The Sound Technology 1000A FM Alignment Generator

The Sound Technology 1000A FM Alignment Generator is a specialized piece of equipment designed for audio professionals and enthusiasts who require precision in frequency modulation (FM) alignment. This device is particularly useful for aligning FM tuners and ensuring optimal performance in audio broadcasting and reproduction. Understanding its features and capabilities can greatly enhance the quality of audio output.

Key Features of the ST-1000A

The ST-1000A is equipped with several notable features that contribute to its effectiveness in audio modulation:

1. Low Distortion Levels: The ST-1000A boasts a maximum total harmonic distortion (THD) specification of 0.1% in mono and 0.2% in stereo, which is critical for maintaining audio fidelity.
2. Internal Oscillator: It utilizes a Wien bridge sinewave generator as its internal audio oscillator, which is essential for generating stable and reliable audio signals.
3. Modulation Metering: The device can be evaluated using a Marconi 2305 modulation meter, which measures the overall distortion, including that from the internal oscillator and stereo modulator.
4. Adjustable Parameters: Users can modify certain settings to improve distortion figures significantly, enhancing the generator's accuracy and versatility.

Understanding Distortion Measurement

Distortion is a critical factor in audio performance, and the ST-1000A provides tools for measuring and adjusting it effectively. The distortion measurement is primarily influenced by the internal oscillator and the stereo modulator. When aligning the generator, it is important to check distortion for both left and right inputs to ensure balanced audio output.

Alignment and Calibration

Proper alignment of the ST-1000A is crucial for achieving optimal performance. The alignment instructions recommend adjusting the resistor R105 to achieve approximately -64 dB (0.06%) THD. This adjustment is a trade-off between distortion and reliable oscillation. Going lower than this threshold may lead to instability in the oscillation, which can negatively impact audio quality.

Modifications for Enhanced Performance

While the ST-1000A is effective in its standard form, several modifications can enhance its performance:

1. Improved Distortion Figures: Simple circuit modifications can potentially reduce distortion figures by an order of magnitude, making the device even more effective for professional use.
2. Increased Versatility: Adjustments can be made to improve the generator's versatility, allowing it to be used in a wider range of applications.
3. Ease of Use: Modifications can also simplify the user interface, making it more accessible for those who may not be as technically inclined.

Conclusion

The Sound Technology 1000A FM Alignment Generator is a valuable tool for audio professionals seeking precision in FM modulation. With its low distortion levels, adjustable parameters, and potential for modifications, it serves as an essential device for ensuring high-quality audio output. Understanding how to effectively use and align the ST-1000A can significantly enhance audio performance in various applications.