Hi-Fi amplifier and pre-production of mini wire broadcasting radio system

Use of a dance hall idle for many years HI-FI amplifier and pre-established set of small cable broadcasting system (Department of second-hand equipment, high cost) see attached. NE5532 dual op amp unbalanced composition - balance converter (if SSM2142, DRVl34 other imbalance - a better balance of transformation-specific integrated circuit, of course), to promote by the "hills" BK2 × 150B dual-channel power amplifier consisting of a pure single BTL power amplifier. Figure (C) of the transformer-coupled line appears to have a superfluous too, does not. Repeated practice shows, BTL (or OCL) amplifier directly promote the horn tweeter, I think is inappropriate. First, the BTL (or OCL) amplifier frequency response is too broad (usually 20Hz ~ 20kHz, ± 3dB), too strong low-frequency energy can easily be the voice coil horn tweeter membrane from tearing down the sound, resulting in repeated for voice coil repeated losses (horn tweeter frequency response is typically only 80 ~ 8000Hz). The second is to impedance matching, must be more than just speakers series and parallel in different ways, as long as one is likely to cause damage to a speaker playback system terminal paralysis. Third, BTL (or OCL) line output voltage is low, a large long-distance transmission line losses. In response to these deficiencies, the author uses EI type power transformer (if higher, according to the design requirements of the audio output transformer winding of the transformer specifically) inverted to form the step-up transformer between the line and coupled transmission line system successfully solved this a contradiction. Measured the transmission system transformer (transformer of course, different systems have different test results) at 80Hz ~ 12kHz frequency response uniformity (lkHz as the base value) is only-ldB, BTL has a very strong drive capability and can compensate for transformer the disadvantages of the coupled system, is ideal for matching with the horn tweeter.

25W16Ω horn tweeter voice coil with smaller wire. Easy to burn, if the speaker has a larger head and the magnetic gap margin, suggested that it be replaced with thicker 50W16Ω voice coil wire, as the following figure (a), (c) were all additional facilities without any wiring changes to the original machine, can be broadcast and Hi-Fi correct.

As for the lightning protection, grounding, or using one-way transmission, cable radio should be strictly in accordance with the implementation of technical regulations.

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