then you said this

QUOTE (SebringDemon @ Dec 16 2005, 10:44 PM)
we are not talking about rated power.

Rated power is exactly what is being addressed.


"I've had OK quality from Kenwood amps but not all watts are created equally" doesnt refer to anything about ratings. if you really want to break it down, you dont make sense because watt is a unit of measurement.

i just want to clear any type of misinformation. people like to repeat what they hear and read, that is how misinformation gets around.

 

Chill out n00b.

Go buy an 800 watt Kenwood and an 800 watt Alpine/RF/MTX/whatever and compare if you need to figure it out for yourself.

 

[QUOTE=SebringDemon,Dec 17 2005, 01:44 AM] seriously...??? youre talking about amp ratings, not watts.

lets see here... can you explain how THD has any affect on wattage power? anything less than .1 is barely, if not even, audible by the human ear.

are you saying that 900 watts from your orion is more powerful than any other amp that

 

n00b? hardly... again, they are rated differently. i understand that amps produce different amounts of power compared to their ratings.

what i am saying is, when 2 amps are benched and produce the exact same amount of power, what kind of power difference is there? other then talking about ratings, explain the power difference.

if you are saying a watt is not a watt, then how are sensitivity levels of a speaker measured?

 

[QUOTE=S2KinVA,Dec 19 2005, 01:32 PM] Let me explain how a Watt is not a watt and how THD affects sound..

Classes of Amplifiers
People sometimes assume that for every portion of the input signal there is corresponding 100% output from the amplifier. However, power dissipation (in the form of heat) and distortion of the audio signal are two key factors in determining the efficiency of an amp. The design of an amp's circuitry determines the class of operation of an amplifier, and each class has its own performance characteristics.

Class A amplifiers are desirable for the high quality of their sound, but, because of the configuration of its transistors, a pure class A amplifier is inefficient and runs very hot. This is because even when there is no audio signal, the output transistor(s) always have current running through them. The current flowing through the output transistor(s) (with no audio signal) causes the amp to heat up unnecessarily, and "waste" input energy. Most car amplifiers that boast "Class A" circuitry are really Class A/Class AB hybrids.

By far the most common car amp design, Class AB amplifiers also allow current to run through the output transistors when there is no audio signal, but at a much lower level. A class AB amplifier runs cooler, and therefore, more efficiently than a class A, with low distortion and high reliability.

Class D amplifiers use output transistors as switches to control power distribution

 

Now you can go play with your Kenwood and pretend it makes the cleanest power!

 

I just dont know how to explain it anymore.... Yes in an ideal world 1 watt of power = 1 watt of power, the key is to get the cleanest watt of power and a lower THD which would produce a cleaner, clearer sound.

Compare a 125watt Kenwood to a 125watt Alpine, the Alpine will not only produce more power, it will be a cleaner signal with a lower THD thus producing a better "watt", We are trying to explain why a better amp produces better power, if you can only argue that a watt is always a watt you may want to read a few car audio forums before coming back in here.

Note the difference in performance between 2 similar amps....

Kenwood KAC-8042 60w x4 channels RMS = 1%THD at 4ohm $249.99
Alpine MRV-F345 75w x4 channels RMS=.3% THD at 4ohm $449.99



Also, can everyone refrain from the flaming.....

 

Sebring Demon - In case you are new here (and it appears so by the date on your profile) this forum is LITTERED with Electronic Engineers. They know their stuff. As well as some world class car audio competitors and enthusiasts. One of the great draws of this forum......almost everyone knows their stuff.

If you are wondering what a "watt" is, look here:

Definition of a Watt - LOTS of them

S2kinVa is correct in that not all watts are created equal. They can be "measured" the same, and have the same "output", but some brands just produce higher quality sound. Whether it be because of better filters or because of the circuitry involved. With respect to Alpine amps, some people have reservations on just how they produce their power (I do not know the specifics, but there are some people on here who could tell you in GREAT detail). THD does play a role in power, and the accurate reproduction of sound. I am not slamming Kenwood, they are a respectible brand. Just not my brand of choice (like Whiskey.....everyone likes different tastes....I like Crown Royal ). Its a matter of taste.

Also, with regards to "rated" power, there are 2 different types of "rated" power. The power represented by the company, which is the minimal threshold that must be met. And the bench test (with "birth certificate" of the amp) that shows exactly what YOUR amp produces. Alpines, along with several other brands, are notorious for being underrated. While others (Sony, etc.) have been notorious for being overrated. That was the cause for the CEA-2006 to be instated. People were feeling ripped off when they were buying a "Pyle" or "lanzar" amp that represent 300wrms, but were really closer to 150-200wrms. Similar to accountants "cooking the books" during the late 1990's. Technically it was correct, because it was "measured," but the techniques or meaurement varied greatly.

Sorry for the rant.....hope you find this site as useful as I have.

John

PS - I found this article that explains a LOT of stuff in language we can all understand. Including THD and it affect on the rating of an amp (quality vs. quantity).

Techlore article

 

the kenwood has a THD of .08% and the alpine has .3%.

for the record, kenwood 8042 doesnt exist. it is 8402.

are you saying that the kenwood is a cleaner amp because the THD is lower than the alpine?

please... i had my brax X2400.2 benched recently. lets just say it did not do as well as it is rated.

THD is much much higher that what is rated and power doesnt exactly meet what is rated either.

if you doubt the tests were done correctly, it was tested by TRU technology. it was a standard AP test.

 

[QUOTE=jwa4378,Dec 19 2005, 06:04 PM] Sebring Demon - In case you are new here (and it appears so by the date on your profile) this forum is LITTERED with Electronic Engineers.