G'day all, as part of an intended 'bedroom' audio system I've made up a simple MK484 AM tuner to the 'performance breakthrough' circuit. Man it works well and sounds great with very nice audio quality! The 'performance breakthrough' circuit as attached really brings out the best in the little MK484!
In my own version I've used my own single transistor audio stage but the 'performance breakthrough circuit around the MK484 is the same. The 100 k bias pot really allows the best out of the MK484 (ZN414, TA7642 and other chips of the same circuit). I use my version as a tuner feeding a small amplifier and speakers and the audio quality is very nice indeed! This whole article is well worth reading:
http://members.iinet.net.au/~cool386/zn414/zn414.html
Other MK484 designs I've built in the past found on the internet have always tended to have slight audio distortion, but not this one. It sounds beautiful and works well as a hot DX radio too if the 'bias' pot is appropriately adjusted! Regards, Felix (vk4fuq).