{"id":73,"date":"2002-07-21T16:18:00","date_gmt":"2002-07-21T21:18:00","guid":{"rendered":"\/?p=73"},"modified":"2002-07-21T16:18:00","modified_gmt":"2002-07-21T21:18:00","slug":"run-silent-go-feep","status":"publish","type":"post","link":"http:\/\/esr.ibiblio.org\/?p=73","title":{"rendered":"Run Silent, Go Feep"},"content":{"rendered":"<p><em>Warning: The following blog entry provides way more than the<br \/>\nrecommended daily allowance of geeking. If you don&#8217;t have a serious<br \/>\npropeller-head streak, surf outta here now before it&#8217;s too<br \/>\nlate.<\/em><\/p>\n<p>I&#8217;m mainly a software guy, but occasionally I build PCs for fun.<br \/>\nDesign them, rather; the further away I stay from actual hardware the<br \/>\nhappier it usually is for everybody.  Last year, I designed an <a href=\"http:\/\/www.catb.org\/~esr\/writings\/ultimate-linux-box\">Ultimate<br \/>\nLinux Box<\/a>; the good folks at <a href=\"http:\/\/www.laclinux.com\/\">Los Alamos Computers<\/a> built it and<br \/>\nwill cheerfully sell you one.  It was a successful design in most<br \/>\nrespects, but unpleasantly noisy.  This year, as we do the 2002<br \/>\nrefresh, I&#8217;m going to be working hard at getting the most noise<br \/>\nreduction I can without sacrificing performance.  I&#8217;m experimenting<br \/>\nnow with ways and means.<\/p>\n<p>So I spent a couple of hours today disassembling the case of my<br \/>\nwife Cathy&#8217;s machine (minx.thyrsus.com) and lining three sides of it<br \/>\nwith <a href=\"http:\/\/www.dynamat.com\/\">Dynamat<\/a>, a kind of stick-on<br \/>\nrubber acoustic insulation often used in car-stereo installations.<br \/>\nThe malevolent god that normally attends me when I futz with hardware<br \/>\nmust have been off tormenting some other hapless ex-mathematician; no<br \/>\nhardware was destroyed, no blood was shed, and I&#8217;m typing this on the<br \/>\nselfsame reassembled machine.<\/p>\n<p>Minx is a pretty generic mid-tower system made with cheap Taiwanese<br \/>\nparts in mid-2002 by my local <a href=\"http:\/\/www.abestpc.com\/\">hole-in-the-wall computer shop<\/a>: I<br \/>\nspent only $150 to have it built, recycling a few parts from an only<br \/>\nslightly older machine. It has a 300W power supply, Athlon 950 mobo<br \/>\nwith stock CPU cooler fan, one 80mm case fan, 7200RPM ATA drive.  I<br \/>\nsucceeded in lining both 14&#8243;-square side panels and the case top; this<br \/>\nused up the 4&#8217;sq piece I bought so efficiently that there was only<br \/>\nabout 10&#8243;sq in two small piece left over.  I used those to cover the<br \/>\nonly exposed solid section of the back panel.<\/p>\n<p>If you want try this yourself, the tools I found useful were a<br \/>\nutility knife and a metal footrule, the latter useful both for<br \/>\nmeasuring to fit and as a cutting guide.<\/p>\n<p>I took before and after measurements with the db meter.  dbA scale,<br \/>\nmeasurements made with the probe one inch above the center-rear edge<br \/>\nof the case.<\/p>\n<table border=\"1\">\n<tr>\n<td>Machine off:<\/td>\n<td>44dbA<\/td>\n<\/tr>\n<tr>\n<td>Machine on, before:<\/td>\n<td>63dbA<\/td>\n<\/tr>\n<tr>\n<td>Machine on, after:<\/td>\n<td>61dbA<\/td>\n<\/tr>\n<\/table>\n<p>In other words, only a 2dbA drop &#8212; marginal when you consider<br \/>\nthat the meter is only rated 1.5dB accurate! but it&#8217;s worth bearing in<br \/>\nmind that the scale is logarithmic; 2dbA is more than it looks like.<\/p>\n<p>I have studio-engineer ears and sensitive musician fingers.  I took<br \/>\nbefore-and-after measurements with those, too, listening to the sound<br \/>\ntambre and feeling for case resonance.<\/p>\n<p>My ears tell me that the box is only slightly quieter, but the noise<br \/>\nspectrum has changed.  The proportion of high-frequency noise has<br \/>\ndropped; more of what I&#8217;m hearing is white noise due to turbulant<br \/>\nairflow, less is bearing noise.  This is a good change even if total<br \/>\nemission hasn&#8217;t dropped much.<\/p>\n<p>My fingers tell me that the amount of case resonance has dropped quite<br \/>\ndramatically, especially on the side panels.<\/p>\n<p>Was it worth doing? I am not sure.  There would probably be more<br \/>\nbenefit on a system emitting more bearing noise from 10K or 15Krpm<br \/>\ndrives.  On this one, I think the power supply is emitting most of<br \/>\nthe noise, and acoustic lining can&#8217;t do much against that.<\/p>\n<p>In fact, my clearest take-away from this is that the big gains in<br \/>\nnoise reduction on conventional PCs are likely to come from<br \/>\nobsessing about power-supply engineering &#8212; including details like<br \/>\nwhether the fan blows through a slotted grille or a cutout with a<br \/>\nwire-basket finger guard (the latter will generate less turbulence<br \/>\nnoise).<\/p>\n<p>I&#8217;d like to retrofit minx with a Papst 12dbA muffin fan and see if<br \/>\nthat makes a measurable difference.  But the best change would<br \/>\nprobably be one of the <a href=\"http:\/\/www.endpcnoise.com\/cgi-bin\/e\/00005.html?id=LhadbVAh\">Enhance<\/a><br \/>\n300W PSUs that are supposed to only emit 26dbA.  I&#8217;ll bet that would<br \/>\nwin big.<\/p>\n<p><a href=\"http:\/\/enetation.co.uk\/comments.php?user=esr&amp;commentid=79200649\">Blogspot comments<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Warning: The following blog entry provides way more than the recommended daily allowance of geeking. If you don&#8217;t have a serious propeller-head streak, surf outta here now before it&#8217;s too late. I&#8217;m mainly a software guy, but occasionally I build PCs for fun. Design them, rather; the further away I stay from actual hardware the&hellip; <a class=\"more-link\" href=\"http:\/\/esr.ibiblio.org\/?p=73\">Continue reading <span class=\"screen-reader-text\">Run Silent, Go Feep<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-73","post","type-post","status-publish","format-standard","hentry","category-technology","entry"],"_links":{"self":[{"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=\/wp\/v2\/posts\/73","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=73"}],"version-history":[{"count":0,"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=\/wp\/v2\/posts\/73\/revisions"}],"wp:attachment":[{"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=73"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=73"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/esr.ibiblio.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=73"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}