RMS, Continuous, Program, Peak, volume vs. wattage etc.
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Posted on Oct 07, 2008 07:44 pm
Gear Addict
Member Since: Jul 09, 2008
I'm a singer not a sound guy (I wish I was both) and my band is looking to maximize our PA setup. Currently we run a Carvin C1644P (4-300 watt power amps. 2 for the monitors and 2 for the mains) with a crossover and a pair of powered subs. For mains we have a pair of community speakers with 2 15" speakers a mid horn and a tweeter. The speakers are rated at 300 watts rms (@4ohms) and I believe 650 watts program. Here is my question. We can add another power amp but I am confused as to wether we need to match RMS wattage with amp to speaker or what. If somebody could please define the different ratings that would help me immensely. Also how does wattage relate to volume? If an amp is rated at 600 watts at 4 ohms and 350 watts at 8 ohms can I expect the same volume from either set of speakers or would the 4 ohm speakers be louder? Any help would be great.
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Oct 07, 2008 08:40 pm Hey Gear addict. These are questions that we have covered a lot here on the HRC. I have written an article that appears under the tips section on the top tool bar. In there I cover all of your questions for you.
One thing I want to help clarify for you, is the fact that RMS, continuous, program, and music ratings, are all the same rating. All of them mean the same thing, just different manufactures prefer to use a different term to mean the same thing. Why you ask? God I wish I knew. they drive me nuts with all of this nonsense. Just like Mackie calling it Trim instead of gain. Both are the same thing, just under a different term. ARRG!
To answer another question that you have, "What happens when you reduce the ohm load on an amp?" when you reduce the ohm load on an amp. You increase the amount of current that an amp can produce. Hence the ratings on the amp. When you increase the current, the wattage goes up. So, more power to your speakers. You just want to make sure that you are not exceeding the wattage of your speakers. In other words. If you have 4 200 watt speakers at a 2 ohm load. You want to make sure that your amp does not exceed 800 watts at a 2 ohm load. 4 x 200 = 800. If it does, then you need to attenuate the input sensitivity down some. Maybe even as much as -9 to -12 dB.
If you wish to add an additional amp. I would suggest making your system a tri-amp PA. This will give you increased headroom over all. By freeing up bandwidth going to each amp. It will take some work. You will need to remove the drivers out of each top box. And add a switch to be able to switch it out of bi-amp mode, and back to passive. Also, you will need a set of new connectors for each box. Such as two Neutrik NL4's per box. I can send you some information on this if you wish. I just may take me some time to put it together for you.
Oct 07, 2008 09:08 pm Thanks for your reply Rob. I'm with you on the watts vs. resistance stuff. Makes sense to me. So if RMS and program are the same thing, why do my speakers say 300 watts continuous and 750 program? The power amp that is on its way to me is rated for 600 watts per channel rms at 4 ohms. Does this mean that my speakers can handle all 600 watts? If so, we will use the 4 amps in the board for monitors, the power amp for the mains and powered subs until I can set up the mains to be bi amped giving us a tri amp (counting the powered subs) set up. If I understand what you said correctly. I looked through the forum before posting this question, but I will try to find your article too. Hopefully soon I will be able to contribute to the forum and not just ask questions. Thanks again.
Oct 07, 2008 09:22 pm Oh, I forgot. You stated that you own Community speakers. They are right in my area. and I know the owner. And I have had arguments with him over this.
He uses the term program incorrectly. It should read peak. Peak meaning the max short burst hit that a speaker can handle.
Now as for what your speakers can handle at a 4 ohm load. You are saying that they are 300 watt continuous. So, if you put two of them on each side of the amp, your right at the correct rating.
Oct 07, 2008 09:25 pm Gotcha. Thanks. I found you article. Very helpful. My brain hurts!
Oct 08, 2008 08:34 am One last thing. The power amp will deliver 600w/channel at 4ohms and 350w/channel at 8ohms. If I connect my 300 watt @4ohm community speakers and my 200w @8ohm peavey speakers in parallel will I be okay?
Oct 08, 2008 10:45 am You should be OK. The total Ohm load will be 2.66 ohms. And the speakers can absorb up to 500 watts. You just may wish to turn the input knobs down around 2 clicks. About -3dB, and that should do it.
ShakuMember
Since: Dec 03, 2008
Dec 03, 2008 06:04 pm Now im very confused, i was wondering about the same thing and I was wondering if you help.
I just was on the Peavey website looking for subwoofers and I am specifically looking at the Scorpion 15" which is the one I believe that I have in the cabinet currently, and im trying to understand the specs.
It notes that Peak, program, and RMS (which i think is the same as continuous) are all different.
Dec 03, 2008 09:06 pm Well, the peak and RMS should be different. Peak is the max, and RMS is what the speaker can run at all day long.
Now Peavey is really bad about adding another rating in there. (So much for an industry standard.) They way they write there specs, is a Min, Standard, and Max settings.
RMS being the min, Program being the standard, and peak being the max. Thanks Peavey. I think Joe is loosing his mind.
The only specs that you need to be aware of, for matching the amp to the speaker are, RMS and Peak.
The RMS value is always .707 down from peak. And that is why we always use these two values for all calculations.
Peavey uses RMS as the minimum that it takes to drive their speakers at full range. Not a very useful spec for matching an amp up. So, what you want to look at for Peavey specs, are the continues spec.
Sorry this is so confusing. So many manufactures seem to decide on there own what to call there specs. If you need any additional information on this, I have written an article that appears here on the HRC. I mainly deals with how to set up a Bi-amp system. But I go into the math that you need for matching up your amp to your speakers in there as well.
If you need any more help on the subject, please ask away.
Jun 29, 2012 05:39 pm So let me get this straight Rob. You are saying in short terms that if you have speakers running a total of 800 watts you want to have an amp that is 800 watts?
So basically you would be running your amplifier at 100%, and you are also saying that if you do exceed 800 watts you should lower your attenuation by -9 to -12 dB?
I have been working in professional A/V for 7 years and have read many white papers and support documents as well, and what you are saying is just not standard. You should never run your amplifier at 100%. You should always give yourself head room when matching speakers to an amplifier and standard head room percentage is 20%. This will prevent the amp from being driven at full speed. Turning the gain down on each channel is necessary to prevent peaking, or you can limit it with a DSP.
I have never matched a speakers wattage to an amplifiers channel wattage, that is a recipe for disaster, clipping, or something going pop which is never good.
Gear Addict - a great rule of thumb is to give yourself head room. So if you have 4-200 watt speakers equaling a total of 800 watts and you split it by channels meaning two speakers on each channel so 400 watts per channel then you would want an amplifier that will push 480 watts or more per channel. Best practice is to provide an amplifier that will be at least 2 times the speakers continuous power rating (to be on the safe side).
You never want to match wattage on the speaker and an amplifiers total output. If you want to do that you will be replacing your amp or a speaker sooner than you expected.
Jul 02, 2012 12:38 pm Hey johnc1977. No, I wasn't suggesting an amp that is only 800 watts. I just wanted Gear addict not to exceed the peak rating on his speakers.
However, I did not clarify that statement in my responses. So, thank you for your addition to this thread. As you are correct that one should never run an amp at 100% EVER! :)
Jul 02, 2012 01:04 pm Turn it up to 11!
J-botByte-MixerMember
Since: Dec 04, 2007
Jul 02, 2012 03:13 pm sizzle....BOOM!
