Speaker 1: Welcome to tech Stuff, a production from I Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host
Speaker 1: job in Strickland. I'm an executive producer with I Heart
Speaker 1: Radio and How the Tech are You? I am working
Speaker 1: right now on a couple of things. When I'm working
Speaker 1: on getting over COVID, I'm almost there, not quite there,
Speaker 1: but I'm getting there. And the other thing I'm working
Speaker 1: on is an episode about a company called San Sui
Speaker 1: that is a or was rather a company that made
Speaker 1: audio equipment like amplifiers and receivers and stuff like that.
Speaker 1: But as I was doing it, I felt like I
Speaker 1: was retreading some ground on a on a previous episode
Speaker 1: called how Speakers and Amplifiers Work? And I thought, why
Speaker 1: not have that episode play out? And then next week's
Speaker 1: Monday's episode will be about San Sui, and I won't
Speaker 1: have to to cover quite as much of the same
Speaker 1: territory again. I can focus more on the company in
Speaker 1: its history because y'all know me. Y'all know that if
Speaker 1: I start talking about a company that makes a certain
Speaker 1: kind of tech or sort of a product that features
Speaker 1: certain tech, I'll end up talking about how the tech
Speaker 1: came about what it does all that kind of stuff,
Speaker 1: but I've already done that. So we're gonna listen to
Speaker 1: this episode how speakers and amplifiers work, and I'll be
Speaker 1: back at the end to kind of tease next week's
Speaker 1: episode on this topic. But sit back and enjoy this
Speaker 1: classic episode. Today we are going to continue our episodes
Speaker 1: about how speakers work and how they are able to
Speaker 1: take electricity and make those sweet, sweet sounds for your
Speaker 1: ear holes. So let us jump back with a quick
Speaker 1: explanation of the electro magna at is um. So, electricity
Speaker 1: and magnetism are very closely related, and you've likely done
Speaker 1: the simple physics exercise of creating a basic electro magnet.
Speaker 1: So you'll take something like an iron nail and you'll
Speaker 1: wrap insulated copper wire in a coil around the nails
Speaker 1: several times. The nail acts as a ferromagnetic core. The
Speaker 1: copper wire coil is a conductor, so connecting the ends
Speaker 1: of the copper wire to a battery will then allow
Speaker 1: current to flow through the wire. Middle flow from one
Speaker 1: end of the battery through the wire down into the
Speaker 1: other end of the battery. As it goes around this coil,
Speaker 1: the flow of electricity creates a magnetic field, the nail
Speaker 1: and coil will behave like a permanent magnet. Would it's
Speaker 1: an electro magnet, but it will behave like a permanent
Speaker 1: magnet with a north pole and a south pole. And
Speaker 1: if you brought it close to a permanent magnet, then
Speaker 1: the opposite poles would attract each other and the similar
Speaker 1: poles would repel each other. So if you brought the
Speaker 1: electromagnets more poll next to a permanent magnets north pole,
Speaker 1: it would push that other magnet away and the polls
Speaker 1: will not change. Because the source of electricity is a battery,
Speaker 1: and batteries provide direct current, which means the current is
Speaker 1: always going to flow in the same direction. It's never
Speaker 1: going to reverse. But if you hooked the same nail
Speaker 1: and coil up to a source of alternating current, things
Speaker 1: would be very different. With alternating current, the direction of
Speaker 1: the flow of electricity changes rapidly every second, and as
Speaker 1: the direction of electricity changes, it affects the magnetic field.
Speaker 1: With electricity flowing in one direction, the head of the
Speaker 1: nail might represent the north pole of the magnet, and
Speaker 1: when the electricity switches to the other direction, the head
Speaker 1: of the nail will become the south pole of the magnet,
Speaker 1: and vice versa. You have created a fluctuating magnetic field
Speaker 1: by running an alternating current through an electro magnet, and
Speaker 1: you can do some pretty cool stuff with a fluctuating
Speaker 1: magnetic field. For example, if you bring this apparatus close
Speaker 1: to a conductive material, you'll induce a change of voltage
Speaker 1: in that material, even without making physical contact between the two.
Speaker 1: So if you do this with a stable magnetic field,
Speaker 1: all you'll do is see a very short spike, but
Speaker 1: then it stops because the magnetic field is not fluctuating.
