Soundhole sizing and design - Cigar Box Nation2024-03-29T09:55:34Zhttps://www.cigarboxnation.com/forum/topics/soundhole-sizing-and-design?groupUrl=superclass&commentId=2592684%3AComment%3A3405440&groupId=2592684%3AGroup%3A869&feed=yes&xn_auth=noHi all,
I thought the hole it…tag:www.cigarboxnation.com,2019-11-07:2592684:Comment:34054402019-11-07T09:28:17.597ZRich Buttershttps://www.cigarboxnation.com/profile/RichButters
<p></p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">Hi all,</p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">I thought the hole itself doesn't affect the sound of the guitar. It is more the actual top (soundboard) of the guitar that generates the sound by vibrating like a drum skin. Usually, up to 80% of the sound is created from two vibration points to either side, and just below the bridge.</p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">If you want to see which part of your soundboard is generating most of the sound - sprinkle some flour or fine sand all over the soundboard and pluck some open notes. You can then see the flour/sand settle into areas where there is no movement, and be bounced away from areas with lots of movement.</p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">The trick is then not to damage or change the areas of maximum movement on the soundboard too much, as this will drastically affect the sound of the guitar.</p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">Then again, if your guitar is TOO bright and you want to dampen the sound down a bit, you can stick bits of blu-tack or plasticine under the soundboard at these vibration points to dampen them a bit. Classical guitarists do this quite often.</p>
<p style="border-image-outset: 0; border-image-repeat: stretch; border-image-slice: 100%; border-image-source: none; border-image-width: 1; box-sizing: inherit; clear: both; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; vertical-align: baseline; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px; padding: 0px; margin: 0px 0px 1em 0px; border: 0px none currentColor;">If you <span style="display: inline !important; float: none; background-color: #ffffff; color: #242729; font-family: inherit; font-size: 100%; font-size-adjust: none; font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; letter-spacing: normal; line-height: inherit; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px;">want more bass resonance I will design the sound hole smaller, and to decrease bass resonance I will increase sound hole size, regardless of sound hole shape. Keep in mind wood type, grain, cellulose density, and thickness also plays a role in tone, but to recap, smaller sound hole=more bass, bigger sound hole=decrease in bass.</span></p> If you have more than one sou…tag:www.cigarboxnation.com,2017-12-02:2592684:Comment:29972402017-12-02T01:54:46.379ZMark Taylorhttps://www.cigarboxnation.com/profile/MarkTaylor
<p>If you have more than one sound hole should they all be this size or add up to this size? For the box volume, should you subtract the losses from the bracing and neck mountings?</p>
<p>If you have more than one sound hole should they all be this size or add up to this size? For the box volume, should you subtract the losses from the bracing and neck mountings?</p> In earlier post I was looking…tag:www.cigarboxnation.com,2016-10-24:2592684:Comment:27141272016-10-24T16:50:16.058ZJimmy Davishttps://www.cigarboxnation.com/profile/JimmyDavis823
<p>In earlier post I was looking at sound hole size and found these 2 formulas.</p>
<p> I set up a spread sheet and ran both formulas listed below using these numbers</p>
<p>Dimensions 10 x 8 x 2</p>
<p>Frequency of 2<sup>nd</sup> lowest string 146.83</p>
<p> <u>Formula for calculating sound hole diameter</u> returned a sound hole diameter of 1.684</p>
<p><u>Helmholtz equation for sound hole diameter for cigar box guitars returned</u> a sound hole diameter of .824</p>
<p> One of these…</p>
<p>In earlier post I was looking at sound hole size and found these 2 formulas.</p>
<p> I set up a spread sheet and ran both formulas listed below using these numbers</p>
