Digital Audio High-end Oscillator Circuit

Introduction

A digital audio high-end oscillator is a must-have for any studio or live recording setup. This specialized piece of equipment uses advanced algorithms to produce clean, accurate sound either at fixed or user-defined frequencies. Oscillators generate trafficable waveforms – sine, square, triangle, and sawtooth – as well as complex modulated waveforms, all with precise amplitude and frequency values. These oscillators are also often equipped with LFOs (low-frequency oscillators), which allow further manipulation of the signal to create phasing, glissading, and other modulation effects. High-quality oscillators deliver smooth transitions between notes and provide the user with unparalleled flexibility in shaping their sound.



Circuit Diagram

of Digital Audio High-end Oscillator

Digital Audio High-end Oscillator Circuit
Digital Audio High-end Oscillator Circuit Diagram



More Circuit Layouts



Working Explanation

of Digital Audio High-end Oscillator

Jitter, the segment noise, is a critical trouble within the linking of 2 or more audio units. It is invariably caused by poorly designed oscillators in the recording equipment when this operates in the slave mode, that is, when it reproduces the system clock of the source equipment with the aid of a phase-locked loop (PLL).

The high-end oscillator may be used to replace such a poor reproduction or as a high-quality master oscillator. In the prototype, no frequency shift was detected under all kinds of operating conditions.

The high-end oscillator has these advantages over the usual design.

  • The crystal is operated in the series mode instead of in the parallel mode as usual, since the resistance of the crystal at the resonance frequency is a minimum, while external resistances do not affect the Q factor to the same degree.
  • The stability is enhanced by the use of an additional LC circuit (L1-C1-C3) tuned to the fundamental frequency.
  • The crystal is shunted by an inductor to compensate for its parasitic parallel capacitance. The inductor also short-circuits any low-frequency noise. The value of the inductor is critical but can be determined empirically.
  • In the slave mode, the oscillator is detuned by var-actor D1, which is part of an external PLL. Since the capacitance of the varactor changes from 4-50 pF by an applied voltage of 1-25 V, the frequency can be shifted by about 150 ppm. Since even small interference signals cause fairly large changes in capacitance, the desired capacitance range should be kept as narrow as possible by using a different varactor, or by connecting a smaller capacitor in series with it. When used as a master oscillator, when the slightest jitter is noticeable, the varactor must be replaced by a fixed capacitor. The apparatus with which it is used must be equipped for genlock operation, that is, must
    have a separate clock input.



With reference to the complete circuit diagram of the high-end oscillator, some additional points should be noted.

Much attention has been paid to the decoupling of the supply lines. Also, the oscillator and buffer circuits have separate supply lines to ensure interference-free oscillator performance.

The clock is buffered by three stages of the non-buffered IC1 (74HCU04). The first stage, IC1a, is arranged as a low-gain amplifier. Too much gain might cause feedback of harmonics into the oscillator. The clock is available at the output via R15.

Diode D2 ensures that the output of the final buffer is high when the oscillator is off. This arrangement enables several oscillators, providing various sampling frequencies, to be used over one clock line via an AND or NAND gate. The desired oscillator is enabled by applying 6.5 V to it.

Components R7, R8, and Co are part of the PLL, which determines their values. Surface mount devices (SMDs) T1‚ and T2 (BF840) may be replaced by standard transistors Type BF494.

The relationship between the sampling frequency, fs' the crystal frequency, fc; and the value of C2 in pF is

Digital Audio High-end Oscillator
Sampling Frequency Relationship



If the oscillator does not work owing to excessive tolerance of L1‚, the parallel capacitance may be balanced by altering the value of C3. It may also be necessary to alter the value of C2.

  • Adjust trimmer C7 to give a voltage of ½/U var in PLL operation.
  • Capacitor Cx, extends the nominal frequency range of the oscillator downwards.
  • The completed oscillator is best housed in a small tin-plate enclosure.
  • The oscillator draws a current of about 40 mA.

Conclusion

The digital audio oscillator has revolutionized the production of enjoyable sounds in music and many other fields. Not only can it accurately generate audio frequencies but its unparalleled capability to easily modify waveforms enable users to create unique sound signatures, whether they want to make melodic music or complex ambiances. It's a user-friendly interface, customizable parameters, and ease of use also contribute to its widespread popularity, while its power and stability ensure that it produces high-quality results on a consistent basis. With the continual development of technology, the potential for digital audio oscillators will only continue to expand in the future.



Digital Audio High-end Oscillator Circuit
Digital Audio High-end Oscillator Circuit
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