# Will 5 extra watts RMS per channel make much difference?



## ThingDriver (Feb 16, 1999)

I have a 97 Jetta that I want an MP3 player in. The Alpine CDA-9813 and 7894
have 27W X 4 RMS/60 peak, most other ones (Pioneer, Kenwood...) have 22 RMS. I hope to keep my existing speakers and avoid getting an amp. Is it worth going the extra $175 for marginally more power? Will it make that much of a difference. Not asking about whether Alpine is better than Pioneer or Kenwood - I know it is - but with the factory speakers, I'm not gonna notice that.
Thanks,
Ted


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## GTakacs (May 17, 2002)

*Re: Will 5 extra watts RMS per channel make much difference? (ThingDriver)*

I'm glad you know that Alpine is better than Pioneer/Kenwood








As far as 27W versus 22W, you should read the specs in detail. If you would, you'd see that the 27W rating is given at 16V supply voltage. And we all know that 16V doesn't really exist in real life applications unless you're planning on running the HU on a test bench with a 16V power supply. I'm sure the other 22W ratins are given at 14.4V, a much more realistic value.
Power = voltage x current
Current = voltage/resistance
Hence Power = voltage^2 / resistance
So the maximum Power you can get ideally from 14.4V source on 4 ohm speakers is:
(14.4Vx14.4V)/4 ohm = 51.84 Watts. That's rougly 26W RMS. But you can only get 26W RMS if you have zero voltage drop on any of the components, and we all know that is not possible.
So in once sentence: it is pathetic to post 27W ratings, it is for nothing more than hype and to get bigger numbers than the others. It seems like Alpine is better in hype, BS and marketing than the others (it almost worked on you







), but it doesn't really mean it is better than the others (can you tell I have a Kenwood HU?







)
But to answer your original question if you'll be able to hear 5W difference (I just showed you it's not even 5W really), the answer is NO. Since our ears work on a logarithmic scale which means that you'd need 10 times the power to get twice the volume, you will not be able to hear the 5W difference at 22W versus 27W. Can you beleive that a 250W sub is only twice as loud as a 25W one???? It's crazy, isn't it? But unfortunately that's how our ears work and there is nothing you can do about it.....
Edit: spelling bugs....


[Modified by GTakacs, 10:50 AM 1-21-2003]


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## EgoTrip (Jun 2, 2001)

*Re: Will 5 extra watts RMS per channel make much difference? (GTakacs)*

Interesting, but wrong.
The peak/RMS power ratings that Alpine lists on the head units is rated at 14.4V. 16V isn't listed anywhere, except maybe where it says (11-16V allowable). 
On one hand, rating power amplifier output at 14.4V isn't exactly "fair" since most car electrical systems won't put out that high. I think on average you get somewhere around 13.5-13.7. But the head unit ratings will work as listed. They require a hard wired power conneection with 10g wiring, but you WILL get the listed output voltage from the head unit.
The 22W RMS rating of the lower power units is rated at a standard 12V.
To answer the original posters question, there IS a difference in power output between the two, but it's not as simple as 22W vs. 27W. You have to remember that the units with the, as they list them, 60W amplifiers, are a higher quality, newer generation amplifier. From listening tests I did at a local installer, comparing the 50W and the 60W head units with the same speakers, the 60W systems had more punch. Noticable difference. I actually did a listen test myself.
And, while the formulas your listed to get power and current are technically correct, it doesn't work that way in the real world of electronics. There's also the issue of amplifier efficiency, linearity, etc. The formula may work at 12V, but you can't make a simple calculation to get true output at 14.4V. Did you ever see the sheets that some amp manufacturers include that show the true output vs. rated output of the amp in the box? They're all different.
The bias in your post was overwhelming, but you could at least have looked up the data you posted.


