Paul McGowan’s Post: More Than Enough

Ron Resnick

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Jan 24, 2015
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. . .

What we want in a power product is called headroom, the ability of a device to exceed demand by an appreciable amount.

Headroom is important on a number of levels: lowering parts stress, relaxing audio presentation, removing strain from both the equipment and the music. If you think you need 100 watts, go for 200 to 300 instead.

It’s easy to understand too little strangles performance. The difficult argument is that bigger is better than enough. Taking your equipment right up to the edge, or anywhere even close to shore, isn’t worth the initial savings on equipment.

When it comes to deciding how big to go, more than enough should be your guiding light.

I post this because I agree with it. More importantly MikeL’s long experience with amplifiers and headroom has lead him to this same conclusion as Paul.
 

Blue58

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Jan 20, 2013
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. . .

What we want in a power product is called headroom, the ability of a device to exceed demand by an appreciable amount.

Headroom is important on a number of levels: lowering parts stress, relaxing audio presentation, removing strain from both the equipment and the music. If you think you need 100 watts, go for 200 to 300 instead.

It’s easy to understand too little strangles performance. The difficult argument is that bigger is better than enough. Taking your equipment right up to the edge, or anywhere even close to shore, isn’t worth the initial savings on equipment.

When it comes to deciding how big to go, more than enough should be your guiding light.

I post this because I agree with it. More importantly MikeL’s long experience with amplifiers and headroom has lead him to this same conclusion as Paul.

I thought I needed 0.75W so went with 2W :)
 

spiritofmusic

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Jun 13, 2013
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I find one girlfriend enough, but obviously I need more.
 

Barry

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Headroom? No problem! 1,300 per channel total into ~ 4 ohms. In my triamped system, 400 tube/SS hybrid watts per side from each of 2 stereo amplifiers for the mains and 500 SS watts on each channel from one stereo amp on the subs. As much benefit is derived from powering the speaker drivers directly, eliminating the passive crossovers both in terms of added tranparency and efficiency. Thankfully the SS sub amp is a good one and is crossed over low enough (80Hz) and rolls off fast enough (24dB/0ctave) that it integrates well and doesn't mess up the sound.
 
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audioguy

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I am a huge believer in this as well. My 94dB efficient speakers can get along quite well on a relatively low powered amp. So 300 watts is way more than enough ... Plus all of the really heavy lifting (south of 80Hz) is done by my subs, each with over 1000 watts.
 

ack

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May 6, 2010
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. . .

What we want in a power product is called headroom, the ability of a device to exceed demand by an appreciable amount.

Headroom is important on a number of levels: lowering parts stress, relaxing audio presentation, removing strain from both the equipment and the music. If you think you need 100 watts, go for 200 to 300 instead.

It’s easy to understand too little strangles performance. The difficult argument is that bigger is better than enough. Taking your equipment right up to the edge, or anywhere even close to shore, isn’t worth the initial savings on equipment.

When it comes to deciding how big to go, more than enough should be your guiding light.

I post this because I agree with it. More importantly MikeL’s long experience with amplifiers and headroom has lead him to this same conclusion as Paul.

At face value, what he claims is correct. The problem is that going for higher headroom involves all kinds of ancillary parameters - like potentially more amplification devices which need to be matched, along with beefier and potentially slower power supplies, or perhaps not even beefy enough; and so many others - therefore the key is getting equally or better sound along with more power. Read the latest Stereophile review of the Pass XA-200.8 carefully, and you'll see in the measurements and listening comments the trade-offs the designer chose to make, plus specific voicing decisions with the 2nd and 3rd harmonics; I was struck by the comments relating to the not-so-tight bass, despite the additional amplification devices over smaller amps in the same line.
 

Empirical Audio

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Oct 12, 2017
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Headroom should also include component tolerances. You can get away with capacitors with 85 degree rating, but they will last longer if they have 105 degree rating. Same with voltage. If you are running 25V on the cap, you need a 50V cap.

Most of the time overkill is a good thing, however there is a trade-off with SQ on some of these decisions, so it is a tight-rope to walk.

Steve N.
Empirical Audio
 

PeterA

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At face value, what he claims is correct. The problem is that going for higher headroom involves all kinds of ancillary parameters - like potentially more amplification devices which need to be matched, along with beefier and potentially slower power supplies, or perhaps not even beefy enough; and so many others - therefore the key is getting equally or better sound along with more power. Read the latest Stereophile review of the Pass XA-200.8 carefully, and you'll see in the measurements and listening comments the trade-offs the designer chose to make, plus specific voicing decisions with the 2nd and 3rd harmonics; I was struck by the comments relating to the not-so-tight bass, despite the additional amplification devices over smaller amps in the same line.

