Amp specs expressed as wattage

[Hoho]

When an amplifier's dynamic headroom is said to be ~1 decibel, as was the standard at Carver Corporation, what is the conversion factor to determine the peak power? In other words, what would be the power peaks when the continuous power rating is 125 wpc, 250 wpc, etc.?

[mtrycraft]

When an amplifier's dynamic headroom is said to be ~1 decibel, as was the standard at Carver Corporation, what is the conversion factor to determine the peak power? In other words, what would be the power peaks when the continuous power rating is 125 wpc, 250 wpc, etc.?

Add about 25% more power to the continuous ratings.

[FLZapped]

When an amplifier's dynamic headroom is said to be ~1 decibel, as was the standard at Carver Corporation, what is the conversion factor to determine the peak power? In other words, what would be the power peaks when the continuous power rating is 125 wpc, 250 wpc, etc.?

Well, power in dB is expressed as: 10* log(P1/P2) So you'll need the ratio to be such that the log is = 0.1 then 10*0.1=1dB

Working it in reverse to get the ratio, it becomes 10^(0.1)/10 = 1.26

So it looks like in order to get 1dB you would need about 26% more power.

-Bruce

[FLZapped]

Well, power in dB is expressed as: 10* log(P1/P2) So you'll need the ratio to be such that the log is = 0.1 then 10*0.1=1dB

Working it in reverse to get the ratio, it becomes 10^(0.1)/10 = 1.26

So it looks like in order to get 1dB you would need about 26% more power.

-Bruce

Phooey.

The last formula should just be 10^(0.1) = 1.26

-Bruce

[bturk667]

When an amplifier's dynamic headroom is said to be ~1 decibel, as was the standard at Carver Corporation, what is the conversion factor to determine the peak power? In other words, what would be the power peaks when the continuous power rating is 125 wpc, 250 wpc, etc.?

How much peak power an amplifier can deliver on musical peaks above its continuous power rating is called Dynamic Headroom, expressed in db. A power amp rated at 100 wpc (RMS) that can deliver 200 wpc for brief periods (measured in milisconds) without severe distortion is said to have 3db of Dynamic Headroom.

Any time you increase volume by 3db, you double the power output of an amplifier.

125 wpc with 1db of Dynamic Headroon = @33.3% or @ 166.625 wpc.
225 wpc with 1db of Dynamic Headroom = @ 33.3% or @ 299.925 wpc.
3db of Dynamic Headroom = !00% increase in power
1.75db of Dynamic Headroom = 50% increase in power.

This is the way I believe manufacturers rate their amps in regards to Dynamic Headroom.

[FLZapped]

How much peak power an amplifier can deliver on musical peaks above its continuous power rating is called Dynamic Headroom, expressed in db. A power amp rated at 100 wpc (RMS) that can deliver 200 wpc for brief periods (measured in milisconds) without severe distortion is said to have 3db of Dynamic Headroom.

Any time you increase volume by 3db, you double the power output of an amplifier.

125 wpc with 1db of Dynamic Headroon = @33.3% or @ 166.625 wpc.
225 wpc with 1db of Dynamic Headroom = @ 33.3% or @ 299.925 wpc.
3db of Dynamic Headroom = !00% increase in power
1.75db of Dynamic Headroom = 50% increase in power.

This is the way I believe manufacturers rate their amps in regards to Dynamic Headroom.

Sorry, but your numbers are wrong. 1dB is only abot 26% increase, go look at the math. The scale is not linear, you can't just take 3dB as 100 percent and assume that 1 dB is 1/3 of that.

1.75dB is 50% though.

-Bruce

[bturk667]

Sorry, but your numbers are wrong. 1dB is only abot 26% increase, go look at the math. The scale is not linear, you can't just take 3dB as 100 percent and assume that 1 dB is 1/3 of that.

1.75dB is 50% though.

-Bruce

Is 3db= 100%?

[psonic]

yea interesting topic, I have a nad 304 with 5.5db of headroom...nad states that continuous power is 35wpc, clipping is 42wpc and peak dynamic power at 120wpc.

All I know is the thing sounds waaaay more powerful than 40wpc (with 91db 8ohm speakers). But the question now, is it better to have more wpc continuous or high dynamic headroom? Also why does my amp have 5.5db headroom, due to current potential of the power supply?

[jbangelfish]

I wondered if NAD and NAIM had fudged numbers to make us think that they have discovered something new. I believe NAIM made a small amp with 40 or 50wpc with 9db of headroom. These small amps with high headroom are probably able to sound very powerful. Whether they are built with smaller power supplies and just unable to sustain the high power ratings for longer periods, I'm not sure but I'd guess that it goes something like that. I prefer an amp that has the continuous power rating in a higher range and worry less about headroom. Probably in most cases, doing it by the NAD or NAIM method, it works out fine as we rarely use the power that we have available for any sustained period.
Bill

[skeptic]

In the horsepower race of the 1960s and 1970 where a given amplifier could be rated at anywhere from 20 watts to 250 watts depending on what mix of science and fiction the advertising department chose to use, the FTC finally stepped in and set ONE standard for advertising amplifier wattage and that had to do with both (today all) channels driven, preconditioning at 1/3 rated power for at least 20 minutes, and specified limits of frequency and distortion, and of course the connected load which is usually 8 or 4 ohms resistive. But amplifier power is much more complicated than the single number consumers would like to put on it. And that truth makes it much more difficult to compare one directly against another in simple quantitative terms.

It is a fact that at the peak of a sine wave an amplifier will deliver 25% more power than on the average of that sine wave. So an amplifier which has a continuous power rating of 100 watts will at the peak of the sine wave be delivering 125 watts for that brief instant. However, amplifiers don't always reproduce sine waves and until large power supply capacitors are depleted of charge, an amplifier could momentarily deliver substantially more power. Ironically, a well designed power supply with a large power transformer as well could deliver all that extra power continuously assuming the output transistors or tubes could take it without being destroyed.

