[{"data":1,"prerenderedAt":656},["ShallowReactive",2],{"page:\u002Flearn\u002Ffilters":3},{"id":4,"title":5,"article":6,"body":7,"description":648,"extension":649,"meta":650,"navigation":6,"path":651,"seo":652,"seoTitle":653,"stem":654,"__hash__":655},"pages\u002Flearn\u002Ffilters.md","Filters: carving the sound",true,{"type":8,"value":9,"toc":632},"minimark",[10,14,23,31,36,54,69,72,99,156,161,168,172,183,218,222,225,228,239,330,334,345,349,363,419,430,434,441,448,485,495,499,535,586,590],[11,12,5],"h1",{"id":13},"filters-carving-the-sound",[15,16,17,18,22],"p",{},"If oscillators are the clay, filters are the chisel. Most of the classic synth sounds you know, from squelchy acid bass to warm brass to dark pads, are a bright waveform with part of it carved away. That's called ",[19,20,21],"strong",{},"subtractive synthesis",": start with too much, then take away.",[15,24,25,26,30],{},"This guide is about ",[27,28,29],"em",{},"why"," that works so well, and how to make a filter move.",[32,33,35],"h2",{"id":34},"what-a-filter-does","What a filter does",[15,37,38,39,44,45,48,49,53],{},"Remember from the ",[40,41,43],"a",{"href":42},"\u002Flearn\u002Foscillators","oscillators guide"," that a bright sound is full of ",[19,46,47],{},"harmonics",": quieter copies of the note at 2×, 3×, 4× its frequency and up. A ",[40,50,52],{"href":51},"\u002Fmodules\u002Fvcf","filter"," turns some of those frequencies down.",[15,55,56,57,60,61,64,65,68],{},"The most common kind, and the one you'll use most, is the ",[19,58,59],{},"low-pass"," filter (",[19,62,63],{},"LP","). It lets the low frequencies pass and cuts the high ones. Everything below its ",[19,66,67],{},"Cutoff"," gets through; everything above is turned down, more and more the higher you go. Lower the cutoff and the sound gets darker and more muffled, like hearing music through a wall.",[15,70,71],{},"The Filter module has four modes:",[73,74,75,81,87,93],"ul",{},[76,77,78,80],"li",{},[19,79,63],{}," (low-pass): keeps the lows. Darker. The classic synth filter.",[76,82,83,86],{},[19,84,85],{},"HP"," (high-pass): keeps the highs. Thinner, airier.",[76,88,89,92],{},[19,90,91],{},"BP"," (band-pass): keeps a band around the cutoff. Nasal, focused, telephone-like.",[76,94,95,98],{},[19,96,97],{},"NOTCH",": removes a band around the cutoff and keeps the rest.",[100,101,104,107],"try-it",{"title":102,"add":103},"Hear the filter","vcf",[15,105,106],{},"A sawtooth VCO is already playing through a Filter to the Output, so there's nothing to patch. Just turn knobs and listen:",[108,109,110,121,127,140,148],"ol",{},[76,111,112,113,115,116],{},"Turn the Filter's ",[19,114,67],{}," slowly down: the sound gets darker and more muffled. ",[117,118],"knob",{"module":103,"param":119,"below":120},"cutoff","300",[76,122,123,124],{},"Bring it back up: bright again. ",[117,125],{"module":103,"param":119,"above":126},"3000",[76,128,129,130,132,133,135,136],{},"Switch to ",[19,131,85],{},": now it's the lows that go. Sweep ",[19,134,67],{}," and hear the sound thin out. ",[117,137],{"module":103,"param":138,"is":139},"mode","highpass",[76,141,129,142,144,145],{},[19,143,91],{},": only a band around the cutoff gets through. Nasal, like a telephone. ",[117,146],{"module":103,"param":138,"is":147},"bandpass",[76,149,129,150,152,153],{},[19,151,97],{},": a band is taken out of the middle. It's subtle on a saw, so sweep the cutoff to hear it. ",[117,154],{"module":103,"param":138,"is":155},"notch",[157,158,160],"h3",{"id":159},"why-filter-a-sawtooth","Why filter a sawtooth?",[15,162,163,164,167],{},"A filter can only remove what's there. A sine wave has no harmonics, so filtering it does almost nothing. A sawtooth has ",[27,165,166],{},"every"," harmonic, so there's lots to carve away, and every cutoff setting sounds different. That's why the classic starting point is a saw (or a square) into a low-pass filter.",[32,169,171],{"id":170},"resonance-the-whistle-at-the-edge","Resonance: the whistle at the edge",[15,173,174,175,178,179,182],{},"The ",[19,176,177],{},"Res"," knob boosts the frequencies right at the cutoff. A little resonance makes the filter's edge more pronounced, so when the cutoff moves you can really ",[27,180,181],{},"hear"," it move. A lot of resonance makes the filter whistle or \"squelch\" at the cutoff frequency. Turn it right up and the filter starts to ring on its own.",[100,184,186,189],{"title":185,"add":103},"Make it whistle",[15,187,188],{},"The same saw through the same Filter:",[108,190,191,200,209],{},[76,192,112,193,195,196],{},[19,194,177],{}," up to about halfway. ",[117,197],{"module":103,"param":198,"above":199},"res","12",[76,201,202,203,205,206],{},"Sweep ",[19,204,67],{}," slowly up and down: a whistle follows it, picking out one harmonic after another. ",[207,208],"turn",{"module":103,"param":119},[76,210,211,212,214,215],{},"Turn ",[19,213,177],{}," right up: the filter rings on its own, a pure tone at the cutoff. ",[117,216],{"module":103,"param":198,"above":217},"25",[32,219,221],{"id":220},"one-envelope-two-jobs","One envelope, two jobs",[15,223,224],{},"A filter that sits still is fine, but the magic happens when the cutoff moves. And the most useful thing to move it with is the same envelope that shapes the note's volume.",[15,226,227],{},"Why does that sound so good? Because real instruments behave that way. Pluck a string, strike a piano key or blow hard into a trumpet and the start of the note is bright, full of harmonics. As the note fades, the high harmonics die away first and it gets mellower. An envelope sweeping a low-pass filter copies exactly that: bright at the start of each note, darker as it fades.",[15,229,230,231,234,235,238],{},"In a modular, any output can go to as many inputs as you like, so one envelope can open the VCA ",[27,232,233],{},"and"," sweep the filter at the same time. The filter's ",[19,236,237],{},"CV Amt"," knob sets how far the envelope moves the cutoff.",[100,240,243,246,289,292],{"title":221,"lesson":241,"without":242},"03-subtractive-synthesis","env.out>vcf.cv",[15,244,245],{},"A complete synth voice, with one cable missing: the ADSR opens the VCA, but nothing moves the filter yet.",[108,247,248,259,278],{},[76,249,250,251,254,255],{},"Play a few notes on ",[19,252,253],{},"A–K",". They start and stop, but the tone sits still, and a bit dull. ",[256,257],"play",{"times":258},"3",[76,260,261,262,265,266,269,270,272,273],{},"Patch the ADSR's ",[19,263,264],{},"OUT"," into the Filter's ",[19,267,268],{},"CV"," as well. Its ",[19,271,264],{}," already goes to the VCA; an output can feed as many inputs as you like. Play again: each note now starts bright and darkens as it fades. ",[274,275],"wire",{"from":276,"to":277},"adsr.out","vcf.cv",[76,279,112,280,282,283,285,286],{},[19,281,237],{}," up and down to set how far the envelope sweeps the cutoff. Watch the ring around ",[19,284,67],{}," follow each note. ",[207,287],{"module":103,"param":288},"amt",[15,290,291],{},"Then play with it:",[73,293,294,309,317],{},[76,295,211,296,298,299,301,302,305,306],{},[19,297,67],{}," all the way down and ",[19,300,237],{}," up: the envelope now does all the work, and you get a plucky bass. ",[117,303],{"module":103,"param":119,"below":304},"100"," ",[117,307],{"module":103,"param":288,"above":308},"0.9",[76,310,211,311,313,314],{},[19,312,177],{}," up high: squelch. That's the sound of acid