RMS@ 8ohms or RMS@ 6 ohms? What's better?

[prankey]

Just a thought, If you are having a voltage stabilizer and the Voltage is also constant and not fluctuating?...

Hehe, no we are not talking of supply voltage here.. At a particular volume level, the amp has a constant output voltage (which may actually increase a bit if the supply voltage is higher - like overclocking a computer ) and max current at that volume level... If the current drain is higher than max supplied by the power transistors (in discrete amps) or ICs (in Integrated Amps), then the voltage drops proportionately due to higher current drain.. Bigger power transformer and capacitors may help a bit (again, sort of overclocking as the transistors and ICs will have their max capacity). However stabilizer can help only if it keeps the voltage high enough for maximum power output...

 

[janarthanan n]

it is incorrect to say the 6? speakers produce more/better sound than 8? speakers (or vice versa). Speaker impedance has nothing to do with sound quality. The sound output is measured in decibels (db) and this is always constant for a given amp. It takes a lot more electrical power to make the sound appear louder. An amp of 120w is not twice as loud as an amp of 60w.

Modern avrs and amps are designed to work with 6? and 8? speakers together. So it is quite natural that at 6? the output will be more. Remember the electrical power equation:

W = v/r

since (output) voltage is always constant, the low impedance (6?) speakers will draw more current from the amp and hence power output will be more. So the same amp will output 90w with 8? speakers but jump to 120w at 6?.

What is said about 6? better for indian condition is not true at all. Indians are obsessed with power and pmpo and what not. So 3200w pmpo (at 4?) sells much more than 1000w pmpo and even better than 90w rms.

Ultimately it is the fidelity of the sound, the elimination of noise, thd, etc. Are more important for the amp. For the speakers, the reproduction of sound, the correct crossover frequency, ability to produce the correct sound even at low volumes, not blaring at high volumes, etc., is important. 6? or 8? does not matter.

hi sir,
i want to know what is the difference between listining music in 6ohms setup and 8 ohms setup. Which is better, kindly reply sir
jana

 

[lake1988]

To make this issue more clear you need to understand how amplifier works. Most of high end systems use multistage feed back amplifier..to explain it clearly each stage add to certain amount of amplification with added feedback to reduce distortion and noise.
So that means when we couple all stages together we get more amplification and very less noise.

Now rms power here is simplified as a product of rms voltage and rms current cause amplifier amplifies ac signal i.e. alternating signal so we need to calculate sqrt((voltage or current)^2 over a period to get rms or root mean square voltage or current.

Another term is PMPO which means peak music power output which is a indication of maximum power output at the peak of loudness.

But rms power is the true term which you need to stick to determine true rating of the amplifier.

Now what is that ohms of speaker means..it means impedance..speaker is not only resistive but also inductive due to coil inside..so total impedance=sqrt(resis^2+induc^2)

Why speakers are rated..cause to deliver maximum output coming from amplifier. Amplifier has various capacitor,inductor to filter dc voltage from entering output stage cause if a very small amount of dc or direct current entered into speaker it will create constant noise.
Due to use of several inductor,capacitor and resistor we at-last calculate the impedance of the output stage and try to get a speaker which matches that value.

Why-cause if the impedance of output stage of amplifier and the speaker is same then power delivered from amplifier to speaker will be maximum..I don't want to go to that calculation now.

So if you mismatch the speaker impedance what will happen..you will get less power/more power..i.e. more or less current will flow through output stage which may result thermal run away of output stage transistor..i.e. damage it simply.