3 ms·

Super cool! But I didn't understand the last panel ("Maximum Stereo or Mono and 1 channel 180° phased")... and, also, how did they do quadraphonic?

anigbrowl 17y ago
Inverting the phase of a mono signal and feeding it to one side of a stereo channel (with the original on the other) isn't true stereo, but flipping the phase of one channel fools the brain into believing it has a spatial dimension - the sound seems louder and more vibrant although in reality all that's happening is that the left and right channels are interfering with each other. It was a trick used on a lot of old record when the music industry was moving from mono to stereo recording, but still effective if you're stuck with a mono sound source (quite often the case in film and TV) and you need to beef it up without changing the timbre of the sound substantially.
- joe_bleau 17y ago
  Wait, isn't that the same effect as a mono signal with one speaker wired backwards? If so, that 'head-swimming' sound that results is awful, and the out of phase drivers will kill much of the bass response. I'm very surprised that this trick was ever used in industry; after all, if someone listened to that old film on a single speaker TV, the signals would sum to zero and you'd have no audio at all! (And yes, our local cable company has managed this very stunt from time to time...flip to mono and the audio goes away.)
  - anigbrowl 17y ago
    Yeah, it can go wrong and it does sound pretty awful. It's good practice to check the final mix out in mono for just that reason but stereo is ubiquitous now and people often don't bother any more.
Devilboy 17y ago
Quadraphonic has 2 more channel 'encoded' in a high frequency carrier (50 kHz maybe) which can't be heard on regular mono or stereo equipment. So each of the 2 stereo channels will have this carrier signal encoding one additional sound channel.

anigbrowl 17y ago

Inverting the phase of a mono signal and feeding it to one side of a stereo channel (with the original on the other) isn't true stereo, but flipping the phase of one channel fools the brain into believing it has a spatial dimension - the sound seems louder and more vibrant although in reality all that's happening is that the left and right channels are interfering with each other. It was a trick used on a lot of old record when the music industry was moving from mono to stereo recording, but still effective if you're stuck with a mono sound source (quite often the case in film and TV) and you need to beef it up without changing the timbre of the sound substantially.

joe_bleau 17y ago
Wait, isn't that the same effect as a mono signal with one speaker wired backwards? If so, that 'head-swimming' sound that results is awful, and the out of phase drivers will kill much of the bass response. I'm very surprised that this trick was ever used in industry; after all, if someone listened to that old film on a single speaker TV, the signals would sum to zero and you'd have no audio at all! (And yes, our local cable company has managed this very stunt from time to time...flip to mono and the audio goes away.)
- anigbrowl 17y ago
  Yeah, it can go wrong and it does sound pretty awful. It's good practice to check the final mix out in mono for just that reason but stereo is ubiquitous now and people often don't bother any more.

Devilboy 17y ago

Quadraphonic has 2 more channel 'encoded' in a high frequency carrier (50 kHz maybe) which can't be heard on regular mono or stereo equipment. So each of the 2 stereo channels will have this carrier signal encoding one additional sound channel.