Speaker 1: To induce electricity to flow by changing voltage in this
Speaker 1: other conductor, the magnetic field has to be fluctuating, or
Speaker 1: the conductor has to be moving in and out of
Speaker 1: the magnetic field constantly. If you get two coils of
Speaker 1: copper wire and you make sure the second copper wire
Speaker 1: has twice as many coils as the first one, you
Speaker 1: can create a transformer. So imagine you've got your first
Speaker 1: coil of wire. Let's say it's got ten coils ten
Speaker 1: ten loops around its core, and you've got a second
Speaker 1: core with copper wire, but there are twenty loops around
Speaker 1: the second core if you run a current through the
Speaker 1: first coil, it will induce current to flow through the
Speaker 1: second coil. Moreover, the voltage in the second coil will
Speaker 1: be higher than the voltage in the first coil because
Speaker 1: the second coil has twice as many coils as the
Speaker 1: first one. So the more times you loop a wire
Speaker 1: around a core, the greater the change of voltage is
Speaker 1: going to be between coil number one and coil number two.
Speaker 1: This particular version of a transformer would be called a
Speaker 1: step up transformer because the secondary coil has more turns
Speaker 1: than the primary coil and steps up the voltage. If
Speaker 1: the opposite were true, if coil number one had ten
Speaker 1: coils or ten loops and coil number two had five loops,
Speaker 1: then that would be a step down transformer. You would
Speaker 1: lower the voltage from primary to secondary. Transformers are what
Speaker 1: made alternating current the more viable solution to supplying electricity
Speaker 1: to homes and businesses back in the early days. Because
Speaker 1: transmitting electricity was all about efficiency. How could you efficiently
Speaker 1: get electricity from a power plant to where it needed
Speaker 1: to be well? If you used alternating current, you could
Speaker 1: create transformers and you could step up the voltage to
Speaker 1: very high levels, and that meant that you could transmit
Speaker 1: power across power lines much more efficiently. If you didn't
Speaker 1: do that, you had so much power loss that you
Speaker 1: would have to have lots of different power generators throughout
Speaker 1: the region in order to supply all the power needs
Speaker 1: of your area, at least back in the old days
Speaker 1: of direct current, because it wasn't easy to step up
Speaker 1: the voltage. And again, high voltage makes it more efficient
Speaker 1: to transmit power across long distances, so in the early days,
Speaker 1: that's why a C went out over d C. These days,
Speaker 1: you could actually do things a little differently if you
Speaker 1: wanted to, and you could go with direct DC power
Speaker 1: if you really wanted to, but it would require a
Speaker 1: big overhaul of the infrastructure. But transformers made a C
Speaker 1: much more practical anyway. Electromagnets are pretty awesome now. With speakers,
Speaker 1: it's not so much about voltage and current as it
Speaker 1: is about making the diaphragm of the speaker move in
Speaker 1: precise ways. With speakers, the electrical current acts as both
Speaker 1: the carrier of information and the means to make the
Speaker 1: diaphragm move. So you start with a steady magnetic field
Speaker 1: inside the basket You can create that steady magnetic field
Speaker 1: either with permanent magnets like I mentioned before, or with
Speaker 1: electro magnets, but it remains the same no matter what.
Speaker 1: The north pole is always going to be the north pole.
Speaker 1: The south pole is always going to be the south pole.
Speaker 1: Inside the frame, that field does not change. The voice
Speaker 1: coil on the cone ends up receiving the variable current
Speaker 1: that came from the transmitter that represents the recorded sound. Now,
Speaker 1: remember the way we record sound, as we typically will
Speaker 1: something like a microphone, and a microphone is essentially a
Speaker 1: speaker in reverse. A microphone has a diaphragm in it
Speaker 1: that vibrates in the presence of sound waves. Those vibrations
Speaker 1: cause fluctuations inside an electric current. You might vary the
Speaker 1: resistance of the circuit, as we talked about with the
Speaker 1: the old Johan Philip Rice approach, and by varying those
Speaker 1: that electric resistance within the circuit, you can fluctuate the
Speaker 1: electric current and then you can send that to a speaker,
Speaker 1: though you would typically send it to an amplifier first,
Speaker 1: but we'll talk about that in a minute. The speaker
Speaker 1: then essentially reverses this process. It takes those fluctuations sends
Speaker 1: them through an electro magnet, which will generate a variable
Speaker 1: magnetic field in response, which then makes the cone vibrate
Speaker 1: within the speaker and essentially do the opposite of what
Speaker 1: the microphones diaphragm was doing and recreate the recorded sound.
