Hey guys ! So I am trying to copy the tone control + loudness circuit from a 1989 Sony amplifier. However I am completely stuck, and everyone else I ask seems to be, at what does that DOT near the potentiometer mean ? 🙂)
So basically that is a stereo pot, it has 6 outputs as expected, two go to signal, two go to ground, and two send the signal forward, in a stereo design. However, it looks like there is a 7th pin that is not connected to anything, and from the pictures I saw on the net ( I don't have access to the amp anymore ) , the pot itself actually does have 7 pins, one larger. What could this be ( mention, it is not a loudness switch, it has a manual loudness switch that does what S304 does in the picture ). Also , the Source Direct switch which the pin serves is a separate button, but to me it seems that the pin is on when source direct is off, so in normal listening mode. Also, the volume does not press or click anywhere , it just turns. Any ideas ? Thanks !
So basically that is a stereo pot, it has 6 outputs as expected, two go to signal, two go to ground, and two send the signal forward, in a stereo design. However, it looks like there is a 7th pin that is not connected to anything, and from the pictures I saw on the net ( I don't have access to the amp anymore ) , the pot itself actually does have 7 pins, one larger. What could this be ( mention, it is not a loudness switch, it has a manual loudness switch that does what S304 does in the picture ). Also , the Source Direct switch which the pin serves is a separate button, but to me it seems that the pin is on when source direct is off, so in normal listening mode. Also, the volume does not press or click anywhere , it just turns. Any ideas ? Thanks !
I suspect it's a tapped potentiometer.... They were used, usually in conjunction with a "loudness" switch, to vary the amount of tonal variation with the volume level. With it, the loudness tone contour would have more effect at lower levels. The pot would have a total of eight pins, instead of the usual 6, like this example:
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but then, why is there a loudness switch on the amp ? could it be a variable loudness design ? where the pot receives both the original signal and the modified signal , and the louder you go the more of the original and the less of the modified you receive ?
Ravenash - it makes the "loudness" function dependent on volume. Sometimes it was called "physiological volume control". Then it's logical why it's linked to the direct switch.
You will have to build the whole circuit as the loudness functions using the impedance from the tone controls as well.
The Pioneer loudness was much simpler.
You can use 2 signal DPDT relays for the implementation
Another 2 relays for the pass through
The Pioneer loudness was much simpler.
You can use 2 signal DPDT relays for the implementation
Another 2 relays for the pass through
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