Ack, do you have a link to that Stereophile review, or the issue #? I could not find it with a Google search. Thanks.
 

ack

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August 2018 issue; the measurements are not looking too good from this vantage point
 

PeterA

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August 2018 issue; the measurements are not looking too good from this vantage point

Thanks. I have not received my copy yet. Can't comment about the measurements. I did directly compare my XA160.5 to a friend's XA160.8 in my system and preferred the .5. I preferred the .8 in his system. I do not really know what that means or if one can draw any conclusions from those observations. I will say that I have heard many great measuring components that did not sound very good in certain system/room contexts.

I do agree with the observation made in the OP. I have always found in my own system that having more power is better, primarily for the sense of ease and effortlessness that it brings to the sound. I understand that there may be potential drawbacks to this extra power.
 

Folsom

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The point is really more like "go with more headroom than you think you need - because your equipment isn't nearly as efficient as you think"

Speakers are not "94db efficient" they are 94db sensitivity. The reactive parts of a speaker along with mechanical properties greatly reduce the efficiency. What this means is the increase in volume to power isn't entirely linear. So when you thought you needed 100w, your speaker efficiency really make you need more because the efficiency of it has bled off many watts into something other than acoustic sound levels.

What is overlooked is that not all amps and such are terrible efficient. And I'm not talking about how much power they use vs. put out. I'm actually referring to the fact that they often suffer various forms sag/sat. So while you might have a 500w amp, it may only be able to produce 200w without any sag/sat, at least on the regular. That doesn't mean it can't do 500w, it just means you can't actually listen at 500w. So the advise to go bigger makes sense. But some amps are very efficient. Tube amps tend to be much more efficient for several reason, and this is pretty easily reflected in the lower power units like Lamm still being able to power lots of high end speakers. It doesn't hurt that they have output transformers that make the speaker look more efficient (easier to drive) to the amplifier, partially anyways.
 

GaryProtein

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Jul 25, 2012
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You have enough amplifier power when you can blow the main on your 100 amp stereo dedicated circuit breaker box. :D

I only have an 80 amp dedicated box and I never blew the main, so I guess I need more amplifier power! :D

Power is good. You need in excess of what your speakers require for a good full clean sound at realistic listening levels. Low sensitivity speakers will obviously require more power than 105 dB/m/W horns. Buy power accordingly.
 

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
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. . .

What we want in a power product is called headroom, the ability of a device to exceed demand by an appreciable amount.

Headroom is important on a number of levels: lowering parts stress, relaxing audio presentation, removing strain from both the equipment and the music. If you think you need 100 watts, go for 200 to 300 instead.

It’s easy to understand too little strangles performance. The difficult argument is that bigger is better than enough. Taking your equipment right up to the edge, or anywhere even close to shore, isn’t worth the initial savings on equipment.

When it comes to deciding how big to go, more than enough should be your guiding light.

I post this because I agree with it. More importantly MikeL’s long experience with amplifiers and headroom has lead him to this same conclusion as Paul.

I'm sure it's no surprise to those who know me I'm a big fan of more than enough headroom throughout a system. Of course the qualifier here is "...assuming all else is equal." Electronics in particular don't always hold that qualifier. We know a lot more now about what electronic behavior matters and what is less audible since earlier solid state efforts boasted dramatically higher power levels. Mixing in different amplifier designs and technologies can make things even more interesting, just as the long standing conundrum of how to rate power for amplifiers and the significant limitations in simpler ratings. Two rather common gotchas can be a matter of absolute noise floor and very low level behavior. While related, I am not referring to signal to noise, but rather the minimum level of noise with no input. With lower sensitivity speakers in the 80dB/1W range this isn't a big deal, but when you get above 95-100dB or in extremely quiet rooms this is a spec to pay attention to, especially if you are considering class D options (some are very good, many are not). Most modern amplifiers behave quite well at low levels, but not all are equal, and a 6-10dB difference (1/4-1/10th power) in speaker sensitivity is easily enough to make a non-issue in one system a concern for another.
 

Al M.

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At face value, what he claims is correct. The problem is that going for higher headroom involves all kinds of ancillary parameters - like potentially more amplification devices which need to be matched, along with beefier and potentially slower power supplies, or perhaps not even beefy enough; and so many others - therefore the key is getting equally or better sound along with more power. Read the latest Stereophile review of the Pass XA-200.8 carefully, and you'll see in the measurements and listening comments the trade-offs the designer chose to make, plus specific voicing decisions with the 2nd and 3rd harmonics; I was struck by the comments relating to the not-so-tight bass, despite the additional amplification devices over smaller amps in the same line.

Most of the time overkill is a good thing, however there is a trade-off with SQ on some of these decisions, so it is a tight-rope to walk.

Steve N.
Empirical Audio

Yes, bigger is not always better. I remember back in the day, 25 years ago, a friend in Austria bought some not so large floor standers for which he needed an amp. We compared a 2 x 60 W, a 2 x 90 W and a 2 x 120 W amp, all from Rotel, on the speakers. The 2 x 60 W amp won, sounding much more lively and dynamic than the larger amps.

