Submitted by caedin8 t3_103appl in askscience
So my understanding of vinyl is that the single needle runs through the groove cut into the vinyl record, and then that vibration is the analog sound signal that gets amplified and played back through the speakers.
If that is true, how does a vinyl record record separate sound for the left and right speaker, if it just has one single groove?
that's really interesting
I was under the (incorrect?) impression that one channel was encoded in the up/down axis and the other in the left/right axis of the stylus
Does encoding them in the way you described improve fidelity/reduce noise/skips or something?
[removed]
[removed]
[removed]
wait are you saying that a third layer of information is encoded ????
[removed]
"The bass" is not separately encoded Ion it's own channel. However it is true that the signal pressed onto a vinyl record is not the original source signal, but it's pre-filtered with the RIAA response curve, effectively dampening low frequencies. During playback, a preamplifier stage reverts that filtering to reconstruct the original waveform.
[removed]
[removed]
No, just left and right. Believe me, I just retired from working 35 years in the HiFi (turntable manufacturing) business. But - in most music recorded by microphone, bass is pretty much mono. The wavelength is so long that the signal picked up by the left and right microphones will be almost identical. That’s why you can put a subwoofer almost anywhere in a room and it won’t make much difference.
If the left and right channels were cut IN PHASE then this common movement would translate to a pure vertical movement of the stylus. This is bad news, as it can make the stylus lose contact with the record surface. So one channel is phase reversed (180 degrees) so that the common signal then translates to HORIZONTAL movement. Only the difference between L & R makes the stylus move up and down.
Note: I had previously forgotten this phase reversal detail, but it came back to me, and so I have now edited this post to correct the above paragraph. This other Reddit post on the subject is very informative!
It is of course possible for an engineer to put a full bass track on one channel, but there’s no real sense in doing that. If they want to make it seem like the bass player is standing on one side, they only need to put the mid and high frequency harmonics over there but the low frequency stuff should be mono, so you don’t overload the bass drivers or amps on one channel, and run the risk of hitting the end stops on bass drivers at high volume, which sounds bad and can damage the speakers.
[removed]
> the low frequency stuff should be mono, so you don’t overload the bass drivers or amps on one channel, and run the risk of hitting the end stops on bass drivers at high volume, which sounds bad and can damage the speakers.
So, has anybody ever done that deliberately? Like encoding a signal that can destroy a record player or speakers? Is there a record of doom out there?!
I recall having a record where the bass is so heavy you can see the groove wiggling and you need to be careful not to spin the record too fast or the needle would jump out...
There's many. I was in the east coast noise scene in the aughts. Many artists recorded many things that either sounded exactly like destroyed speakers or destroyed speakers if turned up too loud or they'd record destroying speakers and destroy speakers playing that through speakers. Or sometimes just use already destroyed speakers to begin with just to get that sound.
Like all true art music, it was more fun to do than to hear.
EDIT: Spleling
On top of what /u/Prestigious_Carpet29 said it also ensures back compatibility with mono systems.
[deleted]
[removed]
[deleted]
[removed]
Are you imagining the system that used L/R and up/down as the two channels being a rectangular groove? If it was still a V-groove, you wouldn't have the problem described in your first paragraph, but I agree that the system that is actually used is better, for the reason described in your second paragraph.
[removed]
not exactly, the vertical move is the sum: left + rigth, and the horizontal move is the difference: left -rigth
the electronics add both and substract both to have left and rigth
this way it is compatible with a mono player
electric_ionland t1_j2y3f3w wrote
The groove is a V shape with 90 degree angle. Each side of the V encodes for a different channel. The result (depending on how they are configured) is that the up and down movement of the stylus give you the sum of both channels while the left to right movement give you the difference between them.