A considerable reinforcement of the treble sounds, centered at 5kHz, can be obtained with this circuit. With it you can use an amplifier exclusively to power a set of tweeters, with unique response in the treble range and a total use of power.
As can be seen from the circuit of Figure 1, the heart of the design is an operational amplifier 741 (but equivalents can be experienced), which has a selective feedback network, which is tuned to a frequency of approximately 5kHz.
The printed circuit board for this fast design is shown in figure 2.
As it is a circuit that operates with signals of low intensity it is very important to observe the shields of the inputs and outputs. The 12 V supply must be made with well filtered source, or taken advantage of the amplifier itself that this circuit should excite.
The sensitivity of the circuit is of the order of 100 mV and the output impedance of 150 ohm. The resistors used are all 1/8 or ¼ W with 5 ° / o or 10% tolerance and the electrolytes for 12 V or more. The other capacitors can be polyester or ceramic.
A very interesting application for this project is jointly musicals reinforcing the sharp sound of guitars.
MATERIAL LIST
CI-1 - 741 - integrated circuit
S1 – On/Off switch
C1 - 1 nF - ceramic capacitor
C2 - 4nF - ceramic or polyester capacitor
C3 - 10 uF - electrolytic capacitor
C4 - 47 uF - electrolytic capacitor
C5 - 220 nF - ceramic or polyester capacitor
R1, R2 - 6k8 - resistors (blue, gray, red)
R3, R4 - 120 k - resistors (brown, red, yellow)
Miscellaneous: printed circuit board, shielded wires, input and output jacks, mounting box etc.
