Embedded Files
1. Welcome to course
1. Welcome to course
Cource "Multimedia Systems"
Cource "Multimedia Systems"
Volume of e-study course - 2 ECVETs
Volume of e-study course - 2 ECVETs
Course authors:
Course authors:
Māris Žugs, Sanita Eihmane
Māris Žugs, Sanita Eihmane
Rīgas Tehniskā koledža
Rīgas Tehniskā koledža
Priit Auväärt; Rita Pillisner
Priit Auväärt; Rita Pillisner
Pärnumaa Vocational Education Centre
Pärnumaa Vocational Education Centre
Authors Sanita Eihmane work titled "Multimedia Systems" is protected by the license Creative Commons Referring to the Author 3.0 Jurisdiction-free license
Authors Sanita Eihmane work titled "Multimedia Systems" is protected by the license Creative Commons Referring to the Author 3.0 Jurisdiction-free license
2.. Cource Introduction
2.. Cource Introduction
Every topic contains some important part of multimedia system. Please read all the materials and watch all the videos.
Every topic contains some important part of multimedia system. Please read all the materials and watch all the videos.
If you feel that you have learned all the materials, please perform self-tests and tasks. If you need any kind of help, please contact to your teacher.
If you feel that you have learned all the materials, please perform self-tests and tasks. If you need any kind of help, please contact to your teacher.
3. Basic theory - sound
3. Basic theory - sound
In-car entertainment has come a long way since 1930, when Motorola introduced the first commercially successful car radio, the Model 5T71. Over the past 80-plus years, car audio has evolved from the basic AM radio receiver with a single speaker to complex electronic systems reproducing music and other entertainment from both over-the-air signals and recorded formats. Many systems today can play music from a staggering array of audio sources: radio, CD. portable music players like the iPod, USB flash drives, SD cards, Bluetooth audio and hard-disk drives.
In-car entertainment has come a long way since 1930, when Motorola introduced the first commercially successful car radio, the Model 5T71. Over the past 80-plus years, car audio has evolved from the basic AM radio receiver with a single speaker to complex electronic systems reproducing music and other entertainment from both over-the-air signals and recorded formats. Many systems today can play music from a staggering array of audio sources: radio, CD. portable music players like the iPod, USB flash drives, SD cards, Bluetooth audio and hard-disk drives.
Decibel
Decibel
A decibel, or dB, is a measure of loudness or sound pressure. You have to increase output by 10 dB to double the volume of sound, something which requires a lot of lectricity — every 3 dB increase in volume requires double the power!
A decibel, or dB, is a measure of loudness or sound pressure. You have to increase output by 10 dB to double the volume of sound, something which requires a lot of lectricity — every 3 dB increase in volume requires double the power!
Why you need to know:
Why you need to know:
Audio quality often comes down to numbers, and dB output is one of the most important things to measure when selecting gear like amplifiers and tuning systems to perform their best.
Audio quality often comes down to numbers, and dB output is one of the most important things to measure when selecting gear like amplifiers and tuning systems to perform their best.
Hertz, Hz
Hertz, Hz
In audio, Hertz is the number of vibrations a speaker makes in a second, which tetermines the pitch of sound. The human ear can usually hear from 20 to 20,000 Hz.
In audio, Hertz is the number of vibrations a speaker makes in a second, which tetermines the pitch of sound. The human ear can usually hear from 20 to 20,000 Hz.
Need to know:
Need to know:
Every speaker has an optimal range, which can be useful to know when programming a digital sound processor or active crossover, setting equalizers levels, picking an amp, or making other adjustments.
Every speaker has an optimal range, which can be useful to know when programming a digital sound processor or active crossover, setting equalizers levels, picking an amp, or making other adjustments.
20Hz- very low (subbass) sound
20Hz- very low (subbass) sound
20000Hz- very high, bearly hearable sound.
20000Hz- very high, bearly hearable sound.
Peak Power
Peak Power
Peak Power is the operating limit for a speaker if the audio spikes above the RMS (see below).
Peak Power is the operating limit for a speaker if the audio spikes above the RMS (see below).
Why you need to know:
Why you need to know:
Matching numbers and limits will let you safely crank your tunes without the risk of blowing your speakers.
Matching numbers and limits will let you safely crank your tunes without the risk of blowing your speakers.
Root Mean Square (RMS)
Root Mean Square (RMS)
Every speaker comes with an RMS rating, which is how much continuous power they are built to handle.
Every speaker comes with an RMS rating, which is how much continuous power they are built to handle.
Why you need to know:
Why you need to know:
When matching amps and speakers, RMS numbers ensure you’ll get the best quality of sound at all volume levels. You won’t blow your speakers or under power them.