<p>Dimensions 10 x 8 x 2</p>
<p>Frequency of 2<sup>nd</sup> lowest string 146.83</p>
<p> <u>Formula for calculating sound hole diameter</u> returned a sound hole diameter of 1.684</p>
<p><u>Helmholtz equation for sound hole diameter for cigar box guitars returned</u> a sound hole diameter of .824</p>
<p> One of these numbers is about half of the other. Am I calculating something wrong or am I completely missing something here. Could the Helmholtz equation be the radius instead of diameter. Any clarification or help would be welcome.</p>
<p> <u>Formula for calculating sound hole diameter</u><br/> <br/> 1.) Calculate box volume(<strong>V</strong>) = Length <strong>*</strong> Width <strong>*</strong> Height<br/> 2.) Solve for the radius of a sphere of the same volume: <strong>radius</strong> = ((3<strong>*V</strong>)/4<strong>*</strong>pie)^(1/3)<br/> 3.) Divide the <strong>radius</strong> by <strong>4</strong>.<br/> 4.) This resulting value is the new radius of the sound hole.<br/> 5.) So, <strong>2 x radius</strong> is the new <strong>sound hole diameter</strong>.</p>
<p>And came up with this example: (2 * (((3 * 8.25 * 5.5 * 2.75) / (4 * 3.14))^(1 / 3))) / 4 = 1.55023303</p>
<p> </p>
<p>Another post gave this formula:</p>
<p><u>Helmholtz equation for sound hole diameter for cigar box guitars</u></p>
<p>The equation is:</p>
<p>Sound Hole Diameter in inches = F<sup>2</sup> x W x L x D x 0.00000023895</p>
<p> </p>
<p>where:</p>
<p>W = box inside width</p>
<p>L = box inside length</p>
<p>D = box inside depth</p>
<p>F = frequency of 2<sup>nd</sup> lowest string in Hz </p>
<p>For example:</p>
<p>The D string on a 4 string CBJ tuned to open G (GDGB) is 146.83 Hz</p>
<p>The inside dimensions of the cigar box are 8 x 10 x 2 inches</p>
<p>Substituting these values into the equation, we have:</p>
<p>Sound hole diameter = 146.83 x 146.83 x 8 x 10 x 2 x 0.00000023895</p>
<p> </p>
<p>Sound hole diameter = .824 inches, or about 53/64”</p>
<p><u> </u></p> Hahahahatag:www.cigarboxnation.com,2016-06-15:2592684:Comment:26263992016-06-15T08:51:13.405ZFomhorachhttps://www.cigarboxnation.com/profile/Fomhorach
<p>Hahahaha</p>
<p>Hahahaha</p> It looks like this thread cam…tag:www.cigarboxnation.com,2013-05-15:2592684:Comment:15660362013-05-15T15:04:34.877ZMichael Recchionehttps://www.cigarboxnation.com/profile/MichaelRecchione
<p>It looks like this thread came back to life, so I'll just add to it instead of starting a new one. I'm trying to find a reference that derives the ratio of soundhole radius to the radius of the "equivalent sphere" for maximum loudness. I've seen this ratio referred to as 1/4 in a couple of places, but the information is given with the caveat that "I don't pretend to understand the math, but I've been told, ..."</p>
<p></p>
<p>I've found a bunch of places where the Helmholtz resonance…</p>
<p>It looks like this thread came back to life, so I'll just add to it instead of starting a new one. I'm trying to find a reference that derives the ratio of soundhole radius to the radius of the "equivalent sphere" for maximum loudness. I've seen this ratio referred to as 1/4 in a couple of places, but the information is given with the caveat that "I don't pretend to understand the math, but I've been told, ..."</p>
<p></p>
<p>I've found a bunch of places where the Helmholtz resonance frequency is derived, various ways to affect it, fudge factors to correct for the fact that the guitar body isn't rigid, etc. But I haven't been able to find a reference that derives the ratio for maximum loudness. </p>
<p></p>
<p>I know these are CBGs, and "there are no rules", and there are all sorts of empirical ways to determine the optimal hole-to-box ratio. So this is kind of intellectual curiosity on my part. But there is a practical element as well. </p>
<p></p>
