Hi-Fi Audio Amplifiers with TL072 Preamp Circuit

The amplifier is very easy to get on the board, and an innovative tone defeat. Instead of completely disabling the sound system, the massive de-sensitized, and they defeated a maximum range. This can be increased if desired, you can have two tone controls, the lifting of 10 dB and a cut and the other with a little help and very subtle 3dB cut - it is quite (surprisingly) a very small adjustment to how you need for day-to-day hearing.

Otherwise, the design is fairly standard, with a great advantage over other models that require virtually no cable. Download the source you want - I suggest you put a switch on the back of the cabinet, and an extension of the tree with the tree in front. This leads to a minimum of wiring and reduces the crosstalk from other active inputs.

Description of the circuit

The input stage is shown with a gain of 2 times (-6 dB), configure, and also acts as a buffer for the tone control. The tone control is a basic form Baxandall, but the addition of R117, 118 and 119 provides the flexibility and ease of reconfiguration, which is the traditional layout.

I have not seen before, this technique is used). As it is 100k, which limits the number of tonal control at a reasonable price + /-10dB. To increase further in section, R119 (R219 and receive) can be omitted. Conversely, reducing the value of a small area is also about 6 dB at 20 Hz and 20 kHz with 7.5dB at 22K.

Audio system (and overall) performance is shown in Figure 2 (in increments of 10% of the pot), and it seems that the midrange is not affected. This is contrary to most of the drawings, in which the control is aligned to 1 kHz, and is very audible in the media. For those who want to use the tone controls, I would suggest that both, with no tone controls are designed and in harmony with reality, minimalist design.

Low Voltage Mini Stereo Amplifier

The circuit is easy to build, it can be done easily on the edge strip, although I never tried to be honest. As always make sure that you insert TDA2822M chip on the board the right way and you get electrolytic capacitors in the right direction, I recently blew one of the greatest speakers I mentioned above. Nothing else is particularly critical, as the amplifier to operate with the lowest resistance and capacitors, you can buy. A log-log pot is recommended because it allows easy adjustment of volume. Everything else can be added as you need to know the tone controls, etc., but it is unlikely that you'll need something else for simple systems.

Voltage range betwen 1.8 V - 18 V

BOSS Octave OC2 Schematic

The OC-2 reproduces three different tones: the original tone, one octave below, and two octaves below. Each part has its own volume control so they can be mixed at will.

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 ).

Simple Scratch and Rumble Filter

This is 12 dB per octave and the beginning of the add-on Rumble filter, which can be connected to "Tape" or the institution responsible for the amplifier.

And 'the usual quadratic filter circuit having a passive high pass filter formed by the ability of C3 and C4 series and parallel resistor R2 and R3 (the latter is also used to bias the transistor Q1 source follower). Passive filter of this type gives only very slowly to the original roll, and the final reduction was only 6 dB per octave. Boot Strapping resistance is then used to improve performance. Above the cutoff frequency, where profit is the district would otherwise drop slightly, R1 is the effect of strengthening the signal. Well below the cutoff frequency, the loss of C4 leads to the signal emitter of Q1 is significantly below the junction of C3 and C4. This leads to some of the signals at the intersection of C3 and is pushed through the R1 and R1 with C3 effectively forming a second network-pass filter. This eliminates the sluts, the number of the original film (in fact, is a small and insignificant in a maximum of about 05dB above the cutoff frequency) and accelerates the depreciation rate for a nominal 12 dB per octave.

The low pass filter works the same way that the high-pass, except, of course, the elements of R and C of the filter have been implemented to provide the correct action of the filter.

With the component values ​​specified for Rumble filter response drops below unity at about 45 Hz, where -6 D13 just above 30 Hz, then drops to a nominal 12 dB per octave. The filter response from zero to unity gain points around 6k5Hz time 6dB points at about 10 kHz, then drops to a nominal 12 dB per octave.