A New Design for Audio Clipping Pre-amplifiers Based on ... - IJME

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Figure 9: 1N914 Diode “smoothed clipping” Figure 10: Op amp distortion withoutdiodes• Wiper to 4.5V DC : (Figure 11, 12): Range of clipping satisfactory with limits ofno vertical clipping reminiscent of the 1N914 diode, to extreme verticalclipping.Figure 11: SCR with wiper to 4.5V Figure 12. SCR with wiper to 4.5V@ 100% of potentiometer@ 0% of potentiometerInternational Journal of Modern Engineering Volume 8, Number 1 Fall 2007 122
• Wiper to ground: (Figure 13, 14): Range of clipping produced was notsatisfactory due to insufficient ‘I GT ’ from RC network.Figure 13: SCR with wiper to groundFigure 14. SCR with wiper to ground@ 100% of potentiometer@ 0% of potentiometerBe<strong>for</strong>e testing the proposed variable clipping modification, an SCR with appropriatecurrent and voltage trigger levels was chosen. After looking into various SCR data sheets,the NTE5400 was selected due to adequate trigger parameters of I GT =50µA , and V GT =0.8V. The NTE5400 was then placed appropriately on the breadboard, and snap shotswere taken of the clipped output with two of the RC network configurations outlined inthe previous section. Two configurations arise as a result of these improvements. Theseresults are demonstrated in the following figures. From these results it is clear that theSCR clipping provides a variable clipping arrangement that is extremely useful <strong>for</strong> tonecontrol. The fact that this is being accomplished using the input signal to the amplifieritself is another advantage. This inline variable clipping approach is new and provides away to control the tone depending on user interaction. It should be worth noting that theRC configuration 3 outlined in previous sections was not tested due to the fact that thecurrent gain it produced was unnecessary.Low End Frequency ResponseFigure 15: Op amp gain with C I = .047uFFigure 16: Op amp gain with C I = 1.047uFInternational Journal of Modern Engineering Volume 8, Number 1 Fall 2007 123
Page 1 and 2: Nr. 2/2004/ Inform
Page 4 and 5: capacitor is located in parallel wi
Page 6 and 7: Z = Z || R(12)INITBWhere: ‘Z IT
Page 8 and 9: waveform. This cau
Page 10 and 11: Modifications in frequency response
Page 14 and 15: The proposed gain frequency respons
Page 16 and 17: frequency response, tone modificati

A New Design for Audio Clipping Pre-amplifiers Based on ... - IJME

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