Speaker 1: It's pretty cool and pretty elegant, really. So the electrical
Speaker 1: signal representing the recorded sound comes into the speaker, feeds
Speaker 1: into the voice coil creates this fluctuating magnetic field. The
Speaker 1: field interacts with the permanent magnetic field inside the basket,
Speaker 1: either pulling the diaphragm forward in the basket and us
Speaker 1: pushing air outward, or pulling the cone back towards the
Speaker 1: back of the basket and allowing air to come further
Speaker 1: in by creating that lower pressure. And these fluctuations happen
Speaker 1: at high frequencies, so the diaphragm is moving very rapidly
Speaker 1: inside the basket. It's not just pushing out then pulling in.
Speaker 1: It's doing this hundreds or thousands of times per second,
Speaker 1: and it increases or decreases the air pressure as the
Speaker 1: cone pushes those air molecules or suddenly moves away, creating
Speaker 1: more space for them. And because sound is vibration. Those
Speaker 1: air molecules carry the sound up to our ears, and
Speaker 1: then we rock out to a C d C or
Speaker 1: whatever band you happen to like. That isn't nearly as
Speaker 1: cool as a C d C. Now, keep in mind
Speaker 1: what I have described is how a driver works. A
Speaker 1: speaker can and often does have more than one driver,
Speaker 1: and drivers come in different shapes, sizes, and purposes. So
Speaker 1: let's talk a little bit about what those are and
Speaker 1: what they do, and why you need to have different
Speaker 1: ones in the first place. Actually, that last question is
Speaker 1: the easiest answer right away. Remember again, sound is vibration,
Speaker 1: and low frequency sounds have longer wave forms. The points
Speaker 1: of high and low pressure are further apart from each
Speaker 1: other than with high frequency sounds. If you could actually
Speaker 1: see the changes in air pressure due to sound, you
Speaker 1: would see that the low frequency sounds have these larger
Speaker 1: gaps between the high and low pressure points in the
Speaker 1: waves as they move out from the source of sound.
Speaker 1: So you need a cone diaphragm that can vibrate at
Speaker 1: a slower frequency and push air effectively at that speed.
Speaker 1: For that reason, you would typically go with a heavier,
Speaker 1: larger diaphragm, both because the wavelengths of sound are longer
Speaker 1: if you're looking at the lower frequencies, and because making
Speaker 1: the material heavy gives it greater inertia, it takes more
Speaker 1: force to move of the diaphragm, and it will move
Speaker 1: at a pace that will reproduce as low frequency sounds
Speaker 1: you want. This type of speaker falls into the whooffer
Speaker 1: or sub whiffer categories. These are the speakers that create
Speaker 1: the base sounds. A sub whiffer tends to handle frequencies
Speaker 1: from around twenty hurts to two hurts. Think of a
Speaker 1: hurts as how long it takes a wave to pass
Speaker 1: through a given point in one second, or how many
Speaker 1: waves can pass through a given point in one second.
