Simple Stereo Synthesizer

There are two common methods for generating a pseudo-stereo effect from a mono signal, the mono signal to both speakers play out of phase, and the use of frequency selective techniques, which usually consists of directing lower frequency signals in a single channel and higher frequency signals in the other. This circuit uses the second technique, but it can also antiphase signals that can give a better effect, especially when using headphones.

Q1 is used an emitter follower buffer stage, which provides two filter networks quagmire of its production is driven low impedance source. If they were driven directly to the input, it is quite possible that they would receive food source impedance of a few ohms or more pounds, which would be more than enough to change their properties effectively.

Both filters are formed by R4 and C3 (low pass), and C6 and R8 (step height). Wind in the price is not essential in this application and the rate of attenuation of 6 dB per octave filters simple as that RC is perfectly adequate. The-3dB point of each filter is about 800 Hz and mixed, therefore, gives an almost flat response, with significant peaks or troughs.

Q2 is connected as an emitter follower buffer stage, which ensures that there is minimum load on the low-pass filter. Q3 also ensures that there is minimum load on the high-pass filter, but this device can also serve as a phase separator. With SW2 switched to the output of the transmitter third quarter, Q3 acts effectively as an emitter follower and makes no phase inversion. With SW2 switched to exit in the third quarter of collectors, Q3, thus effectively act as a common-emitter stage with negative feedback of 100% (and a unity voltage gain) due to R11. 1t also provides a phase change of 180 °, so the two output signals are in phase opposition. A phase conditions are necessary to give a good stereo image center and use of anti-phase signals tend to give an impression of greater separation channel.

Stereo recording in an orchestra, it is normal for the violins from the left channel, with cellos and basses in the right way. Therefore, the high frequency signals are routed to the left channel and low frequency signals are routed to the right channel so that the device gives a similar effect (although this will obviously work well with the outputs connected both ways ).

Sub Woofer Filter

The sound spectrum spans 20Iz very low frequencies and reaches the 20000Iz at high frequencies. At low frequencies is degraded in the sense of direction. This reason leads us to use the loudspeaker for the allocation of very low frequencies. Manufacture of you, we suggest to distinguish between these frequencies lead to the corresponding amplifier. Acoustic filters are located in various parts of sound systems. Baxandal knownest The application filters to control the frequencies of light tone and low and high acoustic filters, which divides the region into sub-areas, leading to the speakers. The application you propose is a simple filter in the region that limits the acoustic region (20-20000Hz) in the region of 20-100Hz.

Schematic

PCB

Parts Layout

R1 = 39 Kohm
R2 = 39 Kohm
R3 = 47 Kohm
R4 = 10 Ohm
R5 = 22 Kohm
R6 = 4,7 Kohm
R7 = 22 Kohm
R8 = 4,7 Kohm
R9 = 10 Ohm
R10 = 220 Ohm
C1 = 39 pF
C2 = 0.1 uF
C3 = 0.1 uF
C4 = 0.2 uF
C5 = 0.4 uF
C6 = 0.1 uF
C7 = 0.1 uF
IC1 = TL062/TL072/TL082

With a production that aims to make an active filter, in order to bring a very low frequency speaker. This can put a speaker among the largest hi-fi speakers. To give you an overview of audio you also need the equivalent of an amplifier. The input circuit that is to connect the two outputs, and the preamplifier or the output line of some of the preamplifier. Production circuit afford to leave to lead a subwoofer to the power circuit. If for some reason you do not have space, so that you can enter the third speaker in the listening space, you can choose a smaller speaker. Power depends on the type of music you hear. If you have room, then when you make a permanent filter, and thanked, it may recommend to friends, or even do nothing, while your friends.

Audio Processor Circuit for Electronic Music Applications

This tour offers an audio processor IC SSM2045, specially designed for use in electronic music and the operational amplifier IC developed circuit 741 is configured as a low pass filter with a DC control voltage to win. The input signal is at a level of work set by the resistor R1 150mVpp.

How does the audio processor. The filter has two output buffers: output pin 2-1 pin and 4-pin 8-pin output. Internally, the outputs of two voltage-controlled amplifier (VCA) is connected.

R15 and R16 are connected to these outputs to obtain a change in the optimal control and eliminate tensions.

P4 is a volume control. Power to pin 15 and 16 shall not exceed a maximum of 250 uA. Balance between the two VCA, and the filter is either a full voltage range -250 mV + 250 mV in 14-pin control.

This tension can be adjusted P2.

Input can be controlled from up to 200 Ω source impedance. When the input level is 0 dBm, the VAC decreases by 6 dB. Bias current required to pin 17 is 120-185 Pa Pa. The cutoff frequency of 20 Hz to 20 kHz can be transferred to a variable voltage pin 5 This can be changed P1. Capacitance values ​​were chosen to spread the characteristics of the Butterworth filter.

The output current of the SSM2045 IC is converted into an output voltage of amplifier 741 All circuits must be disconnected from the DC sybsequent IC2. Voltage noise ration over 80 dB.

NJW1186 Surround Sound System

A very simple 5.1 surround audio system can be constructed using NJW1186 is a surround processor for 5.1 channel speaker system regenerates center, surround and subwoofer channel signal from normal stereo signal input. NJW1186 contains the passive matrix circuit, BPF with the center channel, LPF for the subwoofer, simulated stereo for the surround channels and size for each channel.

All internal status and variables are controlled by I2C bus.

As you can see from the diagram, this 5.1-channel surround sound system is very simple to design and require few external electronic components.

NJW1186 surround processor is manufactured by New Japan Radio Co. Ltd.

This draft of the electronic audio 5.1 surround sound processor can be powered from a wide range of input voltages from 7.5 volts to 13 volts.

Outputs of a surround system: subwoofer channel SWOUT, RSout-right surround channels, the left-channel output LSout surround channel field-Center.

Noise Limiter

The noise limiter circuit is easy to build, in collaboration with 4pin or 8pin BA741 very attentive, and uses a balanced diet. When the audio input level is between the output of 20mV and a constant signal is 20V 25mV. Audio limiters can be used in a scheme issuer or in any circuit you need a constant level.

components
R1 = 100K
R2 = 1K
R3 = 1M
R4 = 68K
R5 = 10K
C1 = 10uF
C2 = 680nF
T1 = BFW11
T2 = BC173C
IC = BA741