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--captions by vitac--
Www.Vitac.Com
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Captions paid for by
Discovery communications
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Narrator: the angle grinder
Created a major buzz
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00:00:55,413 --> 00:00:57,241
In the workplace
When it was developed
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00:00:57,241 --> 00:00:59,758
In the middle
Of the 20th century.
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00:00:59,758 --> 00:01:01,689
This power tool
Could do it all --
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Cut, grind, and polish
Metal or stone.
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00:01:05,413 --> 00:01:07,517
Just change the disk
Or brush attachment
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00:01:07,517 --> 00:01:09,000
To match the job,
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And work gets done
Automatically.
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00:01:14,206 --> 00:01:16,310
With numerous
Attachments available,
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The angle grinder
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00:01:17,448 --> 00:01:19,448
Could be equipped
For many different jobs.
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That makes it one
Of the most useful things
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On any job site.
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Making angle grinders starts
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00:01:26,620 --> 00:01:30,413
With these blocks
Of pure aluminum.
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Fired in a furnace,
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The aluminum melts
Into a liquid form.
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The factory casts
The molten aluminum
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To create gear housings.
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00:01:42,551 --> 00:01:44,931
A robot transfers
One of the gear housings
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To a milling station
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00:01:48,068 --> 00:01:50,448
And then retrieves
A finished part.
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The door of the machine closes,
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00:01:55,758 --> 00:01:57,896
And a computerized cutter
Carves threads
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00:01:57,896 --> 00:02:00,137
Into the center bearing seat
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00:02:00,137 --> 00:02:03,172
And generally improves
The profile of the part.
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00:02:06,413 --> 00:02:10,103
Next up is the rotor
For the electric motor.
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00:02:10,103 --> 00:02:13,517
An automated system pushes
Special cardboard end disks
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00:02:13,517 --> 00:02:16,517
Onto the rotor shaft.
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00:02:16,517 --> 00:02:20,551
The part on the right
Is equipped with end disks.
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The system now installs a part
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Called the collector on one end.
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00:02:26,241 --> 00:02:27,827
Made of copper and plastic,
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00:02:27,827 --> 00:02:30,827
The collector will transmit
Power to the rotor
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00:02:30,827 --> 00:02:33,103
And ensure that the grinding
Or polishing attachment
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Can turn.
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00:02:37,448 --> 00:02:42,241
The part on the right
Has had the collector installed.
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00:02:42,241 --> 00:02:44,482
Spinning arms wind copper wire
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00:02:44,482 --> 00:02:47,379
Into grooves in the rotor
At both ends.
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The wire will serve
As an electromagnet
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00:02:50,275 --> 00:02:52,344
And maximize power output.
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00:02:55,413 --> 00:02:58,034
Moving forward,
The system inserts covers
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00:02:58,034 --> 00:03:01,310
Into slots in the rotor wall.
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00:03:01,310 --> 00:03:03,000
They both insulate the rotor
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00:03:03,000 --> 00:03:05,482
And stabilize the copper coil.
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00:03:05,482 --> 00:03:07,862
Spinning devices
Wrap copper wire
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00:03:07,862 --> 00:03:10,241
Around each half of the stater.
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00:03:10,241 --> 00:03:12,724
This stater creates
The electromagnetic field
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00:03:12,724 --> 00:03:14,068
Around the rotor.
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A robot puts the two halves
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Of the stater
Together in a fixture,
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00:03:20,241 --> 00:03:22,724
And welds make
The assembly permanent.
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00:03:29,689 --> 00:03:32,137
Over to an injection
Molding machine now,
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00:03:32,137 --> 00:03:37,241
It forms plastic into outer
Casings for the grinder.
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A robot transfers the casing
To a platform for printing.
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This stamp adds silver ink
To the embossed company logo,
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Giving it greater visual appeal.
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00:03:49,241 --> 00:03:54,000
A worker then slides the plastic
Housing over the stater,
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00:03:54,000 --> 00:03:57,172
And a pneumatic machine
Press-fits the two together.
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The worker then wires
The on/off switch
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For the angle grinder.
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00:04:06,241 --> 00:04:08,482
The gear housing has,
By now, been equipped
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With a drive gear and brake.
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He installs the gear system
On one end of the rotor.
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00:04:16,413 --> 00:04:19,344
He then inserts the rotor
Assembly in the stater.
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An automated system
Screws everything together
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To complete
The angle grinder motor.
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00:04:30,137 --> 00:04:35,000
Next, a nozzle fills
The gear head with grease.
