How much power is enough power

[Goliath]

Hi there,

People generally say that you need beefy amplifiers to drive low impedance loads. That AVRs can't handle low impedances, and that you need something with "balls".

My question is, if you take two amplifiers, one, a poverty spec Onkyo (80 watts into 2 channels 8 ohms) and a Krell (600 watts into 2 channels into 8 ohms), if my Onkyo amplifier was not clipping, would the voltage and current by the same on both the Onkyo and the Krell amplifier?

Some people think that power amps deliver more current automatically, but if my volume levels don't call for huge power and my amplifier is not clipping, my thinking is that my power demands have been met. Am I wrong in thinking like this? Would a Krell deliver more current even if my SPL don't require it?

 

[PENG]

but if my volume levels don't call for huge power and my amplifier is not clipping, my thinking is that my power demands have been met. Am I wrong in thinking like this? Would a Krell deliver more current even if my SPL don't require it?

Interesting question, but the volume levels don't tell the whole story. We need to know at what SPL at the listening position, impedance characteristics and sensitivity of the speakers in the particular room, and then also factor in the maximum frequent peak and occasional peak ranges of the music/movie contents one listens to. For example, in my case at my listening position in my two channel room I can achieve 70 dB C scale on my RS meter with average power of less than 0.1W and never peaks above 10W. If I crank things up to the loudest I can tolerate, it may peak above 20W occcasionally. So if I subsitute my 150W Marantz amp with that 80W Onkyo you mentioned, my speakers should not know the difference and neither would I. Either way they would get the current they need. It has been said in this forum that one cannot have too much power, but can have enough power.

 

[Nestor]

All things except the amps being the same, if the speakers are putting out the same SPL, then both amps are providing the same voltage and are able to supply the same current to do it. The Krell wouldn't be doing anything different.

 

[Goliath]

So then I would be correct in saying that if my amplifier is not clipping at my particular SPL, whether it be 75 dB, or 85 dB, or X, then I have all the voltage and current required at my particular SPL?

This is an interesting question for me because I think many audiophiles just assume bigger amplifiers are needed for speakers that have low minimum impedance. For example, the B&W CM9 have a minimum impedance of 3.14 ohms at 120 Hz. The claim therefore is that this speaker needs a beefy amp, at least that's what I've heard.

But the claim doesn't make much sense. My way of thinking is that it really all depends on listening habits and the seated distance and the source signal. If you don't listen loud, you don't need super duper high current amplifiers and you can still get away with loud SPL without needing a super duper high current amplifier.

 

[ImcLoud]

I think the easiest way to figure this out os to demo a more powerful amp and see if you can tell the difference, I could tell a difference between the upa200 and the xpa2, and when I went from an avr to the xpa5 for my surround sound again a really noticeable difference... So try it out, or if you are happy with your system leave it alone..

 

[Goliath]

ImcLoud[/URL]"]I think the easiest way to figure this out os to demo a more powerful amp and see if you can tell the difference, I could tell a difference between the upa200 and the xpa2, and when I went from an avr to the xpa5 for my surround sound again a really noticeable difference... So try it out, or if you are happy with your system leave it alone..

Yeah but perhaps the difference you heard was due to the gain level differences between the UPA200 and the XPA-2. I think it also depends on volume level - if you are trying to replicate a full-on orchestra in your room then you'll probably need a hell of a lot more power for dynamic peaks. If you maintain a given SPL and your previous amp wasn't complaining then I don't see how an uber amp is going to change things. I could be wrong, I am still learning.

 

[MidnightSensi2]

But the claim doesn't make much sense. My way of thinking is that it really all depends on listening habits and the seated distance and the source signal. If you don't listen loud, you don't need super duper high current amplifiers and you can still get away with loud SPL without needing a super duper high current amplifier.

If your speakers are an easy enough load for your amplifier, there is no advantage I can think of for using one that is more powerful. Also, simply because a speaker has power handling of a certain amount of watts, doesn't mean you need to use it all. My JTRs have more than 1000wpc power handling (and I've given them at when I was using them dual purpose), but at home... I could run them off a receiver technically and still have enough headroom because they are sensitive. That said, of course I had to use separates, because it's a hobby.

 

[big2bird]

Hi there,

People generally say that you need beefy amplifiers to drive low impedance loads. That AVRs can't handle low impedances, and that you need something with "balls".

My question is, if you take two amplifiers, one, a poverty spec Onkyo (80 watts into 2 channels 8 ohms) and a Krell (600 watts into 2 channels into 8 ohms), if my Onkyo amplifier was not clipping, would the voltage and current by the same on both the Onkyo and the Krell amplifier?

Some people think that power amps deliver more current automatically, but if my volume levels don't call for huge power and my amplifier is not clipping, my thinking is that my power demands have been met. Am I wrong in thinking like this? Would a Krell deliver more current even if my SPL don't require it?

The average car takes 35-40 HP to maintain 60 MPH. Whether the car has 100 HP or 700HP.

 

[MidnightSensi2]

The average car takes 35-40 HP to maintain 60 MPH. Whether the car has 100 HP or 700HP.

I like this analogy! People could argue it over generalizes, but, it's a great way of explaining it!

