to explain it to me besides Reblitz.</div> <div></div> <div>In the octave interval, if I were to tune a 4:2, the fourth partial of the lower note theoretically has the same frequency as the 2nd partial of the upper note.  Do those partials normally dominate each octave?  How can I tell whether to tune a 4:2 or a 6:3?</div> <div></div> <div>Oh, and lets leave inharmonicity for another post.  I am just trying to grasp this main theoretical concept.</div> <div></div> <div>Thank you!<br />Matthew</div> <p></p> <hr size="1" />Need a vacation? <a href="http://us.rd.yahoo.com/evt=48256/*http://travel.yahoo.com/;_ylc=X3oDMTFhN2hucjlpBF9TAzk3NDA3NTg5BHBvcwM1BHNlYwNncm91cHMEc2xrA2VtYWlsLW5jbQ--">Get great deals to amazing places </a>on Yahoo! Travel. </div> </body> </html>