Generator Output Bits (Left / Right)

Macros: GenBitsL, GenBitsR

The default here is 16 bits, which is the maximum resolution of most sound cards. You may reduce that to simulate operation on another system, or to experiment with special effects like dither.

For a dramatic demonstration of dither, start with Bits at maximum and set up a sine wave of about 440 Hz on Stream 0 with 75% Level. You should hear a clean sine wave.

Next, set up a continuous White noise source on Stream 1 with 25% Level, and you will hear the original sine wave with a lot of background hiss. Turn the noise stream Off, and you will again hear a clean sine wave.

Now set Bits down to 2. The waveform becomes a staircase of 4 levels (counting 0), and you hear very strong harmonic distortion. Check the Spectrum, and you can see all the harmonics. But toggle Stream 1 on and you again hear a lot of background hiss, yet the sine wave is miraculously undistorted. You can see from the spectrum that the distortion components have indeed gone away, not just been buried in noise. Their energy has been redistributed from a series of large peaks, down into the lower background noise floor.

You can improve upon this further by using noise with a different amplitude distribution, which concentrates more of its levels near zero. This can be done with a Gaussian source, but the most common distribution used in digital audio is triangular. This not only does a good job, but is also easy to create.

To create a triangular noise distribution, you simply add together two uniform sources. Cut the Stream 1 Level down to 12.5%, and set up a different continuous White source on Stream 2, also at 12.5%. With both of these on, the average noise level is lower by 3 dB, but you still get rid of the distortion.

Macro Notes:

GenBitsL=12 sets the Left Output Bits to 12. Alternatively, GenBitsL=>1 increments and GenBitsL=>-1 decrements the current value.

GenBitsR works the same way for Right Output Bits.

See also Signal Generator Control Dialog.