How does a speaker work? I cant get my head around it..
How does a speaker work? I cant get my head around it..
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Discussion

Tokoloshe

Original Poster:

376 posts

208 months

Tuesday 12th January 2010
quotequote all
Can anyone explain basically how a speaker wproduces sound? I understand the concept, move the cone in and out rapidly using electrical current to vibrate the air, and a sound is produced, but if you have a single speaker for instance, how does that single cone vibrating in and out produce (eg) 5 different instruments that you can hear all at the same time?

A full range speaker cone would need to vibrate quickly and shallowly to produce the high notes, but also longer and more in and outty to produce the bass sounds, but it cant do this at the same time, so how does it make all the sounds come out at the same time?

Ive read up on speakers and they dont cover that point anywhere I can find, also they talk about the cone vibrating and making the sound, so how come if I wave my hand in the air it doesnt produce any sound? (im serious, I know it's basic stuff but I cant get my head around it). If I vibrate the speaker cone, nothing, if electricity does it, loads of sound, and the ability for a single cone to produce multiple pitches, notes, and sounds at the same time.

Please someone explain....

eharding

14,648 posts

314 months

Tuesday 12th January 2010
quotequote all
Tokoloshe said:
A full range speaker cone would need to vibrate quickly and shallowly to produce the high notes, but also longer and more in and outty to produce the bass sounds, but it cant do this at the same time
That's exactly what it is doing.

Bullett

11,182 posts

214 months

Tuesday 12th January 2010
quotequote all
Which is also why good speakers have multiple cones, woofers and tweeters. Just remember a microphone is basically a speaker in reverse it takes vibrations and converta them into electricity. The speaker then converts them back into vibrations.


"No, I don't want stupid things like woofers and tweeters"

eharding

14,648 posts

314 months

Tuesday 12th January 2010
quotequote all
Bullett said:
"No, I don't want stupid things like woofers and tweeters"
Do you want a paper bag on your head?

Plotloss

67,280 posts

300 months

Tuesday 12th January 2010
quotequote all
Waving you hand around is a wee bit slower than the speed at which a speaker moves though which at its lowest (audibly) is 20 times a second.

If you were to clap however, this would cause an audible wave.

Once you've finished with speakers read up a bit about the ear - now that is an utterly fascinating instrument.

Puggit

49,811 posts

278 months

Tuesday 12th January 2010
quotequote all
And why do they all have those 2 little drips coming out of the central bit?

eharding

14,648 posts

314 months

Tuesday 12th January 2010
quotequote all
Puggit said:
And why do they all have those 2 little drips coming out of the central bit?
I'm sure there is a Jedwood gag to be had here, but frankly, I can't be arsed.

Quaint

658 posts

224 months

Tuesday 12th January 2010
quotequote all
eharding said:
Bullett said:
"No, I don't want stupid things like woofers and tweeters"
Do you want a paper bag on your head?
How many watts, exactly?
biggrin

MartG

22,820 posts

234 months

Tuesday 12th January 2010
quotequote all
Puggit said:
And why do they all have those 2 little drips coming out of the central bit?
They cover where the connections from the coil on the cone are connected to the fixed part of the speaker

Mars

10,129 posts

244 months

Tuesday 12th January 2010
quotequote all
Flap your hand as though waving, as fast as you can.

At the same time and the same arm, move your arm up and down.

That's essentially how both the high frequency and low frequency sounds are produced by a single speaker.



"D'you wanna an amp?"

ccr32

1,983 posts

248 months

Tuesday 12th January 2010
quotequote all
Mars said:
Flap your hand as though waving, as fast as you can.

At the same time and the same arm, move your arm up and down.

That's essentially how both the high frequency and low frequency sounds are produced by a single speaker.



"D'you wanna an amp?"
How does that work though? I thought a loudspeaker only moves along one axis - aren't you suggesting that it does not?

hondafanatic

4,969 posts

231 months

Tuesday 12th January 2010
quotequote all
Mars said:
"D'you wanna an amp?"
Sorry, I'm going to spoil the fun, but are we refering to the 'Not the Nine O'Clock News' sketch, or am i showing my age?

BMWBen

4,906 posts

231 months

Tuesday 12th January 2010
quotequote all
Think about what it's possible for the air to transmit. It can only pass one compression wave.

When you have multiple instruments, all of their waves interfere and produce one single wave.

Open up a wave file on your computer in sound recorder - it's a single wiggly line that contains all the information about the sounds. That's all the speaker has to produce.

