I have a 755, and was reading the HT review of a Classe amp. The amp was advertised as a 180 watt amp. It could do this with 1 channel. However, when they measured all channels driven, it drop'ed to 130W (@.1% distortion). I was taken aback as this was a 4 grand amp.

First question, has anybody seen a review (or measured themselves) the 755 to see if it is really 200wpc all channels driven?

2nd question, Doesn't the FTC require a power spec to be all channels driven, with a max of 0.1% distortion when rating an amp?

stabie:

I'm led (hey, isn't it a sad fact of life that us doggies are ALWAYS led around on a leash -- literally!) to believe that the FTC rules don't say that you have to measure at a specific frequency or distortion, but rather that you have to disclose what the # of channels, frequency, impeadance, and THD were when the measurements were taken.

The situation you discribe is within the rules, and indeed it points to their value, since the disclosure made you think about what was REALLY being said there.

But what do I know, I'm only a dog!

ARF ARF says Iggy.

Classe did not disclose the fact, HT did in the small lab test box part of the review. HT didn't mention it in the article. They gave it a glowing review (as always).

I believe the old FTC rule applied only to stereo (two channel) and mono amplifiers, either separate or in a receiver. It did not apply to amp/speaker combinations, such as a subwoofer, or to automobile products. For several years the FTC has been considering a new standard for multi-channel amps/receivers and while I don't think it is official yet, many manufacturers follow it, or ignore it as they please. As I understand, the new multichannel standard was devised by (don't laugh) Sony, Panasonic, and Bose (haha), so don't be surprised to hear that it only requires full power into ONE channel! Which is why many receivers rated at 5 X 100 watts really only put out about 30 watts all channels driven into 8 ohms. So buyer beware.

Dsmith

I run into this one every day at work. Our line of products is not what one might consider 'high-end' but we have some respectable product for the money. At any rate, it's near to impossible to explain to Joe-Schmoe how come a Sony reciever will be rated at 110 watts by 6 channels and the Yamaha will be only 75 by 6 and yet the Yamaha can deliver more usable power to the speakers. They can always hear the difference, however, when I play the two side by side at the same spl across the same set of speakers. It is beyond annoying, and the car audio market has lost its head in this problem. I consistenly see new amplifiers for car audio that claim 1200watts of power, but when you dissect the actual included performance numbers they're 150watts RMS at 4 ohms. It gets rather tiresome to sift these pathetic marketing numbers from reality. The key is as it always has been. When you listen to the receiver you'll be able to tell (or if you can't tell, then you'll have to base your decision on some other criterion, like features or price).

embries i feel your pain. it is pretty near impossible to say in words what high-current, oversized components, etc. do for the sound of a system. rated watts are what most people look for, but there is no standardization at all as to how rating is observed. most times the rating methods are not fully disclosed by the manufacturer, so this leaves more gray area. we all know that an amp driving one channel at a specific frequency is going to perform differently driving multiple channels at a full range of frequencies. most "high end" companies rate their power in a realistic scenario, but they all dont, and you can drop a wad on some amps that are junk. at least they spend your money designing their logo.... the best thing a company can do is fully state how they derived their power ratings (accurately of course), that way they dont have anything to hide, if their product is inferior then so be it...

I don't think I've ever seen measurements of an Outlaw amp with 1 ch vs all channels driven. However, I have seen reviews of ATI amps with those measurements. (The 750 is made on ATI's production line, and I'm 95% certain that the 755 and 770 are too.) The ATI's all meet their specs, all channels driven, *and* full bandwidth signal 20 Hz to 20 kHz, not just at 1 kHz as some amps are tested.

I was looking through my old reviews. SGHT measured power in a 770 back in July/Aug issue. Easily met is specs. Good review overall.

Kevin C.Brown QUOTE
"I was looking through my old reviews. SGHT measured power in a 770 back in July/Aug issue. Easily met is specs. Good review overall."

Kevin, I read the review twice and could not determine that SGHT actually measured the power. It appears to me that they just published Outlaw's Specs. What am I miss reading?

Shoot, I put the review back into the big pile under my coffee table... But, look for the green "measurements" box.

Here is the example from the 750 that I have more easily at hand:

The 750 was rated at 165/250W into 4/8 ohms all channels driven.

They measured 186W/ch all channels driven into 8 ohms, 347W/ch with two channels into 4 ohms, and 550W into 1 ch into 2 ohms. 1% THD+noise, 1kHz.