At­ten­u­a­tors ex­plained

Use at­ten­u­a­tion to con­trol the level of a CV sig­nal

Future Music - - FEATURE -

Let’s dive deeper into semi- and full-mod­u­lar tech­niques. Again, us­ing the MiniBrute 2 as an ex­am­ple, if we patch LFO 1’s out­put into the Fil­ter Cut­off in­put, we break the prewired ‘LFO to pitch’ con­nec­tion, and we can now mod­u­late that fil­ter fre­quency with the LFO. Sim­ple! How­ever, un­like reg­u­lar mod ma­trix patch­ing, we have no con­trol over the amount or depth of mod­u­la­tion – the LFO is con­stantly at max strength. Hand­ily, this is where CV at­ten­u­a­tion comes into play, which can be used as an in­ter­me­di­ary ‘level amount’. Patch the LFO’s out­put into an at­ten­u­a­tor’s in­put, then patch the at­ten­u­a­tor’s out­put into that Cut­off in­put. Voila: you can now twist the At­ten­u­a­tor knob to in­crease or de­crease the LFO’s in­flu­ence over cut­off mod­u­la­tion. At­ten­u­a­tion is useful for con­trol­ling the level of any CV sig­nal, which is why most semi-mod­u­lar synths fea­ture at least one, and why many mod­u­lar ob­ses­sives own at least one ded­i­cated at­ten­u­a­tor mod­ule for con­trol­ling lev­els.

The prob­lem here is that the LFO is sweep­ing the full range of pitch up and down, and there’s no way to dial this back. So in­stead, we patch the LFO Out into the Att 1 In­put, then grab another ca­ble and patch Att 1 Out into the Osc 1+2 In­put.

In this ex­am­ple, we’re us­ing the Behringer Neu­tron. Over on the patch­bay, the synth’s LFO out­put is plugged into the Osc 1+2 In­put, mean­ing the LFO is mod­u­lat­ing the pitch of both os­cil­la­tors.

Now we can use the At­ten­u­a­tor 1 knob on the in­ter­face as an ‘amount’ or ‘mix’ con­trol to gov­ern the amount of LFO mod­u­la­tion – we’ll pull this knob back to re­duce this pitch mod­u­la­tion.

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