Hi. I have looked around site as well as googled up a storm for help on this. While I understand if I run two 8 Ohm speakers in parallel then the impedance is 4 Ohm. As I am looking to buy and match an amp to my speakers, my question is related to the speakers being rated at 8 Ohms.
Yamaha power rates these speakers at noise/program/max (75/150/300) and 8 Ohm. From Googling around I think I need to take the middle number as the power I need to match with the amp. My question is, if I run them in parallel will an amp at 75watt and 4 Ohm be the right one ie. if I knock the Ohm down, does the power needed to run the speaker also become less?
I cannot find this missing link in anything I read. Seems to follow logically but don't wish to be wrong as I am afraid I may not getting enough noise out of them should they still require 150 watt.
Final question: If my logic is correct, from what I am reading, wattage nearly doubling the required is usually best so should I really go for an amp rated 4Ohm in the 100 to 150 range?
Thanks
Yamaha power rates these speakers at noise/program/max (75/150/300) and 8 Ohm. From Googling around I think I need to take the middle number as the power I need to match with the amp. My question is, if I run them in parallel will an amp at 75watt and 4 Ohm be the right one ie. if I knock the Ohm down, does the power needed to run the speaker also become less?
I cannot find this missing link in anything I read. Seems to follow logically but don't wish to be wrong as I am afraid I may not getting enough noise out of them should they still require 150 watt.
Final question: If my logic is correct, from what I am reading, wattage nearly doubling the required is usually best so should I really go for an amp rated 4Ohm in the 100 to 150 range?
Thanks
Lets say you have one speaker and are driving it to its fullest with 1 watt at 8 ohms. If you add a speaker in parallel, each speaker will be taking 1 watt so you need a 2 watt at 4 ohms amplifier.
Clear as mud?
Yes you should ideally look for an amp that produces about 150w/ch at 8ohms.
No it doubles, so you would want an amp capable of delivering 300w/ch at 4ohms.
I'm also gonna mention that speakers don't "require" any particular amount of power, they will work just fine with anything from fractions of a watt up, but if you want to be able to get all the sound level they are capable of delivering you need an amp that delivers at least the speakers program power rating.
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Well, RonE is not making that any clearer than mud.
Two drivers in parallel are 4 ohms.
Run connected to the SAME amp, that WAS running 1 watt into the 8 ohms, the amp will now produce MORE power, since the voltage remains the same coming out of the amp, but the current is increased since the impedance is halved.
Use Ohm's law, E = I * R and P = I * E, run the numbers see what happens.
This *assumes* something that is not *always* true - that the amp can double the current. Many amps can not.
Also if the two paralleled speakers are closely spaced you will get an acoustic gain as well as the apparent electrical gain (due to the lowered impedance, and the effect on the amp) of (allegedly) 6dB *more* output.
Paralleled speakers should always be identical drivers.
Now, what you ought to buy depends a whole lot on what ur trying to do, and how loud you want to play ur speakers. Since you have said nothing about that, there's no good advice to offer. 😀
Two drivers in parallel are 4 ohms.
Run connected to the SAME amp, that WAS running 1 watt into the 8 ohms, the amp will now produce MORE power, since the voltage remains the same coming out of the amp, but the current is increased since the impedance is halved.
Use Ohm's law, E = I * R and P = I * E, run the numbers see what happens.
This *assumes* something that is not *always* true - that the amp can double the current. Many amps can not.
Also if the two paralleled speakers are closely spaced you will get an acoustic gain as well as the apparent electrical gain (due to the lowered impedance, and the effect on the amp) of (allegedly) 6dB *more* output.
Paralleled speakers should always be identical drivers.
Now, what you ought to buy depends a whole lot on what ur trying to do, and how loud you want to play ur speakers. Since you have said nothing about that, there's no good advice to offer. 😀
Not sure I'm doing the quote thing right.
This setup is PA system. Singing for 90% but may add keyboard
If I am reading this right Bear, it is as I thought? Though the speakers can be driven at 150watt under 8 Ohm, if I put them in parallel (with less impedance) I can get away with about ha lf of the watts? This would be in opposition to what Ron E said right? Thanks
I'm somewhat concerned about the ratings of the speakers?, what is this 'noise/program/maximum' lark?.
