[Rclark]

From the Roger Sanders interview on Dagogo:

As an aside, I continue to be amazed by the fact that most audiophiles are not aware that they are using underpowered amplifiers that are clipping and distorting most of the time. It is easy to show that most speakers need around 400-500 W/channel to play dynamic music at the loud levels audiophiles enjoy. If you doubt this, just connect an oscilloscope to your speakers and watch it. You will see the trace run into an invisible "brick wall" when the amplifier runs out of power and clips. In most systems, you will see the amplifier clipping constantly on musical peaks.

oh wow. So much for puny little amps.

[JLM]

"Conventional" thinking say that instanteous musical peaks are around 105 - 110 dB, but some say closer to 130 dB (roughly 200 times the wattage difference!!).

So my 90 dB/w/m speakers, in a typical room (say 12 ft x 20 ft) would need 40 dB of gain or 10,000 wpc to cover the peaks!?  But the saving grace is how loud you listen.  Most audiophiles I know do serious listening at an average of 80 dB, which would be "only" 1,000 wpc.

0 dB of gain = 1 wpc; 10 dB = 10 wpc; 20 dB = 100 wpc; 30 dB = 1,000 wpc  (Add your speaker efficiency to dB of gain you're after to see how much power you're talking about.)

[mgalusha]

Bob Cordell did a demo at one of the first RMAF shows between a good 35W PP tube amp and a 250W SS amp. On a dynamic recording played at a fairly loud level the average power was only a few watts with either amp. The peak power with the tube amp was right at 35W, which is of course all it could manage. He switched over to the big SS amp and the peaks were about 200W. This was all level matched within .1dB. It was exceedingly clear that the tube amp was clipping the peaks and that most people don't have nearly enough power.

My speakers are ~95dB/W/M and when played loud with say 105dB peaks, I measured average levels of a bit over 2W but the peaks were at 105W. I am firmly in the camp that believes most people have inadequate power amps. A friend has 90dB sensitive speakers and uses a 600WPC Krell FPB to drive them. It seems just about right for his room and speakers. I've heard a 40W tube amp in that system and while it does OK, there is a definite lack of ease that his giant (and I do mean giant) Krell has.

Me, I've decided that I need at least 150WPC with the current set up. I want an utter lack of strain at any level and that means no clipping, ever.

[Atwood]

But with that much power, how much use of the preamp volume control do you have? Are you stuck around 9 o'clock with little room for adjustment?

SS watts are relatively cheap, yet Alan Shaw, designer of the moderately efficeint Harbeth speakers says a 55-watt SS amp drives his speakers to ear-shatteringlevels.

[poseidonsvoice]

But with that much power, how much use of the preamp volume control do you have? Are you stuck around 9 o'clock with little room for adjustment?

SS watts are relatively cheap, yet Alan Shaw, designer of the moderately efficeint Harbeth speakers says a 55-watt SS amp drives his speakers to ear-shatteringlevels.

You are completely confusing power output with overall voltage gain with the comment regarding preamp volume control.

Anand.

[mgalusha]

As Anand points out, gain and power are not the same thing. I have the gain structure of my system arranged so that I can run the volume control on the preamp wide open on low level tracks and not clip the amplifiers.

And yes, I can play it ear shatteringly loud with less power but part of what is shatteringly loud is the sound of an amplifier clipping. If the speakers don't have much distortion and don't suffer from power/thermal compression, it's somewhat surprising just how loud it can play without causing distress. Obviously I don't do this often or for very long, but sometimes ya just gotta turn it up to 11.

But with that much power, how much use of the preamp volume control do you have? Are you stuck around 9 o'clock with little room for adjustment?

SS watts are relatively cheap, yet Alan Shaw, designer of the moderately efficeint Harbeth speakers says a 55-watt SS amp drives his speakers to ear-shatteringlevels.

[Atwood]

You are completely confusing power output with overall voltage gain with the comment regarding preamp volume control.

Anand.

So if I have a 100 watt amplifier and a 200 watt one, both with 26db gain, and I set the volume control at 9, both will play at the same volume?

[Atwood]

As Anand points out, gain and power are not the same thing. I have the gain structure of my system arranged so that I can run the volume control on the preamp wide open on low level tracks and not clip the amplifiers.

And yes, I can play it ear shatteringly loud with less power but part of what is shatteringly loud is the sound of an amplifier clipping. If the speakers don't have much distortion and don't suffer from power/thermal compression, it's somewhat surprising just how loud it can play without causing distress. Obviously I don't do this often or for very long, but sometimes ya just gotta turn it up to 11.

Maybe, but it's just as possible it's too loud.

How have you set your "gain structure" to attenuate the power from your amp? I'm interested because I use a TVC and unless I want to go to "11" I never go much past 9-10 o'clock. That's one reason why I want to go to a lower-powered amp.

