[es] - Spajanje zvucnika

marinbnm

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^{27.12.2012. u 22:39 - pre 137 meseci}

Ovako.....imam sub koji je bass reflex i u sebi ima dva 18'' basa, fora je u tome da je svaki 18'' bas 1000E AES i 4Ohm, te su sad spojeni u seriju tako da kutija kao takva ima 2000W 8Ohm. Trenutno ih pogonim sa pojacalom koje ima 1200W/8ohm. Malo sam mislio kad bi ucinio slijedece bili dobio kakvu razliku, znaci:

Sad imam dva 18'' 4ohm basa u serijii to je 1200W/8ohm i tjera ih pojacalo u bridge modu.

A iduca fora je spojiti posebno svaku 18'' jedinicu na stereo pojacalo koje ima 2X600W/4Ohm....na kraju je snaga ista samo u drugom slucaju imamo jedan vod više i svaki driver ima svoje pojacalo i naravno zbog 4ohm mozda malo veci gubitak u vodu nego pri 8ohm.

Zanimaju me misljenja jer sam negdje procitao da ako su zvucnici spojeni direktno na svaki kanal pojacala pri istoj snazi da imaju 1.5dB vecu efikasnos, nemam pojima zašto bi bilo tako, jer mi na kraju dođe isto ako spojim 2X600W/4ohm, ili ako isto pojacalo ubacim u bridge i imam 1200W/8ohm.

frffr

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44250

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Re: Spajanje zvucnika - subwoofera

^{28.12.2012. u 15:20 - pre 137 meseci}

Citat:

marinbnm: Ovako.....

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A iduca fora je spojiti posebno svaku 18'' jedinicu na stereo pojacalo koje ima 2X600W/4Ohm....na kraju je snaga ista samo u drugom slucaju imamo jedan vod više i svaki driver ima svoje pojacalo i naravno zbog 4ohm mozda malo veci gubitak u vodu nego pri 8ohm.

Zanimaju me misljenja jer sam negdje procitao da ako su zvucnici spojeni direktno na svaki kanal pojacala pri istoj snazi da imaju 1.5dB vecu efikasnos, nemam pojima zašto bi bilo tako, jer mi na kraju dođe isto ako spojim 2X600W/4ohm, ili ako isto pojacalo ubacim u bridge i imam 1200W/8ohm.

Sad sam kući pa mogu sa računara:

link: http://www.sound.westhost.com/bi-amp.htm

konkretan dio teksta:

"1.4 - Actual vs Effective Power
If we assume that our 100 Watt amplifiers will be handling exactly the same peak amplitudes with typical program input, then we have a total of 200 Watts for the combined program material. So, where does the magic come into this? This amp combination will sound (and measure) as if it were 400 Watts - twice as much "effective" power as there is real power. For this to make sense, we need to back track a little.

Imagine a sine wave signal of 100Hz at an amplitude of 28V RMS. For an 8 ohm load, this equates to about 100W (98 actually). The same amplitude at 1000Hz will be exactly the same power. Now add the two signals together, in the same way that signals add together in music. We are interested only in the peak amplitude, the RMS value indicates that the power is only 3dB higher, but it is only when an oscilloscope is used that the true picture emerges.

We will now see a low-frequency waveform, with a higher frequency waveform superimposed - the high frequency signal will be riding up and down the path of the low frequency signal. If we were to perform a calculation (or simply measure the combined signal with an oscilloscope), we will see that the peak amplitude has doubled. The effective RMS value (most multimeters will get this wrong unless they are true RMS types) is 40 Volts, and this would imply 200W. Although this is the real RMS voltage, it totally underestimates the amplifier power needed to reproduce it cleanly. An oscilloscope shows 80V peak for the same waveform, so the amplifier must be capable of passing an 80V peak signal - a 400W amplifier.

To illustrate this point, Figure 2 shows two signals, each of 1 Unit peak amplitude. As can be seen, when the two are combined, the amplitude is much greater. The maximum peak amplitude is now 2 Units - double the peak voltage and four times the peak power of each signal individually. Power increases as the square of voltage, so twice the (peak) voltage is four times the power. Real ('RMS') power increases by 3dB or double the power, but this is a misleading figure and cannot be used. An oscilloscope is essential.

Note: Peak-to-peak amplitude is actually double the values quoted above, but since amplifiers are generally symmetrical (capable of equal positive and negative voltage swings) it is more convenient to simply refer to the peak amplitude only.

This is not to say that the actual music will be symmetrical. It isn't, but it is completely unpredictable in nature. As a result, it is possible (for example) to set up an amplifier asymmetrically and adjust the phase to suit with a switching circuit, since it will change. AM radio actually does this (or they used to) - a circuit is used to switch the phase so that slight over modulation causes more transmitter power, but never reduces it below the acceptable minimum. I shall not be going into details, since I believe few audiophiles would find this acceptable - I know I wouldn't.

All signal sources have the same characteristics as shown above in Figure 2, even a solo voice or musical instrument. In these cases, the fundamental frequency forms the low frequency component, while the harmonics 'ride the wave' as it were. Not surprisingly, the 'equal power' frequency will change (often dramatically) from the 250 to 350Hz range quoted above, but the basic principle does not alter.

Completely beside the point (but interesting anyway) is that in many musical instruments, the harmonics are actually at a greater amplitude than the fundamental. (File this away under 'Useless Information'.)

Note: It must be explained here that the 3dB effective power increase is the absolute maximum that can be obtained. In most cases it will be less - I have examined sections of music where the power gain was less than 1dB, and it can be reasonably safely assumed that the real gain will lie somewhere between 1-2dB in most cases. The real figure depends a lot on the type of music, the actual crossover frequency, and the peak to average ratio of the two separated signals. Just this topic alone is sufficient for a complete article in its own right."

-što će reći da nema poboljšanja ako zvučnike iste vrste vezuješ u most serijski-redno jedan na drugi ili svaki na svoj kanal,da je bi- ili tri- amp sistem u pitanju-već je druga priča.

"chop your own wood and it will warm you twice..."

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