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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.

Jump toexplanation of each component ...

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. CanThis 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 facilitategive 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 missedthe 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 bereplaced with 2x TL072/NE5532/4558.

This be Noise Filter Circuit for filter the frequency disturbs all well. By use base type equipment the FET transistor number 2N3819 and Electronic part The other a little again. It can be usable economize with. By the circuit will decrease frequency tall signal more 20KHz well. Then can apply in side sound circuit well , and still have still can fine decorate filter noise level has as well yes.

The signal from a microphone is two weak for a standard line input. This low-noise DC-coupled microphone amplifier provides a solution for anyone who wants to connect a microphone to his or her hi-fi installation. As can be seen from the schematic diagram, a good circuit does not have to be complex. A differential amplifier is built around T1 (MAT-03E), which is a low-noise dual transistor. The combination of T2 and LED D1 forms a constant-current source for the input stage. A low-noise opamp (OP-270E) amplifies the difference signal that appears at the collectors of the dual transistor. The result is an analogue signal at line level.

The bandwidth of the amplifier ranges from 1 Hz to 20 kHz. Within the audio range (20 Hz to 20 kHz), the distortion is less than 0.005 percent. Since only half of the OP-270E is used, the remaining opamp could be used in the output stage of a stereo version. The amplifier can be powered from a stabilized, symmetrical supply with a voltage between ±12 V and ±15 V. Such supply voltages are already present in many amplifier