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## GTakacs (May 17, 2002)

*Re: Will 5 extra watts RMS per channel make much difference? (EgoTrip)*

OK, I stand corrected (kind of)......
This is from the spec sheet of the 7894 verbatim:
Power Requirement: 14.4V DC (11-16V allowable)
Maximum Power Output: 60Wx4 Under maximum operating voltage and input signal into 4 ohm loads.
Continuous Power Output: 27Wx4 Per EIA-517 standard, 40Hz to 20kHz, 0.8% THD with 14.4V DC suppy.
Again, to get 60W maximum into 4 ohm you would need (as per the equation above) around 15.5 V ((15.5^2)/4=60.0625W). And that is without any loss. So to even say that there is a 60W maximum is pathetic since we all know that good old mr. Ohm doesn't lie and it is only possible at 15.5V! Note that 16V is listed as "maximum allowable power" and the 60W rating is given at "maximum operating voltage". So I took the liberty and assumed that the two are the same, that is where I got the 16V rating from. So I DID do my homework and read the specs before I posted.
Also to get the 27W RMS rating you'd need 54W max rating that equates to 14.7V. I might be wrong on my math, Alpine is definetely not too conservative when it's giving out ratings. I think I ned to look up the EIA-517 standard to see how they "fudge" the numbers.....
As far as hearing the 5W difference, you must have some excellent hearing capabilities if you can pick up the volume difference between the limits of acceptable distortion in a car traveling 50mph (even if it's a dub and sounds very quiet). Just FYI 22W vs. 27W is a 0.89 dB gain and we all know that most of us can't hear differences less than 3dB. And as far as the 60W "having more punch" it is clearly a definite measurement of volume! The more punch could have been due to different equalization, I'm not talking about the equalizer that you set, I'm talking about the "flat" line base that is unique to each HU and to the fact that no two HU will sound the same.
Note that I have not compared the 22W vs 27W RATED output stereos in person, but I would not worry much about the difference between these numbers.
Also EgoTrip, I'd welcome the time when you show me "birth sheets" of internal amps that are built into HUs. I know you were referring to separate amps, but why bother bringing up stuff that has absolutely NOTHING to do with the matter in question?
Oh, and I keep wondering at which point was I biased toward anything in my post? Just because I stated the obious that manufacturers (any and all) keep on boasting numbers just to seem better?


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## EgoTrip (Jun 2, 2001)

*Re: Will 5 extra watts RMS per channel make much difference? (GTakacs)*

The 60W and 50W ratings they list are peak values anyway, so they shouldn't even be under consideration. I wish companies would quit listing peak ratings since it almost equates to a lie. Can you reach a 60W output for .01 seconds, for .1 seconds? There's no standard. RMS, the "true" power output in the real world is much better.
There's a local installer who has little cards with some cursory info and prices attached to the units for sale. Some list RMS, some list peak ratings. Talk about confusing! I would say I know a lot about this, and I was still confused as to what amps/head units I would need for my setup. I ended up giving up, going through on-line literature, then going back to the store to do the listen tests.
I did hear a difference between the 27W and 22W units. And I made sure that each one was set flat, no EQ, no bass boost, loud, extra treble, etc. just to make sure each was on as even a level as possible. Unfortunately, a volume of "20" on one wasn't the same as "20" on the other, so you had to play with those values a little. In a very unscientific "blind test" with a friend of mine who was along, and also buying a new HU, she could also hear a difference.
I'm not equating the noticable difference to a "measly 5W'. I'm sure that, if anything, the extra power is only half the picture. Alpine notes that the amp circuitry in the "V-Drive" units is a higher quality amp. Listen to a subwoofer on a 500W Sony amp, then on a 500W Audiobahn amp. There is definately a difference, even though they both have the same ratings. I have no doubt in my mind that the 7894 had more punch to it, like it was connected to a higher power amp. I also should say the listening test was inside an installers shop, not in anyone's car.
I believe the only true rating to compare is the 22w vs. 27w, and is the question the original poster asked, if the 5w difference was a big deal.
I only mentioned the amp ratings sheets to explain my point. I wish HU's would include a spec sheet on actual ratings, but since the numbers are so much lower than an average amp, I imagine each HU would be pretty close in it's actual output.
The bias I mentioned was your sarcastic knock on Alpine being superior, and mentioning your dislike of Alpines tactics and that you owned a Kenwood. Not overt bias, but bias none the less. I personally could not agree more with Alpine's ratings system on their amps. They're all rated at 14.4V, and they also mention 12V output, but if you compare their "real world" output at 12V, and compare them to other amps, their prices don't look so good anymore. I bought, and returned an Alpine amp because of this. After talking with the installer about my plans, he looked at the sheets for the amp and told me I would need a better electrical system to get those numbers. Talk about embarassing...


