I'm building a Stepped Tone Generator (AKA Atari Punk Console (APC)) based circuit, which is not a stand alone device, but which will feed into a number of subsequent stages/circuits.
The majority of the schematics out there show the audio output referenced to GND, like so:
- The tip/pin of the jack in this case is connected to the +V and the sleeve to the output
- The sleeve (and ring, if jumpered) is to +V and pin to the audio output
- The speaker, in the original circuit, is connected between the output and +V.
I understand that the DC bias of an audio signal is irrelevant, and is blocked by C3
- In the first example, with +V connected to the tip, the effect output is effectively the "right way up", but with a moving ground, as the signal is now the ground, especially if connected to an amplifier (where the amplifier's input sleeve is connected to GND).
- In the second example the signal would appear to be inverted, as the ground is now +V.
- Why did Forrest M. Mimms not connect the speaker between the output and GND?
- Shouldn't the GND line be used, especially if connecting the APC to another piece of grounded audio equipment, such as an amplifier?
- Does it make a difference, if +V or GND is used, as the DC bias of the signal is not relevant?
- Are there any advantages to doing this (using +V en lieu of GND)?
I am confused, but that could just be due to my conditioning that signals should be referenced to GND. I have never seen (or maybe noticed) this +V referenced type of signal/circuit before. Is this related to virtual-grounding?