most recent 30 from http://socialsounddesign.com 2013-05-23T01:36:14Z http://socialsounddesign.com/feeds/question/14101 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://socialsounddesign.com/questions/14101/the-formula-for-10-and-31-multi-band-eq-frequency-ranges JM V 2012-05-28T08:44:23Z 2012-10-04T05:55:27Z

<p>hi again nother quick one, I hope you guys can help, I know there is a formula to calculate the bands ranges of an eq on a mixer, the first few are each doubled i.e 20 25 31.5 40 50 63 80 100 125 160 200 250 315 400Hz etc I would like to know how it is calculated. For instance when does it change from double ranges to decade ranges?</p> <p>Alternatively could some kind should give me a list of frequency ranges on a 10 band equalizer and then a 31 band equalizer and I can work it out? </p> <p>look forward to your reply stay gold</p>

http://socialsounddesign.com/questions/14101/the-formula-for-10-and-31-multi-band-eq-frequency-ranges/14102#14102 Bit Depth 2012-05-28T09:00:45Z 2012-05-28T09:00:45Z

<p>An octave is a 2:1 ratio between frequencies (doubling). I think you'll find that a 10-band EQ uses bands (frequencies) an octave apart. A 31-band EQ uses bands that are 1/3 of an octave apart. This is a standardized form that was specified by ISO (International Standards Organisation).</p>

http://socialsounddesign.com/questions/14101/the-formula-for-10-and-31-multi-band-eq-frequency-ranges/14111#14111 Mark Durham 2012-05-29T09:09:23Z 2012-05-29T09:09:23Z

<p>Yes, they double in frequency for each step. Seems like 10band eq's tend to start at 32hz and double through to 16k</p> <p>Like this:</p> <p><img src="http://www.scmsinc.com/uploads/ecomm/eq210colora.jpg" alt="alt text"> </p> <p>It's also nice to have a chart like this to put it in perspective:</p> <p><img src="http://www.beantownboogiedown.com/storage/Hertz-Chart.png?__SQUARESPACE_CACHEVERSION=1260244426517" alt="alt text"></p> <p>If you can't make that out here is the <a href="http://www.beantownboogiedown.com/storage/Hertz-Chart.png?__SQUARESPACE_CACHEVERSION=1260244426517" rel="nofollow">link</a> . So actually those frequencies are between B and C for most octaves.</p> <p>If you do an image search for 31 band eq you will find a load of pictures of hardware eq's with the frequency bands marked on them.</p>

http://socialsounddesign.com/questions/14101/the-formula-for-10-and-31-multi-band-eq-frequency-ranges/15600#15600 Victor 2012-10-04T05:55:27Z 2012-10-04T05:55:27Z

<p>The standard ISO for a 31 band Eq is as follows HZ:20/25/31.5/40/50/63/80/100/125/160/200/250/315/400/500/630/800/1K/1.25K/1.6K/ 2K/ 2.5K/3.15K/4K/5K/6.3K/8K/10K/12.5K/16K/20K.</p> <p>But I think that this wasn’t the question, the question was how to calculate it, right?</p> <p>First, every octave doubles or divides per two a chosen frequency. </p> <p>Let’s take as a reference 400 Hz, the upper octave of this frequency is 800, and the lower 200. Let’s assume that you want a 1/3 octave Eq: 800Hz-400Hz=400Hz; </p> <p>Then 400Hz/3 = 133.33^Hz This means that the frequencies would be: 400/ 533.33^ (400+133.33^)/ 666.66^ (400+133.33^x2)/ 799.99^ (400+133.33^x3)</p> <p>And for the lower octave 400-200=200; 200/3=66.66^; So: 200/ 266.66/333.3266/399.99</p> <p>Notice that standard ISO has rounded those numbers 200/250/315/400</p> <p>If you want an 1/12 octave for the frequencies among 400 and 800, then 400/12=33.33^ Then: 400/433.33^/466.66^/etc. and then rounded.</p> <p>Notice also that the upper octave of 16K is 32K, so out of human range. I hope it helps. Regards.</p>