Amplifiers of identical power ratings may not seem to sound equally loud before distorting. That is because amplifiers with even slight peaks in frequency response at certain frequencies will sound louder and they will also sound louder if they produce more distortion. These may be two reasons which explain why some vacuum tube amplifiers which have notoriously higher harmonic and intermodulation distortion and less uniform frequency response over the audio band may seem louder to some listeners than solid state amplfiers of comparable power.

[Geoffcin]

Yes, the FTC have regulated the standard, but manufactures are still trying to get around it. You would think that they would have to post all the amp specs to one standard, but this seems not the case. After reading through some receivers specs, which I thought were pretty good @ 100 watts continues with .1% THD 20-20khz. After a little further reading it states that this is for the front mains only, NOT the 5 other channels! They are rated @ 1% distortion, and only @ 1khz sine wave.
I think what's going on here is that when the FTC made the ruling multichannel amps weren't even invented yet, and so they fell through the cracks.

[skeptic]

The FTC revised their standards a few years ago to require that measurements be made with ALL channels driven.

A real problem stems from the fact that non technical consumers want a single simple number so that they can compare one amplifier with another. The reality is that amplifier performance is much more complicated than this and relying on one number or a few numbers alone can be deceptive and misleading.

Serious home audio systems are generally bought piecemeal through a series of upgrades rather than well planned out and engineered. This can lead to a costly series of disappointments and endless trading and upgrading looking for something that doesn't exist.

The best advice proven over time is to build a sound system around loudspeakers, not amplifiers. By choosing a loudspeaker first, you have zeroed in most closely on the kind of sound you are looking for. Then buy an amplifier suitable for it. People who choose the amplifier first often find that they have boxed themselves into a corner they can't get out of easily. That 9 watt per channel SET class A amplifier that sounds so sweet will only have sufficient power for a small fraction of the loudspeakers on the market and the amplifier that cannot deal with any loads under 8 ohms that seemed such a value will run into all kinds of unpredictable problems with a large number of loudspeakers.

Are you an audiophile? Here's my new definition. Count up the number of times you have bought a new piece of audio gear in the last five years because you no longer were satisfied with the previous one which still worked perfectly fine. Now count the number of pairs of shoes you have worn out and replaced in those same five years. If the first number is larger than the second, you are an audiophile and are in need of mental help. If the second number is larger, you may be normal.

[Geoffcin]

Are you an audiophile? Here's my new definition. Count up the number of times you have bought a new piece of audio gear in the last five years because you no longer were satisfied with the previous one which still worked perfectly fine. Now count the number of pairs of shoes you have worn out and replaced in those same five years. If the first number is larger than the second, you are an audiophile and are in need of mental help. If the second number is larger, you may be normal.

HA! So you subscribe to the idea that audiophiles are some kind of "audioholic" or better yet "audio deviant". I will respectfully disagree and put forth my definition.

Audiophile; A person who is so obsessed with the quality of audio reproduction that he devotes many hours of his life to it. Obsessed even to the point of modifying components that he feels are deficient in some perceived way. (do we know anyone who does this)? Perhaps he's even unhappy with the designated standards of surround sound reproduction and builds his idea of what it should be. (I only know one person who does that!) Yes, audiophilia is an obsession, and not one that can be treated, it can only be fed!

[Geoffcin]

The best advice proven over time is to build a sound system around loudspeakers, not amplifiers.

Total agreement! A rarity on this website. I have found that the difference, especially among top quality amps, is very subtle. Speakers on the other hand, nearly everyone can hear the difference between. Amps make voltage, speakers make soundwaves.

I look to design when picking speakers, not necessarily brands, although I have my favorites. In my view a well built two way speaker with a 8" woofer, and a dome tweeter, will sound much like another brands well built two way with an 8" woofer and a dome tweeter. No matter if they use silver wiring or not!

I've been accused of audiophilia, but it's more of hord-o-philia, as I still have two sets of EPI's and my beloved KLH model 6's, in addition to my current Cambridge Soundworks T500's and Magnepan 3.6's.

[skeptic]

I also still have my pair of KLH 6s and they sound great and are in perfect condition after nearly 40 years of use.

The current audiophile speaker design consists of two woofers one possibly acting as a midrange as well (2 1/2 way speaker) or two woofers and a midrange and a soft dome tweeter. The woofers are 6 to 8 inches, the tweeter is one inch and if there is a midrange it is about 5 inches. The crossover is Linquist-Riley second order and the the enclosure is ported and designed along Theil-Small parameters and is a small tower which is supposed to sit several feet from the back wall. These usually run anywhere from about $1500 to $5000 a pair depending on how much "balls" the manufacturer has. (You can easily build these yourself with parts from places like Parts Express.) They tell you if you want really deep bass, buy a subwoofer which they will also be glad to sell you for another $1000 to $1500. They generally sound shrill and thin to my ears, not very musical and stress what some people call imaging as opposed to tonal accuracy. Needless to say, I have not been impressed and still prefer older technology which is available at a small fraction of the cost, sometimes even at giveaway prices.

[E-Stat]

The best advice proven over time is to build a sound system around loudspeakers, not amplifiers.

Indeed. That was advice given to me about thirty years ago from an audio dealer and friend. I've used the same speakers (with some internal enhancements) for the past twenty years. I prefer full range electrostatics for their incredible purity and coherence. Large ES speakers can play loudly without sounding loud. They have continued to reach ever deeper into the recordings following improvements elsewhere in the system.

rw