- Category: Radioamator i Krótkofalowiec
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High-quality 2x10W stereo reproduction set
Michał Gołębiowski, Radioamator i Krótkofalowiec 1970/05
(The description concerns a model made in cooperation with the editorial office of the magazine and practically tested by the designer)
Despite the rapid progress of transistor technology, electroacoustic devices equipped with electron tubes are still quite often made by radio amateurs. This is justified due to the still high cost of semiconductor elements and the fact that starting transistor devices is generally more difficult and troublesome than their tube counterparts and requires good knowledge of the issue and extensive practical experience.
This description is addressed to radio amateurs who already have some achievements in the construction of electroacoustic devices and would like to obtain a higher quality reproduction set at a relatively cheap cost.
Technical data of the stereo amplifier
- Maximum output power with non-linear distortions in the band 40Hz ÷ 16000Hz and Rload = 7.5Ω less than 1% (sinusoidal signal): 2x10W.
- Frequency characteristics (1.5dB band): 30Hz ÷ 20000Hz.
- Sound tone adjustment in relation to the frequency of 100Hz:
at 60Hz: + 6dB ÷ -12dB
at 12kHz: + 6dB ÷ -15dB
- Crosstalk attenuation between the channels in the 30 ÷ 16000Hz band: ≥ 40dB.
- Stereo balance control: ± 6dB.
- Input resistance:
"magnetic adapter" input - 100kΩ
"crystal adapter" input - 100kΩ
"microphone" input - 80kΩ
"radio" input - 1MΩ
"additional" input - 0,5MΩ.
- Input voltage for maximum output power at f = 1000Hz and Rload = 7.5Ω:
"magnetic adapter" input - 5mV
"crystal adapter" input - 70mV
"microphone" input - 4mV
"radio" input - 330mV
"additional" input - 150mV.
- Signal-to-noise ratio at maximum output power: ≥50dB.
- Change in output voltage when the load is disconnected: ≤1dB.
- Mains power: 220V, 50Hz, maximum power consumption 55W.
- The remaining parameters are presented in the form of appropriate characteristics in Figures 5, 6, 7, 8 and 9.