Speaker 1: Al Right, guys, we got some more to chat about
Speaker 1: with speakers. Before I jump into that, Let's take a
Speaker 1: quick break to thank our sponsor. Human hearing ranges from
Speaker 1: twenty hurts, which is twenty waves passing a given point
Speaker 1: in one second, to twenty killer hurts or twenty thousand
Speaker 1: waves passing through a point in one second. This really
Speaker 1: tells you more about the wavelength of the wave itself
Speaker 1: and thus the frequency and then the pitch. Remember, the
Speaker 1: lower frequencies are the lower pitches. The higher frequencies are
Speaker 1: the higher pitches, and that's the frequency range for typical
Speaker 1: human hearing twenty hurts to twenty thousand hurts. Now, I
Speaker 1: can tell you from my experience using a frequency sweeper,
Speaker 1: which will slowly go through a selection of frequencies that
Speaker 1: is all set at the same volume, so you get
Speaker 1: a standard volume across all of them, that while I
Speaker 1: can technically hear stuff at twenty hurts, it's not until
Speaker 1: you hit a frequency of about fifty hurts that it
Speaker 1: quote unquote sounds loud to me, even though actual volume
Speaker 1: of the two tones remains the same, so the amplitude
Speaker 1: is exactly the same, But until you get to a
Speaker 1: frequency of about fifty hurts, it just doesn't sound loud
Speaker 1: to me because my ears are not great at picking
Speaker 1: up those lower, super low frequencies. Also, I should mention
Speaker 1: that while sound waves come in different frequencies, sound itself
Speaker 1: travels at a speed that is dependent upon the medium
Speaker 1: through which it travels. So, in other words, low frequency
Speaker 1: sounds and high frequency sounds travel at the same speed
Speaker 1: through the same medium. Otherwise you would have all the
Speaker 1: high pitched sounds hitting your ears before the low pitched
Speaker 1: ones and conducting an orchestra would drive you crazy. The
Speaker 1: speed of sound is defined as the distance traveled by
Speaker 1: a sound wave in a certain unit of time. But hey, Jonathan,
Speaker 1: some of you might be saying you were just talking
Speaker 1: about frequencies. If a high frequency sound has twenty sound
Speaker 1: waves pass a certain point in the second, and a
Speaker 1: low frequency sound has twenty waves passing that same point
Speaker 1: in the second, are they traveling at different speeds? No,
Speaker 1: they're not. This is easier to imagine if we take
Speaker 1: an analogy. So let's say you're standing on the side
Speaker 1: of the road. Every single vehicle going past you on
Speaker 1: this one way road is traveling at a smooth twenty
Speaker 1: miles per hour or about thirty two kilometers per hour
Speaker 1: if you prefer. But they're all going that speed. Doesn't
Speaker 1: matter what kind of card is, they're all going exactly
Speaker 1: twenty miles or thirty two kilometers per hour. Some of
Speaker 1: these vehicles are very tiny, little smart cars. Some of
Speaker 1: them are super long extended buses, but they're all traveling
Speaker 1: at that same speed. So even though they're going at
Speaker 1: the same speed, the buses take more time to pass
Speaker 1: you than the smart cars do because the buses are longer.
Speaker 1: In the time it takes one super long bus to
Speaker 1: go buy you, like the front passes you and you
Speaker 1: time it out. Maybe for smart cars could go buy
Speaker 1: you and that same amount of time, even though they're
Speaker 1: all going at twenty miles. The same is true with
Speaker 1: sound waves, so we're not just talking about speed but wavelength.
Speaker 1: So low frequency sounds and high frequency sounds are traveling
Speaker 1: at the same speed. It's just you can fit more
Speaker 1: of the waves in at that time than others because
Speaker 1: of the length. All right back to the speed of sound. Now,
Speaker 1: I cannot give you a standard speed of sound for
Speaker 1: all occasions because the speed of sound depends on a
Speaker 1: lot of little things, For example, how much moisture is
Speaker 1: in the air or how cold is the air. Sound
Speaker 1: passes through the air, and air is made up of gases,
Speaker 1: and gases are made up of molecules. So as you
Speaker 1: heat up a gas, the molecules move apart from each
Speaker 1: other and they bounce around more. They're more able to move.
Speaker 1: As gas is cool, the molecules pack around together and
Speaker 1: they move around less, so they get more tightly packed.
