<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html><head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head>Here's another way to look at it. The amount of potential energy in the system is represented by the sum of the compression in the soundboard system (as Nick describes) plus the amount that can be delivered by the hammer, much like a wrecking ball at the peak of its arc poised to crash into the building. Different systems may have those two sources in different proportion. For the same energy output you might have one system that relies on a greater amount stored in the soundboard and one that relies on a greater amount delivered from the hammer. The differences in the way the energy is released by virtue of that proportional difference and how that manifests itself acoustically might go some way toward answering the JD question and the notion of "bloom", whatever that is . With more energy stored in the board the total system relies less on hammer input and the same total release of energy can be achieved with less energy coming from the hammer. When you think about the differences between that Steinway we loved with very light and soft hammers that seems to come alive at the slightest touch and the Yamaha that requires some greater input of energy it all seems to fall into place.<br/><p>David Love<br/>www.davidlovepianos.com<br/>(sent from bb)</p><hr/><div><b>From: </b> Nicholas Gravagne <ngravagne@gmail.com>
</div><div><b>Sender: </b> pianotech-bounces@ptg.org
</div><div><b>Date: </b>Fri, 18 Mar 2011 08:36:53 -0700</div><div><b>To: </b><pianotech@ptg.org></div><div><b>ReplyTo: </b> pianotech@ptg.org
</div><div><b>Subject: </b>Re: [pianotech] What is bloom,</div><div><br/></div>I think so. This has to be the heart and soul of the whole matter. Voicing, then, evens things out and brings out the best balance, but the choice of hammers is important, after which the voicer can only work with the foundation offered by the belly. <br>
<br>Potential energy (PE) is achieved, and is proportional to, the measurable compression of the soundboard assembly under the force of downbearing. We already know that a string is useless until it is stretched to a high tension; PE is introduced and ready to be tapped. Likewise, hammer felt stretched and compressed over a molding contains PE, also ready to be tapped. PE becomes Kinetic Energy (KE) when tapped, or set in motion. The more PE stored, the more KE is available.<br>
<br>Clearly, too much of good thing spoils the effect. There are limits and points of diminishing returns.<br><br><div class="gmail_quote">On Fri, Mar 18, 2011 at 7:59 AM, David Love <span dir="ltr"><<a href="mailto:davidlovepianos@comcast.net">davidlovepianos@comcast.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Meant to add here, if that’s true, then what exactly impacts the shape of that curve? I still like the idea of how much potential energy is stored in the system and the relationship between the tension of the two springs (string and soundboard). </span></p>
<div class="im"><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p><div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">David Love</span></p><p class="MsoNormal">
<span style="font-size: 11pt; color: rgb(31, 73, 125);"><a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a></span></p></div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
</div><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;"><p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> <a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a> [mailto:<a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a>] <b>On Behalf Of </b>David Love<br>
<b>Sent:</b> Friday, March 18, 2011 7:51 AM<div><div></div><div class="h5"><br><b>To:</b> <a href="mailto:pianotech@ptg.org" target="_blank">pianotech@ptg.org</a><br><b>Subject:</b> Re: [pianotech] What is bloom,</div></div>
</span></p></div></div><div><div></div><div class="h5"><p class="MsoNormal"> </p><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I like the psychoacoustic explanation and it might well be a good one and relate to the actual shape or slope or rate of change of the sustain curve as well as the relationship between the chaos phase and the sustain phase. A sustain curve exhibiting a slower rate of change after the chaos period (or showing a relative flattening out) might be interpreted as a bloom when compared to a more rapid rate of decay. Voicing could then be understood to influence bloom in terms of shaping the relationship between the chaos phase and the sustain phase. It’s certainly a simpler explanation and those are generally more attractive, Occam’s Razor. </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p><div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">David Love</span></p><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a></span></p>
</div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> <a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a> [mailto:<a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a>] <b>On Behalf Of </b>Delwin D Fandrich<br>