house. ",[117,315],{"module":103,"param":198,"above":316},"20",[76,318,319,320,322,323,326,327],{},"Set ",[19,321,237],{}," negative: now each note ",[27,324,325],{},"closes"," the filter instead of opening it. ",[117,328],{"module":103,"param":288,"below":329},"-0.2",[157,331,333],{"id":332},"keeping-high-notes-bright","Keeping high notes bright",[15,335,336,337,340,341,344],{},"There's one more cable in that patch: the keyboard's pitch also goes into the filter's ",[19,338,339],{},"V\u002FOCT"," input. Without it, a high note sits closer to the cutoff than a low note does, so high notes sound duller. With it, the cutoff follows the keyboard, and every note sounds equally bright. This is called ",[19,342,343],{},"key tracking",".",[32,346,348],{"id":347},"filtering-noise","Filtering noise",[15,350,351,352,356,357,359,360,362],{},"Filters aren't only for oscillators. ",[40,353,355],{"href":354},"\u002Fmodules\u002Fnoise","Noise"," contains every frequency at once, so a filter can pick out any part of it. Keep a narrow band with a resonant ",[19,358,91],{}," filter and sweep it slowly: wind. Keep only the very top with ",[19,361,85],{},": the sizzle of a hi-hat.",[100,364,367,370],{"title":365,"add":103,"source":366},"Wind and hats from hiss","noise",[15,368,369],{},"A Noise module is already playing through a Filter to the Output. Just turn knobs:",[108,371,372,385,392,405],{},[76,373,374,375,377,378,380,381,305,383],{},"Switch the Filter to ",[19,376,91],{}," and turn its ",[19,379,177],{}," right up. ",[117,382],{"module":103,"param":138,"is":147},[117,384],{"module":103,"param":198,"above":316},[76,386,202,387,389,390],{},[19,388,67],{}," slowly up and down: whistling wind. ",[207,391],{"module":103,"param":119},[76,393,129,394,396,397,399,400,305,402],{},[19,395,85],{}," and turn ",[19,398,67],{}," up high: only the sizzle at the top is left, the sound of a hi-hat. ",[117,401],{"module":103,"param":138,"is":139},[117,403],{"module":103,"param":119,"above":404},"6000",[76,406,407,408,411,412,415,416],{},"Switch the Noise to ",[19,409,410],{},"PNK"," or ",[19,413,414],{},"BRN"," and hear the whole thing get deeper. ",[207,417],{"module":366,"param":418},"color",[15,420,421,425,426,344],{},[40,422,424],{"href":423},"\u002Fplay?lesson=11-noise-wind-and-hats","Lesson 11"," builds both at once, with a clock turning the hiss into a hi-hat rhythm. It'll make more sense after the ",[40,427,429],{"href":428},"\u002Flearn\u002Frhythm","rhythm guide",[32,431,433],{"id":432},"formants-filters-that-talk","Formants: filters that talk",[15,435,436,437,440],{},"Your mouth is a filter too. When you say \"aah\" or \"ooh\", your vocal cords make the same buzzy tone, and the shape of your mouth filters it, boosting a few bands called ",[19,438,439],{},"formants",". Each vowel has its own pattern of formants. That's how you can hear the difference between \"ee\" and \"oo\" sung on the same note.",[15,442,174,443,447],{},[40,444,446],{"href":445},"\u002Fmodules\u002Fvowel","Vowel"," module is a set of filters tuned to those patterns. Feed it a buzzy saw and it starts to sound like a voice.",[100,449,453,456],{"title":450,"add":451,"set":452},"Make it talk","vowel","oct=-1",[15,454,455],{},"A sawtooth VCO, an octave below middle C, is already buzzing through a Vowel module to the Output. Just turn knobs:",[108,457,458,467,476],{},[76,459,460,461,463,464],{},"Turn the Vowel's ",[19,462,446],{}," knob slowly from A to U. Hear it go \"aah… eh… ee… oh… ooh\". ",[117,465],{"module":451,"param":451,"above":466},"3.5",[76,468,211,469,472,473],{},[19,470,471],{},"Focus"," up: sharper formants, more robotic. ",[117,474],{"module":451,"param":475,"above":316},"q",[76,477,211,478,481,482],{},[19,479,480],{},"Shift"," to