Cuious about Oscillator Tuning - Kyma Forum

Cuious about Oscillator Tuning

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Author	Topic: Cuious about Oscillator Tuning
David McClain Member	posted 10 January 2002 01:00 Hi, I tried playing around with making some anti-aliased oscillators by sending a waveform into a FunctionGenerator, through a tunable LowPassFilter and then into a MemoryWriter. The MemoryWriter used a sample block size of 4096 samples. The output of this MemoryWriter was then used as (A) the wavetable for an Oscillator or (B) the wavetable for a Sample playback with looping enabled. In the case (A) of the Oscillator, I found that I had to specify a frequency of (!Pitch - 24) nn to get the correct pitch. In the case of (B) the sample player I had to set the frequency to ((!Pitch + 60) nn - (SignalProcessor sampleRate / 4096) hz nn). I'm curious about why these particular adjustments were needed? I do realize that some kind of adjustment is needed, just why these particular values? In particular, why 2 octaves downward for an oscillator, and middle-C upward adjustment for the sample player. I can understand the need for subtracting the original funciton generator frequency of (SignalProcessor sampleRate / 4096) hz. I don't mean to be dense here, but these seem curious values... - DM IP: Logged
SSC Administrator	posted 14 January 2002 11:12 For the sample player case, the sample player transposes the original sample relative to the frequency stored in the sample file's header. For MemoryWriters, Kyma uses a default value of 60 nn. For the Oscillator case, Kyma assumes one cycle of the waveform fits in the 4096 samples, and computes the pitch accordingly. Could you have had 4 cycles of the waveform in your recording? IP: Logged
David McClain Member	posted 14 January 2002 21:18 No, honestly... I thought of that and I put an O'scope on the oscillator to check. But I swear I only put 1 cycle in that oscillator. That's what was so strange to my way of thinking. I can certainly understand the behavior of the Sample player, taking your description into account. ??? - DM IP: Logged
SSC Administrator	posted 15 January 2002 03:05 Can you email us your Oscillator version? We will check it out when we are back in the US. IP: Logged

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