Historically, prefixes for civilian vessels often identified the vessel's mode of propulsion, such as, "SS" (screw steamer), "MV" (motor vessel), or "PS" (paddle steamer). Alternatively, they might have reflected a vessel's purpose, e.g. "RMS" (Royal Mail Ship), or "RV" (research vessel).
root-mean-square abbreviation
No, ohms does not relate to sound quality. It does related to the amount of energy an amplifier can transfer from its circuitry to the speaker device.
There are many factors how loud a speaker can play while consuming 100W RMS. Say one speaker is 88dB and another is 98dB per RMS watt at 1m . For 100W RMS consumption, first speaker will play 108 dB and second speaker will play 118dB. If the first speaker wants to play 118dB it will need 1000W RMS.
In fact, most amplifiers labeled as 1000 watts PMPO have a true RMS output of 10 watts or less. One that I measured put out 7.5 watts per channel.
1 amplifier is rated for 1200 watts RMS @ 1 ohm. If the subwoofers are wired to a total impedance of 4 ohms, this amp will only produce 400 watts @ 4 ohms.
Let's say they are mounted in the same box, the higher rms sub can handle more power so therefore, should be louder (depending on sensitivity).
RMS ratings realistically measure how much power the speaker can handle on a continuous basis, not just for a short period of time. A system rated at "2-50 watts RMS" will make a better match for your low-powered stereo than another system rated "10-80 watts RMS."
Much depends on your listening habits and your speaker's efficiency. If you like loud uncompressed music and your speakers are 90dB efficient, 200 Watts is likely plenty of power for you. If you only listen to light classical, jazz and don't expect them to rock the house, 50 Watts is adequate.
Sample Amplifier Power Rating Chart:
| # of Speakers | Each Speaker Rating (RMS) | Recommended Amplifier Power (RMS) |
|---|
| 1 | 100 watts | 30-100 watts |
| 2 | 100 watts | 60-200 watts |
| 3 | 100 watts | 90-300 watts |
| 4 | 100 watts | 120-400 watts |
A.C. is said to be four to five times more dangerous than D.C. For one thing, A.C. causes more severe muscular contractions. The frequency of the AC has a lot to do with the effect on the human body. Unfortunately, 60 cycles is in the most harmful range. At this frequency, as little as 25 volts can kill.
220V is the RMS value of domestic AC electric supply. This can be verified using a multimeter. Multimeter always shows an RMS value of AC voltage.
The RMS value is equal to the peak value divided by the square root of two. The average value is zero since the voltage is negative for the same amount of time that it is positive. For a fixed DC voltage, the peak, average, and RMS voltages are all equal.
The term "RMS" stands for "Root-Mean-Squared", also called the AC equivalent to DC voltage. The RMS value is the square root of the mean (average) value of the squared function of the instantaneous values.
Simple: the average of a sine is zero. so to get average power you calculate average voltage squared. RMS gives you the equivalent DC voltage for the same power. If you would measure the resistor's temperature as a measure of dissipated energy you'll see that it's the same as for a DC voltage of 0.71 V, not 0.64 V.