slide all the formants together, like a smaller or bigger mouth. ",[207,483],{"module":451,"param":484},"shift",[15,486,487,491,492,494],{},[40,488,490],{"href":489},"\u002Fplay?lesson=15-vowel-make-it-talk","Lesson 15"," lets an LFO move ",[19,493,480],{},", so the voice keeps changing as you play.",[32,496,498],{"id":497},"eq-turning-parts-up-and-down","EQ: turning parts up and down",[15,500,501,502,506,507,510,511,514,515,518,519,522,523,526,527,530,531,534],{},"An ",[40,503,505],{"href":504},"\u002Fmodules\u002Feq","EQ"," is a gentler cousin of the filter. Instead of cutting everything past a point, it turns broad areas of the sound ",[19,508,509],{},"up or down",": ",[19,512,513],{},"Low"," (bass), ",[19,516,517],{},"Mid"," (a middle band you choose with ",[19,520,521],{},"Mid Freq",") and ",[19,524,525],{},"High"," (treble). Filters are for ",[27,528,529],{},"making"," sounds; EQ is mostly for ",[27,532,533],{},"fitting"," them together, which is why you'll usually find it at the end of a patch.",[100,536,539],{"title":537,"lesson":538},"Shape a drum loop","45-eq-shape-the-tone",[73,540,541,553,571],{},[76,542,543,544,547,548],{},"Click ",[19,545,546],{},"BYP"," on the EQ to hear the loop without it, then click it again to switch the EQ back on. ",[117,549],{"module":550,"param":551,"is":552},"eq","bypass","true",[76,554,555,556,558,559,561,562,564,565,305,568],{},"Find a problem the way engineers do: turn ",[19,557,517],{}," all the way up, sweep ",[19,560,521],{}," until it sounds worst, then turn ",[19,563,517],{}," down there. ",[117,566],{"module":550,"param":567,"above":199},"mid",[207,569],{"module":550,"param":570},"midf",[76,572,573,575,576,578,579,305,583],{},[19,574,513],{}," and ",[19,577,525],{}," right down: a phone call. ",[117,580],{"module":550,"param":581,"below":582},"low","-12",[117,584],{"module":550,"param":585,"below":582},"high",[32,587,589],{"id":588},"what-to-remember","What to remember",[73,591,592,602,605,611,617,623],{},[76,593,594,595,598,599,601],{},"A ",[19,596,597],{},"low-pass filter"," keeps the lows and turns down everything above its ",[19,600,67],{},". Lower cutoff, darker sound.",[76,603,604],{},"Filter something bright (saw, square, noise): you can only remove harmonics that are there.",[76,606,607,610],{},[19,608,609],{},"Resonance"," boosts the cutoff frequency, so you can hear the filter move. Lots of it squelches and whistles.",[76,612,501,613,616],{},[19,614,615],{},"envelope on the cutoff"," makes notes start bright and get darker, like real instruments do.",[76,618,619,622],{},[19,620,621],{},"Key tracking"," (pitch into the filter's V\u002FOCT) keeps high notes as bright as low ones.",[76,624,625,628,629,631],{},[19,626,627],{},"Formants"," are the filter patterns of vowels; ",[19,630,505],{}," turns broad parts of a sound up or down.",{"title":633,"searchDepth":634,"depth":634,"links":635},"",2,[636,640,641,644,645,646,647],{"id":34,"depth":634,"text":35,"children":637},[638],{"id":159,"depth":639,"text":160},3,{"id":170,"depth":634,"text":171},{"id":220,"depth":634,"text":221,"children":642},[643],{"id":332,"depth":639,"text":333},{"id":347,"depth":634,"text":348},{"id":432,"depth":634,"text":433},{"id":497,"depth":634,"text":498},{"id":588,"depth":634,"text":589},"A beginner's guide to filters on a modular synth. What cutoff and resonance do, why you filter a bright sawtooth, how one envelope makes a filter \"sing\", and how formants and EQ fit in.","md",{},"\u002Flearn\u002Ffilters",{"title":5,"description":648},"How synth filters work — cutoff, resonance and subtractive synthesis explained","learn\u002Ffilters","MvCeID9kRUSjAsE8au1-eOvI6UMMEODt-XnaOYjlp5I",1792599837967]