<p>For any box, if the urban legend is true, there's going to be a soundhole diameter that gives the maximum loudness when you play it unplugged. That soundhole radius to volume ratio will correspond to a particular Helmholtz resonance frequency, which, for best results, should be close to the pitch frequency of the second-lowest string on the instrument (at least that's what's done on regular guitars - it should certainly be a higher frequency than the lowest string, and biased towards the bass). Which means that, for any box, there's a configuration of strings and tuning that will give not only the loudest, but also the best balanced sound. It would be cool to know (sort of), in advance, what sort of instrument a particular box is best suited for if it's to be played unplugged.</p>
<p></p>
<p>Or maybe it's just intellectual wanking... :) In any case, does anyone know if this urban legend of a ratio of 1/4 between the radii of the soundhole and the "equivalent sphere" is true? And, if it is, can anyone point me to the reference where it's derived?</p>
<p></p>
<p>Thanks!</p> I did the math, and I've atta…tag:www.cigarboxnation.com,2013-05-03:2592684:Comment:15501672013-05-03T19:44:40.671ZBrian Dechanthttps://www.cigarboxnation.com/profile/BrianDechant
<p>I did the math, and I've attached a quick and dirty version of the Helmholtz equation in word format, with an example for a "typical" CBJ. Hope this helps, or at least provides a starting point.</p>
<p> </p>
<p>I did the math, and I've attached a quick and dirty version of the Helmholtz equation in word format, with an example for a "typical" CBJ. Hope this helps, or at least provides a starting point.</p>
<p> </p> yeah i like the sound holes i…tag:www.cigarboxnation.com,2012-08-25:2592684:Comment:12210712012-08-25T12:45:23.021ZMike Gregoryhttps://www.cigarboxnation.com/profile/MikeGregory
<p>yeah i like the sound holes in the black one,,,ill try them again,,,,,you never know,,</p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p>yeah i like the sound holes in the black one,,,ill try them again,,,,,you never know,,</p>
<p> </p>
<p> </p>
<p> </p>
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<p> </p> Mike -
Are all four guitars e…tag:www.cigarboxnation.com,2012-08-24:2592684:Comment:12201952012-08-24T11:25:35.632ZHabanera Halhttps://www.cigarboxnation.com/profile/HalSpalter
<p>Mike -</p>
<p>Are all four guitars equal in all other ways? (Box size, wood thickness, scale, bridge height, string size, etc.?) Do you notice any difference in volume or prjection? Looks like there is a plate on top of the black box (lower right corner) that may be reducing the soundboard vibration accounting for the duller tone? The black one has the most artistic ones - I may have to steal them, LOL. Nice job.</p>
<p>Mike -</p>
<p>Are all four guitars equal in all other ways? (Box size, wood thickness, scale, bridge height, string size, etc.?) Do you notice any difference in volume or prjection? Looks like there is a plate on top of the black box (lower right corner) that may be reducing the soundboard vibration accounting for the duller tone? The black one has the most artistic ones - I may have to steal them, LOL. Nice job.</p> The warmest tone comes from t…tag:www.cigarboxnation.com,2012-08-24:2592684:Comment:12199212012-08-24T10:23:29.225ZMike Gregoryhttps://www.cigarboxnation.com/profile/MikeGregory
<p>The warmest tone comes from the round hole,,next best is th F holes,,,the black one is a bit dull sounding,,,thats what ive found with my first few builds</p>
<p>Mike</p>
<p>The warmest tone comes from the round hole,,next best is th F holes,,,the black one is a bit dull sounding,,,thats what ive found with my first few builds</p>
<p>Mike</p> Find where you want a hole. A…tag:www.cigarboxnation.com,2012-07-02:2592684:Comment:11581182012-07-02T01:45:30.489ZRTZGUITARShttps://www.cigarboxnation.com/profile/RTZGUITARS
<p>Find where you want a hole. And drill or cut it. Start small and test drill bigger test till you like what you hear. Next time you know how big a hole to drill , but where sould you drill same place or try a new place your ears will tell you what works.</p>
<p>Find where you want a hole. And drill or cut it. Start small and test drill bigger test till you like what you hear. Next time you know how big a hole to drill , but where sould you drill same place or try a new place your ears will tell you what works.</p>