Tone control or pre-amplifier is an amplifier circuit supporters. Sometimes some of us do not know where a good amplifier, a raft alone and the results are not much different or even the same. Therefore we must know the character of the advantages and disadvantages of each amplifier equipment.
Tone control low noise here does not mean without noise, but noise compared with the lowest tone control on the market, for example Ronica transistor 4, TL-084, TC-2 LM833 etc.
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Potensio 1 serves to regulate the intensity / level of the incoming signal is assisted potensio 2 as balance / counterbalance. Potensio 2 is still installed and is usually an optional component. 1-2uF/250V capacitor R1 is actually a brand name, but I prefer to replace it with a 1K resistor / 5% normal for reasons to avoid hum and interference sensitive. R2 R3 while minimizing interruption to adjust the impedance OP-amp 1. R4 and R5 serves to increase the gain of 1.3 times. Pre amplifiers typically use a strengthening standards by 2 times, but by most of us think it has a noise. So I chose the value of 1.3 times, but the most minimal noise signal from the volume is enough to make the lamp light peak.
For low noise ... Cause of noise in op amp 1, apex audio even eliminate this stage. Can This step is also used as a buffer (jumper R5), the strengthening of a time. Lower values increase the value of R5 or R4 with consequent gains to be less, but remains at a value above 1 times due to input non-inverting path to take, so that the signal and noise can be reduced. R4 can also be replaced with a 10K trimpot and middle leg into the bass range adjuster (bass resonance).
C1 and C6 as a filter to reduce the treble / high frequency of excessive or often called oscillation prevention. R6 is actually an optional component of the impedance a little help customize the system. Ideally the same as the R8 R7 to facilitate give the sign of the gain on potensio panel tone control. C2 and C3 form a series circuit treble filter (high pass filter), its value is greater then the sound that passed the mid. C4 and C5 assisted by R9 and R10 form the low pass filter (filter bass), the greater the value of C is a bass sound that will be missed the soft / low (maximum of 47nF), the smaller the value of c is the bass signal that is passed will further dip (dig-dig, c4 = c5 = 22nF). This value is suitable for 27-33nF, 47nF instead (depending on taste). Pot 3 & 4 pot set treble and bass levels, the greater the greater the value of this potensio gains (bass & treble including potensio volume). R11 adjusts the output impedance, while the R12 and the red LED indicator that shows if the amplifier Peak has been given a full signal.
15V maximum supply. TL074 IC can, but in designing the PCB, IC can be replaced with 2x TL072/NE5532/4558.