Speaker 1: So a cold gas will transmit sound at a slightly
Speaker 1: slower speed than a warm gas will. If the temperature
Speaker 1: outside is sixty eight degrees fahrenheit or about twenties celsius
Speaker 1: and the air is dry, sound will travel at one
Speaker 1: thousand per second or three forty three per second. And
Speaker 1: it doesn't matter what frequency sound waves you're working with,
Speaker 1: that's the speed they're going to travel at. And again,
Speaker 1: at different temperatures and there are different media, sound will
Speaker 1: travel at a different speed. All right. Now, let's go
Speaker 1: back to the different types of drivers. After you handled
Speaker 1: the sub whoffers and the whoofers, well, the whoffers will
Speaker 1: still handle lower frequencies, but subwhiffers are are specialized whoffers,
Speaker 1: largely because they will frequently be paired with special circuits
Speaker 1: and cabinets dedicated to creating those very very low frequencies
Speaker 1: in an effort to produce a specific quality of sound,
Speaker 1: such as let's say you're watching an action film and
Speaker 1: something done blowed up real good. You want to have
Speaker 1: that rumbly low base for those moments, you know, the
Speaker 1: kind where you can actually feel it because it's vibrating
Speaker 1: the chair and the air around you, and so it's
Speaker 1: it's that kind of rumble you can feel in your chest. Well,
Speaker 1: that frequently means you need a dedicated subwhoffer unit that
Speaker 1: has its own power supply to generate the vibrations with
Speaker 1: enough force necessary to create that effect. So it's not
Speaker 1: just the speed but how hard it's pushing. After subwhiffers
Speaker 1: and whoffers, you've got mid range drivers or mid range speakers,
Speaker 1: and as the name suggests, these drivers are responsible for
Speaker 1: producing sounds in the middle range frequencies of human hearing.
Speaker 1: A typical range might include two fifty hurts to two
Speaker 1: thousand hurts. You may have also the term squawker when
Speaker 1: referencing mid range speakers. They're made of lighter materials and
Speaker 1: they can vibrate at higher frequencies than whiffers and subwhiffers,
Speaker 1: which is necessary to create those mid range tones. And
Speaker 1: then you have tweeter speakers. These are made of the
Speaker 1: lightest weight material and they vibrate the fastest in an
Speaker 1: effort to reproduce frequencies on the upper levels of human hearing,
Speaker 1: which tends to be between two thousand and twenty thousand
Speaker 1: hurts at least for consumer speakers. There are tweeters that
Speaker 1: can be made for special purposes that can generate sound
Speaker 1: frequencies well above the range of human hearing, some of
Speaker 1: them as high up as a hundred kill hurts or
Speaker 1: one hundred thousand hurts. That's five times higher than the
Speaker 1: highest frequency the average human is capable of perceiving. So
Speaker 1: why would you want a tweeter that could go beyond
Speaker 1: the range of human hearing. Well, you might use it
Speaker 1: for scientific research purposes, like finding out what high high
Speaker 1: high pitches the ultrasonic pitches might due to affect animal behavior.
Speaker 1: So you might be able to do that to learn
Speaker 1: how high a pitch a dog might be able to hear,
Speaker 1: for example, because dogs can hear at a different range
Speaker 1: than humans can. Or you might want to do experiments
Speaker 1: to see if those imperceptible frequencies have an effect on
Speaker 1: the sounds we can here. So there are audio files
Speaker 1: who insist that frequencies beyond the human range of hearing
Speaker 1: can change the quality of the sounds that we do here,
Speaker 1: and thus it's imperative to get a sound system and
Speaker 1: a type of media capable of reproducing sound frequencies at
Speaker 1: every level if you want a true reproduction of an
Speaker 1: original sounds quality. This falls into the realm of psychoacoustics
Speaker 1: the study of sound perception. Because hearing involves processes in
Speaker 1: the brain, there is a subjective component to it that
Speaker 1: cannot be easily described through physics. We can talk all
Speaker 1: about the physics of sound waves and sound propagation, but ultimately,
Speaker 1: when it comes to the way we experience sound, we
Speaker 1: have to take gray matter into account, and that gets
Speaker 1: tricky since our experience of perceiving sound can depend upon
Speaker 1: other things unrelated to the actual physics of the sound itself.
Speaker 1: For example, if I were to tell you that I
Speaker 1: have a sound system, and I've set it up and
Speaker 1: it consists of the most expensive and most technologically advanced components,
Speaker 1: and the media that was going to play represented the
Speaker 1: most true reproduction of an actual sound, that might be
Speaker 1: enough to influence your perception of the sound. Even if
Speaker 1: what I was really using was just good equipment, not
Speaker 1: the best, but just good stuff. Even if all all
Speaker 1: that stuff I told you wasn't true, your perception of
Speaker 1: sound might make it seem like you're listening to the
Speaker 1: most perfect reproduction of the original performance as could be attained.
Speaker 1: Or if I did play a sound back on what
Speaker 1: really was an amazing sound system, but Before I did it,
Speaker 1: I made a whole bunch of apologies for how the
Speaker 1: system I was using could not faithfully represent high tones,
Speaker 1: or had a very weak base output, or something like that.
