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Dealing With Noise or Storing.
Para suhu, mohon bantuannya untuk melengkapi posting ini yha...
Berikut hasil saya membaca dan merangkum.
What is noise?
In any audio system, there are several potential noise sources.
• Thermal noise
• Induced noise
• Noise caused by a ground loop
Thermal noise sounds like the hiss that you hear between stations on your FM radio.
Thermal noise occurs because mankind chooses to live at 300 degrees above absolute zero. Thermal noise occurs because of the random movement of electrons caused by thermal agitation. At absolute zero, thermal agitation ceases to exist. Unfortunately, we haven’t found a way around this problem yet.
Just because we live at temperatures other than absolute zero doesn’t mean that we can’t deal with thermal noise. Careful design, along with attention to detail can minimize this type of noise.
Remember...the word is minimize not eliminate.
Induced noise has a variety of causes. Induced noise is sneaky. Sometimes it gets into your system through the power wiring, other times, it may sneak in via two adjacent wires. Still other times, it just gets in through the air.
The alternator wiring carries fairly high currents, even though the voltage is relatively low. Passing an electrical current through a wire is a sure-fire way to generate a magnetic field. Higher currents generate higher strength fields. Now, if you put two wires in close proximity to each other, and one of them is carrying an electric current
. Alternator noise sounds like a whine whose pitch is proportional to engine speed.
Ground loops are insidious. They are caused by the non-zero resistance of the wire used to interconnect the equipment. Typically, ground loops are created by a piece of equipment having multiple connections into the grounding system.
In autosound, this problem is exacerbated by the rather callous belief by auto makers and certain other folks that the metal frame of the vehicle makes a good ground. While this may be true for cigarette lighters and tail lights, applying this belief to audio systems is a gilt-edged invitation to disaster.
How To Deal With Noise:
1. Make sure that the signal going to the power amplifier is as strong as possible. This helps to subjectively reduce noise that may be induced between the head unit and the power amplifier by making the signal in the cable much stronger than the induced noise.
2. Bypassing the alternator output with a capacitor may help
3. It may help to add an RF bypass capacitor at the amplifier end of the power cable to auto body ground. It may also help to add a second bypass capacitor from the positive side of the cable to the negative lead that runs back to the electrical system ground
4. Level matching helps minimize hiss: the residual noise output of the head unit. Level matching can help make other noise sources (alternator noise, etc.) less evident by making the useful signal much louder than the noise. This is the reason for keeping the volume setting high, and the amplifier sensitivity low
Identifying noise sources
All the noise filtering in the world won’t help unless you can identify the various potential noise sources in the system.
Sounds like a whine whose pitch varies with engine speed. It can be caused by poor or careless grounding, ground loops, poor wiring practices, or bad level matching. Bypassing the alternator output with a capacitor may help.
A ticking sound that changes with engine speed (the clicks get closer together). It can be caused by poor or careless grounding, ground loops, poor wiring practices, or bad level matching. Resistor spark slugs may help, especially when tuners are affected.
A clicking sound synchronized with the turn signals. Make sure that the auto body ground connections to the lamps are secure. Bypassing the input and/or output to the flasher unit with a capacitor may help. Other possibilities include poor or careless grounding, ground loops, or bad level matching.
Dash Lamp Dimmer
A buzzy whine whose pitch varies with the dimmer setting. Try bypassing the dimmer input lead with a capacitor and/or different grounding points for the autosound system.
A buzzing sound, synchronized with the horn (how did you guess?).
Again, a bypass capacitor should fix this too.
Amplifier Power Supply
High-powered amplifiers sometimes cause problems because the DC to DC converter inside of them radiates EMI (electromagnetic interference) into the electrical system of the car. This type of noise sounds like a nasty buzz, that isn’t affected by engine speed and is usually affected by some or all of the system controls. Sometimes (especially when the units are mounted on a board in the trunk) the manufacturer will leave the chassis of the amp floating (not connected). This turns the amp chassis into an effective antenna. Connecting it to the auto body ground will turn the amp chassis back into a shield, which is what it should be.
Mohon Bantuan para suhu.
Originally Posted by setiawanhandoyo
1. Untuk ByPass Alternator, yang dipakai kapasitor jenis apa, ukuran brapa Farad, dan brapa volt?
2. Untuk RF ByPass Capasitor, dikatakan adalah [B]Ceramic Bypass Capasitor[/B
mohon penjelasan Ceramic Bypas Capasitor tuh apa yha?]
Mantap nih infonya bro Setiawan
Originally Posted by setiawanhandoyo
Mungkin maksudnya gini bro,
Biasanya jarang yah orang pasang langsung di teminal output alternator mobil, karena tempatnya sudah tidak memungkinkan lagi. Yang mungkin dilakukan ya memasang capacitor bank dekat terminal poweramplifier itu sih. Tapi yang penting cablingnya dulu yg bener, pisahin antara jalur audio dan power. Kalau alternator ga bener ya diservis dulu. Besar faradnya ya tergantung daya power yang dipasang. Kalau lebih besar biasanya gpp, kalau kekecilan yg ga boleh (IMO).
Capacitor Ceramic bypass itu capacitor yang mmg bahan dasarnya dari ceramic, biasanya dipasang di jalur power supply dekat component aktif seperti transistor atau ic, bentuknya bulat gepeng warna kuning tua, umumnya nilainya 100nF atau di body ada tulisan 104. Sekarang banyak tuh diganti sama Merek WIMA yg lebih bagus, ada yg MKP, MKM, MKS, dll.
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