Disc 4: Setting Amplifier Levels

• Track 1: Sample from Sheffield lab's "Sonic Detour" by Freeway Philharmonic, serves as an audio reference

Tracks 2-6 demonstrate the subjective increase in loudness that can be obtained by providing a specified amount of "gain overlap" at the power amp of an audio system. Although gain overlap can increase the usable loudness of a system, it is a compromise. For every dB of increased loudness, there is an equal decrease in the signal-to-noise ratio at lower listening levels. There is also an increase in peak distortion at high listening levels. Good system performance is a result of optimizing the trade-offs:

• Track 2: Demonstrates 0 dB of gain overlap
• Track 3: Demonstrates 5 dB of gain overlap
• Track 4: Demonstrates 10 dB of gain overlap
• Track 5: Demonstrates 15 dB of gain overlap
• Track 6: Demonstrates 20 dB of gain overlap

Tracks 7-12 are used for setting the max level (clipping threshold) of electronic components:

• Track 7: 40 Hz @ 0dBFS useful for adjusting subwoofer crossover)
• Track 8: 100Hz @ 0dBFS useful for setting midbass of an electronic crossover
• Track 9: 400Hz @ 0dBFS useful for x-over setting at this frequency
• Track 10: 1kHz @ 0dBFS used to set x-over midrange output
• Track 11: 4kHz @ 0dBFS useful to set tweeter output of an electronic crossover
• Track 12: 8kHz @ 0dBFS useful to set tweeter output of an electronic crossover

Tracks 13-18 are used to obtain 5 dB of gain overlap:

• Track 13: 40 Hz @ -5 dBFS
• Track 14: 100 Hz @ -5 dBFS
• Track 15: 400 Hz @ -5 dBFS
• Track 16: 1 kHz @ -5 dBFS
• Track 17: 4 kHz @ -5 dBFS
• Track 18: 8 kHz @ -5 dBFS

Tracks 19-24 are used to obtain 10 dB of gain overlap:

• Track 19: 40 Hz @ -10 dBFS
• Track 20: 100 Hz @ -10 dBFS
• Track 21: 400 Hz @ -10 dBFS
• Track 22: 1 kHz @ -10 dBFS
• Track 23: 4 kHz @ -10 dBFS
• Track 24: 8 kHz @ -10 dBFS

Tracks 25-30 are used to obtain 15 dB of gain overlap:

• Track 25: 40 Hz @ -15 dBFS
• Track 26: 100 Hz @ -15 dBFS
• Track 27: 400 Hz @ -15 dBFS
• Track 28: 1 kHz @ -15 dBFS
• Track 29: 4 kHz @ -15 dBFS
• Track 30: 8 kHz @ -15 dBFS

Tracks 31-35 are the same as tracks 2-6. However, the levels of these tracks have been adjusted to compensate for the loudness increase:

• Track 31: Reference track with 0 dB gain overlap
• Track 32: 5 dB of gain overlap w/recording level lowered 4.9dB
• Track 33: 10 dB of gain overlap w/recording level lowered 9.4 dB
• Track 34: 15 dB of gain overlap w/recording level lowered 13.3 dB
• Track 35: 20 dB of gain overlap w/recording level lowered 16.2 dB