RyanJE

Power rating ?

Ive heard people talk about pure/clean watts. I was wondering what are the differences between power ratings. I ask because im looking to buy a new avr. Some Harmon's are rated at 55xN and other brands are 100-130xN, how can this be. Any good links or articles.

Justin_D

Simply put, some Harman Kardon recievers have different and better amps than others.

When people say "clean" or "pure" watts, what they means is what a reciever REALLY puts out as opposed to what they SAY they put out. For instance, some lower end Sony recievers (non-ES line) claim to put out 100 watts into 6 channels with 8 ohms resistence. In actuality it is closer to 35 watts/channel CONSTANT. 100 watts is really with 1 channel driven into 1 khz. When in a movie is only 1 channel playing at a single frequency? Never.

Also, H/K are usually underrated. Some more than others, but you can trust that you are getting the wattage they promise.

RyanJE

I wonder that. I have speakers that are rated 50-200 watts and I have to crank my sony str-de595 way up to get decent volume. How can you tell before purchasing if your getting clean watts or not.

Tingwe

case in point. my pio 1014 has 110watts per channel x 7 on the box and on the pioneer website, but has been tested to go 115 watts ALL-channels driven. give it a try. you also can't go wrong with the HKs, they di underrate their power all the time.

Jose G

Ryan, you should take a look at this link from the HT Primer. The primer is full of great info.

José

RyanJE

I dont fully understand what THD is after reading the primer, r what to look for. Heres the same model I have only in 6 channel mode...

---STR-DE597 User Manual (2.03 MB)

• 6 Channel Power Rating: 100 Watts Per Channel x 6 (8 ohms 1 kHz, THD 0.7%)
• Stereo Power Rating : 90 Watts Per Channel x 2 (8 ohms 40 Hz-20 kHz, THD .09%)

What does this all mean and why is stereo power rated from 40-20khz?

Kent Y

Regarding the stereo frequency range, the amp obviously couldn't push enough power to drive the lower ranges (20-40Hz) at 90 watts, so rather than list the full range wattage, Sony cut down the range. There must have been a big drop off for the lowest frequencies. 100 watts is the holy grail for many of the lower end mass market receivers, so they try to do everything they can to put that number on the box. Notice even the 90 watts is into 6 ohms. And, while the 100wpc in 6-channel mode is into 8 ohms, it was only measured at 1kHz, and the THD is very high at 0.7%. Very possibly with only one channel driven as well; certainly not with all six.

Jose G

THD =Total Harmonic Distortion
Basically the amplifier outputs an amplified version of the input signal, right? Right. But, it also adds any distortion created by the amplifier. All amplifiers and signal processors add distortion to the signal, so this is a way to rate the distortion. Now can we hear the differences? There are many factors that contribute to this and you can make yourself nuts trying to figure it all out. But do a search on the web for "Total Harmonic Distortion" and you will see what I mean.

John S

For a good idea, on non-digital amps is simply look at the rating of what it pulls from the wall.


Example:

6 x 100 watts, the back of the AVR should be close to 1000watts to truly provide that.

If you look though, many of them will state like 280watts, the laws of physics just don't work out at all on that.


I have no experience with the newer "Digital amps", but as I understand it, they require much less from the wall to provide the same sort of power to the speakers.

RyanJE

I did notice that. It seems like the high end avr's are taking about 500 watts to run in 100x7 or 6 and my cheapo avr only uses 240 watts. Man do you guys have the upgrade bug too. I keep finding things I want everyday on this forum. Its killing me.

Shiu