Can you figure out RMS from MAX?

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krstofer

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Winning Blue Mazda 3 hatch
Hey guys, can you figure out the RMS wattage of an amp from the MAX wattage? is it like half or quater or something like that?

Thanks,
Krs
 
most of the time it turns out to be about 1/2, but some companies really over-rate their stuff, so it could be less.
 
There is no figureing it out. Look at the paper work that came with the amp or look it up on the web. You really can't just guess....BUT you could get close anyway...close enough to purchase other equipment that will compliment it. What kind of amp and what does it say?
 
I am just looking for a new amp since I fried mine last night. Some of the specs only show max power. I am shopping on etronics.com which has a store in NYC. I want to narrow my search before I go there today.
 
krstofer said:
Hey guys, can you figure out the RMS wattage of an amp from the MAX wattage? is it like half or quater or something like that?

Thanks,
Krs
Click to expand...
It depends on how truthful and accurate is the manufacturers power rating. If by maximum power output the mfg means the actual peak power of the amp (NOT the peak to peak power) as referred to the RMS power, then the RMS power can be calculated. The peak power = the square root of two (1.414) X the RMS power. Therefore, maximum (peak) power / 1.414 = RMS power.
 
DO NOT concern yourself with max power....it is not information that tells you anything you need to know. You want RMS or Nominal power. The MAX power is a number the amp hit for a second during testing. I call it "Power Before Flame" meaning it hit that number for one second so they say "Hey it can do it" RMS and Nominal power is a sustained number, a power number the amp could do every day all day.
 
krstofer said:
I am just looking for a new amp since I fried mine last night. Some of the specs only show max power. I am shopping on etronics.com which has a store in NYC. I want to narrow my search before I go there today.
Click to expand...
Tell us the brands and model numbers...we can get you RMS. ;)

--edit--
or...you can even tell us what your old amp was, what it was powering (speakers, subs, components) and we can suggest stuff to look into.
 
Last edited:
A couple more points.

Imported amps IN GENERAL seem to be smaller and produce very clear sounds. But sometimes lack that real low end. IN GENERAL USA built amps are larger, are less accurate and have nice low end balls. Now understand this is in general. There are always exceptions to the rule. Example: Alpine amps and say Rockford Fosgate. Each are good and have there place. I'm just not sure I'd push say 2 10's with an alpine amp. Not saying it wouldn't hit but a rockford amp would be better in that application.
 
I am looking to get a 4 channel (or 2 2-channel) amp to power the stock speaks, but something I can use when I upgrade. Around 100-150w RMS. I would also like to keep the price around $150. There are a few on the site that show RMS like the one below, but I also want something that will look nice. ;)

I am thinking of this on:
http://www.etronics.com/product.asp?stk_code=lanvibe428&store=&catid=306

here is the image:
http://www.carreview.com/Amplifiers/Alarms+VIBE428/PRD_286159_1806crx.aspx


I know MAX power means nothing. That's why i wanted to figure out RMS.
 
servoeyes said:
That's voltage though...means you have to work that math into the power equation.

P= (I^2) * R

V= I*R

Hence, P = (V^2 / R^2) * R or sqrt(P*R) = V, which is how we tell true power when we meter.
Click to expand...
(omg)

[edit]
Hey! My 100th post!
[/edit]
 
krstofer said:
I am looking to get a 4 channel (or 2 2-channel) amp to power the stock speaks, but something I can use when I upgrade. Around 100-150w RMS. I would also like to keep the price around $150. There are a few on the site that show RMS like the one below, but I also want something that will look nice. ;)

I am thinking of this on:
http://www.etronics.com/product.asp?stk_code=lanvibe428&store=&catid=306

here is the image:
http://www.carreview.com/Amplifiers/Alarms+VIBE428/PRD_286159_1806crx.aspx


I know MAX power means nothing. That's why i wanted to figure out RMS.
Click to expand...
NO!!!!!!!!!!!!

