wattage consumption vs. wattage speaker output...

[vivisimonvi]

I've had this stereo power amplifier for as long as I remember since I was about 5 (my dad gave it to me years ago). It's a Pioneer A-88X integrated amp we've had for about 20 years. There are connections for two pairs of speakers...

According to the manual, it has an average continuous power output of 120 wpc (at 8 ohms). There are also some other figures: DIN, continuous power output 150 wpc, and dynamic power at 169 watts. Why are these figures different and what do they mean (aside from how loud it goes)??

On the back panel of the amplifier it says it consumes 670 watts of power. Is it correct to assume that I should NOT drive two pairs of 4 ohm or less speakers? I would be trying to drive out more than 240 wpc or more through 4 channels that would exceed the amps power output. What would be the dangers be in doing this? Would the only danger be if I 'hypothetically' use that much power (or turn it loud enough) for my speakers...

[spacedeckman]

First of all, take a deep breath. Pretty much NONE of anything on your post has anything to do with reality. You are thinking too hard about all this, but it is to be expected.

First, the consumption thing. You will never see the point where this thing is going to draw 670 watts from your wall for any continuous length of time. That is the maximum output of the power transformer in the box. The good thing is that the numbers look okay. 120x2=240 Assume 50-60% efficiency and you have some capacity left over. But this is only for "feel good" engineering purposes. Most normal people will never come close to using the 120 watts.

Two sets of 4 ohm speakers? Within reasonable volume levels, it shouldn't be an issue with something that appears to be fairly well built. Really loud, you may have a problem.

1 watt of output is pretty loud, and most listening is done far less than that. DIN rating isn't as strict as FTC (which isn't very strict either) which gives the higher rating. Dynamic power at 169 watts means momentary peak power output, which doesn't mean much, but looks good on paper. This thing won't be able to put out 240 watts into a 4 ohm load, but as stated, you will never see that anyway. The 240 watts would require a huge power supply with a superconductor impedance...Buck Rogers stuff. Exists only with number fudging in the Krell world.

Don't worry, be happy.

[vivisimonvi]

That does sound reasonable. I'll admit I have little knowledge in electronics in general. I've read having a higher power amp is safer than a lower powered one (for those who generally listen to higher volumes that 'normal'). I don't think I like this amp much anymore, it can go loud but doesn't sound as good.

When I was little I used to mess with the speaker wire, by putting the + and - on my tongue (don't ask why). At a reasonable volume it does feel like a 9-volt battery and you feel the electronic pulse of the music (the lower frequencies more specifically). Doesn't sound as lethal when you think of 1 watt.

[poneal]

Kids can be kids! Little pulses in sync with the music--that must have been a stunning/electrifying experience LOL. You are pretty funny. Im having a hard time typing this im laughing so hard.

[skeptic]

I've had this stereo power amplifier for as long as I remember since I was about 5 (my dad gave it to me years ago). It's a Pioneer A-88X integrated amp we've had for about 20 years. There are connections for two pairs of speakers...

According to the manual, it has an average continuous power output of 120 wpc (at 8 ohms). There are also some other figures: DIN, continuous power output 150 wpc, and dynamic power at 169 watts. Why are these figures different and what do they mean (aside from how loud it goes)??

On the back panel of the amplifier it says it consumes 670 watts of power. Is it correct to assume that I should NOT drive two pairs of 4 ohm or less speakers? I would be trying to drive out more than 240 wpc or more through 4 channels that would exceed the amps power output. What would be the dangers be in doing this? Would the only danger be if I 'hypothetically' use that much power (or turn it loud enough) for my speakers...

First lets separate input power from output power. Input power is the power the amplifier draws from the wall outlet. This is made up of two parts, an idling or base power draw which is what the amplifier requires and uses when there is no signal present and then the part that depends on how much power the amplifier is delivering to the speakers at any time. The most power it can draw is when both channels are delivering full rated output power continuously, in your case this draw is 670 watts. Since the amplifier is powered at 120 volts, it draws a maximum of about 5 1/2 amps. This is usually not enough to overload most 15 or 20 amp circuits in most homes but if your amplifier causes your circuit breaker to trip or your fuse to blow out periodically, you would have to reconnect some appliances to other circuits, not use them at the same time as your amplifier is playing very loud, or have another circuit installed. This is a most unusual condition and probably isn't applicable to you.

The output power rating is the maximum strength of the signal it will deliver to loudspeakers. If you attempt to push amplifiers further, they will produce severe distortion, shut themselves down for portection, or can even be damaged in some instances. Back in the bad old days of amplifier horsepower races, manufacturers wanted to be able to advertise that their amplifier was very powerful. So they invented many different tricky ways to rate amplifiers that were so misleading and confusing to the public that it was impossible for many consumers to compare one unit to another. There could be many different power ratings for the same amplifier. Your amplifier are a case in point. So in the mid 1970s, the FTC stepped in and set a single standard for how all amplifiers were to be measured and rated for advertised power output. And while the actual performance of audio amplifiers is far more complicated than this single number, what we have now is much more useful than the numbers we saw prior to this ruling.

As for driving one or more pairs of speakers having four ohm impedences or less, that is impossible to know without contacting the manfucturer. Some amplfiers could safely handle such loads. Crown DC300 immediately comes to mind. Many others can't. And if the manufacturers' engineers don't know and can't find out because the unit was discontinued a long time ago, don't be surprised. If you want to be on the safe side, learn about installing fuses and resistors in series with your loudspeakers.

[vivisimonvi]

I've always wondered HOW amps worked differently from each other. Now I know watts has little to do with it. For instance:

I used to have a 25 watt QRX-5500 Sansui receiver. I drove a set of some 15 watt speakers (I don't know the model but they were Magnavox ones), and noticed the cones really MOVE (sounded really good I might add). I would think the woofers move even more using a higher power amp like my 120 watt Pioneer. This is the complete OPPOSITE. Driving the speakers with the Pioneer amp, the cones didn't seem to move much at all, and the bass was very weak (even using the tone controls). They were loud but didn't seem to make much movement with the cones (they sounded like crap). I eventually blew out one of the woofers and tweeters with the Pioneer amp and tossed them.

Made my next investment in some fuse-protected speakers. I should get a new amplifier sometime along the road, I'm not that satisfied with the way they sound.

About the wire thing when I was little. I used to do this to test if there was a signal one day when I noticed nothing was coming out of the speaker (the ones I blew out). Became a habit of mine for awhile... just don't go anywhere near fillings. From hearing and feeling the music, who would've thought of "taste the music" :)

[skeptic]

There is much more to amplifier performance than wattage but even in something as seemingly simple as wattage, there is a lot to understand. The FTC requires that amplifiers be rated in a way that qualifies wattage according to certain criteria including the power bandwidth, distortion, and a preconditioning period where all channels are driven at 1/3 rated power for 20 minutes prior to testing. Only the continuous power rating is allowed. But there are many other factors which influence amplifier performance such as frequency response and damping factor. There are other interactions between loudspeakers and amplifiers which I think quite frankly are not well understood at the current state of the art. Anyway, people who want one or a few simple numbers to compare one amplifier with another precisely would be disappointed to know that the truth is far more complicated.