Watts! How many do we need?

Let’s assume the meters are not very accurate. How much off are they? By a factor of 10 so 10 watts peak? Or by a factor of 20 so 20 watts peak? And then we make the sound twice as loud (+3db). Now 20 or 40 watts.  Sill far below the amount of watts modern amps are offering. 

The meters found on most amps are very rarely calibrated, and more often mislead rather inform.

I doubt those meters are able to measure actual peak power, it gets difficult to measure when a speaker is involved. 

The 1.5 watts of “audio magic” of the 45 tubes is plenty for me. My backloaded horns are 102 db efficient. Korneff integrated amp with Emission Labs 45 wire mesh tubes. Although I must admit that I cheat. With organ music I turn on a Velodyne 18GS subwoofer that has a built in 1500 watt solid state amp. Go figure…

Peaks are between 75 and 80db. I’m sitting and measuring about 8 feet from the speakers which are 7 feet apart. They are almost 3 feet from front wall and are 5 feet from side walls. Plenty of opportunities for sound absorption. The room is 17 x 15 and is carpeted and is not what I would call a live room as it has furniture as well. The peaks are as loud as I would want and doubling the loudness would apparently require 2 watts. When would I ever need 10 watts let alone 150? BTW these peaks I hear are produced effortlessly with a balanced presentation. No instruments or frequencies are emphasized. It’s a smooth delivery. 

I would be curious to know what actual volume you are listening at? A crude app for your phone will tell you peaks at your listening position, and if you are feeling inquisitive, you can measure at 1m from the speakers. 
 

1 watt at 1m will give you 86db from your speakers. It’s math. As was stated above, every 3dB step  above that, will require a double amount of watts.

The other thing, is higher powered amps, have bigger power supplies. They will have more power in reserve at lower watt output.

Provided the transistors, and the topology of the amp is such that it is operating in a linear manner at low output, they will sound “better” at low volumes than a lower powered amp with an inadequate power supply.

Which brings us full circle back to Nelson Pass, and the relevance of the first watt.

It’s a new Accuphase amp and the meters are accurate. The amp is rated at 150 watts per channel into 8 ohms and 300 into 4 ohms. I think we are all using a lot fewer watts than we think even  in peaks. 

Maybe those meters do not capture those peaks.  I would not go less than 100 watts.  But that's just me.

@bpoletti 

That’s the issue I was addressing. The meters in my amp are set to freeze at the highest peak reached. So at the end of the night when I check them they never exceed 1 Watt. And that’s with me listening to full Classical orchestral recordings at  room filling volume that are very dynamic.  So even my large peaks  that are  musically dynamic do not move the meter past 1 watt. 

@ghdprentice  I assume it makes a great deal of difference on the individual speaker you are using.  I've always heard there is a difference between "tube" watts and SS watts.  On this very sight I have read that tube watts are roughly 3 times as powerful as SS watts.  To this end I've found this lengthy article penned by Roger Sanders to be quite interesting.  Especially as I am driving a set of SoundLab Majestic 745's.  Cheers.  

https://sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors

And my tube amp sounds better in every respect with my speakers in ultra linear mode, which is double the power. Also, with its 60 watt/ch it feels significantly more powerful than my previous 80 watt/ch ss amp at the same volume level. Well, you don't compare VAC to Burson, anyway.

Normal to loud-side for most speakers is around 1 - 2 watts.  Figure out what it is for your speakers and multiply by 100 to 200 to cover the peaks without capping out the amp's capacity.  And YES, momentary peaks can take that amount of power.

I have an original Schitt Aegir (20 w/ch 8 ohms) and a pair of Ohm 1000 speakers in a 15' X 24' room with a vaulted ceiling -- absolutely no problem reaching my desired listening level (85 dB average) with no hint of clipping or compressed dynamics.  Two caveats, however.  First I use a powered subwoofer and roll off the deep bass to the Ohms. Deep bass can be a power hog  Second, as many know, the relationship between watts and volume level is logarithmic, not linear. Doubling the power gets you 3 dB more volume. Doubling the perceived volume takes 10 times more power. So, if you are a headbanger, and have medium or low sensitive speakers, or have a large room, you're going to need a lot more power than I do.

But, as others have noted, lotsa watts are an attractive advertising carrot. And Class D amps have made it easier to offer that carrot these days.

@ghdprentice 

I’m puzzled by your experience. I don’t doubt it but since current x volts equals watts. What you are describing is that lower current sounds better. So something else is going on when you switch to high watts. 

From my experience with solid state, current was the primary determinant if the amp was up to the task, the more the better. From my tube amp experience, it is far, far less important. So I went from high current 350 wpc solid state to 70 wpc tube amplification and my system sounds so much better it is amazing. It is a high quality amp… I am sure there is a difference between 70 wpc with an inexpensive light weight tube amp and a good one.

I happened to be looking at the meters the other day and noticed they were peaking at 1.5 watts output. I realize analog meters are slow and will not capture the full extent of what is going on and perhaps the meters use a proxy parameter to measure watts… but still interesting. Seems there is some truth in the saying “it’s the first watt that is most important.”

I can switch my amp between 70 wpc and 140 wpc. I noticed the same average power output in either mode but the peaks in sound would send the meters quickly far to the right (higher output) in 70 wpc mode… which makes sense. Even at deafening volume my tube amp does not run out of power. While my past experiences with 75 - 150 wpc solid state either never had good solidity or loss it when pressed to higher volumes (not necessarily ear splitting). The other thing I notice is that my amp sounds much more natural and musical without loss of dynamics in the 70 wpc triode mode vs the 140 wpc ultra linear mode.

One. Million. Watts. (Max total peak)

FYI

there are several Stringrays at a good price here in Audiogon.

as well as a great pair of Snappers; if you have a little extra and want 100wpc.

I keep going down in watts. I do have high-efficiency Klipsch Cornwalls.

My amp voyage has been....

NAD M23 200 wpc

to 

Threshold CAS1 75 wpc

to

Manley Stringray switchable between 20 wpc (triode) or 40 wpc (ultra-linear) 

All have sounded great, but each has been a step up in quality; in my opinion.

I love the sound of the Manley in ultra-linear mode.

It is FAR easier to sell something on more-is-better because that is easy to understand. If the extra power does not come at an expense in terms of sound quality, that would mean no harm in having way too much power in reserve.  But, that is not really the case.  Of curse it is a matter of taste, but, I generally prefer the sound of low-powered tube amps over other types.  Often, my least favorite amps are high-powered tube amps running multiple KT88, KT150, KT170, etc. tubes (the sound is "hard" and harsh sounding to me).  These days, most good solid state amps are smooth and not harsh sounding at all, but, they tend to sound a bit lifeless and unengaging unless the volume is push up higher than one would play the speakers running good tube amps. 

I know Harbeth advocates for a lot of power and their speakers are somewhat inefficient, but, the best I have heard them sound was with medium powered amps.  A good 20-100 watt pushpull tube amp would be my choice.

How about this? Or this?

Or maybe that? Or that?

And who could forget this?

Search engines...I wuv you.

Current uber alles.

Looking at my own meters, it’s movies that are going to push the amps.

For the record, every meter I’ve seen is really a voltage meter in disguise. A low impedance speaker won’t push the needle further up. Perhaps someone has invented a smarter meter though. :)

On a slightly different angle than the OP has asked Nelson Pass has long advocated that the performance of an amp in the first few watts is what matters most.