Dude...a good 4x100 amp is expensive for a reason! Don't spend 150$ on one, because chances are that you'll regret it on down the road. Plus...100W to the stock speakers is pretty insane, in and of itself! :)

Is there a reason that you want a 4 channel to provide that much power to all the speakers? A decent 2 channel for the fronts and continuing to run the rears off of the stock deck is usually what I suggest. I prefer to have the sound stage in front of me, not behind. My car has about 80-100W (I don't have a test CD so I can't measure it right) to the fronts and ~20W to the rears. But...if you like a sound that's all around you, i can understand your reasoning.

Now...for an idea of how much a good 4-channel costs: My eclipse ea3422, their bottom line, drops 50x4 RMS and is clean as hell, was 250$. Can you spend less? Sure! But you'll be sacrificing some things...like THD, SN Ratios, actual power output, and overall SQ.
 
114 dollar Lanzar rated at 1000. Sounds too good to be true. Be careful how cheap you go. You want good power but not cheap ass junk HIGH power. Better off with maybe less watts and higher price.....to get better quality.
 
servoeyes said:
NO!!!!!!!!!!!!

Dude...a good 4x100 amp is expensive for a reason! Don't spend 150$ on one, because chances are that you'll regret it on down the road. Plus...100W to the stock speakers is pretty insane, in and of itself! :)

Is there a reason that you want a 4 channel to provide that much power to all the speakers? A decent 2 channel for the fronts and continuing to run the rears off of the stock deck is usually what I suggest. I prefer to have the sound stage in front of me, not behind. My car has about 80-100W (I don't have a test CD so I can't measure it right) to the fronts and ~20W to the rears. But...if you like a sound that's all around you, i can understand your reasoning.

Now...for an idea of how much a good 4-channel costs: My eclipse ea3422, their bottom line, drops 50x4 RMS and is clean as hell, was 250$. Can you spend less? Sure! But you'll be sacrificing some things...like THD, SN Ratios, actual power output, and overall SQ.
Click to expand...
WELL SAID!
Very well said. Go for a good brand, spend more and get less power and it WILL sound better.....ever look in the JC Whitney catalog.....6 inch amp rated at 2000 watts for $19.99. lol
 
servoeyes said:
NO!!!!!!!!!!!!

Dude...a good 4x100 amp is expensive for a reason! Don't spend 150$ on one, because chances are that you'll regret it on down the road. Plus...100W to the stock speakers is pretty insane, in and of itself! :)

Is there a reason that you want a 4 channel to provide that much power to all the speakers? A decent 2 channel for the fronts and continuing to run the rears off of the stock deck is usually what I suggest. I prefer to have the sound stage in front of me, not behind. My car has about 80-100W (I don't have a test CD so I can't measure it right) to the fronts and ~20W to the rears. But...if you like a sound that's all around you, i can understand your reasoning.

Now...for an idea of how much a good 4-channel costs: My eclipse ea3422, their bottom line, drops 50x4 RMS and is clean as hell, was 250$. Can you spend less? Sure! But you'll be sacrificing some things...like THD, SN Ratios, actual power output, and overall SQ.
Click to expand...
I don't plan to run full power to the stock speaks with the amp I buy now, so I won't blow them. I do plan to replace them in the very near future. I want to amp all the speakers because I don't like the sound of music coming from one direction ( I always got hte sweet spot in the house and movie theaters).

$250 is a bit much for me to spend right now, I am looking for something that can be disposable. I am going to plunk down a pretty penny on an amp to pump my RF sub so I need to go cheap for now for this amp.


besides, I promised my wife I wouldn't spend too much money today since we are going on vacation next week.:D
 
Damn you guys.... No I am like, well maybe I should just wait. :)

I really want to get something though so....

If you had to buy an amp under 150, which would it be? any channel any wattage.

Krs

[edit]

I am hot to get one now because I am driving from NJ to NC on saturday. Otherwise I would probably order something online.
[edit]
 
krstofer said:
Damn you guys.... No I am like, well maybe I should just wait. :)

I really want to get something though so....

If you had to buy an amp under 150, which would it be? any channel any wattage.

Krs

[edit]

I am hot to get one now because I am driving from NJ to NC on saturday. Otherwise I would probably order something online.
[edit]
Click to expand...
Don't worry about one stupid long trip....there will be more trips to have louder tunes. Wait, save up a bit and get something on eBay, just be careful and read up on the amp you choose.
 
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