If you are using multiple delay units linked together, you could be causing feedback loops between them, even if they aren’t audible. You can avoid this issue by turning the phase parameter on the oscillator(s) slightly. While most synthesizers are designed to avoid DC offset as much as possible, once in a while, a dding detuned unison voices that are in phase with the original signal will cause a DC offset. Soundcards, audio interfaces, microphones, phantom power supply, and mixers are often the culprits here. When one of the hardware in your signal chain adds DC voltage (one that doesn’t alternate) to an AC circuit (one that alternates), the output AC voltage will have a bias towards one kind of value.
This topic is probably the most common cause of DC offset. Let’s explore the causes a little further: In the digital world, a delay unit, hand-drawn wavetables, certain filter combinations, and so on can cause DC Offset. There are several causes of DC offset, and you’re more likely to face them in audio recorded with faulty devices and in renders from a complex signal chain. In fact, in rare cases, DC offset can cause damage to your speakers/amplifiers due to extreme peaks despite a low perceived audio level. For example, if your audio is biased towards either a positive or negative signal, your dB peak meter will read much higher than what you perceive. Similarly, you will have the same issue when looping an audio clip as it has no zero-crossing.ĭC offset can also cause metering software/hardware to go haywire. Since the “zero” of an audio clip with DC offset has a value, it will create an audible “pop” when you split/splice it. The second issue you will face with DC offset is while editing. Notice how the height (peak level) is the same, but it’s clipping. The following pictures demonstrate the clipping problem: A typical waveform – note the height of the sine wave. You might also face issues in editing and metering. When a waveform is biased towards either the positive or the negative value, the higher value will reach the clipping level quicker. The worst problem with DC offset is that your audio will clip before it would as a normal audio waveform. And since DC offset essentially makes the waveform lean more towards one kind of signal over the other, we also call it DC bias. Now, if the waveform started alternating between +6v and –4v, you have a DC offset. Suppose you have a regular audio clip, and the waveforms are alternating between +5v and –5v. DC Offset is an imbalance between the positive and the negative signals in an audio waveform, where the zero becomes a different value, either positive or negative. In an audio clip, the horizontal line in the middle is zero, and the audio signal is recorded in positive (up) and negative (down) values.
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