# matching speaker RMS to amp RMS



## truebluefoo (Jun 1, 2011)

Do I need to match the component speaker RMS to the amps RMS ?

i want to run Hertz HSK 165-XL (150W RMS) do i need an amp that runs at 150W RMS @ 4ohms for max performance......or possibly 200W RMS @ 4 ohms? or possibly 110-120W RMS @ 4 ohms?

Also I'm looking at those HERTZ speakers vs Audison AVK6 and a Zapco 750.2 amp, Massive Audio HD 800.4 amp, maybe an Arc Audio SE....Any opinions?

Also, should i look for a 2 channel amp, a 4 channel amp running just 2 of 4 channels, or a 4 channel bridged to fufill my speakers 150W RMS rating


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## nick650 (Feb 7, 2011)

To get the most out of it, you want to match the rms or exceed it.


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## eggyhustles (Sep 18, 2008)

Exceeding would be ideal, but not required.


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## truebluefoo (Jun 1, 2011)

appreciate the response....any experts with additional info on the subject?


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## jalba (Dec 20, 2010)

My preference is to first pick speakers/subs that you want. Then find an amp that will do the rated power of the speakers plus some. The "plus some" depends on how the amp is rated. It's also important to do your research and try to find out if the speakers/subs are underrated/overrated, and take that into account.

Here's an example of a single 12" sub setup...

AQ HDC312 - underrated at 1000W RMS. Will handle 2500W, start getting mechanical noise at around 2600W. I personally want to put around 1500W to it. So I pick an amp that will do 1500W+. Amp A is rated at 1500W at 1%THD, meaning to get a cleaner, 0.1%THD type signal, it might only put out 1200-1300RMS or less. Amp B is rated at 1700RMS @1%THD, meaning I could probably put a 0.1% THD signal @ 1500W RMS to the sub. Amp C is rated @1600W RMS @0.1%THD. 

In this case I would go with Amp B or Amp C, not Amp A. Because it's not just about power, it's about signal. If you had more money to spend, you could go with even higher numbers above these two selections, which is nice in case you ever want to upgrade to subs that will handle more power, etc... But B and C would be the bare minimum if I decided that I wouldn't ever use that amp to power a bigger setup. Also take into account that bigger amps, once you get to a certain point, will require major electrical upgrades like extra alternators or a good quality HO Alt, better and more batteries, etc..

And I personally would recommend 0ga wire for the big 3 and for amp wiring on ANY size amplified system.


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## truebluefoo (Jun 1, 2011)

awesome, good info


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## jalba (Dec 20, 2010)

Another thing to keep in mind...

If an amp is rated at 1500 RMS @ .01%THD, that might be at a point where the gains are only turned up 1/3. A second amp might be rated at 1500 RMS @ 1.0%THD, which may be 2/3 or 1/2. And a third amp might be rated at 2000 RMS, @ 10%THD and 7/8 or full gain. A lot of newbies seem to think that an amp does it's rated power with the gains turned all the way up, but that couldn't be further from the truth. You have to be careful because that 1500W rated amp may actually send 3KW if you turn it all the way up, and it could blow both your speakers and amp. Finding an amp that will put out a clean signal at the exact RMS wattage you need to precisely match the actual RMS daily handling of your speakers/subs is just half the battle. To verify these things and to properly set your gains to match those numbers requires double checking math and formulas, and having the tools to measure the variables. This will invariably be a DMM (preferably one that can measure RMS), and an oscilloscope. Even better would be to add an ammeter with 300A+ capability, and a clamp to use this function. Top Tier tools like a RTA and Termlab aren't really needed unless you're seriously competing, or just have a lot of free time and a lot of money, and want to expand your hobby.

Don't let the easy to find high prices scare you away from "high tech" tools like Oscopes. They make a portable Oscope that can fit in your pocket, measures RMS voltage, signal, and all the other things an oscope measures, and is only $70 brand new. It's not a perfect Oscope, but it's just about perfect for car audio needs. You can always find insanely low prices of things, you just have to do a little digging. I can save you the digging if you're interested.


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## truebluefoo (Jun 1, 2011)

ya I am interested actually. I plan to learn more about the sound and electronic theory behind this stuff for fun. I enjoy mathematics, I'm not anything close to math whiz but I enjoy it. Anyways, any info about these audio tools and how they are used correctly would be sweet.


