Minggu, 08 September 2013

Amplifier HI-END audio quality

Amplifier HI-END audio quality

Your attention is an amplifier with a very soft, like a tube amp sound, but superior to tube amps by other parameters (signal / noise ratio and harmonic distortion).
Playable Audio Response: 10Hz to 25kHz
S / N ratio: not less than 92dB (unweighted)
Harmonic distortion: 0.001%
Pushed me to the creation of such an amplifier, the love of a very good quality sound.
After reviewing a lot of various schemes, made a small sketch of the concept amplifier. Later, faced with finding a good sound quality of the operational amplifier, took a chip search on the Internet at that time about 2 weeks.
The first condition - that the op amp must be high voltage, the second - a very high quality by the ratio of signal / noise ratio. Before that I was picking good amplifiers for domestic element base and K574UD1 K544UD2 chips, as well as high-power output transistors KT818 and KT819. At that point, their parameters I was completely satisfied.
But with the appearance on the shelves of our modern imported equipment requirements for such an amplifier are much higher, like a very high-quality sound that is comparable to the sound of tube amplifiers.
So, with all the ingredients I decided, began direct assembly of the amplifier, and because at that time I was working in the service center, the setting and with the build on the work done in his spare time repairing.
The first version of the amplifier looked like - it was just the beginning.
Since that time I have not had any body or board finally divorced, the device was collected in a box of DVD player packs. As such, it worked for about a month, and no incidents in the work did not happen. 
After that, I took up the tight PCB routing, and this is what came of it.
Well, look like boards of industrial production:
Circuitry of the amplifier is quite easy to assemble and does not contain scarce elements. 
All components can be purchased at any radio. 
classic skhemopostroenie as the input and output stages, allows to perform very simple to assemble and an amplifier circuit that much important there is no need to configure it. Yes it is in the configuration, it does not need, because the scheme is no regulatory elements adjust the output stage quiescent current, temperature stabilization system etc.
After assembly, the amplifier must then be included in the network to check the amplifier output voltage constant, it must be in the range +20 /-20mV, with the input of the amplifier close to the ground. If this voltage is within normal limits amplifier is ready for use, be sure to only vypayat bridge over the entrance. 
On an operational amplifier assembled circuit voltage gain, with a gain of about 25. Transistors VT1, VT2, VT5, VT6, VT7 and VT8 included under the scheme ERs and act the current amplifiers by a factor of 10. 
 At transistors VT3 and VT4 collected thermal stabilization of the amplifier circuit, and they, like the output transistors are also located on the radiator. If these transistors are not fastened to the radiator, the power instantaneously heated to a temperature above 90 degrees. 
maximum heating temperature under load amplifier and its continuous operation was 70 degrees. 
coil L1 comprises from 16 to 20 turns wound in a single layer wire NDV 1mm 2 . 
capacitors C2 and C7, it is desirable to use a metallized, and other multi-layer ceramic. 
Transistors can be imported to use, suitable to the parameters. 
Under certain changes in the pattern of the power amplifier can be raised up to 100W.
Below is a photo of the collected amplifier:
Unfortunately, I am not master of metal and wood, but here's what I came out of it. 
This amplifier operates reliably for over 8 years and no problems occurred. The quality of his sound is very decent, somewhere and superior tube amplifiers for soft sound, not to mention the noise and nonlinear distortions themselves tube amps. Yes, yes I misspoke. 
were produced comparing the sound quality with such models as the NAD, Rotel, Arcam and Yamaha, this amplifier circuit has surpassed all of the above models for softness and sound quality. 
boards have two options under the left side and a right side, The archive is only the left side of the board layout.

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