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00:04:35,000 --> 00:04:36,551
A worker places the spindle
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00:04:36,551 --> 00:04:39,724
And safety clutch
Over the gear head,
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And a mechanized system
Screws it in place.
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She then wires
The electrical plug
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To the angle grinder motor.
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She encloses the electrical
Wiring with a plastic cover.
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She locks the cover
In places with screws,
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Using a metal template
To aid in their placement.
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This angle grinder
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00:05:20,241 --> 00:05:25,034
Is now ready to undergo
Quality control tests.
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This one depresses
The angle grinder switch,
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While a computerized system
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Analyzes the motor's
Performance.
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If it passes all the tests,
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The angle grinder
Is ready to take a chunk
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Out of someone's workload.
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Narrator: long before
The development of pottery,
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People looked to the forest
For containment materials.
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00:05:56,206 --> 00:05:59,965
They made berry baskets
From the bark of birch trees.
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The baskets were
Lightweight and waterproof,
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Due to natural
Resins in the bark.
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The making of these baskets
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Is a tradition that carries on.
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For containing nature's bounty,
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Birch bark is a natural choice.
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This berry basket
Is made entirely
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From materials found in nature.
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Making one starts
With birch bark
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That's been carefully
Pried off the tree
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To avoid damage
To the inner layer of bark.
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This cardboard pattern
Will be used as a template.
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The basket maker
Examines the bark
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For any holes or serious flaws.
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He flips the bark over.
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He'll use the inner side
For the outside of the basket.
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He traces around the pattern,
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Using a scribe that
Lightly scores the bark.
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This light scoring creates
A visible outline on the bark.
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Using scissors
For cutting leather,
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He follows the pattern lines
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To cut the bark
To the pattern shape.
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00:07:08,689 --> 00:07:10,689
The contours
Are harder to follow,
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00:07:10,689 --> 00:07:12,241
So he switches to scissors
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With curved blades
To cut them out.
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He punches holes
In the basket corners.
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This will stop the bark
From splitting in these spots
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When it's folded.
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Using a pointed instrument
Known as a divider,
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00:07:27,310 --> 00:07:31,862
He now etches stitch lines
Around the perimeter.
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He maps out the location
For the stitch holes
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00:07:34,482 --> 00:07:38,103
By lightly piercing the bark
Along the etched lines.
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Using a ruler for support,
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He bends the flaps
Of the pattern up,
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Creating creases that will
Become permanent folds later.
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He punches out stitch holes
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Where he had lightly
Pierced the bark.
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He drapes a damp towel
Over the birch bark
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00:08:03,896 --> 00:08:07,068
And irons it.
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00:08:07,068 --> 00:08:09,896
This softens the bark
So that it doesn't split
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00:08:09,896 --> 00:08:13,551
As he now forms the final bends
Along the crease lines.
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He overlaps the ends
Of the basket.
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He clips the structure
To hold it together
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00:08:20,931 --> 00:08:24,344
While he inserts wooden dowels
In some of the stitch holes.
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00:08:26,965 --> 00:08:30,931
Once the dowels are in,
He removes the clips.
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The dowels will keep the basket
Together for stitching.
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00:08:34,827 --> 00:08:36,724
But first, he tapers the stem
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00:08:36,724 --> 00:08:40,172
From a willow shrub
Using a wood plane.
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00:08:40,172 --> 00:08:42,896
He inserts the stem
In a cylindrical container
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00:08:42,896 --> 00:08:46,758
And fills the cylinder
With hot water.
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The tapered stem
Soaks overnight.
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It softens and becomes
Extremely flexible.
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Using a wooden form,
He shapes the stem into a ring.
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00:08:57,724 --> 00:09:00,482
The tapered ends overlap
For a consistent thickness
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All the way around.
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00:09:05,206 --> 00:09:08,241
He clips the ring
To the inner rim of the basket
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00:09:08,241 --> 00:09:12,689
And also tacks it in place
With a few stitches.
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00:09:12,689 --> 00:09:14,551
This willow ring
Will add support
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00:09:14,551 --> 00:09:16,482
To the lip of the berry basket.
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00:09:19,724 --> 00:09:22,448
Next, he stitches
The seams together
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00:09:22,448 --> 00:09:25,724
Using the root of a spruce tree
For thread.
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00:09:25,724 --> 00:09:29,931
Its tapered tip serves
As a needle.
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00:09:29,931 --> 00:09:31,724
He does precise backstitches
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00:09:31,724 --> 00:09:34,172
And ensures all
The seams are tight.