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## truebluefoo (Jun 1, 2011)

interesting about the gain controls....just like you said ....I thought of course the Max RMS rating would be with the gain control at 100%.......I'm wondering why that wouldn't be some sort of industry standard at least for quality products....


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## jalba (Dec 20, 2010)

truebluefoo said:


> interesting about the gain controls....just like you said ....I thought of course the Max RMS rating would be with the gain control at 100%.......I'm wondering why that wouldn't be some sort of industry standard at least for quality products....


The Oscope is called the ARM DSO Nano, there are different versions of it. Some are 1 channel, some are multi-channel. Some have tone generators built in, some don't. So read up on them, watch the youtube vids where people show how to use them, etc... Here's a link to the one I got for $70, it's a single channel model.

ï¼�2Msps sampling rateï¼ŽARM DSO Nanoï¼ŽPocket Oscilloscope | eBay

And regarding the gain settings, it would indeed be easier for consumers to understand. There are probably some VERY high end amps throughout history that have been made so that the gain pots are set so that the max is at the actual rated voltage, but it's a topic that I've never really seen discussed. And I was unaware of this problem myself until I started testing amps. Car audio, and audio in general is a subject so vast that even if you had an electrical or audio engineering degree, you would still learn new things all the time, the more you brainstormed with other people, tested new theories, new equipment, etc... It's a field that involves many different fields of science, so to ever expect to fully understand all of it would be foolish for anyone to think.


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## truebluefoo (Jun 1, 2011)

Thanks for the info jalba...im definitely thinking about picking one up........another question I have is about my component speakers are rated at 125 RMS...my 4 channel amp puts out 100x4 @ 4ohms........if i bridge them...im looking at 350-400W per channel.....can i do that and set the gains low....or do you think it will definitely be blasting the hell out of my speakers....some1 said I should be good if I set the gains right...just wanted another perspective


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## Fricasseekid (Apr 19, 2011)

I have some PG comps rated for about 125 watts rms. They are currently on amp that's rated 100x2 @ 4ohms. I only have my gain up 1/4 of the way and they get loud and stay clean!
I measured my output with a DMM and I'm only puting 50-60 watts continuous power to the speakers right now. 
It does not take alot of power for mids and highs to sing, it just takes clean power for them to sound good. 

Do a search on how to set gains. Look up the method Bikinipunk recommends that involves playing a silent track (or switch your HU to aux) then cranking the gain until the noise-floor is just below audible. Keep those speakers at 4 ohms and you should end up with plenty of volume and enough overhead to keep you happen. Plus this method protects your speakers and amps as well.


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## Fricasseekid (Apr 19, 2011)

I'm not beyond a bit of spoon feeding, so here ya go:

http://diymobileaudio.com/forum/diy...ed/99024-setting-gains-whats-your-method.html

Post #2 specifically, but there's alot of good info in this thread. Basically oscopes and RTAs and all that fancy equipment will tell you exactly what your system sounds like to a computer, but it's your ears that matter. I'm if the opinion that if you need all that fancy equipment (unless your doing time alignment or something) to tune your system then you making adjustments that are beyond the level of what you can hear anyways. Tune it so it sounds good to you, enjoy it! I believe Bikinipunk says something to the
same effect.


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## truebluefoo (Jun 1, 2011)

badass...thanks for info...im not even going to bridge channels since you mentioned it. I'll check this article out too..Thanks!


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## Buzzman (Jul 26, 2007)

The answer to your question depends on whether the speaker power handling recommendations are in fact based on RMS standards, as compared to "music power" or "program power." A lot of speaker manufacturers' power recommendations are based on the latter, which are definitely different from the RMS standard. Here is an article that explains all of this really well and provides good guidance:

Speaker Selection and Amplifier Power Ratings


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## truebluefoo (Jun 1, 2011)

Thanks for the update....good info..I'm reading it now


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## antikryst (Feb 26, 2011)

ive heard hertz milles running on 65W RMS audison amps on a soundboard a couple of days ago and they sounded awesome and real loud. trying to figure this out myself too since im looking for a new amp for my focal v30s and im just running them using a cheap no brand supposedly 80W rms amp currently and looking to improve the SQ.


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## ZAKOH (Nov 26, 2010)

It's a crazy RMS finding. How many 4-channel amplifiers out there that are rated for 150watts RMS per channel? Most free air/IB subwoofers will not be able to handle so much power, yet the component set with 6.5 woofers will? 

Anyways, I suspect the answer depends on each individual speaker. Some will sing happily with an amp rated 1/2 or 1/3 of speaker RMS rating. The RMS rating is supposedly just the thermal rating. It's not the mechanical rating. It's possible for a speaker to overexcurt mechanically at the rated wattage.


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## Buzzman (Jul 26, 2007)

ZAKOH said:


> It's a crazy RMS finding. How many 4-channel amplifiers out there that are rated for 150watts RMS per channel? Most free air/IB subwoofers will not be able to handle so much power, yet the component set with 6.5 woofers will?
> 
> Anyways, I suspect the answer depends on each individual speaker. Some will sing happily with an amp rated 1/2 or 1/3 of speaker RMS rating. The RMS rating is supposedly just the thermal rating. It's not the mechanical rating. It's possible for a speaker to overexcurt mechanically at the rated wattage.


In normal listening situations, depending on the efficiency of the speaker you are using and the music you are playing, you might be shocked at how little power on a continuous basis your amps are really putting out. Some speakers need only 1 Watt to produce 95 db or higher levels of output! Amplifier rated power and actual power are two very different things. Do not conclude that the rated power is what your amp is actually sending to your speakers when playing music. There may be peaks in music that causes your amp to approach or even exceed its rated power, but that occurs in short bursts.


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## truebluefoo (Jun 1, 2011)

Ya, I read the material above for info regarding matching RMS rating on amp vs speakers, It talks alot about program power vs. RMS power. So far while buying speakers I haven't read anything rated at Program power (I'm new though), everything is rated at RMS, so I'm still under the impression that it is best to closely match [email protected] Ohms per channel to the [email protected] specific Ohms per speaker. Probably best to get an amp rated *above* the rated RMS of the speakers to avoid clipping and because the speakers will be able to handle brief spikes in power above it's RMS rating(be mindful). However, based on what a couple people have said, the components I'm looking at (Audison AVK6) will most likely be plenty loud running at significantly less watts than the speakers are rated for, which is a great thing for the amp and the speakers. For example a good match would probably be 4x150W @ 4ohms RMS (amp) : 125W @ 4ohms RMS (speakers) or perhaps 50x4W @ 4ohm (making roughly 200W @ 4ohm when bridged). Another important fact someone told me...which might be in this thread is that: Full Gain on your amp most likely does not correlate at all with the RMS rating of your amp and may even be below Half-Gain.


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## Fricasseekid (Apr 19, 2011)

ZAKOH said:


> It's a crazy RMS finding. How many 4-channel amplifiers out there that are rated for 150watts RMS per channel? Most free air/IB subwoofers will not be able to handle so much power, yet the component set with 6.5 woofers will?
> 
> Anyways, I suspect the answer depends on each individual speaker. Some will sing happily with an amp rated 1/2 or 1/3 of speaker RMS rating. The RMS rating is supposedly just the thermal rating. It's not the mechanical rating. It's possible for a speaker to overexcurt mechanically at the rated wattage.


If you were to take comps rated to handle 125 watts and throw 70 watts at them; with a 60 hz sine wave they might be destroyed but play that same power at 200 hz and they mught play it happily. The mechanical and thermal power handling isn't gonna be the same depending on what the speaker is playing. That's why the I/B subs can't handle so much cause they are working alot harder to reproduce those lower frequencies.


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## Fricasseekid (Apr 19, 2011)

Fricasseekid said:


> If you were to take comps rated to handle 125 watts and throw 70 watts at them; with a 60 hz sine wave they might be destroyed but play that same power at 200 hz and they mught play it happily. The mechanical and thermal power handling isn't gonna be the same depending on what the speaker is playing. That's why the I/B subs can't handle so much cause they are working alot harder to reproduce those lower frequencies.


Working alot harder with less air to suspend them. 

Not a very technical explanation. But I believe this is part of how it works.


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## tyroneshoes (Mar 21, 2006)

Also, these rms number are done fullrange. Put a higpass crossover on your components and power handling increases significantly.


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## truebluefoo (Jun 1, 2011)

I see your rockin the Zapco DC 1000.4 .....exactly what i was looking for considering 4x150W @ 4ohm RMS if i remember correctly...settled on Massive Audio Nx4 and Nx2 considering price and good reviews....plus I'm a noob and I don't understand the whole symbilink deal or any extensive tuning procedures involved with nice amps......correct me if I'm wrong but symbilink converts analog signal to digital?


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## Fricasseekid (Apr 19, 2011)

tyroneshoes said:


> Also, these rms number are done fullrange. Put a higpass crossover on your components and power handling increases significantly.


Are you sure, cause my PG comps are rated for 125 RMS and there is now way they could handle any low frequencies at that amount of power. I have them at about 60 watts and they are pushing it high passed at 80 hz. They do get loud though!


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## Bayboy (Dec 29, 2010)

Fricassee, what first must be considered is how the manufacturer rated them. Yes they may handle 125, but did the manufacturer rate that high passed? Yes they may play as low as rated, but again does the manufacturer state at what power level? There's only a few companies that put out that info... the rest use marketing tactics. I wouldn't say they lied, just don't give the full data. Other than that the next best thing to do is use your ears.

Sent from my SCH-I500 using Tapatalk


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## truebluefoo (Jun 1, 2011)

couple questions off topic....what are I/B subs ?? 
and Would it be wise to set the amp's high pass crossover running to my components?


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## Fricasseekid (Apr 19, 2011)

Bayboy said:


> Fricassee, what first must be considered is how the manufacturer rated them. Yes they may handle 125, but did the manufacturer rate that high passed? Yes they may play as low as rated, but again does the manufacturer state at what power level? There's only a few companies that put out that info... the rest use marketing tactics. I wouldn't say they lied, just don't give the full data. Other than that the next best thing to do is use your ears.
> 
> Sent from my SCH-I500 using Tapatalk


Thier probably rated high pass. But no biggie, they sound great!


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## tyroneshoes (Mar 21, 2006)

truebluefoo said:


> I see your rockin the Zapco DC 1000.4 .....exactly what i was looking for considering 4x150W @ 4ohm RMS if i remember correctly...settled on Massive Audio Nx4 and Nx2 considering price and good reviews....plus I'm a noob and I don't understand the whole symbilink deal or any extensive tuning procedures involved with nice amps......correct me if I'm wrong but symbilink converts analog signal to digital?


Symbilink is kinda confusing to explain but zapco breaks its down in a pdf you can dl from their site. Consider it a line driver that also makes it very hard for any noise to enter your system. Gives the amp something like 18 volts max. After using symbilink, I dont really ever want to return to rcas and if I do, it would be with a high quality line driver.

I got the zapco because I always have good experience with them and I needed eq and time alignment and my sony es wouldnt fit. Plus if I want, its really easy to add and control another amp should I go active. yep 150x4, or 500x2. Very happy with the amp.


Other person, yes highpassing your comps will allow them to take much more power.


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## Fricasseekid (Apr 19, 2011)

truebluefoo said:


> couple questions off topic....what are I/B subs ??
> and Would it be wise to set the amp's high pass crossover running to my components?


Set your amps high pass so that your comps pick up where your subs leave off. I have mine at 80 and it keeps the mids real clean.


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## tyroneshoes (Mar 21, 2006)

CDT rates their comps to take like 200 watts rms (highpassed at 90 hz though). Look at the fine print.

Yeah 80 highpass on the comps and 80 lowpass on the sub is great starting point. Then try switching sub phase.


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## truebluefoo (Jun 1, 2011)

nice, will do ...thanks


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## Bayboy (Dec 29, 2010)

tyroneshoes said:


> CDT rates their comps to take like 200 watts rms (highpassed at 90 hz though). Look at the fine print.
> 
> Yeah 80 highpass on the comps and 80 lowpass on the sub is great starting point. Then try switching sub phase.




That's why you gotta give CDT much respect for their honesty. Not a whole lot of companies willing to put their rep on the line. Their website graphs showing the different performance of each driver in various installs (enclosed, door, etc) is excellent as well.


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## mgood (Nov 5, 2012)

ok i could use a little help here as well I have the hertz hsk 165xl for my front stage running on my jl slash 300/4 v2 bridged pumping 150rms to them.. I am not sure if its really 150 more or less. but today i had to epoxi the bottom of the cone of one back to the butil rubber ring. So i am just thinking some one shyed on the glue.... the speaker them selves coil wise are just fine just comin g apart a tad. How ever my poor polk mm 691 cross overs blew apart on my jx amp.. So I am wondering do i get a biger amp for the Hertz speakers. like 200 or 300 my self.. someone told me i needed the rms to the hertz to be in that range. so what amp.. hdp 900x5 and put 300 t the hertz and 500 to a sub.. and the slash to the polk for cleaner power?????????????????? how much is everyone pushing th the hertz


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## Bayboy (Dec 29, 2010)

Good lawdamercy!! What the heck are you doing to your gear?


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