Build your own Preamp – FABModules – FiveFish Audio Building Blocks for DIY Projects Blog Articles

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How to make your own cable – 10pin Female-to-Female Ribbon Cable

We now sell a 6″ long Female-to-Female Ribbon Cable for use with FABModules. Click here to BUY a ready-made cable.

This 10-pin ribbon cable is required to connect the Power Supply FAB1215 to your FAB Module setup. If you’re using a FAB-to-Cable crossover adapter (FAB9001), you’ll also need this cable.

Step 1:  Cut your cable 7.5″ long.  Position cable as shown below, then crimp the connector. You can use an adjustable jaw pliers. I suggest wrapping the plastic connectors with cloth/rag to protect it before using the pliers.

CableStep1

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Decibels and Voltages. dB, dBu… How do I convert from Volts to dB?

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Okay, how do we find out what’s the maximum output capability of your FAB module system? To answer this question, we first need to segue and talk about decibels.

Wikipedia says: The decibel (dB) is a logarithmic unit that indicates the ratio of a physical quantity (usually power or intensity) relative to a specified or implied reference level.

Basically, it’s saying that decibel is nothing but a RATIO between 2 numbers. Example: Instead of saying the 2nd number is 2X the value of the 1st number, we say it’s 6dB larger, or 6dB more.  A decibel allows us to compare 2 numbers logarithmically, comparing 2 numbers whose ratio are either very, very small or very, very large.

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FAB2110 – Loading your Input Transformer, Square Wave Testing

For testing audio, square waves are typically used because they can reveal a lot about the system’s response with just a quick visual analysis. What’s so special about square waves? Why not use a typical “Sine Wave” or “Triangular Wave” for testing instead?

The reason is (if you remember your calculus class), the “ideal” Square Waves are composed of an infinite summation of sine waves of different frequencies. It has a single sine wave fundamental frequency, and all it’s odd harmonics. The amplitude of each odd harmonic is 1/n.   Represented by this equation: (credits: Wikipedia)

squaresum

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