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00:09:38,896 --> 00:09:41,310
Moving back to the rim
Of the basket,
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He punctures the bark
Just below the willow ring,
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Creating a row of holes
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To loop the root
Around the rim.
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00:09:51,827 --> 00:09:54,655
This spruce root wrap
Protects the rim ring,
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00:09:54,655 --> 00:09:57,724
And gives the basket
A more finished look at the top.
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00:10:02,724 --> 00:10:04,586
He slices a piece of cedar bark
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00:10:04,586 --> 00:10:06,862
Into long, narrow strips.
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00:10:09,103 --> 00:10:12,275
He'll use these strips to make
A handle for the basket.
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He weaves the cedar
Into a five-strand braid.
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He loops the cedar
Braid at the ends
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And uses the loops
To stitch the handle
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To the berry basket.
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00:10:31,655 --> 00:10:33,551
It takes this artisan
About a day
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00:10:33,551 --> 00:10:36,275
To craft a birch bark
Berry basket.
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00:10:39,965 --> 00:10:41,413
His efforts will no doubt
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Bear fruit
For many years to come.
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Narrator: choosing the right
Speakers for your sound system
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Depends on how you prefer
To hear music.
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Unidirectional speakers radiate
Sound in a single direction.
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00:11:09,241 --> 00:11:12,344
Omnidirectional speakers radiate
In all directions,
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00:11:12,344 --> 00:11:15,379
So the sound bounces
Off the ceiling and walls.
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This omnidirectional speaker
System has four towers --
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Two main system towers
And two subwoofer towers.
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The towers contain the drivers
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That radiate sound frequencies
Out of the speaker.
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00:11:32,103 --> 00:11:34,655
This computer-guided mill
Shapes brass sheets
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00:11:34,655 --> 00:11:38,413
Into mounting plates
For the main system towers.
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00:11:38,413 --> 00:11:42,310
Each of the main system towers
Contains six drivers --
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00:11:42,310 --> 00:11:46,724
Two tweeters, two mid-ranges,
And two woofers.
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00:11:46,724 --> 00:11:49,103
Each subwoofer tower
Contains six drivers
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For the lowest human
Audible frequencies.
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00:11:53,103 --> 00:11:55,827
After the brass mounting plate
Comes off the mill,
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00:11:55,827 --> 00:11:58,172
Workers grind
The top surface smooth
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To prepare it for polishing
And chrome plating.
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00:12:02,862 --> 00:12:05,241
The mill then
Shapes brass rings.
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00:12:05,241 --> 00:12:07,655
These are bases for the woofers,
191
00:12:07,655 --> 00:12:10,827
Which fit an opening
In the mounting plate.
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00:12:10,827 --> 00:12:13,379
Brass is the metal
Of choice for these parts,
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00:12:13,379 --> 00:12:16,586
Due to its acoustical
Properties.
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00:12:16,586 --> 00:12:19,310
For aesthetics, the rings
Are painted black,
195
00:12:19,310 --> 00:12:21,172
And the mounting plates
Are electro-plated
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With galvanized chrome.
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00:12:24,724 --> 00:12:26,103
In this part of the plant,
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00:12:26,103 --> 00:12:29,620
They build tweeters
For the main system towers.
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00:12:29,620 --> 00:12:31,310
The first step is to lay strips
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00:12:31,310 --> 00:12:33,586
Of resin-impregnated
Carbon fiber
201
00:12:33,586 --> 00:12:37,413
In semi-circular molds.
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00:12:37,413 --> 00:12:39,241
After removing
The protective film
203
00:12:39,241 --> 00:12:40,862
That covers the carbon fiber,
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00:12:40,862 --> 00:12:44,344
They lay foil strips
At each end.
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00:12:44,344 --> 00:12:46,000
These will direct heat
From the oven
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00:12:46,000 --> 00:12:47,655
To the carbon fiber strips
207
00:12:47,655 --> 00:12:50,000
And prevent the resin
From flowing out.
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00:12:52,862 --> 00:12:56,827
They assemble the molds
And clamp them shut.
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00:12:56,827 --> 00:12:59,931
They place the molds
In an oven for 45 minutes
210
00:12:59,931 --> 00:13:03,000
At a programmed series
Of temperatures.
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00:13:03,000 --> 00:13:05,448
This heats the resin
In the carbon fiber,
212
00:13:05,448 --> 00:13:08,724
Stiffening and forming
The strips to the mold shape.
