Same watts at 8 and 4 ohms?


I'm in the market for an integrated amp and trying to sort through tech specs. My understanding of the tech aspects of hi-fi gear is limited. Looking for some clarity in regard to watts-per-channel specs.

It is my understanding that wpc at 4 ohms is typically 1.5x -2x the wpc at 8 ohms.

But I'm seeing a number of respectable mid-fi integrateds with the same wpc for both 8 and 4 ohms. The NAD 388 is one and I think this is true for several of the Cambridge Audio units at a similar price point ($1500-$2000).

The NAD features make a point of saying " 4-ohm stable for use with a wide range of speakers". 

Would appreciate any insight to what these specs mean and what 4 ohm stable really means to me. My speakers are 4 ohm speakers.

Thanks,

George
n80

Showing 4 responses by millercarbon

Millercarbon, are your Talons for sale?

The Talons went in a heartbeat. Well its hard for people to believe. They look at my system and it doesn’t look all that special. https://systems.audiogon.com/systems/8367 In fact most of what’s going on is far from obvious. Even when like Michael came over and I explained everything. Even like the guy who bought the Talons. Warned him before playing anything there is a lot going on they will not sound like this when you get them home. Doesn’t matter. Dude heard one song, he was sold. Never even tried to talk me down. And I had em priced way high to allow for that.

I know this is hard for people to believe but the truth is its the mostly invisible tweaks that make this system punch way above its weight. Way above.

Then on top of that he was so impressed he wound up buying cables and amp, some old gear I had been sitting on forever not even trying to sell. Altogether he darn near paid for the Moabs. Only downside was this all sold so fast I wound up with no music at all for almost two whole months!

Next time I will be waiting for the Raven before selling the Melody!
Every time a question like this comes up it reminds me what a good decision I made way back in the 1970’s to avoid hard to drive speakers with low sensitivity. It just makes life so much easier. Doesn’t hurt that every hard to drive low sensitivity speaker I ever heard never sounded that good to me. Maybe because they were never used with an amp that could make them sound good? That could be it. But whatever, who cares, not my problem!

It was only much later on that I discovered tube watts and solid state watts are nowhere near the same. People can howl all they want, throw all the technical mumbo jumbo they want, when you hear 50 tube watts have more authority than 200 SS watts you have to admit all the words in the world can’t change the fact tubes just plain sound way more powerful than they measure.

Put it all together and you blew it once, and are blowing it again. Just not by as much this time. But its no hallucination. If anything stands a chance of making those speakers sound good its a good tube amp. I drove Talon Khorus for 15 years with 50-60 watt tube amps, and they went a lot louder than you're talking. So you will probably be fine.
Its only mind-numbing if you make it that way. Most of the guys here are experts at spinning you so far down the rabbit holes you'll wish you'd taken up something fun and easy like nuclear physics or MMA. 

Your speakers are at the low end of acceptable, but then so were mine until recently. Here's what I had, and they were the same 90dB only mine were nominal 8 ohm. https://systems.audiogon.com/systems/8367 Notice that is a 50wpc tube amp. Notice that is a pretty big room. I listen fairly loud, sometimes really loud, and was just able to do that with these speakers and amp. Now with Tekton Moab speakers, 98dB, in spite of being 4 ohms they are a lot easier to drive and play really loud with a fraction of the power the Talons required. Because, remember, log function. 

So again, forget power. Forget who likes what. Least useful thing imaginable is some reviewer telling you they liked it. Only way that has any meaning at all is if you know the reviewer, he's your best bud, you heard all kinds of stuff together and agree on everything. Otherwise, ignore. Only thing matters is what they say they heard. Pay attention to how they describe the sound. How they say it compares to other amps. Pay attention to what they regard as a higher standard. Because its all relative. There's a million levels. You can find great gear at every level. But the more time you spend thinking about watts and ohms the harder it gets to find them.


Its one of the more useless things to know. What matters most with amps isn’t the power of the amp but the sensitivity, and to a lesser extent the impedance, of the speakers. Because if you have speakers with at least 90dB sensitivity and the impedance isn’t whack then you will be fine with just about any amp of around 50 watts. If your speakers are 95dB or greater and never go below 4 ohms you will be fine with virtually any amp of any power. But if you go below 90dB, to say 85dB, and if they also drop below 4 ohms, then good luck! So its the speakers, not the amp.

Still, marketing departments find it easier to sell amps by talking about watts. A lot of audiophiles get sucked into it. Don’t. Here’s why its BS and why what I said is the most important technical thing you can learn about amps: sound and power are logarithmic.

What this means is, what you hear when going from 90dB to 93dB is only a tiny little bit louder. But that same 3dB requires TWICE as much power! Going from 90dB to 100dB sounds about twice as loud, but takes TEN TIMES as much power.

So what happens is most of the time, the vast vast majority of the time, even when listening quite loud, your amp is putting out fractions of a watt. Only when you turn it up real loud, then it goes from one watt to ten to a hundred in nothing flat. If you screwed up and bought the 85dB speaker good luck, you now need a thousand watts.

So you can forget power. Its not power that makes a speaker sound good anyway. I can prove this to you all day long going back and forth between 20 watt tube amps and 200 watt solid state. All. Day. Long. And no its not even tubes and SS, because there’s low watt SS amps that sound more powerful than high watt tube amps. Not many. But they’re there. Point is its not about watts. Its about sound quality.