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## GTakacs (May 17, 2002)

*Re: Will 5 extra watts RMS per channel make much difference? (EgoTrip)*

EgoTrip, I'm so glad you didn't take my post the wrong way! I'm glad we're on the same page! Anyone who is serious about their tunes should consider an external amp and turn the internal one off anyway.......
As far as my bias goes, I have nothing against Alpine (I think they produce quality stuff) and I do own Kenwood (I think the also produce quality stuff) and my sarcastic commets were meant to be funny







. Cheers!


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## 83 Rabbit GTI (Jun 26, 2002)

*Re: Will 5 extra watts RMS per channel make much difference? (GTakacs)*

quote:[HR][/HR]Again, to get 60W maximum into 4 ohm you would need (as per the equation above) around 15.5 V ((15.5^2)/4=60.0625W). And that is without any loss. So to even say that there is a 60W maximum is pathetic since we all know that good old mr. Ohm doesn't lie and it is only possible at 15.5V! Note that 16V is listed as "maximum allowable power" and the 60W rating is given at "maximum operating voltage". So I took the liberty and assumed that the two are the same, that is where I got the 16V rating from. So I DID do my homework and read the specs before I posted.[HR][/HR]​The one thing overlooked in these dicussions is that The Alpine "V-Drive" in their HU actually ramps up the rail voltage to 16 volts or so. ( according to Alpine )To my knowledge, theirs is the only HU that does this, allowing the amp to put out 27 watts RMS. I'm not familiar with the method they allegedly use to do this. The Kenwoods, Pioneers, Blaupunkts, etc. do no bump the rail voltage and usually muster about 15 watts or so ( despite Kenwood's and JVC's claim of 22 watts ). I also have HU's made by Pioneer, Kenwood Excelon, JVC, and Blaupunkt. The Alpine V-Drive is noticeably the most powerful. One thing I have noticed though, and it could just be me, is that the Alpines on occasion generate more harshness in certain midrange bands ( around 3000 hz ) than the other makes I mentioned. I don't think it is their amp, as mine will do it even when paired with an outboard amp. Other than that, they have noticeably better output. The JVC - SH909 must have a wonderful preamp section as it seems to have the smoothest sound and wonderful stereo separation. They are all good though.


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## Bimmer (Dec 15, 1999)

*Re: Will 5 extra watts RMS per channel make much difference? (83 Rabbit GTI)*

Agree with GT and Ego, main thing is to ignore minor things like the power difference and instead focus on listening to the sound quality back to back, and also play with the controls/ergonomics/functionality and pick the one that you like best.


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## Non_Affiliated (Feb 12, 2002)

*Re: Will 5 extra watts RMS per channel make much difference? (Bimmer)*

I eliminate all concerns for deck power, I prefer non-amplified headunits. I hate those darn amplified finger warmers.


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## EgoTrip (Jun 2, 2001)

*Re: Will 5 extra watts RMS per channel make much difference? (Bimmer)*

quote:[HR][/HR]Agree with GT and Ego, main thing is to ignore minor things like the power difference and instead focus on listening to the sound quality back to back, and also play with the controls/ergonomics/functionality and pick the one that you like best.[HR][/HR]​Ah yes, controls/ergos/functionality. A very important factor. After you buy your neat little toy, you have to live with it. Logically, I should not have bought the HU that I did, because the controls are a nightmare to learn, but I'm used to the product line, so...
Personally, I liked the controls of the Sony MP70 and the Pioneer 9400 the best. That Pioneer's menu system and multi-function buttons make the uber-complex OS easy to work with. Too bad it's so expensive.
But Bimmer has an important point to consider. You can shop online and work only with stats and looks, but you may find you really don't like USING the thing.


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## ThingDriver (Feb 16, 1999)

*Re: Will 5 extra watts RMS per channel make much difference? (EgoTrip)*

OK, thanks, fellers. I would love to do everything I'd like to - new HU, amp, new speakers... but I'm starting up my own company right now and need to keep costs down. Plus I'll prolly only have the car for another year or so. That's why I'm trying to get just a HU and still get as much power for the $$$ as possible. 
One thing that may or may not make a difference to you powerheads - these units have to be connected directly to the battery.


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