213
00:13:10,689 --> 00:13:12,068
Using a punch press,
214
00:13:12,068 --> 00:13:14,275
Workers slice
Each carbon fiber strip
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00:13:14,275 --> 00:13:16,448
Into several thinner strips.
216
00:13:23,620 --> 00:13:25,068
They construct each tweeter
217
00:13:25,068 --> 00:13:27,206
By gluing 24
Of those thin strips
218
00:13:27,206 --> 00:13:28,965
To the tweeter's voice coil,
219
00:13:28,965 --> 00:13:31,344
A ring made of
Wound copper wire.
220
00:13:34,620 --> 00:13:37,206
They brush silicone
In between the strips,
221
00:13:37,206 --> 00:13:39,793
Coat the entire surface
With more silicone,
222
00:13:39,793 --> 00:13:42,551
Then place an aluminum
Cover plate on top.
223
00:13:44,689 --> 00:13:48,068
They construct each mid-range
Driver the same way,
224
00:13:48,068 --> 00:13:49,689
But with carbon fiber strips
225
00:13:49,689 --> 00:13:51,344
That are thicker and stiffer
226
00:13:51,344 --> 00:13:53,724
And therefore radiate
Lower frequencies better
227
00:13:53,724 --> 00:13:56,758
Than the thinner,
More flexible tweeter strips.
228
00:13:59,586 --> 00:14:01,758
Placing the strips with tweezers
229
00:14:01,758 --> 00:14:04,103
And aligning them properly
With a toothpick
230
00:14:04,103 --> 00:14:08,000
Requires a good eye,
Excellent dexterity,
231
00:14:08,000 --> 00:14:10,068
And a lot of experience.
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00:14:12,689 --> 00:14:14,758
Like the tweeter,
The mid-range driver
233
00:14:14,758 --> 00:14:17,551
Goes into an oven
For 45 minutes
234
00:14:17,551 --> 00:14:20,172
Through a specific cycle
Of temperatures.
235
00:14:26,724 --> 00:14:29,379
Once the driver comes out
Of the oven and cools,
236
00:14:29,379 --> 00:14:31,517
They glue strips
Of sound-dampening foam
237
00:14:31,517 --> 00:14:33,103
To the inside,
238
00:14:33,103 --> 00:14:36,862
Sealing the gaps between
The carbon fiber strips.
239
00:14:36,862 --> 00:14:39,448
This prevents sound
From radiating inward
240
00:14:39,448 --> 00:14:41,344
Rather than out the speaker.
241
00:14:43,551 --> 00:14:44,655
They solder the cables
242
00:14:44,655 --> 00:14:46,586
That bring the incoming
Electrical signal
243
00:14:46,586 --> 00:14:50,137
That carries
The sound frequencies.
244
00:14:50,137 --> 00:14:52,379
That signal moves
The voice coil up
245
00:14:52,379 --> 00:14:55,827
While the driver's magnet
Moves it back down.
246
00:14:55,827 --> 00:14:57,724
The repeated up and down motion
247
00:14:57,724 --> 00:15:00,379
Flexes the carbon fiber strips,
248
00:15:00,379 --> 00:15:03,620
Radiating the sound frequencies.
249
00:15:03,620 --> 00:15:06,413
After installing a center rod
Made of carbon,
250
00:15:06,413 --> 00:15:09,068
Workers stuff the hollow space
Inside the driver
251
00:15:09,068 --> 00:15:12,000
With sound-dampening wool.
252
00:15:12,000 --> 00:15:13,344
They pour lubricating oil
253
00:15:13,344 --> 00:15:16,103
Into a narrow gap
In the driver's magnet,
254
00:15:16,103 --> 00:15:19,620
Then insert the voice coil
Into the gap.
255
00:15:19,620 --> 00:15:21,344
The oil contains iron,
256
00:15:21,344 --> 00:15:24,310
So it conducts the electrical
Signal to the coil.
257
00:15:26,896 --> 00:15:28,517
They screw an aluminum
Mounting plate
258
00:15:28,517 --> 00:15:30,413
To the magnet's posts...
259
00:15:32,862 --> 00:15:36,275
...Then apply a disk of a stiff
Sound-dampening material.
260
00:15:39,758 --> 00:15:43,000
They install the tweeter's
Magnet on the mounting plate,
261
00:15:43,000 --> 00:15:44,931
Feeding the tweeter's
Electrical cables,
262
00:15:44,931 --> 00:15:48,172
Not yet soldered to the tweeter,
Through the center rod.
263
00:15:50,793 --> 00:15:52,827
Next they'll make the woofers.
264
00:16:04,724 --> 00:16:07,758
Narrator:
The sound system's amplifier
Delivers the electrical signal
265
00:16:07,758 --> 00:16:10,310
That carries all
The sound frequencies.
266
00:16:10,310 --> 00:16:12,482
Inside each main system speaker,
267
00:16:12,482 --> 00:16:14,793
An electronic component
Called the crossover
268
00:16:14,793 --> 00:16:16,620
Separates the frequency ranges
269
00:16:16,620 --> 00:16:19,241
And sends them,
Via designated cables,
270
00:16:19,241 --> 00:16:21,103
To the appropriate driver.
271
00:16:24,379 --> 00:16:26,206
They make each
Melon-shaped woofer
272
00:16:26,206 --> 00:16:28,620
Out of 12 aluminum segments.
273
00:16:28,620 --> 00:16:31,413
They glue acoustic foam
To each segment,
274
00:16:31,413 --> 00:16:34,172
Then trim the foam
To the shape of the aluminum.
275
00:16:36,620 --> 00:16:38,793
Workers assemble the woofer
Upside-down
276
00:16:38,793 --> 00:16:41,275
In an assembly fixture.
277
00:16:41,275 --> 00:16:42,724
They glue the segments
Vertically
278
00:16:42,724 --> 00:16:44,586
Between this woofer's
Voice coil,
279
00:16:44,586 --> 00:16:46,448
Which has two cables
Attached to it
280
00:16:46,448 --> 00:16:49,241
And a mounting plate.
281
00:16:49,241 --> 00:16:50,517
The structural rod
282
00:16:50,517 --> 00:16:52,517
Through which they'll feed
The other driver's cables
283
00:16:52,517 --> 00:16:53,931
Is in the center.
284
00:16:59,206 --> 00:17:01,965
Once all the segments
Are aligned and fixed in place,
285
00:17:01,965 --> 00:17:04,000
They coat the edges with glue.
286
00:17:06,965 --> 00:17:10,413
Then they adhere rubber gaskets
In between the segments
287
00:17:10,413 --> 00:17:13,206
To block the gaps
And prevent air from exiting.
288
00:17:19,896 --> 00:17:22,655
They seat copper strips
In the segment's grooves,
289
00:17:22,655 --> 00:17:27,310
Hooking the ends into holes
At the top and bottom.
290
00:17:27,310 --> 00:17:30,689
Brass, aluminum, copper --
Every type of material used
291
00:17:30,689 --> 00:17:34,965
In these speakers has specific
Acoustical properties.
292
00:17:34,965 --> 00:17:38,586
The combination produces
A natural sound balance.
293
00:17:41,000 --> 00:17:42,965
They fill the hollow
Interior space
294
00:17:42,965 --> 00:17:47,137
Around the center rod
With sound-dampening material.
295
00:17:47,137 --> 00:17:49,206
First, synthetic insulating wool
296
00:17:49,206 --> 00:17:51,689
With long, coarse fibers.
297
00:17:51,689 --> 00:17:53,206
Then, on top of that,
298
00:17:53,206 --> 00:17:55,448
A barrier
Of cotton-insulating wool
299
00:17:55,448 --> 00:17:57,000
To prevent those coarse fibers
300
00:17:57,000 --> 00:17:58,793
From touching the voice coil.
301
00:18:01,172 --> 00:18:03,517
Next, they install
The painted brass ring
302
00:18:03,517 --> 00:18:04,896
They milled earlier,
303
00:18:04,896 --> 00:18:09,344
Which now has the woofer's
Magnet fixed to it.
304
00:18:09,344 --> 00:18:13,413
They place a spacer,
Thread a screw,
305
00:18:13,413 --> 00:18:16,655
Pull the voice coil's two
Cables through the center,
306
00:18:16,655 --> 00:18:18,206
Then solder those cables,
307
00:18:18,206 --> 00:18:20,379
Together with the cables
From the other drivers,
308
00:18:20,379 --> 00:18:23,551
To a main cable that will plug
Into the crossover.
309
00:18:27,551 --> 00:18:29,482
They flip the woofer
Right side up
310
00:18:29,482 --> 00:18:31,586
And pour a liquid
Sound-dampening compound
311
00:18:31,586 --> 00:18:34,551
Into the center rod.
312
00:18:34,551 --> 00:18:36,448
The cables inside
Are too delicate
313
00:18:36,448 --> 00:18:38,482
To be shoving in
Insulating wool.
