I have a short question... would have helped a lot if I could attach the schematic...well, anyway.
After have gone through quite a few patents of compressor circuits, mostly filed in the early sixties, I've realised that there were a lot of different solid-state topologies around (even that early on). And many of them were variations of one another, based around bipolar transistors and diodes. However, none of these designs seem to have made it to a commercial level...wierd?
One specific that I was looking at was a design from 1962 (a US patent by Martin-Marietta Corporation). Here the input signal is passed through two emitter followers, then rectified and used to charge a capacitor. A negative resistance diode is connected across this capacitor and is connected to the output. As the voltage across the capacitor increases, the resistance of the diode decreases, thus decreasing the signal sent to the output.
Looking at this topology (and similar from this time), where bipolars are used for amplification, and were a capacitor and a negative resistance diode were used for compression, what are the downsides, the disadvantages? Why didn't a design like this one make it commercially? I guess, in the early sixties, a solid-state topology would have been very welcome.
As far as I understand, the audio doesn't actually pass through the diode, which I understand would cause distortion and other problems. And according to the patent applciation, the attack time achieved was very fast.
Wish I could attach the schematic...but unfortunatley I don't have a scanner.
Cheers=)
/R :roll:
After have gone through quite a few patents of compressor circuits, mostly filed in the early sixties, I've realised that there were a lot of different solid-state topologies around (even that early on). And many of them were variations of one another, based around bipolar transistors and diodes. However, none of these designs seem to have made it to a commercial level...wierd?
One specific that I was looking at was a design from 1962 (a US patent by Martin-Marietta Corporation). Here the input signal is passed through two emitter followers, then rectified and used to charge a capacitor. A negative resistance diode is connected across this capacitor and is connected to the output. As the voltage across the capacitor increases, the resistance of the diode decreases, thus decreasing the signal sent to the output.
Looking at this topology (and similar from this time), where bipolars are used for amplification, and were a capacitor and a negative resistance diode were used for compression, what are the downsides, the disadvantages? Why didn't a design like this one make it commercially? I guess, in the early sixties, a solid-state topology would have been very welcome.
As far as I understand, the audio doesn't actually pass through the diode, which I understand would cause distortion and other problems. And according to the patent applciation, the attack time achieved was very fast.
Wish I could attach the schematic...but unfortunatley I don't have a scanner.
Cheers=)
/R :roll: