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  #1  
Old 04-29-2007
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True Rms power?

After what I found out on the profile amp I bought, I started looking around to get an idea of what might replace it, but I dont know. What companies put out true rms ratings? I was talking to a guy at the local absolute audio store, and he said that you pay about a dollar a watt, and that most companies display higher rms than it actually puts out b/c its all about numbers.
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Old 04-30-2007
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you are extreamly right companies do blow up the RMS of their amps...the most Underrated would be Rockford Fosgate, basically if you stick with a name brand like Kicker..JL AUDIO, RF, Hifonics...your going to usually get what they advertise..however car audio is all about you get what you pay for...just do some research theres countless boards on car audio just type "car audio forums" into yahoo/google and you get a bunch of hits..just start dropin some questions in there..
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Old 04-30-2007
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I think im going to return my profile amp, and get a Kicker ZX400.1. I can get a new one off ebay for 150 bucks, and its ratings are true. I read a review on crutchfield saying that it came with a certificate sayin that it was tested at 489rms, and its advertised at 400.
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Old 04-30-2007
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For a measure of true RMS power rating, I think you have to find an amp with a rating like CEA-2006 Compliant.

I just picked up an Alpine MRD-M605 which is CEA-2006 rated at 600w rms into 2ohms. Hopefully it'll make my new 12" L5 bang! I have an Audiobahn 600w 4channel amp (75w at 4ohms) for my highs and it didn't come with a birth sheet or anything like the Alpine amp.

For the record, when I hooked up my Rockford P2 12" to the rear two channels of the Audiobahn it realy started to bang. Literally, it was a huge increase in SPL with more power to it. I had a 125w at 4ohm Alpine amp running it before, and when I put (supposedly) 300w rms to it with the Audiobahn it bumped pretty hard for 1 12" sub.
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Old 04-30-2007
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Yea, the kickers have a CEA-2006. The profiles dont.
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Old 04-30-2007
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All good comments.

"True" RMS power at a given distortion level (which can vary from amp to amp by the way -- if the level of distortion isn't given, you might as well assume it's clipping) can be represented for a number of different conditions:

1. Continuous

2. Intermittent

For the continuous condition in particular, environmental factors determine if an amp needs to be "derated".

In the industrial world, we commonly run into devices which give their specifications for a given sorrounding temperature and humidity range. As the temperature particularly changes, then the device may be derated -- have it's spec's lowered -- by a certain amount.

Sadly, most consumer audio gear doesn't have that kind of rating available for it for the most part.

I guess the thing you need to look for is compliance with a standard (as SeminaryRanger pointed out) which allows comparison between units that are rated to that spec, or to look for the distortion level and the continuous output power indication.

Now, having said that, continuous RMS isn't always an indicator of how well it will work. The rhythmic nature of most music gives a duty cycle where full power is not used all the time. Most audio manufacturers count on that in fact.

By the way, RMS stands for "root-mean-square" which is a shorthand for the calculation used to get the "true" power. In this case, we are measuring the "area under the curve" to determine the equivalent power.

Otherwise, they would just use the peak voltage -- but the AC waveform doesn't spend all it's time there during a cycle.

For pure sine waves, the RMS voltage is 0.707 times the peak voltage -- useful where pure sine waves are concerned but not useful for complex waveforms.

Anyway, too much information, but that's my .02
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Old 04-30-2007
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I personally have the ZX400.1. I got it from Ebay as well and I haven't had any problems. I say go for it. Mine was rated at 458 rms at 2 ohm so I like it.
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Old 04-30-2007
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The bottom line is: does it sound like what you want it to, lol...if it does, then the specs don't really matter.

Still, replacing a component that was "right" with one of unknown utility is tough.
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Old 04-30-2007
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If your going to go with a more powerful sub >500 watts rms, the rockford fosgate p6001 is awesome. It puts out more 35 more watts than it says and will drive any 500-700 watt sub with ease. You can get it for $210.
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  #10  
Old 04-30-2007
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Quote:
Originally Posted by n3elz
The bottom line is: does it sound like what you want it to, lol...if it does, then the specs don't really matter.

Still, replacing a component that was "right" with one of unknown utility is tough.
in one word.....NO. lol If I would have known that it wasn't going to put out what it says it will, I would have never bought it. I would have spent 70 bucks more and got a name brand amp that had a CEO rating. Lesson learned.

Now im trying to decide between a Rockford Punch P6002, and Kicker ZX750.1.

Also, will I need a capacitor for an amp like that? and if so, what Farad?

Last edited by SouthernMudSlinger; 04-30-2007 at 03:45 PM.
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Old 04-30-2007
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I'm not completely sold on the "value" of a capacitor, lol. I've read some convincing arguments on how they don't do as much as we would like for them to do in our minds.

As to the amps, I was looking at that same Kicker amp real hard and comparing it to that same Rockford mono amp. In my mind, they're not really comparable other than the fact theat they're both monoblocks. The Kickers, from what I can gather, are pushing over 900w rms at 2ohm on their birthsheets whereas the Rockford amp is somewhere just above 600w at 2ohm. There seems to be about a $200 price difference in the two as well. At SonicElectronix, they are selling the ZX750.1 for $220 but it is a refurb. unit. The Rockford P600.1 goes for $210 new.

Have you ever decided wat sub(s) you're going to run?
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Old 04-30-2007
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im not too sold on fosgate stuff. so if i were you, i'd go with the kicker amp ZX750.1 or whatever it was. now, as far as capacitors, with that amp, i'd say, if you really wanted one, get a 1-2 farad cap. in my experiance, they don't really work, but i like long bass notes, instead of a, like, bass drum, thump thump thump...if that made any sence? caps only work for short periods of time, for like, the bass drum kinda stuff. i'd rather save the $100 on the cap, and save it up for a bigger alternator.


my $0.02
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  #13  
Old 04-30-2007
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Quote:
Originally Posted by seminaryranger
I'm not completely sold on the "value" of a capacitor, lol. I've read some convincing arguments on how they don't do as much as we would like for them to do in our minds.

As to the amps, I was looking at that same Kicker amp real hard and comparing it to that same Rockford mono amp. In my mind, they're not really comparable other than the fact theat they're both monoblocks. The Kickers, from what I can gather, are pushing over 900w rms at 2ohm on their birthsheets whereas the Rockford amp is somewhere just above 600w at 2ohm. There seems to be about a $200 price difference in the two as well. At SonicElectronix, they are selling the ZX750.1 for $220 but it is a refurb. unit. The Rockford P600.1 goes for $210 new.

Have you ever decided wat sub(s) you're going to run?
There is a seller on ebay that has the Kicker zx750.1 for 230 bucks brand new. I got the profile amp from the same seller. Its a big company. Im wondering if I should go with the kicker zx400.1 b/c if the 750.1 actually pushes out close to 1,000 watts, thats alot of power for a reg cab, and I might have more of a battery drainage problem, and I dont really have that much money to get a bigger alternator. the ZX400.1 will probably push out close to 500rms.

And as far as subs go, I still dont know.

Last edited by SouthernMudSlinger; 04-30-2007 at 05:11 PM.
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  #14  
Old 04-30-2007
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If your worried about "power" with that kind of wattage..honestly dont be concerned..im running

http://mobile.jlaudio.com/products_amps.php?amp_id=402 wired to two ohms..for two 12in JL's then i have http://www.alpine-usa.com/US-en/prod...model=MRP-F450 running infinity components in the rear and front..and i experience no dimming with the stock battery and alt. from what i understand you dont start to have noticeable dimming until your past the 1000-1200watt mark..however this is all just from my experiences..from what your saying..it'd also help some of the people here to know what sub(s) you are planning on running so perhaps one of the more knowledgeable members can point you in the right direction i mean..whats the point of buying a 900wat amp when your going to push a 300wat sub? Do you see my meaning...get set on a sub, then come up with a few ideas about the amps then maybe we can give a more precise answer. If i missed where you said what driver you were going to be running i apologize

-Trevor
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  #15  
Old 04-30-2007
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Im not going to run my old subs, im just not sure what sub im going to use. Really the only thing that is making me undecided on a sub is the fact im not sure what the max mounting depth I can get away with. I just need to do some more measuring. My old Rockford P1s have a mounting depth of 5-3/8"...im not sure if thats with or without the plastic peice on the back, but I think 5.5" is about as far as I can go depth wise for a sub. I want to try to get a normal sub instead of a shallow mount sub.

I like the Rockford T1 b/c it looks really beafy and all, but its a bit on the spendy side, and its dept is about an 1" too deep, although the price is a bit of a bigger deal than the depth.

Last edited by SouthernMudSlinger; 04-30-2007 at 06:21 PM.
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  #16  
Old 04-30-2007
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Capacitors are only good for "sudden" hits that blow over quickly really. If you run into an really extended time of high power, the cap drains quickly -- even a large setup.

The very best thing you can do is use the heaviest gauge wire you can run, and run a ground wire besides. If you don't run the separate ground, then have a look at the body to frame grounding and keep everything low resistance by improving and/or cleaning them up.

This applies to ham radio operators running huge mobile setups also.
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  #17  
Old 04-30-2007
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you could pick up a JL W6v2 online for cheaper than the T1 and it doesnt require much space at all.
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  #18  
Old 04-30-2007
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Quote:
Originally Posted by 0sixsport
you could pick up a JL W6v2 online for cheaper than the T1 and it doesnt require much space at all.
7.6" deep? Im not sure what you mean by that it doesn't require much space......looks like it does.......its the 12" version.....cant find specs for 10".
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  #19  
Old 04-30-2007
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Quote:
Originally Posted by SouthernMudSlinger
7.6" deep? Im not sure what you mean by that it doesn't require much space......looks like it does.......its the 12" version.....cant find specs for 10".
I have the ten inch and it fits perectly behind the passenger seat. I guess it wouldn't fit in a regular cab, it has a 6.9 mounting depth. My bad.
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  #20  
Old 04-30-2007
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Quote:
Originally Posted by 0sixsport
I have the ten inch and it fits perectly behind the passenger seat. I guess it wouldn't fit in a regular cab, it has a 6.9 mounting depth. My bad.
hmmm........kinda tough findin a sub to fit and handle that much power. Has this been done before? (high powered amp and big sub in a Reg cab ranger). I know bigger boxes have been done in a reg cab ranger, but they eat up valuable leg room.
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  #21  
Old 04-30-2007
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Mounting a sub in the single cab is going to be difficult if you don't go with a shallow mount sub it seems like. Installing a powerful sub ain't going to make it any easier.

I know you aren't particularly interested in the shallow mount, but you might give these a look.

Kicker CVT 12
Rockford Fosgate P3 12

Just some suggestions. I know a lot of people like the Kicker CVT subs and say they hit really hard. And the 2007 model P3 are worlds better than the Punch subs they replace.


Just trying to help.
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  #22  
Old 04-30-2007
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Quote:
Originally Posted by seminaryranger
For a measure of true RMS power rating, I think you have to find an amp with a rating like CEA-2006 Compliant.

I just picked up an Alpine MRD-M605 which is CEA-2006 rated at 600w rms into 2ohms. Hopefully it'll make my new 12" L5 bang! I have an Audiobahn 600w 4channel amp (75w at 4ohms) for my highs and it didn't come with a birth sheet or anything like the Alpine amp.
I have one of the Alpine MRD-605's pushing a JL-10w3v3... man it's good. hahah. I'm sure you will love it. FWIW, I have it in my cobra, and I have to keep the bass turned down most of the time! :p
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Old 04-30-2007
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If "true power" is a big deal to you, go for something with CEA-2006 compliance. Most Rockfords, Alpine & MTX amps are underrated to their actual power, but the CEA-2006 compliance gives you a good RMS the amps will produce (even though MOST of these amps will blow the RMS away).
My MTX amp has a RMS of 45w per channel, but the birth certificate states 55w per channel or 225w bridged.

Profile amps aren't bad from what I hear, they just aren't CEA-2006 compliant. It doesn't make them bad, it just means their actual power may not be the power they're rated at on the box.
If your current profile amp isn't powerful enough, try stepping up to the next size (as long as it's within your sub's RMS power range). Assuming the place where you bought it has a decent return policy.

I've been looking at the AP1000 & AP1200 for my 15" sub, but I also like the Rockfords & MTX amps.

As for caps, they're mostly a band-aid to a more serious issue. If your lights (headlights or interior) dim severely when your bass hits (while the vehicle is running) chances are that your alternator isn't outputting enough power to handle your normal electrical load PLUS your amp.

For subs in a reg cab.... back in the early 90's I saw tons of S-10's & Rangers with FOUR ten's squeezed behind the seat. There wasn't ANY room left back there, but the boxes didn't come above the back of the seats. The amps usually went under the seat or sometimes hidden behind the glove box area. A few guys put their amps, crossovers, etc. out back using the old aluminum tool box trick.

Good sound depends on the installer, the subs & how well the box is built.
If you build your box out of 1/2" osb and use $29 subs, it probably isn't going to sound very good.
If you build your box with 3/4" MDF or Particleboard and use $200 subs, it's definitely going to sound better. Pay attention to details! Internal bracing & angles cut on the individual panels will affect how strong & sealed your box will be. Sometimes I'll even make the front (where the subs are mounted) with two layers of 3/4" MDF or Particleboard that's been glued & screwed together.
I prefer sealed boxes. They will usually yield better sound quality, but have less SPL than ported boxes. To me, ported boxes sound too loose & boomy. A sealed box will require more power than a ported box to produce the same SPL.

Once upon a time, I had a friend who wanted me to build him a sealed box for his reg cab Nissan truck. He bought 1/2" osb. I told him he should have spent the extra $10 for 3/4" particleboard if he wanted it to last. He didn't want to spend the extra cash. Ok, I built the box with internal bracing, glue, caulk, the works. The subs were two 10" MTX Blue Thunder (they would handle 200w RMS each. He had a 400w amp (forgot the brand) Long story short, in a few months he came back to me & wanted me to build him a new box. He had been cranking the stereo full blast (it's a wonder he didn't go deaf) all the time & he'd blown the BOX apart. Even with ALL the extra effort I put into the build, the osb had started to break apart.
Needless to say, the second time he bought 3/4" particleboard. That was about 10 years ago & I haven't heard anything bad about that second box.

If your sub is rated 200w RMS & 300 max, you could get by with as much as a 250w amp (that's CEA-2006 compliant) and you should be fine.
If your sub is rated 200w RMS & 300 max, I wouldn't get a 300w amp (that's CEA-2006 compliant). That's over the border for me.

Power, grounding & fusing the amp properly will affect the power of the amp too. I always go one or two steps above what's recommended when it comes to power & ground size. For my 400w MTX amp with two 25amp fuses, I'm running 4ga power & ground wires. I could get by with 8ga wires, but I like knowing that my amp will not starve for power due to a small wire.
Grounding is just as important as the power. Ground needs to be the same gauge as the power (and as short as possible) & attached to a solid point on the body (preferably sanded clean) with a secure nut or bolt.
Again, I go the extra mile & I drill a new hole in the body (sanding both sides clean) for a stainless hex bolt to attach ALL the ground wires. Attaching all grounds to a common point helps eliminate ground loops.

Good luck!
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  #24  
Old 04-30-2007
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Buggman beat me too it. look for CEA-2006 compliance for those certified RMS ratings.
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  #25  
Old 05-01-2007
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Arc audio actually puts out more than what the amp is haha. Like they have a 4000 watt amp but it really puts out 4300 or something like that. I think alpine also puts out true RMS. My JBL 1200 puts out 1100rms which is kinda close.
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