 

[PENG]

Yeah but perhaps the difference you heard was due to the gain level differences between the UPA200 and the XPA-2. I think it also depends on volume level - if you are trying to replicate a full-on orchestra in your room then you'll probably need a hell of a lot more power for dynamic peaks. If you maintain a given SPL and your previous amp wasn't complaining then I don't see how an uber amp is going to change things. I could be wrong, I am still learning.

Placebo effect is real, and often works with wonder. That's why we have blind test protocols. People who also claimed hearing day and night difference not only due to power but just between say a $10K amp and a $3K amp (both class AB SS) could perhaps easily fail such tests.

Then there are counter arguments that claim differences could have take long term listening to discover such that blind tests could not do reveal. My issue with that claim or argument is that if it take a long term to feel the differences then they cannot be day and night, huge or whatever adjectives used by many audiophiles and that such differences may exist but would be subtle to the point that people could feel yet probably still not quite audible as such.

 

[Adam]

The average car takes 35-40 HP to maintain 60 MPH. Whether the car has 100 HP or 700HP.

But how long it takes to get to 60 MPH depends on if you have 100 HP or 700 HP (yes, yes...everything else being equal). I'm no EE, but would that be an analogy for the power capacitors or some other transient feature on the amp?

Back in 2007, my Pioneer receiver did awesome at my normal listening levels. At higher levels, it was still loud, but it sounded kind of muffled...the dynamics just weren't there. Vocals were off and things like cymbal crashes were duller. When I added a two-channel amp for the front speakers, the dynamics were maintained at higher levels - everything still sounded clean and crisp. My impression has always been that's due mostly to the power caps because I think those handle the short transient requirements for much higher power levels.

 

[ski2xblack]

This is an interesting question for me because I think many audiophiles just assume bigger amplifiers are needed for speakers that have low minimum impedance. For example, the B&W CM9 have a minimum impedance of 3.14 ohms at 120 Hz. The claim therefore is that this speaker needs a beefy amp, at least that's what I've heard.

Here's my wild eyed guess: If in your room and desired spl levels you need x watts to get there, and the amp is able to deliver x watts into the load at those impedances, you're good to go. I would think that most AVRs, at least mid level and up, could handle those speakers. Those AVRs may not double down, but if they provide enough power into such loads for your needs, I don't think it really matters. Most folks would implement bass management, which further eases the load on the amps.

Now someone with a larger room and greater distance to the speakers may need to flog them with more power, but as the situation gets more extreme it becomes a strong argument for more sensitive speakers.

The stalwarts on AVS (Arny and Ethan) mentioned having 20db dynamic power over normal listening levels. (That seems like a lot until you realize that typically you're using mere fractions of a watt most of the time.)

Power and Hoffman's Iron Law in my home:
system 1: 86db/w studio monitors, 150w amp (class g/h type, can push 400 clean watts)
system 2: 92db/w floor standers, 75w amp (110w dynamic power 4ohms per IHF method)
system 3: 96db/w ginormous speakers, misc power amps (60w ss, 35w tube, 6w se tube)

 

[Irvrobinson]

But how long it takes to get to 60 MPH depends on if you have 100 HP or 700 HP (yes, yes...everything else being equal). I'm no EE, but would that be an analogy for the power capacitors or some other transient feature on the amp?

Sorry, Adam, but electrical circuits don't work like mechanical systems. In the event of insufficient power in an amplifier circuit you get waveform clipping, but transient behavior is unaffected by the power output capability of the amp.

 

[Adam]

Sorry, Adam, but electrical circuits don't work like mechanical systems. In the event of insufficient power in an amplifier circuit you get waveform clipping, but transient behavior is unaffected by the power output capability of the amp.

I thought that the capacitors stored up energy to deliver the large transient spikes that are required for things like cymbals. So what causes the audio to sound muffled? Is that clipping?

 

[Irvrobinson]

I thought that the capacitors stored up energy to deliver the large transient spikes that are required for things like cymbals. So what causes the audio to sound muffled? Is that clipping?

I don't know exactly what is causing the muffling you describe, but I suspect anti-clipping circuits in the amp. Does the marketing material for your amp or receiver call out special protection circuits for clipping?

 

[Goliath]

Irvrobinson, so if my receiver is not clipping then I have all the power I need at my listening levels? Adding more will serve no logical purpose?

 

[PENG]

I don't know exactly what is causing the muffling you describe, but I suspect anti-clipping circuits in the amp. Does the marketing material for your amp or receiver call out special protection circuits for clipping?

He said that muffling happened at higher levels, so I think you are right about the anti-clipping circuit, or otherwise clipping was taking place.

 

[PENG]

Irvrobinson, so if my receiver is not clipping then I have all the power I need at my listening levels? Adding more will serve no logical purpose?

He also mentioned the anti-clipping circuit. Don't get fixated on clipping alone. A safer way to figure that out is to find out how much power you really need to get the spl you need from you listening position, and listening to the kind of music contents.

 

[Goliath]

Don't get fixated on clipping alone.

Okay, but if my amp is not clipping then my question is why would I not have enough power? Are you saying that regardless whether an amp is clipping or not, adding more power can be beneficial?

 

[Goliath]

A safer way to figure that out is to find out how much power you really need to get the spl you need from you listening position, and listening to the kind of music contents.

Yes, but that begs the question. How would I figure that out? Again, if my amp isn't clipping and I don't notice anything unusual in the sound, does that mean my power requirements have been satiated? What else do I need to consider?