The relationship of compressor types with sound characteristics and music styles

In audio technology, compressors are tools for providing dynamic range control. With the developing technology over time, different types of compressors have emerged. The most known and widely used types are field effect transistor (FET), tube (valve, lamp), optical (optic) and VCA (voltage controlled amplifier) compressors. Due to design differences, each compressor has its own sound character. The two most important factors that determine these sound characteristics are timing behavior of the compressors and their effects on timbre. Although they were originally produced for dynamic range control, compressors have started to be used by many sound engineers over time not only for dynamic range control, but also for adding sound characters to the signal. Also questions such as which compressor will be applied to which sound source, which compressor will display more functional behavior in which musical style, are based on personal taste and experience in additional to technical requirements today. This research was carried out to answer the mentioned questions. The four most known and commonly used compressor types are determined for this thesis. For each compressor design; emulations (software, plug-ins) of the most known and preferred brands and models of their kind were selected. The four types of these plugins are: (1) Waves PuigChild 660/670, tube compressor, (2) Waves CLA-76, FET compressor, (3) Waves CLA-2A, optical compressor and (4) Waves dbx 160, VCA compressor were used. In this research firstly, character identification tests of the compressors were carried out. These tests consist of timing and gain reduction tests. To observe the behavior of compressors in the lower, middle and upper frequency regions, sine waves of 100 Hz, 1 kHz and 5 kHz were sent to each compressors. In the second part of the characters identification include timing tests which were carried out with all timing constants and combinations of compressors. Since the timing settings of Waves CLA-2A and Waves dbx 160 are made automatically, signals with different amplitudes are sent to these compressors and it is determined whether these compressors determine their timing values according to amplitude or amplitude envelope. In the timing tests, the total harmonic distortion (THD) behavior of the compressors in all timing variables and the differences in the waveform display were determined. Thirdly, in the gain reduction tests, the THD behaviors of each compressor at 3 dB GR, 6 dB GR and 9 dB GR values were determined in three different frequency regions. After these tests, the compressors were compared with each other in terms of THD and timing. In addition to these tests, compressors were observed on jazz, rock and Turkish folk music multi-track recordings. Each compressor is set to apply a maximum of 5 dB GR. Waves PuigChild 660/670's timing constant is TC 2, Waves CLA-76's attack and release potency is set to 5 position. Then applying the compressors, the frequency spectrum (LTAS) and amplitude values (dBTP, RMS, dynamic range and LUFS) of each musical element (vocal, guitar, etc.) were analyzed. As a result of the tests, it was determined that the compressor with the fastest attack and release time was Waves PuigChild 660/670, and the compressor with the slowest attack time was Waves dbx 160. In the averages of all frequency regions, Waves PuigChild 660 has the highest THD value and Waves dbx 160 has the lowest THD value. Also it was determined that the highest THD value in the lower frequency region observed to Waves PuigChild 660, and the highest THD value in the middle and upper frequency regions observed to Waves CLA-76. Since the effects of compressors on music were examined, it was concluded that Waves dbx 160 would give successful results in music styles and sound sources with low dynamic range, Waves PuigChild 660 in music styles with high dynamic range and rhythm instruments resonating in the lower frequency region. It was concluded that Waves CLA-76 increased in the presence region (presence, 4-6 kHz) and when applied to sound sources such as vocals and guitar, these sound sources would be heard more clearly. It has been determined that the Waves CLA-2A shows an increase in the upper harmonic region (7-15 kHz), and the bell etc. in this frequency region. It has been concluded that it will give successful results in sound sources that resonate at high frequencies and need brightness.