Modernizacja wzmacniacza lampowego

Celem modernizacji było poprawienie jakości dźwięku przenoszonego przez wzmacniacz. Wprowadzono modernizację obwodu wejściowego siatkowego pierwszej triody. Dodatkowo zmieniono ustawienie transformatorów głośnikowych względem transformatora sieciowego eliminując brum 150Hz pochodzący z transformatora sieciowego. Osłoniono również lampy siatką ozdobną zapewniając właściwe chłodzenie i zabezpieczając lampy przed przypadkowym uszkodzeniem mechanicznym.

Poniższe rysunki i zdjęcia przedstawiają wynik modernizacji wzmacniacza lampowego.

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Pioneer A10 and Tube amplifier Warmar acoustic spectra

Measurements of spectra signal using a Fast Fourier Transform (FFT) in the domain of time are performed in a finite time. In other words, the portions of a waveform of the signal of the specified length are measured. Fragments are cyclically extracted and then subjected to the FFT. Fragments of the waveform on shores contain discontinuities, because they are collected at intervals. Discontinuities cause blurring to spectra. The spectra of the downloaded portions of the waveform are different from the spectra of the whole continuous signal subjected to measurement. To reduce blur spectra signal is passed through a time window. The Time window reduced spillage of energy in the domain of frequency. Measurements were made for spectra of acoustic signals Pioneer A10 amplifier and Tube amplifier Warmar. The signal was passed through a time window. The time window Blackman  was used. The time window is a function shaping the signal measured undergone FFT. In the domain of time, signal is the function of time and was multiplied with the function describing by the time window. In the domain of frequency the convolution of these functions occurs. The result of the signal is subjected to FFT.

The results of the measurements of the acoustic signal spectra are following:

Picture above shows Pioneer A10 amplifier which carries sinusoidal signal about 1 kHz.

Picture above shows Tube amplifier which carries sinusoidal signal about 1 kHz.

Signal source supplied both apmlifiers in the same time. Next, there was measured how amplifiers carries a music.

Tube amplifier is playing music.

Pioneer A10 amplifier with on function loudness is playing music.

Pioneer A10 amplifier with on function loudness and Tube amplifier are playing music at the same time.

Pioneer A10 amplifier and Tube amplifier are playing music at the same time.

The acoustic spectrum of the test room background is shown below.

Acoustic monitors and amplifiers used to test.

Acoustic spectra for radio signal DAB and FM

Measurement of Spectra a signal using a Fast Fourier Transform FFT in the domain of time are performed in a finite time. In other words, the measured are portions of a waveform of the signal of the specified length. Fragments extracted cyclically subjected are to the FFT. Fragments the waveform on shores contains discontinuities because are collected at intervals. Discontinuities cause blurring to spectra. The spectra of the downloaded portions of the waveform are different from the spectra of the whole continuous the signal subjected to measurement. To reduce blur spectra signal is passed the signal through a time window. The Time window reduced spillage of energy in the domain of frequency. Measurements were made for spectra of acoustic signals DAB and FM. The signal was passed through a time window. Used were of the time window: Rectangular, Bartlett, Hanning, Hamming, Blackman, Blackman-Harris, Flat-Top. The time window it is function shaping the signal measured undergone FFT. In the domain of time, signal is as function of time and was multiplying with function describing by the time window. In the domain of frequency occurs weave these functions. The result of the signal is subjected to FFT.

 

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Acoustic spectra DAB and FM