The rating you really need is continuous watts RMS, which allows sensible comparisons - other figures are just 'made up' and usually highly imaginary.
PA amps and speakers usually give sensible ratings, are the Yamaha ones actually PA speakers?.
Just vocals is pretty 'easy' on the amp and speakers, but adding keyboard is a different matter - keyboards are commonly used for long continuous notes, and have a vast frequency range, so you need pretty conservative ratings for the amp and speakers.
I would assume the speakers in question are fairly small?, and probably actually only rated at 75W RMS ('proper' power), so an amplifier that provides 150W RMS in to 4 ohms would be a reasonable match.
But there's nothing 'cast in stone' about amplifier/speaker ratings - you can use a 1000W amplifier to feed 10W speakers perfectly safely, as long as you NEVER turn it up too loud. Personally I would rather have speakers rated higher than the amplifier, as you've less chance of damaging the speakers as they aren't pushed to their limits as much.
The rating you really need is continuous watts RMS, which allows sensible comparisons - other figures are just 'made up' and usually highly imaginary.
PA amps and speakers usually give sensible ratings, are the Yamaha ones actually PA speakers?.
Just vocals is pretty 'easy' on the amp and speakers, but adding keyboard is a different matter - keyboards are commonly used for long continuous notes, and have a vast frequency range, so you need pretty conservative ratings for the amp and speakers.
I would assume the speakers in question are fairly small?, and probably actually only rated at 75W RMS ('proper' power), so an amplifier that provides 150W RMS in to 4 ohms would be a reasonable match.
But there's nothing 'cast in stone' about amplifier/speaker ratings - you can use a 1000W amplifier to feed 10W speakers perfectly safely, as long as you NEVER turn it up too loud. Personally I would rather have speakers rated higher than the amplifier, as you've less chance of damaging the speakers as they aren't pushed to their limits as much.
Thanks Nigel. Yes, they are PA speakers. Part of Club Series from Yamaha but old enough nothing more on specs available (that I can find.) 150 is what I am taking to mean RMS.
Clearly you take a conservative (cautious) approach on your matching and will note it for keyboards and overall power.
Given 150 watts RMS, might you suggest an amp rated at 4 ohm and 200 watts should I care to run the 8 ohm speakers with stereo music? I'd watch how high I put volume of course.
One additional question though. When buying an amp rated at x power, does this always mean total power available or would this apply that amount of power per speaker direct to speaker (in stereo)?
Thanks
Clearly you take a conservative (cautious) approach on your matching and will note it for keyboards and overall power.
Given 150 watts RMS, might you suggest an amp rated at 4 ohm and 200 watts should I care to run the 8 ohm speakers with stereo music? I'd watch how high I put volume of course.
One additional question though. When buying an amp rated at x power, does this always mean total power available or would this apply that amount of power per speaker direct to speaker (in stereo)?
Thanks
Nigel is right.
75/150/300 is carefully worded to look more than what it actually is.
75 W is RMS, rthe only actual rating there , and by "noise" they probably mean a sinewave, which is what's used to get that rating.
They call it "noise" because "that's not really Music, is it?" Marketing dept. BS.
"Program* is a "Home Hi Fi" rating, where they consider you'll never max your amp (you are listening to a CD in your living room, you do not want distortion and anyway there's neighbours around).
"Max" is purely made up, in the PMPO area.
And you can't be counted on not pushing your system to the max in a somewhat larger than you expected Club or outdoors, so the sensible PA power with those speakers is **real** (RMS) 150/200W into 4 ohms if mono and 2 x 75/100W per channel if stereo.
And I consider a 200W (total) amp *only* because program includes vocals which you won't let distort horribly.
*IF* it were a guitar amp or teen DJ system, 100W tops would be max sensible power, since they are oblivious to distortion.
75/150/300 is carefully worded to look more than what it actually is.
75 W is RMS, rthe only actual rating there , and by "noise" they probably mean a sinewave, which is what's used to get that rating.
