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NEW High Quality Audio PerformancePure Anti-Aliasing OscillatorsThe new version of the JXSynth now has full, high quality Anti-Aliasing Oscillators and high quality filtering. Here at JXPlugins we feel that just rather just state these facts we will actually prove these statements. There are many standards of Anti-Aliasing Oscillators so to show you the degree of quality available in the JXSynth 1.2 the follow presentation has been produced. What is Aliasing? In digital synthesis the simple generation of waveforms produces noise called Aliasing. This noise occurs due to the nature of digital sampling and appears as 'reflected' frequency components. These extra and unwanted frequency components can dirty an audio signal, drowning out the wanted frequency components. The problem is especially noticeable in high notes. Anti-Aliasing prevents the unwanted frequency components from appearing and the result is a pure sound which emulates the equivalent hardware synths. Spectrum Analysis To demonstrate the difference between the Anti-Aliasing Oscillators in JXSynth v1.1 and the new Anti-Aliasing Oscillators at the heart of the new JXSynth 1.2 we present actual spectrum analysis of the JXSynth. Spectrum analysis gives you a very clear picture of frequency content of an audio signal. Content which is sometimes very difficult to pick out just by listening. Anti-Aliasing Performance Figure 1: Four octaves of the note D Waveform: Square Wave
As you can see from the spectrum display, the left signal contains Aliasing. It appears as the light blue bands (frequency components) in-between the green bands (wanted frequency components). The right signal, which is the new high quality Anti-Aliasing, contains no Aliasing and demonstrates what should be seen. Compare the wanted signal (right) the the signal containing Aliasing (left). Figure 2: High D pitch modulated Waveform: Saw Wave
The left signal shows clearly the 'reflecting' frequency components which are the Aliasing noise. The pitch of the note in this example is being moved up and down, this pitch modulation really demonstrates how much Aliasing noise can appear in just a simple saw wave oscillator. The left signal actually has some very simple Anti-Aliasing filtering, but as you can see it doesn't remove anywhere near as much as the new high quality Anti-Aliasing filter in the right signal. Figure 3: High E,F,G with full pulse width modulation Waveform: Square Wave
Anti-Aliasing doesn't just befit pitch modulation. As you can see in this example when full phase modulation is used the Normal Quality Anti-Aliasing Oscillator produces large bands of noise at the far ends of the phase modulation (0-10%,90-100% duty cycle). The new High Quality Anti-Aliasing Oscillators perform impeccably, no Aliasing noise at all. High Quality Filter Performance In the new JXSynth 1.2 there is now an option to use high quality filters. To demonstrate the audio performance of the high quality filters the following spectrum analysis has been produced. Figure 4: Low Pass filter with high resonance and 50% frequency modulation
The high performance filtering produces the best filter response the JXSynth can offer. As you can see in the spectrum analysis, the Normal Quality filtering produces bands of noise around the cutoff frequency. The high quality filtering produces no such noise. Figure 4: Low Pass filter with high resonance and a positive Envelope
The spectrum analysis in this example shows clearly that if no cutoff frequency movement is present the Normal quality filter performs as well as the High Quality filter. The sustain section in these to signals is identical. The high quality filtering is really only needed when a filter sweep or cutoff modulation is being used. | The JXSynth Audio Engine - JXPlugins Website - JXPlugins © 2010 |
