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A complete three-tube stereo amplifier

At the earlier as a beginner self-construction project much described stereo amplifier with only two tubes ECL86 bothered me, that with the existing high and low tone control no increase but only a reduction of the respective frequency components was possible. In addition, the balance controller left a lot to be desired and the circuit for the auricular frequency correction (loudness) could not be turned off. With an additional stereo amplifier stage with a tube ECC83, the losses of a reasonable tone control network and balance adjuster could be compensated. The channel separation was not the best, but still better, as in broadcast, where uses MPX method.

A device built in such a way and housed in a wooden case in the design of transistor amplifiers of the 1970s served me for a long time to listen to music. The achievable volume was at the available 2x 4 watts and with the boxes with oval speakers from Saba - so-called Green Cones - for the bass and piezos for the heights in any case, large enough having trouble with the neighbors. The sound was much livelier for my feel than with the then modern closed boxes, which essentially produced only a rumble in the lowest frequency range and made it almost impossible to follow bass lines.


It was also important to me to switch the signal sources and able to record them. The device thus got a signal source switch and inputs for phono, radio and tape. The latter also obtained output lines for the recording. I connected here a cassette deck in the then common flat construction (Philips N2507). For listening to vinyl, I used a record player, which I built by installing a turntable chassis P-157 from BSR together with an equalizing preamplifier in a self-made wooden housing. Such chassis were offered at that time by many electronics stores. The circuit of the preamplifier can be found here elsewhere. As pickup system, I used a Shure M75 then.

Back then, so in the mid of the 1970th, probably friends often smiled a little at the fact that I mostly listened to music on my self-made devices. Having Japanese transistor amplifiers, e.g. from Rotel, one were up to date. But if I look around the Internet today, I would probably be pretty trendy again with my former system. Unfortunately it does not exist any more, because I scrapped it (unhappily!) many, many years ago.

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