MikeVistaBlue06

Thanks for the kind words Skrappy and the link.

I've always seen amps rated by either peak power or RMS power, RMS being the measure that is accurate. I never have seen one in peak to peak.

RMS is basically the DC equivalent of an A/C source.

Here are a couple of good links I found:

http://users.chariot.net.au/~gmarts/amppower.htm

http://sound.westhost.com/efficiency.htm

Since I have an extra bolt left over [sm=jawdrop.gif]where I pulled out my subs and amps the otherday when I was applying the Damplifer Pro, I'm going to pull them out again, and then take one of the four off and see what is on the bottom of it.

Also, I was following the calculations and wondered if this described the ratings based on peak to peak values:

Vpp = 2Vp --> Vp = Vpp/2

Ipp = 2Ip --> Ip = Ipp/2

Vrms = Vp/sqrt(2) = Vpp/(2*sqrt(2))

Irms = Ip/sqrt(2) = Ipp/(2*sqrt(2))

Prms = Vrms * Irms = VppIpp/(4)(2) = Ppp/8

So if they are using peak to peak values the Shaker 1000 would be 125W rms and the Shaker 500 would be 62.5W rms. Right??

Just remember, to be an EE you only have to know when and where to either multiply or divide by either SQRT(2) or SQRT(3)


Thx,

Mike

(Geez, I can't even divide correctly today! )

Philostang

Mike, Scrap, Al, you guys rock! [sm=groupwave.gif]

I've long since known about the rules of thumb, but it's nice to review a more precise account of amp power, etc.
What I really appreciate was the intelligent discussion/disagreement/clarification in the exchange--some recent posts in the rest of the forum were getting me down lately with the lack of respect going around. Nice to see this kind of discussion.

I really wanted to +1 CrazyAl's point about the driving aspect of "car" stereo systems. Virtually everything in the context of an automobile conspires against an audiophile's ideals (which, as we see can be approached in a very sophisticated and rigorous way). In a car, you have an active, highly variable, environment that you can't control and is filled with noise; the running engine/exhaust itself is a negative factor; you're seated in the wrong place; there's obstacles inside the car; the acoustics of the cabin size/shape are bad, etc. etc. Oh, and! let's not forget Al's question--you are driving aren't you? I mean even your attention, a key factor in appreciating music, is (should be) drawn away from the intricacies of the listening experience. If you want to devote your financial resources to a beautiful sound system, there are far better places to do it. All of this, to my mind, reinforces the mantra: if it sounds good to you, it's the perfect system...if it doesn't sound good or good enough, build it till it does (just keep in mind that you're waging an uphill battle).

Best,
-j

MikeVistaBlue06

Thanks so much for the comments!

As for noise, try Second Skin's Damplifer Pro. I've got 48 sq.ft. in my 06 now and it really helped quieten it down. I'm going to add about 8 more sq.ft. to the front as well.

Damplifer Pro does the same thing as Dynamat Extreme but it costs much less!

Mike

Skrappy

Thank You for the kind words, we are all just trying to get to the right answer here. I know it is hiding in here somewhere.

As CrazyAl said, the method of measurement can have a huge affect on the rating vs. output of the system in the real world.

A fewe key things to look at with amp specs:

1. What input voltage do they do their calculations at 12V, 13.8V, or 14.4V. 14,4 is becoming more prevelent, but two amps that have the same output and one is tested at 12V and the other is at 14.4V. The 12V amp is going to be more powerful to the tune of near 25%.

2. What frequency does the amp output get tested at. Typically it is at 1k Hz. That is what you should be looing for.

3. MOST IMPORTANT! Good Amps cost real money. You should be spending at the very least $1/Watt for quality sound, for the total watts of the amp with all channels combined. If an amp is $150 and is 2x100, it is a cheap amp, it should cost at least $200, probably more. You will see that there are amps that are 500Watts for $300, stay away (if you want good sound). A 200Watt amp costing the same $300 will kick it's butt all over the place. Don't be fooled by big numbers thinking you are getting ahead, Watts are not created equal and you need to pay for them.

4. Look for a "high current" rated amp. High current components are the most expensive an the hardest to produce and likewise create the best sound. Remeber BASS is CURRENT FLOW. You need a significant ammount of current to create low frequencies, but very little to crate high frequencies. As an example. If crossed over properly, you can run all of your door speakers to defening levels off just the 20Watts from the deck if you cross them over at 100Hz or higher (Total 4x20= 80WRMS for everything from 100Hz to 20,000Hz. But to finish the system you may need 300Watts RMS just for the Subwoffer that only takes care of the 100Hz and below. This is where the current comes in.

Just more info,

Skrappy

sonicblue05

i dont know what you guys are listening to, but if i turn up the base on my rock (aerosmith, blink 182, breaking benjamin,coldplay, disturbed, greenday, incubus, that kinda stuff) it just vibrates the whole time becaust the subs just put out the base guitar the whole time and it just is like a buzzing. granted some of it sounds great with the bass up, but most of it...no.

its all upito you, and i have been in both 1000 and 500, and the 1000 is really cool with rap, but when "shaker mode" is on it is too much bass for rock IMHO. everyone likes what they like.

BTW my bass is at about 1/2 way plus one or two bars on a normal day.