Hi-Fi headphone amplifier circuit and Qsurround, BBE (high-fidelity headphone)
High-fidelity headphones have a wide frequency response and low distortion that are unmatched by desktop Hi-Fi audio, especially some brand-name headphones, even some of the best speakers can not be compared with it.
The use of high-fidelity headphones to listen to music is of high resolution, without the need for overly complicated configurations, and it can get several times the playback level of its desktop audio combination at a low cost. The influence of time and environment, even if the "aircraft cannon bombing" in the middle of the night, don't worry about affecting others. High-fidelity headphones have a balanced sound field, clear levels of detail, and sufficient dynamics, especially in the reproduction of mid-to-high frequencies, with a clear, sweet, warm and true tone.
Why are headphones good? First, the tone is pure and true. Enthusiasts all know that the pronunciation unit of the headset does not need more power, and the signal from the sound source does not need to pass through the level-by-level amplification circuit like the traditional audio system, thereby maintaining the original sound of the sound. As we all know, the more "levels" the signal passes, the more distortion and pollution the sound will have, and the sound quality will be impure. The frequency response index of some high-end headphones can be better than 20Hz-20KHz. For example, the frequency response of the Sennheiser HD580 is: 12Hz-38000Hz, I would like to see if some of the best speakers on the market have such a wide frequency response?
The vibration quality of the headphone unit is small, only in the order of milligrams, and the ordinary speaker is a few grams, or even dozens of grams, and the movement of the speaker is affected by the "piston" movement, etc., which reduces the quality of sound reproduction. The vibration quality of the headphones is small, so the transient is very good, the control ability is strong, the resolution is high, the dynamic range is large, and the sound is of course pure.
Second, the headset has an accurate sense of orientation. There is only one sound point of the headphones. As long as you put on the left and right headphones accurately, you can enjoy a very accurate sense of stereo orientation, accurately reproducing the stereo orientation processing of various sound sources and musical instruments by the sound engineer, making you feel like you are there. Realism of the environment. The traditional sound is affected by environmental noise, speaker positioning, left and right channel crosstalk, listening position, listening environment and the phase shift of the speaker crossover, distortion, plus the quality of the amplifier, sound source and other equipment, improper matching, etc. Disadvantages, how easy is it to get immersive on-site effects?
Third, the headset is full of space. The distance between the sound of the traditional audio and the earphone is very different from the human ear. The sound field experienced by the earphone is centered on the head and spreads forward in a spherical shape, while the sound field of the sound system is spread in front of the listener left and right and in depth. Listening to music with headphones, people are absorbed in the wonderful music, which is deeply infected with the ups and downs of music. Listening to music with headphones seems to be isolated from the world, like a paradise, it is no longer hindered by the acoustic characteristics of the environment, and the crosstalk of the left and right channels is eliminated, and the sound is directly transmitted to the ear, which can bring shocking and accurate sound effects.
Putting on headphones is like entering the realm of ecstasy and savoring music, so in addition to choosing a good headset, choosing a good headphone amplifier circuit is also a job that needs to be paid attention to. Of course, if you have more than two silver pockets, of course you can choose Buy more than a thousand yuan of finished earphone amplifiers! Saving is a traditional virtue of our Chinese people. Here we introduce to the enthusiasts a pure DC Hi-Fi headphone amplifier circuit designed by the author. Its sound quality is pure, the level of detail is clear, the dynamic is sufficient, the bandwidth is very good, and the cost is not expensive. Many, those who are interested may wish one.
The circuit schematic diagram is shown in Figure 1 (only one channel is drawn in the figure, the other channel is the same), the author design is pure DC type, the music channel does not have a coupling capacitor, so that the music signal is as smooth as the vehicle enters the highway Unobstructed, high and low frequency without any sound dyeing and modification, directly push the headphones after amplification, and release pure music authentically.