When matching amps and speakers, RMS numbers ensure you’ll get the best quality of sound at all volume levels. You won’t blow your speakers or under power them.
PRACTICAL TASK - take your family car sound system and describe that. (Powerpoint, 4-5 minutes)
PRACTICAL TASK - take your family car sound system and describe that. (Powerpoint, 4-5 minutes)
4. Components
4. Components
Component System
Component System
A component system has a separate subwoofer, mid-range speakers and tweeters, placed around your vehicle for the best sound quality.
A component system has a separate subwoofer, mid-range speakers and tweeters, placed around your vehicle for the best sound quality.
Subwoofer sounds aren’t directional and can be heard clearly when placed in your trunk, for example, but you want your tweeters to point towards your ears.
Subwoofer sounds aren’t directional and can be heard clearly when placed in your trunk, for example, but you want your tweeters to point towards your ears.
Why you need to know:
Why you need to know:
Component systems are usually at the highest end for sound quality because each speaker is designed to focus on an audio range without any design compromises.
Component systems are usually at the highest end for sound quality because each speaker is designed to focus on an audio range without any design compromises.
Coaxial / Triaxial / Full Range
Coaxial / Triaxial / Full Range
In a home audio speaker box there are usually two or three different-sized speakers for bass, mid-range and high-range sounds.
In a home audio speaker box there are usually two or three different-sized speakers for bass, mid-range and high-range sounds.
However, audio manufacturers have also figured out how to combine up to five different speakers into a single speaker basket — each with its own independent driver.
However, audio manufacturers have also figured out how to combine up to five different speakers into a single speaker basket — each with its own independent driver.
Why you need to know:
Why you need to know:
Some vehicles have limited space for speaker placement, and coaxial and triaxial speakers are a great option to get a richer overall spectrum of sound. When all you have is mid-range speakers, like most factory systems, you’re missing out on the full range of audio.
Some vehicles have limited space for speaker placement, and coaxial and triaxial speakers are a great option to get a richer overall spectrum of sound. When all you have is mid-range speakers, like most factory systems, you’re missing out on the full range of audio.
Speakers devide in:
Speakers devide in:
Subwoofer is used to play very low tones. In cars we use as low
Subwoofer is used to play very low tones. In cars we use as low
frequencys as we can get, for example: 20-100Hz or even 20-70Hz.
frequencys as we can get, for example: 20-100Hz or even 20-70Hz.
Midbass is used to play low middle and high middle frequencys. They
Midbass is used to play low middle and high middle frequencys. They
work on 40- 70Hz or 2500- 4000Hz.
work on 40- 70Hz or 2500- 4000Hz.
Fullrange speakers are for middle tones. Working frequency is from
Fullrange speakers are for middle tones. Working frequency is from
75- 20000Hz.
75- 20000Hz.
Tweeter speakers ar for the highest tones. Works from 2000-
Tweeter speakers ar for the highest tones. Works from 2000-
200000Hz.
200000Hz.
Why you need sound filters?
Why you need sound filters?
For every speaker to play specific frequency, becouse big speaker
For every speaker to play specific frequency, becouse big speaker
cannot play 200000Hz high frequency, but small speaker can’t make
cannot play 200000Hz high frequency, but small speaker can’t make
big bass. For speakers not to overplay each other, and dont try to play the same music.
big bass. For speakers not to overplay each other, and dont try to play the same music.
Saund filters are needed because:
Saund filters are needed because:
For amlifier and speaker power efficient use.
For amlifier and speaker power efficient use.
To decrease audio distortions.
To decrease audio distortions.
If speaker gets to big power or frequency we are not only making
If speaker gets to big power or frequency we are not only making
audio distortions, but we can damage speaker too Sound filtration
audio distortions, but we can damage speaker too Sound filtration
To filter tones you have two options:
To filter tones you have two options:
HPF(high pass filter) – lets troug tones above seperation frequency, chokes down lower tones.
HPF(high pass filter) – lets troug tones above seperation frequency, chokes down lower tones.
LPF(low pass filter)- chokes down tones above seperation frequency, let’s pass lower tones.
LPF(low pass filter)- chokes down tones above seperation frequency, let’s pass lower tones.
There are two type filters:
There are two type filters:
Passive filter- located behind amplifier, before speaker.
Passive filter- located behind amplifier, before speaker.
Active filter- located before amplifier, usualy have changeable parameters.
Active filter- located before amplifier, usualy have changeable parameters.