Don't listen to this bks about different bits of the cone moving differently. The only reason you have tweeters, woofers etc is so that you split the single wave into higher and lower frequency component parts and deliver them through a speaker which is specially designed to produce them accurately. It all adds back together in the air to make a single wave again, and is not actually necessary, just adds quality.


Mars

10,129 posts

244 months

Tuesday 12th January 2010
quotequote all
ccr32 said:
Mars said:
Flap your hand as though waving, as fast as you can.

At the same time and the same arm, move your arm up and down.

That's essentially how both the high frequency and low frequency sounds are produced by a single speaker.



"D'you wanna an amp?"
How does that work though? I thought a loudspeaker only moves along one axis - aren't you suggesting that it does not?
No I'm not.

Use both hands/arms then (best do this in an environment where you cannot be ridiculed) and imagine you're looking at the cross section of a loudspeaker cone. You are actually moving in precisely the opposite way to a speaker which is energised from the middle but the principle of you operating at both high and low freqiencies is sound.

ccr32

1,983 posts

248 months

Tuesday 12th January 2010
quotequote all
BMWBen said:
Think about what it's possible for the air to transmit. It can only pass one compression wave.

When you have multiple instruments, all of their waves interfere and produce one single wave.

Open up a wave file on your computer in sound recorder - it's a single wiggly line that contains all the information about the sounds. That's all the speaker has to produce.
idea

Tokoloshe

Original Poster:

376 posts

208 months

Tuesday 12th January 2010
quotequote all
Thanks all, it's starting to make slightly more sense, so BMWBen, the speaker would create a sound for a drum snare and a split second later create the sound for the bass drum, the two sound waves would intermingle and form one "medium" wave?

Okay, I still dont get it frown

I have some single cone Anthony Gallo Micro Ti speakers which I changed to after having large Mission floortstanders that had bass, mid, and treble speakers. The Missions kinda made sense in that I figured each speaker had it's role, but now I look at the Gallos with one single speaker and listen to an entire orchestra of sound coming out of it, and it just doesnt seem possible for the cone to vibrate all of that accurately and the sound to come out as if all at the same time.

If it produces one sound, then another, then another, extremely quickly one after the other, would you notice more of a "split" between the frequencies the more differently pitched instruments you have?

Plotloss

67,280 posts

300 months

Tuesday 12th January 2010
quotequote all
Do you have the Gallos with a sub?

If so, its the sub that is doing the majority of the work from the mids down, the construction of the Micro itself is relatively clever but its by no means a 'full range' speaker.

Interesting thread this, it's like a train wreck in slow motion!

Tokoloshe

Original Poster:

376 posts

208 months

Tuesday 12th January 2010
quotequote all
I have a sub, and amp set to pass any frequencies below 120Hz to the sub, the Gallo's do the rest.

The sub is also one speaker frown oh god, this is getting worse.

BMWBen

4,906 posts

231 months

Tuesday 12th January 2010
quotequote all
Tokoloshe said:
Thanks all, it's starting to make slightly more sense, so BMWBen, the speaker would create a sound for a drum snare and a split second later create the sound for the bass drum, the two sound waves would intermingle and form one "medium" wave?

Okay, I still dont get it frown
No! smile

Think of the real world, go back to when the sounds were recorded. You have a bass drum and a snare, both hit at the same time. They both produce a compression wave in the air. The air can only have one compression wave flowing through it at any one time, as the particles of air can only be in one place at a time (ignore quantum mechanics, we're talking about molecules). So the two waves interfere and produce a "sum" wave in the air. Still only one wiggly line, just created by two seperate sources that have interacted. This wave is recorded by a microphone, and the electrical wave output captured on the recording medium. One wave.

The speaker just does the opposite, it turns that single wave on the recording medium back into a single wave in the air. if you have tweeters/woofers/subs, you STILL only end up with one wave in the air, containing the reproduced recorded wave, added to anything that was already there like a car going past outside, the OP farting etc.

Making any sense?

Plotloss

67,280 posts

300 months

Tuesday 12th January 2010
quotequote all
There isn't one wave, how could there be? If there were all sound from various point sources would sound equal irrespective of the way you were facing.

There are lots of waves all at different amplitudes travelling at different speeds.

A 20Hz wave is 22ft long, a 20KHz wave less than an inch.

How could one wave contain both these frequencies yet (whilst extreme) a speaker could reproduce both at the same time?