Ok, here’s a question. And the trick here is I don’t want a technical answer, I want it in layman’a terms, an idiot proof answer that will make me go ‘aaaah! I see!’ after all these years.
I can just about ‘get’ how a mono record stylus would make sounds – the tiny bumps in the record vibrate the needle and those vibrations are then amplified into sound – check. That does me, I don’t want to hear any more about mono sound.
But how do you get STEREO sound, two completely different sounds, from a single needle on a single groove?
I need a snappy answer here, something I can pass off as my own knowledge if I need to at one of my many dinner parties.
I’ve had people talk to me about a river with two sides, I’ve heard talk of ‘sum vs difference’ and whatnot…. but can someone just EXPLAIN how it works?
Honestly I wish someone had just lied to me and told me there are actually two separate tiny needles, not one. I probably would have died happy and I wouldn’t even have bothered to check.
Can anyone put me out of my misery?
Moose the Mooche says
The needle sits inside the groove and reads the bumps on the left and the bumps on the right. A mono needle simply scrapes along the top.
That’s how I understand it.
Arthur Cowslip says
Yebbut yebbut
How can one needle read both sides of the groove at once? It can’t vibrate both ways at once can it?
Moose the Mooche says
It has a triangliar tip*, therefore two surfaces. This clearly has nothing to do with the truth (see below) but it’s the explanation I’m sticking with.
(*I know, it’s incredible)
Vulpes Vulpes says
Nah, it’s done with pixies, really small invisible pixies who live in the end of the tone arm most of the time and just lower themselves down the tip of the stylus and press pixie-ear-trumpets to either side of the groove when called upon. Simple.
Moose the Mooche says
Distant relatives to those other sons of fun, The Numskulls.
Lodestone of Wrongness says
Oh, for goodness sake – it’s magic and you can never explain magic. Simples.
Arthur Cowslip says
I’ll come back to this as it just might turn out to be the right answer…
NigelT says
It’s a good question. Frankly, I’ve never understood how you can get anything at all from scraping a needle round a plastic groove other than a….er…scraping sound, let alone recognisable music.
It is something to do with the stylus moving in two planes rather than one….but I’m bluffing really.
Arthur Cowslip says
Good attempt. (Pats Nigel’s head).
Harold Holt says
Over at arse technica (https://arstechnica.com/civis/viewtopic.php?t=742923) the most convincing assertion is left-right wiggling for one channel, up-down wiggling for the other. Truth and certainty I can’t give you. Moose and Nige appear to be confirmed too.
Black Celebration says
In the style of BBC TV’s Tomorrow’s World:
Keiran Prendeville (with headphones on, closed eyes, is snapping his fingers to a record, singing “starry starry night”). Oh! Erm…sorry. (takes off headphones). Have you ever wondered how we to get the sound through to these special stereo headphones – sometimes called “cans” – from the needle – sometimes called a stylus – onto the record?
Well – this is where it gets interesting – the needle acts like a this tuning fork ( ding! ) reacting in tiny ways to the small grooves put there by a studio boffin like George Martin. He records the songs and puts some of the sound on the left side and some of the sound on the right side of the groove. One groove can have up to eight different sounds. The stylus conducts the sound it picks up from the grooves and we hear in stereo through our cans because we have two ears.
Stereo is actually how our brain prefers to hear things naturally. That’s why it sounds so much better than if we only had one ear, listening to things in “mono”. Isn’t that right, Vincent?
Unfunny Sidekick Presenter sitting at a table (dressed as Van Gough with bandaged ear) – “pardon?”
Keiran Prendeville – “exactly”
USP – “a cup of tea? No thanks – I’ve got one ear!”
Keiran Prendeville – now over to William Woolard, who’s just been down Argos.
fentonsteve says
Essentially*;
Horizontal wiggles = Left + Right (mono)
Vertical wiggles = difference between Left and Right.
So it is backwards-compatible with mono players, which only detect horizontal wiggles. Just like FM stereo radio can be received in mono by ignoring the difference channel.
(*) it is actually a bit more complicated than that, however, with modulation angles of +/-45 degrees from vertical.
I prefer to think of it as witchcraft, though.
Arthur Cowslip says
‘Difference between left and right’… ‘Difference between left and right’….
Nope. I don’t get it. But I’ll give you another chance to explain to us simpletons as I suspect you know what you are talking about… please try to come down a bit more to our level….
fentonsteve says
Let me try explaining through the medium of maths.
Horizontal encoding = L+R
Vertical encoding = L-R
Mono decoding (ignores the vertical) = L+R
Stereo decoding: Sum plus difference and Sum minus difference.
Left = (L+R)+(L-R) = 2L
Right = (L+R)-(L-R) = 2R
Any clearer?
Moose the Mooche says
Oh yes, ignore the vertical missus
Arthur Cowslip says
Nnnnnngh…. it’s coming… I can feel it….
Let me ponder that… and then probably come back to ask you to go back to ‘encoding’….
Where do you live? I can come round with some pencils and graph paper….
davebigpicture says
Can you try the medium of interpretive dance?
Moose the Mooche says
Worst TED Talk ever.
Arthur Cowslip says
Just wait until I ask him to explain quad…
Moose the Mooche says
The engines cannee teek it Captain!
Sewer Robot says
Aaah! Not maths! You’re writin’ at someone who’s not even sure where to put the decimal point in Anderso.n Paak..
minibreakfast says
There are two hamsters.
Moose the Mooche says
There are seven levels.
minibreakfast says
It’s fine, there’s a little elevator.
Moose the Mooche says
Never mind the hydraulics!
Moose the Mooche says
Answer 2: Otis Lifts, Marvin Elevates.
Black Celebration says
“Rat-ernoster” lifts for your hamsters are easy to make using sticky backed plastic and an old cornflakes packet. Powered by one of those stupid little wheels they insist on having.
Moose the Mooche says
The Hamster Insists Pts I-IV, appears on Shut Up & Play Yer Guitar vol. 5.
daff says
Put the needle on the record and pray!
Moose the Mooche says
Put the needle on the reckid
Put the needle on the reckid
Put the needle on the reckid and the drumbeats go like this….
NigelT says
Going off on a tangent….or +/- 45 degrees….I would question whether the brain ‘prefers’ stereo to mono. Good hifi stereo creates a soundstage where you can hear individual instruments and vocals (if you are sat in the right spot), but I’ve always thought of headphones as a compromise – great for those records where things pan around (1968 must be peak stereo playtime – listen to Hendrix, The Fabs, Traffic), but everything happens inside your head, which isn’t how we hear the world. At a concert, the sound is more mono than stereo as it all comes at yer from in front, and sometimes from a long way away.
Moose the Mooche says
Not if you’re watching an orchestra. I think stereo was developed mainly to replicate the experience of sitting in the stalls in a concert hall and having a piccolo coming at you from one o’clock and a bassoon from stage left. Parrrp!
Sewer Robot says
Eh? Whatchutalkinbout Nigel? I hear the world inside my head.
Right now it’s saying
ALL WORK AND NO PLAY MAKES JACK A DULL BOY
ALL WORK AND NO PLAY MAKES JACK A DULL BOY
ALL WORK AND NO PLAY MAKES JACK A DULL BOY
ALL WORK AND NO PLAY MAKES JACK A DULL BOY
(*Sharpens axe*)
Baskerville Old Face says
I usually put a black disc with a hole in the middle on the turntable and place the needle on it. Is this a record?
Arthur Cowslip says
If you drop it on a concrete floor you’d be a record breaker.
Vulpes Vulpes says
Ping…………………………………………………………………………………………………………………..Pong
Baron Harkonnen says
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^That`s it^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^