Cabel crosscut, depending on electric load
Cabel crosscut, depending on electric load
Cabel crosscut max electric load:
1,0 mm²- 7,5 A
1,0 mm²- 7,5 A
1,5 mm² - 15 A
1,5 mm² - 15 A
2,5 mm² - 25 A
2,5 mm² - 25 A
4,0 mm² - 30 A
4,0 mm² - 30 A
6,0 mm² - 35 A
6,0 mm² - 35 A
8,0 mm² - 40 A
8,0 mm² - 40 A
10 mm² - 50 A
10 mm² - 50 A
16 mm² - 60 A
16 mm² - 60 A
21-25 mm² - 100 A
21-25 mm² - 100 A
26-35 mm² - 140 A
26-35 mm² - 140 A
36-45 mm² - 200 A
36-45 mm² - 200 A
46-55 mm² - 300 A
46-55 mm² - 300 A
Head Unit
Head Unit
A high-end home audio system uses separate electronic components — a radio tuner, CD player, preamp, amplifier — connected by
A high-end home audio system uses separate electronic components — a radio tuner, CD player, preamp, amplifier — connected by
various cables. Since space is at a premium in a vehicle, automakers have to cram as many of these components as possible into one device: the head unit. Because of this, the head unit performs multiple duties, but its two main functions are controlling the overall system volume and the various audio sources in a vehicle.
various cables. Since space is at a premium in a vehicle, automakers have to cram as many of these components as possible into one device: the head unit. Because of this, the head unit performs multiple duties, but its two main functions are controlling the overall system volume and the various audio sources in a vehicle.
Head units can also be used to control media players like the iPod or navigate the content of a USB flash drive that's connected to the stereo system. Head units with Bluetooth audio can also play music that's streamed wirelessly from a compatible mobile phone.
Head units can also be used to control media players like the iPod or navigate the content of a USB flash drive that's connected to the stereo system. Head units with Bluetooth audio can also play music that's streamed wirelessly from a compatible mobile phone.
In addition to controlling the system's volume, head units usually include basic tone controls such as bass and treble to tailor the sound to the listener's taste. Many audio systems also include signal processing that automatically adjusts the volume, depending on the ambient noise in a moving vehicle. Some high-end OEM audio systems also have a separate subwoofer and subwoofer-level controls.
In addition to controlling the system's volume, head units usually include basic tone controls such as bass and treble to tailor the sound to the listener's taste. Many audio systems also include signal processing that automatically adjusts the volume, depending on the ambient noise in a moving vehicle. Some high-end OEM audio systems also have a separate subwoofer and subwoofer-level controls.
Amplifier
Amplifier
A car stereo system has to have an amplifier to increase the power of an audio signal so it's strong enough to move the speakers and create sound. Amplification is a two-stage process handled by a preamp and a power amplifier.
A car stereo system has to have an amplifier to increase the power of an audio signal so it's strong enough to move the speakers and create sound. Amplification is a two-stage process handled by a preamp and a power amplifier.
The preamp is usually housed inside the head unit and takes data from a radio, CD player or other audio source and prepares it for the power amplifier. This process includes slightly boosting the audio signal, which makes it compatible with the input of the power amplifier and ensures that it's resistant to noise that can radiate from other electronics in a vehicle. The power amplifier then takes the preamp's low-level signal and significantly boosts it so it can move the speakers and create sound.
The preamp is usually housed inside the head unit and takes data from a radio, CD player or other audio source and prepares it for the power amplifier. This process includes slightly boosting the audio signal, which makes it compatible with the input of the power amplifier and ensures that it's resistant to noise that can radiate from other electronics in a vehicle. The power amplifier then takes the preamp's low-level signal and significantly boosts it so it can move the speakers and create sound.
Speakers
Speakers
The most basic automotive speakers are designed to be "full range" to
The most basic automotive speakers are designed to be "full range" to
over the entire frequency range. But by trying to cover the entire frequency spectrum, bass response is generally nonexistent and higher
over the entire frequency range. But by trying to cover the entire frequency spectrum, bass response is generally nonexistent and higher
frequencies are dull. You can get more accurate sound reproduction by
frequencies are dull. You can get more accurate sound reproduction by
using an assortment of speakers dedicated to reproducing a smaller
using an assortment of speakers dedicated to reproducing a smaller
range of sound.
range of sound.
Woofers and subwoofers are large speakers designed to reproduce only low-frequency bass sounds. The aptly named midrange drivers handle the middle-range frequencies. Some systems take it one step further and use a specialized midbass driver to handle the troublesome frequencies between low bass and midrange. Tweeters are the smallest
Woofers and subwoofers are large speakers designed to reproduce only low-frequency bass sounds. The aptly named midrange drivers handle the middle-range frequencies. Some systems take it one step further and use a specialized midbass driver to handle the troublesome frequencies between low bass and midrange. Tweeters are the smallest
of the specialized drivers and reproduce the upper treble frequencies.
of the specialized drivers and reproduce the upper treble frequencies.