Speaker 1: You might perceive the playback as fall lewing these trends
Speaker 1: that I had mentioned, even if scientific recording instruments were
Speaker 1: to show that the playback didn't suffer from those problems
Speaker 1: at all. All that being said, the psychological aspect of
Speaker 1: how we perceive sound does have limitations. No amount of
Speaker 1: snake oil salesmanship is going to convince you that a
Speaker 1: truly subpar stereo system is capable of reproducing the glory
Speaker 1: of the Philharmonic Orchestra, for example. But because there is
Speaker 1: the subjective element and how we perceive sound, there's the
Speaker 1: opportunity to exploit that element and make a lot of
Speaker 1: money in the process. I've talked before about how certain
Speaker 1: manufacturers have used this to market high end audio equipment,
Speaker 1: and some of that has little to no scientific evidence
Speaker 1: to back up the claims that they make about those gadgets,
Speaker 1: and yet they're able to set exorbitant prices for components
Speaker 1: that audio files will cover it because they're always in
Speaker 1: a quest to get that perfect representation of a sound. Uh,
Speaker 1: so this stuff does happen. I also covered this when
Speaker 1: I talked about MP three compression, because if you remember
Speaker 1: an MP threes, part of the compression strategy is to
Speaker 1: take all the different parts of a sound that we
Speaker 1: humans typically don't notice, and you just cut them. You
Speaker 1: get rid of them, because that way you cut down
Speaker 1: on the size of the sound file. The strategy is,
Speaker 1: if you can't perceive it, then we don't need it
Speaker 1: in the information. We can just cut it that. Audio
Speaker 1: files say no, if you do that, it affects the
Speaker 1: stuff that we can here, and thus you are changing
Speaker 1: the nature of the audio recording. Just because you couldn't
Speaker 1: hear the thing doesn't mean the thing wasn't doing something else.
Speaker 1: I think the jury is still out on that in
Speaker 1: a large part. I mean, there are some legitimate arguments
Speaker 1: to make about harmonics and things that do come into play,
Speaker 1: but I'm not sure it gets to the level of
Speaker 1: subtlety that a lot of audio files argue. At least
Speaker 1: I don't see the scientific evidence supporting it. That doesn't
Speaker 1: mean it's wrong, It just means I haven't seen the
Speaker 1: evidence supporting it. Anyway, As soon as we come back.
Speaker 1: I'm gonna go into talking about amplification and why that's important,
Speaker 1: but first let's take another quick break to thank our sponsor.
Speaker 1: All right. Now, Back when I was talking about the
Speaker 1: development of the loud speaker, I mentioned that Rice and
Speaker 1: Kellogg observed there needed to be advancements in amplification, and
Speaker 1: by that they meant there needed to be a way
Speaker 1: to boost the electrical signal from the risk the transmitter
Speaker 1: the microphone in order to give a speaker enough umph
Speaker 1: to vibrate at a force strong enough to play back
Speaker 1: the sounds at a suitable volume. Without amplifiers, the signal
Speaker 1: strength might only allow a speaker to play back a
Speaker 1: sound at a low volume, or if the signal is
Speaker 1: very weak, it might not even move the speaker significantly
Speaker 1: enough at all to create any real sound. The reason
Speaker 1: the signal tends to be weak goes back to the
Speaker 1: limitations we face when we record sound in the first place.
Speaker 1: So using the microphone effect, we transform sound into electrical
Speaker 1: signals by making the microphones diaphragm vibrate, mimicking the way
Speaker 1: our ear drums work. Right, So it's like we're speaking
Speaker 1: into someone's ear. When we talk into a microphone. Then
Speaker 1: we transform sound into electrical signals by making that microphone
Speaker 1: diaphragm vibrate, and those small vibrations introduce fluctuations into an
Speaker 1: electrical signal in some way. But for sound to affect
Speaker 1: the diaphragm at all, the diaphragm has to be very lightweight,
Speaker 1: very sensitive, and it has to make very small movements.