Having said that, my tube amp of 2 x 100 W is 5 x overkill for my 92 dB sensitive monitors, which can easily be driven with great dynamics by 2 x 15 W amps. However, the 2 x 100 W amp is even more dynamic. My subs each have an 1800 W amp built in.
 

Audiocrack

Well-Known Member
Aug 10, 2012
2,175
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. . .

What we want in a power product is called headroom, the ability of a device to exceed demand by an appreciable amount.

Headroom is important on a number of levels: lowering parts stress, relaxing audio presentation, removing strain from both the equipment and the music. If you think you need 100 watts, go for 200 to 300 instead.

It’s easy to understand too little strangles performance. The difficult argument is that bigger is better than enough. Taking your equipment right up to the edge, or anywhere even close to shore, isn’t worth the initial savings on equipment.

When it comes to deciding how big to go, more than enough should be your guiding light.

I post this because I agree with it. More importantly MikeL’s long experience with amplifiers and headroom has lead him to this same conclusion as Paul.

Paul’s view is apparently based on the following premise: more (and more and even more) watts do not deteriote the quality of these watts. However, based on my listening experiences with a lot of powerful poweramps, in particular many solid state poweramps, this premise is in many cases incorrect in our real audio world (and really transparent audio systems casu quo hifi systems with a (very) low noisefloor will demonstrate this). I am not willing to substitute quality for quantity.
 

caesar

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May 30, 2010
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Gentlemen, great discussion. Is there a definition of "headroom"? I also think we may need to distinguish between power and current...

Experientially, I think most modern speakers like the wilsons, magicos, mbls, as well as all electrostatics and magneplanars I have heard Suck with low powered ss amps and with most tube gear- they just sound dead and syrupy. Unless one is prioritizing midrange over dynamics.

High efficiency stuff is different, however. I think many trade off dynamics in favor of that rich, intoxicating tone. Interestingly, I have experienced 300b on high efficiency sound much more extended and NOT syrupy than , say , an arc, bat, vtl, etc., on the low efficiency, popular brands I mentioned above.

Not sure why people don't just go with 300b and high efficiency speakers instead of say, arc and Wilson, or say Martin Logan with bat, etc....
 

cjfrbw

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Dunno about the OP assertion. I can play my Pass designed VFET 20 watt Class A amp (push pull, so it probably does transients of 80 to 100 watts into class AB) on my 89 db efficient panel without a crossover in my 19' by 13' room as loud as I can stand it with no sign of struggle, clipping or lack of ease, and the sound is amazing. It is probably one the best amps I have heard by sheer ethereal sound quality, challenging even my memory of the Lamm ML3 on Steve William's Danville system.

I personally like Pass' First Watt philosophy, where he believes the best sound comes from the simplest circuits with the fewest output devices and very careful parts selection and build execution. Pass has in inference stated that he likes the sound of lower power amps, but since he produces the behemoth testosterone amps, he can't really go on record to that effect.

I know at audio shows I always prefer the smallest Pass Labs amps by sound quality, and I also have a remarkable sounding First Watt M2 which rings in at 25 watts of Class A with a single pair of push pull MOSFETs per channel. That amp also plays my 89db panel in my room to excruciating levels without strain.

Also, single ended 300b tubes are amazing on the right set up.

So, as a generalization, the notion that high power is essential or even desirable for sound *quality* falls short for me. It depends, but I do have the prejudice that massive amps with huge numbers of outputs are not going to be conducive to the best possible sound quality.

I am not really sure about the "ease" that huge power amps create, either. It's one of those audiophile/audio critic generated notions that sound like justification rather than performance reality. I have never really 'heard' it as such from monster amps at shows. The monster Pass VFET amp sounded great when I heard it, but most of the big SS ones always sound a bit gritty or steely. The enormous tubed units can sound majestic, but they don't seem to have the inner detailing of simpler tubed amps.

That being said, I routinely have a couple of VFET amps on my front speakers that rate over 120 watts each (260 watts total on two ribbons, with perhaps another 3db transient overhead) for the 80 to 350 HZ region and the 350 to 7K HZ region with active crossover, with subwoofs at a total of 500 watts for four. Power meters aren't that accurate, and some like to argue that there is in ineffable overhead requirement of 10 to 20 db, but the peaks indicate on very loud listening of about 15 watts on the 80 to 350Hz range ribbon and 10 watts on the 350 to 7K Hz ribbon.

However, I can sub in the 25 Watt M2 and the 20 watt VFET, and the sound is just as good if not better.

So, as far as raw power and sound quality, I think that no generalization is the best generalization.
 
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NorthStar

Member
Feb 8, 2011
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The first few watts count the most.
Low noise low distortion amplifier.
Stability into complex loads, stress-free.

For realistic live music orchestral concert levels, plenty enough matching power for your loudspeakers.
 

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