In many car sound systems, two speakers of different sizes are combined on one frame to create a two-way speaker. For example, a coaxial speaker mounts a small tweeter directly above and on the same axis as a small woofer. That creates a full-range speaker from two separate drivers.
In many car sound systems, two speakers of different sizes are combined on one frame to create a two-way speaker. For example, a coaxial speaker mounts a small tweeter directly above and on the same axis as a small woofer. That creates a full-range speaker from two separate drivers.
Crossover
Crossover
Part of the preamp processing typically involves circuitry known as a crossover. It electronically divides the full-range audio signal that's fed to the amplifier into separate frequencies. Think of a crossover as an audio-signal traffic cop, directing specific frequencies so they can be reproduced by specialized speakers, such as woofers and tweeters.
Part of the preamp processing typically involves circuitry known as a crossover. It electronically divides the full-range audio signal that's fed to the amplifier into separate frequencies. Think of a crossover as an audio-signal traffic cop, directing specific frequencies so they can be reproduced by specialized speakers, such as woofers and tweeters.
Many audio systems use two types of crossovers. An active crossover is a preamp component that divides the full-range, line-level signal before amplification so an amplifier or an amplifier's separate channels handle only a certain frequency range for specific speakers.
Many audio systems use two types of crossovers. An active crossover is a preamp component that divides the full-range, line-level signal before amplification so an amplifier or an amplifier's separate channels handle only a certain frequency range for specific speakers.
A passive crossover accepts an audio signal after it's been amplified and siphons off frequencies for specific speakers.
A passive crossover accepts an audio signal after it's been amplified and siphons off frequencies for specific speakers.
Scandinavia 2-way passive crossover
Scandinavia 2-way passive crossover
A passive crossover designed for use with Scandinavia 165 bass / midrange driver and Scandinavia 30 tweeter.
A passive crossover designed for use with Scandinavia 165 bass / midrange driver and Scandinavia 30 tweeter.
High quality ribbon air coils and MXP polypropylene capacitor in the tweeter section. The tweeter level can be adjusted in 2 steps,
High quality ribbon air coils and MXP polypropylene capacitor in the tweeter section. The tweeter level can be adjusted in 2 steps,
Specifications:
Specifications:
- Impedance 4 ohm
- Impedance 4 ohm
- Description / type
- Description / type
- 2-way filter with slope: LP 6 dB / HP 12 dB
- 2-way filter with slope: LP 6 dB / HP 12 dB
- Crossover point (Hz) 4 kHz
- Crossover point (Hz) 4 kHz
- Dimension (W x D x H) 145 x 85 x 45 mm / 5,7 x 3,35 x 1,77"
- Dimension (W x D x H) 145 x 85 x 45 mm / 5,7 x 3,35 x 1,77"
Match pp 62dsp
Match pp 62dsp
Capacitor
Capacitor
Today’s car audio amplifiers needs huge amounts of current. Often the vehicle’s electrical system is unable to provide it. When a big bass note hit’s or you are listening music very loud, there may be not enough energy to keep up.
Today’s car audio amplifiers needs huge amounts of current. Often the vehicle’s electrical system is unable to provide it. When a big bass note hit’s or you are listening music very loud, there may be not enough energy to keep up.
A capacitor stores current, its super low internal resistance alows it to give up that current very fast, so amplifier never starve itself. As fast as it discharge it will charge too.
A capacitor stores current, its super low internal resistance alows it to give up that current very fast, so amplifier never starve itself. As fast as it discharge it will charge too.
Many head units have a small, built-in low-power amplifier that can "drive" smaller speakers. This allows the audio system to be reduced to just a head unit and a few speakers. But better sound requires more power. So higher-end systems have separate power amplifiers that are mounted away from the head unit due to their size and the heat they generate.
Many head units have a small, built-in low-power amplifier that can "drive" smaller speakers. This allows the audio system to be reduced to just a head unit and a few speakers. But better sound requires more power. So higher-end systems have separate power amplifiers that are mounted away from the head unit due to their size and the heat they generate.
5. Connecting components
5. Connecting components
Connecting with standard head unit
Connecting with standard head unit
Connecting with standard head unit, match, crossover and subwoofer.
Connecting with standard head unit, match, crossover and subwoofer.
Connecting with standard head unit, match, crossover, subwoofer and amplifier.
Connecting with standard head unit, match, crossover, subwoofer and amplifier.
Connecting with standard head unit, match.
Connecting with standard head unit, match.
Summary
Summary
If you are so far, you should have acquired all the topics about car multimedia systems.
If you are so far, you should have acquired all the topics about car multimedia systems.
If you have any suggestions to the lecturer about the content, volume or breakdown of the course, please let him know immediately.
If you have any suggestions to the lecturer about the content, volume or breakdown of the course, please let him know immediately.
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