Speaker 1: Otherwise we'd have to make sound an enormous amplitudes or
Speaker 1: volume in order to generate the force necessary to vibrate
Speaker 1: the diaphragm. So it has to be very lightweight, very
Speaker 1: very sensitive, and it's moving in a very small distance,
Speaker 1: so it can only make tiny changes in electrical current
Speaker 1: or generate a very tiny electrical current. Now that's good
Speaker 1: enough for the purposes of recording the sound. You can
Speaker 1: do that. You can use that to record sound. It's
Speaker 1: fine because it can record at those tiny details. But
Speaker 1: if you want to play the sound back on a speaker,
Speaker 1: you have to boost that signal in order to drive
Speaker 1: the speakers to physically move them. You want to make
Speaker 1: the signal more powerful, but you also want to keep
Speaker 1: all the fluctuations of the signal, all the dynamics of
Speaker 1: the signal, So that way, you can represent when a
Speaker 1: song gets louder or more quiet, or when one element
Speaker 1: is taking over over another element. All of these things
Speaker 1: are very subtle, and you have to preserve that. So
Speaker 1: you want the signal not just to be boosted, but
Speaker 1: for all the different fluctuations of that signal to be
Speaker 1: represented in that boost. You want it all to be
Speaker 1: at the same relative strength as they were in the
Speaker 1: weaker signal. Now, an amplifier does this through the use
Speaker 1: of two separate circuits. The first circuit is the input circuit.
Speaker 1: That's the weaker of the two signals, that's the one
Speaker 1: that's coming from the microphone. The second circuit is your
Speaker 1: output circuit, which sends a stronger signal out to this speakers,
Speaker 1: and it draws upon the amplifier's power supply to boost
Speaker 1: the signal. So you have an amplifier, it has its
Speaker 1: own power supply. It's generating the signal that's going through
Speaker 1: this output circuit. The power going through the output circuit
Speaker 1: is a direct current, so it's flowing in a set direction.
Speaker 1: It does not change. If you have an amplifier and
Speaker 1: you've hooked it directly up to your house, is alternating
Speaker 1: current there's a power supply element inside the amplifier that
Speaker 1: converts it from alternating current to direct current. Now, think
Speaker 1: of the output circuit as always pushing a strong signal
Speaker 1: out towards the speakers. It's just most of the time
Speaker 1: this signal is not carrying any information. But when the
Speaker 1: amplifiers on, that's what's doing. It's pushing the strong signal
Speaker 1: out to the speakers. The input circuit's job is to
Speaker 1: use the original weak electrical signal as a way to
Speaker 1: vary the resistance in the output circuit, so the variable
Speaker 1: resistance recreates the voltage fluctuation in the original signal. So
Speaker 1: what you're doing is you've got this strong signal going out,
Speaker 1: use the weak signal to introduce the same fluctuations into
Speaker 1: the strong signal, and then the strong signal will reflect
Speaker 1: the weaker one. It will be exactly the same, except stronger.
Speaker 1: In the good old days, amplifiers relied upon vacuum tubes
Speaker 1: as an integral component, and in fact some amplifiers still do,
Speaker 1: particularly for stuff like professional electric guitar amplifiers. There are
Speaker 1: professional musicians who swear by vacuum tube amplifiers and they
Speaker 1: will not use anything else. Vacuum tubes are pretty interesting technology,
Speaker 1: and they date back to the early twentieth century. So
Speaker 1: let's talk about how they work for just a second. First,
Speaker 1: they look a lot like light bulbs, and in fact
Speaker 1: they operate very similar to light bulbs. They are glass tubes.
Speaker 1: Inside this glass tube is a filament like a light bulb.
