Radioelectronics, December 1990, volume XLI (139)
FROM THE COUNTRY AND FROM THE WORLD (cover page 2)
ANNOUNCEMENTS (1)
ELECTROACOUSTICS - "Duetto-Stereolith" SPEAKER SYSTEM (2)
The company REVOX, known for its high quality products, offers a stereo loudspeaker system operating in accordance with a new concept. As it is easy to reproduce and gives interesting sound effects, it is worth getting to know it better.
The classic way of stereo reproduction requires the use of two loudspeakers separated by a distance, the so-called base. The optimal stereo listening position is in front of the loudspeakers, symmetrically to them. It has long been noticed that when using loudspeakers with a wide angle of sound or omnidirectional radiating units, the position of the listener in relation to the loudspeakers is less critical, but the stereo image of the sound becomes less accurate, especially in terms of the location of the apparent sound sources.
The Swiss acoustician - Walter Schupbach - proposed a solution consisting in placing the speakers of both channels in one housing in such a way that they radiate in opposite directions, i.e. to the left and to the right of the listener. It turned out that the best results are achieved by a housing with a triangular cross-section (see the drawing), divided by a wall into two parts. This solution can be compared to the radiation of sounds by one source, in principle omnidirectional, but the sounds radiated to the left and right and their reflections differ due to the fact that they correspond to different stereo channels.
DISTORTIONS CAUSED BY ELECTROLYTIC CAPACITORS (2)
When designing electronic circuits, capacitors are considered linear elements. This does not correspond to reality, especially in the case of electrolytic capacitors, which under certain conditions may cause nonlinear distortions. This is the subject of this article.
We know that the capacitance of electrolytic capacitors varies significantly with temperature changes (it decreases rapidly at subzero temperatures) depending on the frequency of the alternating current. The capacity of a good, fully functional and formed electrolytic capacitor changes slightly depending on the value of the DC bias voltage, as shown in the figure.
It follows that in the case of electrolytic aluminum capacitors there is an increase in capacitance with an increase in the polarizing voltage, and in the case of tantalum capacitors - on the contrary, there is a decrease in capacitance.
Radioelektronics, may 1989, volume XL (120), 5'89
Cover: Even when designing shoes, a computer is used (Foto Siemens)
FROM THE COUNTRY AND FROM THE WORLD (cover page 2)
ANNOUNCEMENTS (1)
ELEKTROACOUSTICS - MICROPHONES (3) (2)
Studio condenser microphone "limiting plane microphone" - AKG type C562BL
Diagrams of powering condenser microphones through a derivative wire path.
Diagrams of connecting microphones to different plugs
UNUSUAL ILLUMINOPHONIC DEVICE (5)
The characteristic features of the illuminophony device described in the article are: the use of Siemens UAA180 integrated circuits (national equivalent of UL1980N) in the device,