The use of pure DC amplification can enhance the strength of the bass and the resolution of the treble, so that the replayed sound sounds plump, thick and clear, and has the charm of a tube amplifier. In order to accurately correct the drift of the ground current potential, this amplifier circuit incorporates a DC servo circuit (see figure IC2 and diode etc.). As a good amplifier circuit, the power supply circuit is also a very important investment project. It must be out of the expectation. The author uses the Panasonic active servo voltage regulator circuit in the well-known audio industry to provide a stable and pure energy for the amplifier circuit. (power supply). In order to facilitate the application of the author, the power circuit and the amplifier circuit are designed together. When used, press a double-watt 12V- 18V transformer, and insert the headphone plug into the headphone socket. Note: For the safety of the earphone, the earphone should be plugged in after the power is turned on. When not in use, turn off the earphone and then turn off the power to prevent the DC impact when the power is turned off to damage the earphone, otherwise it will really "burn!"
Good horse with gold saddle, component selection: â‘ The circuit board adopts silver plating process (helps to improve the analytical power of small signals, you can hear more levels of detail); â‘¡The resistance is all imported metal film with low noise and precision (Â± 1% ) Five-color ring resistance; â‘¢ Inductive capacitors use Japanese Roxy metalized non-inductive CBB capacitors or Dutch Thomson MKP capacitors; the rest of the electrolytic capacitors should use Japanese ELNA, black diamond, Roxy, ruby â€‹â€‹and other recognized high-quality products; For potentiometers with high-quality W Â· L brand, (conditional ones can use Japanese ALPS better); â‘¤All the op amps on this circuit use the op amp king NE5532N, if you want to get a better grade, you can put IC1 With OP275, AD827JN, etc., it makes no difference whether IC2IC3 is replaced or not, and there is no need to waste money. â‘¥ The direction of the circuit ground wire should be properly handled, and the input and output grounds must be connected to the power capacitor.
The component welding inspection is correct, and do nâ€™t rush to plug in the headphones, because you will drive the ship for thousands of years! Turn on the power first to check if there is DC voltage at the output end. Is the IC abnormally hot? The faults are eliminated one by one, the input potentiometer is adjusted to the minimum, the signal source is connected to the earphone and the potentiometer is turned on to adjust the reasonable volume to listen to the sound. At this time you can start to enjoy wonderful music?
If you are not satisfied, then you have to come up with a big magic weapon-BBE sound effect enhancement processing circuit, BBE sound effect enhancement technology is a patented audio technology used by the US BBE Sound Inc. to improve the quality of listening It can correct and restore the signal loss and phase deviation of the audio system due to various reasons, so that the sound can be reproduced truly, so that the listener feels rich and low bass, and the positioning clarity and brightness are close to the ideal live effect. At present, BBE circuits available in China are BBE2150, BA3884, XR1071, XR1075, etc. Among them, XR1075 is the best, XR1071 and XR1075 are similar, BA3884 is mid-range, the price is not expensive, BBE2150, the lowest price, Figure 2 is the BBE and headphone amplifier circuit Connection method diagram.
Maybe some audiophiles will ask: Can you get Dolby multi-channel surround home theater effect with headphones? The answer is yes. And there are finished products on the market! For example, Sennheiser â€™s LUCAS surround sound headphone processor (market price is about 2,000 yuan), and there are AKG surround sound headphones. These surround headphones plus a portable portable VCD / DVD player can form a â€œportable "Cinema" meets the needs of individuals who are traveling on a business trip. The "Cinema" who needs to play on the computer can also work with the computer. The effect is even better! As hands-on and enthusiasts, we can certainly make one ourselves!
We can use the Q-Surround virtual Dolby surround sound technology chip QS7779 from Q-Sound of Canada to decode the mixed signal of Dolby directional logic or Dolby Digital AC-3, and then perform three-dimensional virtual processing, and then send it to the headset of Figure 1 Amplifier circuit, so that you only need to wear headphones to achieve the multi-channel Dolby surround sound effect with two channels, and the sound movement, positioning and effect are better than the virtual surround effect released by the two speakers. Sometimes if If you can see it, you will involuntarily evade when the plane flies over your head from the rear, and you will reach out to fight with the fist in front! ! ... realistic!
Figure 3 is the connection method diagram of QS7779 and the headphone amplifier circuit. If it is convenient for use, the two circuits and transformers can be installed in a small box (conditional ones can find a large aluminum alloy material and elaborately make it look better. Creative), to make a finished machine, and the investment is only more than 200 yuan, which can be described as excellent value for money. !
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