Speaker 1: The filament inside uses electrical resistance to heat up. The
Speaker 1: filament either content aines or is somehow wrapped around a
Speaker 1: material like tungsten, which, when it's heated to very high temperatures,
Speaker 1: starts to boil off electrons. That would be the cathode
Speaker 1: of the vacuum tube. It's the source of electrons. The
Speaker 1: electrons accept only so much energy, and then after that
Speaker 1: they effectively jump ship. They're ready to burst off of
Speaker 1: the atoms that they were previously connected to. Now, also
Speaker 1: inside the vacuum tube is a plate that has a
Speaker 1: relative positive charge to it compared to the cathode. That's
Speaker 1: called the anode. The electrons are negatively charged, and so
Speaker 1: they're attracted to the positively charged anode, and the negative
Speaker 1: charged electrons flow towards the positively charged anode. Now, if
Speaker 1: this were all, there were to a vacuum tube, it
Speaker 1: would just be a diode. That means it would be
Speaker 1: an element in a circuit that would allow electricity to
Speaker 1: pass one way from the cathode to anode, but not
Speaker 1: back the other way. However, there's a third element, and
Speaker 1: that's what creates the amplification sho effect. That element is
Speaker 1: a grid of spiral wires or a mesh material. The
Speaker 1: acts as a sort of control grid or cage between
Speaker 1: the cathode and the anode, so it essentially surrounds the cathode. Now,
Speaker 1: if you apply a voltage to this control grid that
Speaker 1: is lower than the cathode itself, it reduces the amount
Speaker 1: of current passing from cathode to anode. By placing a
Speaker 1: large positive voltage on the plate and then feeding a
Speaker 1: signal to the control grid, you can affect the voltage
Speaker 1: across the load on the circuit. So you make tiny
Speaker 1: changes in the control grid's voltage and you get a
Speaker 1: much larger change across the load of the circuit amplifying
Speaker 1: the signal. So again, you you put a large positive
Speaker 1: voltage on this plate, you feed the input signal into
Speaker 1: the the control grid, and then you amplify that signal
Speaker 1: across the entire load, and that load would it typically
Speaker 1: involve speakers or an amplifier or These days most amplifiers
Speaker 1: do not use vacuum tubes. Instead, we use solid state transistors.
Speaker 1: To describe all those transistors work gets a little complicated,
Speaker 1: but in general, and basic transistor has three components. You've
Speaker 1: got an emitter, a base, and a collector. The emitter
Speaker 1: and the collector are both in type UH semiconductors, meaning
Speaker 1: that they have more electrons. They have a surplus of
Speaker 1: electrons there. You can think of it almost like a
Speaker 1: negative charge. The base is a P type semiconductor. It's
Speaker 1: sandwiched between the emitter and the collector. It has what
Speaker 1: would we would call a positive charge or holes for electrons.
Speaker 1: Feeding the input current between the emitter and the base
Speaker 1: creates a much larger output current between the emitter and
Speaker 1: the collector, thus amplifying the signal. Now, the output signal
Speaker 1: should ideally match the input signal exactly, except again everything
Speaker 1: is just bigger as an amplified and that signal would
Speaker 1: be strong enough to do the work of moving those
Speaker 1: speaker diaphragms and generating the sounds we enjoy. Well, I
Speaker 1: hope you enjoyed health speakers and amplifiers work. Like I said,
Speaker 1: next week we're going to have the story of San
Speaker 1: Sui and it's rise and fall and what the company
Speaker 1: did and UH the various products that it produced and
Speaker 1: why they were important. Why certain audio files to this day,
Speaker 1: we'll seek out San Sui UH components like receivers in particular,
Speaker 1: there's certain receivers that are highly prized among audio files.
Speaker 1: Even though spoiler alert, this company doesn't exist anymore. So
Speaker 1: that will be next week's episode. But I'm glad that
Speaker 1: I did this so that way you know, I'm not
Speaker 1: just repeating something I've already done in the past. I
Speaker 1: know that can be very frustrating, and due to my
Speaker 1: terrible memory, it happens pretty frequently without me even being
Speaker 1: aware of it. So I hope you enjoyed this episode.
Speaker 1: If you have suggestions for future topics, because San Sui
Speaker 1: is actually going to be that's a listener request. I'll
Speaker 1: talk about that more next week. So if you have
Speaker 1: a request, like if there's a specific topic in tech
Speaker 1: you want me to talk about. Maybe it's a particular company,
Speaker 1: a trend in technology of particular type of tech, and
Speaker 1: you want to know more about it, send me a message.
Speaker 1: I love getting those. It always gives me a great
Speaker 1: starting point to jump into some research, and the best
Speaker 1: way to do that is to send it over on Twitter.
Speaker 1: The handle for the show is tech Stuff hs W
Speaker 1: and I'll talk to you again really soon. Tech Stuff
Speaker 1: is an I Heart Radio production. For more podcasts from
Speaker 1: my Heart Radio, visit the i Heart Radio app, Apple Podcasts,
Speaker 1: or wherever you listen to your favorite shows.