They call it "noise" because "that's not really Music, is it?" Marketing dept. BS.
"Program* is a "Home Hi Fi" rating, where they consider you'll never max your amp (you are listening to a CD in your living room, you do not want distortion and anyway there's neighbours around).
"Max" is purely made up, in the PMPO area.
And you can't be counted on not pushing your system to the max in a somewhat larger than you expected Club or outdoors, so the sensible PA power with those speakers is **real** (RMS) 150/200W into 4 ohms if mono and 2 x 75/100W per channel if stereo.
And I consider a 200W (total) amp *only* because program includes vocals which you won't let distort horribly.
*IF* it were a guitar amp or teen DJ system, 100W tops would be max sensible power, since they are oblivious to distortion.
"Noise" probably means "pink noise" which is about the same as the AES rating being used currently. It's about 2X RMS. If they actually do a power test, and some do, it will usually be with pink noise because it can tolerate more of it than it can a sinewave and it more closely resembles music (spectrally). "Pink" noise takes into account the fact that the tweeter can't handle as much power as the woofer - hence the "red shift". "Program" is 2X the AES, or 4X the RMS, and is about as big an amp as you should run.
proffesional speakers have a measurement called noise which a noise generator testing the speaker to it,s limit for 2 hours and it,s more hard than rms.
looking the specs of pro speakers rms is twice the noise so my guess is the rms is the 150 watts for your speakers.
looking the specs of pro speakers rms is twice the noise so my guess is the rms is the 150 watts for your speakers.
can somebody explain the concept or misconception of "matching" amp wattage to speakers is there a belief that the "correct match" has a performance benefit?
over the years i've spent doing live sound i've encountered many different approaches/philosophies on the subject.
indeed overrating an amp with respect to speaker can kill it fast but an inadequate amp driven to heavy distortion can kill a driver just as quickly(the foresics of failures i've examined is in the first case over excursion ie physical damage to surrounds and spiders the second condition results in the typical "crispy" voice coil)
in summation a reasonable estimation of wattage with respect to speaker will suffice so long as the power is delivered undistorted(which in pa application makes the case for limiter/compressors)
all of this is without consideration of the speakers relative efficiency some drivers will happily eat watts but not give much spl in return
over the years i've spent doing live sound i've encountered many different approaches/philosophies on the subject.
indeed overrating an amp with respect to speaker can kill it fast but an inadequate amp driven to heavy distortion can kill a driver just as quickly(the foresics of failures i've examined is in the first case over excursion ie physical damage to surrounds and spiders the second condition results in the typical "crispy" voice coil)
in summation a reasonable estimation of wattage with respect to speaker will suffice so long as the power is delivered undistorted(which in pa application makes the case for limiter/compressors)
all of this is without consideration of the speakers relative efficiency some drivers will happily eat watts but not give much spl in return
An adequately sized amplifier will allow the end user to get the full potential from the speakers meaning as much clean sound level(SPL) as they were designed to generate. There is a misconception that an amp this size is an absolute requirement or that the speakers could be damaged with an "undersized" amp, but if the combination delivers the required SPL below amp clipping levels those ideas are false and a larger amp provides no benefit.
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anyone who tries to do PA work without a soft knee limiter and *knowing* where the output power of the amps are WRT the max their speakers/drivers can handle is both asking for trouble and is a rank amateur or worse. so, this means that you can use ANY power amp OVER the ratings of the speakers, never ever clip it and never run into distortion.
First, amps are usually constant voltage devices. That means at a given volume setting, the signal voltage will not change much if you change the load impedance.
Since that is the case, lets use the voltage formula:
Power = Voltage * Voltage / Resistance. Halving the resistance doubles the power required.
If you want to use the program power rating you will need an amplifier that can supply 300 watts/ channel into 4 ohms.
Amplifiers are limited both in how much electrical pressure (volts) and how many electrons per second (amps) they can supply. If the load resistance is too high, power will be limited by the maximum voltage the amp can deliver, too low a resistance and power will be limited by maximum current.
A good amp's spec sheet will tell you the maximum power available at each impedance.
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