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

[Harris]

Dear experts

I'm a little confused if RMS @8 ohms is better than RMS @ 6 ohms or are they the same. Because of this,I hear certain AVR and speaker system brands do not match..

What is a more prevalent choice for India?

Thanks

harris

 

[prankey]

You need to expand your question. Amps work better with load capacities in either of them... Usually 8 Ohm speakers generate lesser distortion and less RMS output then 6 Ohms. So, if you go for an 8 Ohm speakers with more sensitivity, you might get more Sound output than another pair of 6 Ohm speakers which may add more distortion... However this can not always be taken as a generalized term and we have to evaluate many other things particularly what Amp and speakers we are talking about...

 

[manu george]

I googled about these things many times and I found amplifier power(rms) should be greater than speaker.how much is proper amp speaker combination.

 

[drkavint]

8 is better but in indian condition of voltage fluctuation and frequent power shorts.. most of the amplifiers are 6 ohms,, (lg, philips are 4 ohms only).. the output of 80 w at8 ohms equals 100w rms at 6 ohms equals 140w rms at 6 ohms.clarity bit increased but at low volumes what we listen not noticable.. indian movies have treble more than bass, so 6 ohms suits better,

 

[just4kix]

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.

 

[TaureanBull]

I googled about these things many times and I found amplifier power(rms) should be greater than speaker.how much is proper amp speaker combination.

I would say none. None is proper as a value. A proper value is a matched value. To say 6ohm or 8ohm is better , does not make sense. Your amp output should match with your speaker suggested amp load. Both these values are listed in the product specifications.

Normally the amp outputs are listed at two impedance load. Eg for Marantz PM 6003 it is listed as (2x 45Watts (8 ohm) / 2x 60 Watts (4ohm).

For a speaker, the nominal impedance is mentioned. Eg for Quad 11L2 its 6ohms. Sometimes its mentioned that compatible with 8ohms. Also, the recommended Amp/maximum input handling are mentioned. Eg for Quad11L2 its 30 - 150 W.

That said, an amp is likely to be damaged if grossly underpowered. Hence, you can buy an amp with slightly higher power. You can google more on this to get technical.

 

[spirovious]

8 ohm is always better than 6(or4)ohm as they are easy to drive by amp.Now if you check most of the amps & THD,with 8 ohm it will be always lower than that of 6 ohms.

 

[manu george]

I have a little confusion in the specs of tower speakers.
for example polk audio tower specs:: the reccomended amp power is 20-150 watts.then what will be its rms power if its rms is 150 then we have to buy an amp having 150watts or above at the desired impedance.please help me to understand this.

 

[spirovious]

Amp with more power(10%)will be better for that speaker as it will drive speaker easily.
But we can still use a low power recommended amp (say 40w)for moderate listening.

 

[gobble]

6 ohm speaker is more difficult load on amp than 8 ohm.

You should check your speaker first is it 6ohn nominal or 8? The impedance varies across the frequency range, so it is quoted as a nominal value that is more orless representative across the range.

Then you buy your AVR rated at at least 1.5 times the nominal impedance of your speaker. "At least" because most AVRs are overrated for their power handling. Having purchased such gear, you should be content to play your AVR without ever cranking up the volume knob beyond 30% on most days.


So for 50W speakers get an amp rated @75W at least, for example.

HTH

 

[baijuxavior]

I googled about these things many times and I found amplifier power(rms) should be greater than speaker.how much is proper amp speaker combination.

I have a doubt. If amplifier power is greater than that can be handled by the speakers, will the speaker get damaged?

 

[soundofmusic]

I have a doubt. If amplifier power is greater than that can be handled by the speakers, will the speaker get damaged?

The speakers are damaged with low powered amps driven in high volumes rather then high powered amplifiers driving speakers at moderate volumes.

 

[baijuxavior]

The speakers are damaged with low powered amps driven in high volumes rather then high powered amplifiers driving speakers at moderate volumes.

So we can drive a 10w speaker system safely with a 20w amplifier and not by a 5w amp?

 

[soundofmusic]

So we can drive a 10w speaker system safely with a 20w amplifier and not by a 5w amp?

Yes we can

 

[avidyarthy]

Then you buy your AVR rated at at least 1.5 times the nominal impedance of your speaker. "At least" because most AVRs are overrated for their power handling. Having purchased such gear, you should be content to play your AVR without ever cranking up the volume knob beyond 30% on most days.


So for 50W speakers get an amp rated @75W at least, for example.
HTH

Always try ask for the instruction manual of the AVR / Amp that you intend to buy before 'physically' buying.

Check for the power output rated for different conditions. This is where 'most' manufacturers tend to oversell the actual specs. Find out the mentioned power output at 20 Hz to 20 KHz at a particular impedance. 'This' power figure 'should' be higher than the maximum rated power of the speakers.

Higher by how much .... do not know. I think for one to remain in safe zone, 'just higher' should serve the purpose.

Higher end amps and AVRs would have specs like:
- 100 W at 8 ohms (or 200 W at 4 ohms)

Similarly, mid/low ends would have specs:
- 100 W at 8 ohms (or 125 W at 4 ohms)

 

[prankey]

8 is better but in indian condition of voltage fluctuation and frequent power shorts.. most of the amplifiers are 6 ohms,, (lg, philips are 4 ohms only).. the output of 80 w at8 ohms equals 100w rms at 6 ohms equals 140w rms at 6 ohms.clarity bit increased but at low volumes what we listen not noticable.. indian movies have treble more than bass, so 6 ohms suits better,

I don't know what you were trying to say as none of your statement is true... It depend on the amp on how much more current it can produce at a constant output voltage (at a particular volume level). Practically amps usually struggle at lower impedance to match the current requirement and hence result in unstable voltage to compensate for the current requirement (if the current drain increases, the voltage will drop proportionately resulting in distorted audio). Hence power output reduces then what ideally should be in lower impedance and THD increases due to this phenomenon...

W = V/R

I wish it could have been this easy for an audio power amp. As the amp has limited current carrying capacity, voltage becomes variable when the current reaches maximum possible by the amp...

 

[baijuxavior]

What prankey said is absolutely right. When connected to a 4 ohm speaker, the amplifier should be capable of supplying twice the current than when a 8 ohm speaker is connected.
The equation connecting Voltage, Current and Resistance is R=V/I. Since R is constant for a speaker, when voltage decreases current increases. And if the amp is not capable of supplying the required current due to low voltage then .... In simple words, to drive a low impedance speaker, the amplifier (the power section) should be capable of supplying high current.

 

[jayan007]

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

What prankey said is absolutely right. When connected to a 4 ohm speaker, the amplifier should be capable of supplying twice the current than when a 8 ohm speaker is connected.
The equation connecting Voltage, Current and Resistance is R=V/I. Since R is constant for a speaker, when voltage decreases current increases. And if the amp is not capable of supplying the required current due to low voltage then .... In simple words, to drive a low impedance speaker, the amplifier (the power section) should be capable of supplying high current.

 

[darshanjoshi]

So if i have a speaker of 225 watts max, Do i need to have an amp higher than that? An Amp with more than 225 watts will make holes in my pocket.

I have an AMp with 100 wpc (20-20khz) and it works absolutely fine even at high volumes.

 

[avidyarthy]

Could you name the speaker and the model ........ please.