314
00:18:40,931 --> 00:18:43,793
Workers now begin
Assembling the speaker,
315
00:18:43,793 --> 00:18:46,862
First soldering the two
Remaining crossover cables,
316
00:18:46,862 --> 00:18:48,551
Mid-range and high frequency,
317
00:18:48,551 --> 00:18:51,724
To the respective driver cables.
318
00:18:51,724 --> 00:18:53,068
The tweeter connection cables
319
00:18:53,068 --> 00:18:55,103
Are attached
To the tweeter magnet,
320
00:18:55,103 --> 00:18:58,586
Installed earlier on top
Of the mid-range driver.
321
00:18:58,586 --> 00:19:03,103
They now mount this unit
On top of the woofer.
322
00:19:03,103 --> 00:19:06,172
They install the connectors
In the crossover.
323
00:19:06,172 --> 00:19:09,172
Its electrical components
Separate the frequency ranges
324
00:19:09,172 --> 00:19:12,896
And send each one
To a designated connector,
325
00:19:12,896 --> 00:19:14,068
Which sends it to the cable
326
00:19:14,068 --> 00:19:17,241
Leading to
The appropriate driver.
327
00:19:17,241 --> 00:19:20,172
After sliding the crossover
Onto the speaker's base,
328
00:19:20,172 --> 00:19:21,896
Made of milled brass,
329
00:19:21,896 --> 00:19:24,758
They close up the top
With the mounting plates,
330
00:19:24,758 --> 00:19:26,689
Between which they've
Since sandwiched
331
00:19:26,689 --> 00:19:28,931
A thick piece of wood.
332
00:19:28,931 --> 00:19:31,034
Screw-in stainless steel
Support posts
333
00:19:31,034 --> 00:19:32,517
Hold everything together
334
00:19:32,517 --> 00:19:34,689
And direct all the weight
Down to the floor,
335
00:19:34,689 --> 00:19:37,103
Rather than into
The speaker structure.
336
00:19:40,000 --> 00:19:42,068
They install
An aluminum crossbar
337
00:19:42,068 --> 00:19:44,241
For structural support,
338
00:19:44,241 --> 00:19:46,724
Then a second set of posts.
339
00:19:49,862 --> 00:19:52,137
They fit the ring
At the base of the woofer
340
00:19:52,137 --> 00:19:55,689
Into the mounting plate hole,
Securing it with screws.
341
00:19:58,931 --> 00:20:01,931
They insert the tweeter's voice
Coil into the tweeter magnet
342
00:20:01,931 --> 00:20:04,827
That's mounted on top
Of the mid-range driver
343
00:20:04,827 --> 00:20:07,379
That's mounted
On top of the woofer.
344
00:20:07,379 --> 00:20:09,034
They solder the tweeter cables
345
00:20:09,034 --> 00:20:12,517
To the two connectors
On the tweeter cover plate.
346
00:20:12,517 --> 00:20:16,586
This completes
The lower trio of drivers.
347
00:20:16,586 --> 00:20:19,068
Now they install
An identical upper trio,
348
00:20:19,068 --> 00:20:20,586
But upside-down
349
00:20:20,586 --> 00:20:22,689
So that the two tweeters
Face each other
350
00:20:22,689 --> 00:20:25,482
In the middle of the tower.
351
00:20:25,482 --> 00:20:28,172
They mount the crossover
For the upper trio
352
00:20:28,172 --> 00:20:31,034
And plug in the connector
That joins the three cables.
353
00:20:31,034 --> 00:20:32,862
That brings
The correct frequencies
354
00:20:32,862 --> 00:20:36,103
To the three drivers.
355
00:20:36,103 --> 00:20:39,862
They run test tones
Through every completed speaker.
356
00:20:39,862 --> 00:20:42,620
A microphone positioned
Just over three feet away
357
00:20:42,620 --> 00:20:44,655
Picks up
The emitted frequencies,
358
00:20:44,655 --> 00:20:47,310
Which a computer
Analyzes for accuracy.
359
00:20:50,068 --> 00:20:52,344
Once the speaker
Passes inspection,
360
00:20:52,344 --> 00:20:55,896
They install a decorative grill
Over each woofer voice coil.
361
00:20:59,068 --> 00:21:02,931
The subwoofer tower radiates
The lowest frequencies,
362
00:21:02,931 --> 00:21:06,448
With six huge drivers
And a built-in amplifier.
28385
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