<b>Sent:</b> Friday, March 18, 2011 12:15 AM<br><b>To:</b> <a href="mailto:pianotech@ptg.org" target="_blank">pianotech@ptg.org</a><br><b>Subject:</b> Re: [pianotech] What is bloom,</span></p></div></div><p class="MsoNormal">
</p><p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";">Yes, well, I continue to wonder just what it is that we’re actually hearing. Below is an idealized illustration of what is happening at, and following, hammer impact. (It’s a little more idealized than I would like but I don’t have any of my own on this computer. This one is borrowed from the Five Lectures website.)The hammer strikes the strings at about 3 sec. There is a chaotic spike immediately following (the period of chaos is typically a bit wider than shown here). The sound immediately begins to decay at some fairly rapid rate but, for this note, at around 5 sec. the rate of decay changes. </span></p>
<p class="MsoNormal" style="margin-right: 0in; margin-bottom: 12pt; margin-left: 0in; text-align: center;" align="center"><b><span style="font-family: "Cronos Pro Light";"><img src="cid:image001.gif@01CBE542.5B911C70" alt="Description: Description: Fig 1. Typical decay of a piano tone as illustrated by the sound pressure level versus time (Eb3 = 311 Hz). The decay process is divided into two parts; an initial attack part with a fast decay (prompt sound) followed by a sustained part with slow decay (aftersound)." width="301" height="223"></span></b></p>
<p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";">From what I’ve been able to figure out, the knee (at around 5 or 6 sec.) is where the strings vibration pattern changes from a predominately transverse motion (perpendicular to the bridge) to a more random, or rotational pattern. The note is still dying out but at a slower rate. It continues thus until the sound dies out or, as in this illustration, the damper drops.</span></p>
<p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";">In all the samples I’ve recorded and studied over the years I’ve never seen the sound level increase after hammer impact and that first chaotic wave pattern. They all end up looking like some variation of this. More ragged and uneven sometimes but they follow this generally pattern. </span></p>
<p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";">It leaves me wondering if what we think we hear as “bloom” isn’t at least partially—perhaps predominately—psychoacoustic. Our ears—or our brain’s interpretation of what our ears detect—quickly become accustomed to that rapid drop-off following the chaotic hammer impact and, when the waveform gets to the knee and the decay rate slows (sometimes dramatically) we interpret the change as “bloom.”</span></p>
<p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";"> </span></p><p class="MsoNormal" style="margin-bottom: 9pt; line-height: 15pt;"><span style="font-family: "Cronos Pro";">ddf</span><span style="font-size: 11pt; font-family: "Comic Sans MS"; color: navy;"></span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Comic Sans MS"; color: rgb(99, 36, 35);">Delwin D Fandrich</span><span style="font-size: 10pt; color: rgb(99, 36, 35);"></span></p><p class="MsoNormal">
<span style="font-size: 10pt; font-family: "Comic Sans MS"; color: rgb(99, 36, 35);">Piano Design & Fabrication</span><span style="font-size: 10pt; color: rgb(99, 36, 35);"></span></p><p class="MsoNormal"><span style="font-size: 10pt; color: rgb(99, 36, 35);">6939 Foothill Court SW, </span><span style="font-size: 10pt; font-family: "Comic Sans MS"; color: rgb(99, 36, 35);">Olympia, Washington 98512 USA</span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Comic Sans MS"; color: rgb(99, 36, 35);">Phone <a href="tel:360.736.7563" target="_blank">360.736.7563</a> — Cell <a href="tel:360.388.6525" target="_blank">360.388.6525</a></span><span style="font-size: 10pt; color: rgb(99, 36, 35);"></span></p>
<p class="MsoNormal"><span style="font-size: 10pt; font-family: "Comic Sans MS"; color: rgb(99, 36, 35);"><a href="mailto:del@fandrichpiano.com%20" target="_blank">del@fandrichpiano.com </a>— <a href="mailto:ddfandrich@gmail.com" target="_blank">ddfandrich@gmail.com</a></span><span style="font-size: 11pt; color: navy;"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Comic Sans MS"; color: navy;"> </span></p><p class="MsoNormal" style="margin-left: 0.5in;"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> <a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a> [mailto:<a href="mailto:pianotech-bounces@ptg.org" target="_blank">pianotech-bounces@ptg.org</a>] <b>On Behalf Of </b>Dale Erwin<br>
<b>Sent:</b> Thursday, March 17, 2011 5:20 PM<br><b>To:</b> <a href="mailto:pianotech@ptg.org" target="_blank">pianotech@ptg.org</a><br><b>Subject:</b> Re: [pianotech] What is bloom,</span></p><p class="MsoNormal" style="margin-left: 0.5in;">
</p><p class="MsoNormal" style="margin-left: 0.5in;"><span style="font-size: 10pt; font-family: "Comic Sans MS"; color: black;">Del<br> Understood. I can't measure it empirically either. Fortunately we can hear it.</span></p>
</div></div></div></div></blockquote></div><br><br clear="all"><br>-- <br>Nick Gravagne, RPT<br>AST Mechanical Engineering<br>
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