[*Scotty*]

Many TVCs have multiple taps on their transformers to enable you to have a choice of how much voltage gain you have. Yours may be set for a higher amount of gain than you need.
 A lower powered amplifier is not the answer. If you can not adjust the gain on your TVC you may want an amplifier with less sensitivity. My amplifier puts out full power, all 108watts/8ohms of it with 1 volt of input signal. A less sensitive amplifier could require 2 volts or more to reach full power output. With an amplifier that had lower sensitivity you might be able to use as much as half of your volume pots travel instead of a quarter of it.
Scotty

[mgalusha]

All amps will clip if driven hard enough. And yes, I've had plenty that did, even with efficient speakers. Earlier in this thread there is a comment about Tom Danley moving too 800W amps with 100dB speakers to avoid this. As others have noted, unless you actually see this measured, it can be difficult to believe.

With speakers that have little thermal and power compression hearing the affect of peak clipping is easier. Most do not own such animals.

As for gain structure, I set the output level of my dac where I wanted it, the same is true of my preamp. They are at levels that will just support full power with most amps having 26dB of gain.

Going to a lower power amp will not necessarily result in your volume control having more usable range. Going to an amp with lower gain will. You need to know the voltage gain of the current amp and that of your prospective purchase, otherwise it's all guesswork.

There is a nice article on gain structure by Michael Mardis on diyaudio, well worth reading. http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html

[dflee]

Does not an amp with X amount of continuous power and Y amount of peak power handle the required power during peak draw.
I have an amp with 225 watt per channel and excess of 25 amperes peak per channel. What is 25 amperes any way?

[Atwood]

All amps will clip if driven hard enough. And yes, I've had plenty that did, even with efficient speakers. Earlier in this thread there is a comment about Tom Danley moving too 800W amps with 100dB speakers to avoid this. As others have noted, unless you actually see this measured, it can be difficult to believe.

With speakers that have little thermal and power compression hearing the affect of peak clipping is easier. Most do not own such animals.

As for gain structure, I set the output level of my dac where I wanted it, the same is true of my preamp. They are at levels that will just support full power with most amps having 26dB of gain.

Going to a lower power amp will not necessarily result in your volume control having more usable range. Going to an amp with lower gain will. You need to know the voltage gain of the current amp and that of your prospective purchase, otherwise it's all guesswork.

There is a nice article on gain structure by Michael Mardis on diyaudio, well worth reading. http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html

Thanks.

I know the gain of my current amp and CD player's voltage output. The CD player's output is non-adjustable. There's no extra gain in my TVC.

I read the article and the thread it generated. It seems it's difficult to find low gain amplifiers (unless you DIY) A buffer seems to be one solution.

But the fact that Roger's amps are said to work great with passives now seems to be a negative in my situation since its input sensitivity is only a little higher than my current amp's.

Thanks again.

[S Clark]

And sometime, just efficiency isn't the key.  My LS9's are quite efficient, but with a dozen midwoofers there is a lot of back emf to be controlled.  Althought 93db efficient, they need about 200 watts to open up during orchestral crescendos.

[Elizabeth]

My take on power is how much A/C I use per month.
The vast majority of the $55.00 I pay per month is from leaving my system powered up 24/7/365.
I have an efficient frig, almost never use the stove, and keep most lights off.
My Prior amp was a 50 watt per channel. Now I have a 200  watt per.

[Freo-1]

Good points made about gain vs. power.  The First Watt F4 has an output of 25 watts @ 8 ohms, but 0 db gain.  In fact, many systems have a preamp/power amp combination which throws away quite a bit of gain.

I have a little different take on this.  I do not subscribe to the view that one needs 800 watts with 100db speakers to get the best sound.  My experience over the years has caused changes with my systems to employ lower power amps with more efficient speakers. 
From the First Watt website:
{ Dick Olsher famously remarked that “The first watt is the most important watt.” This sentiment has also been expressed by others as “Who cares what an amplifier sounds like at 500 watts if it sounds like crap at one watt?” }

I have found this to be closer to the truth than the high power wattage approach.  For example, an 800 watt amp  in Class B with a lot of feedback just does not very musical to me.  So, the answer to the question is: It depends on several factors:
1.  The type of speakers used
2.  The listening environment
3.  Preferred listening levels
4.  Type and quality of amp used

[Roger A. Modjeski]

From the Roger Sanders interview on Dagogo:

Below is Roger Sanders opinion on power previously quoted here and in his whitepaper:

As an aside, I continue to be amazed by the fact that most audiophiles are not aware that they are using underpowered amplifiers that are clipping and distorting most of the time. It is easy to show that most speakers need around 400-500 W/channel to play dynamic music at the loud levels audiophiles enjoy. If you doubt this, just connect an oscilloscope to your speakers and watch it. You will see the trace run into an invisible "brick wall" when the amplifier runs out of power and clips. In most systems, you will see the amplifier clipping constantly on musical peaks.

I routinely use an oscilloscope to look at power in my system. I have permanently installed a classic Textronics rack mount scope in my rack so I dont have to fetch one off the bench when I am curious.

I set the brick wall at the top of the screen and indeed watch how close I come to it. The headroom I see (the distance from the peak to the brick wall) is often 10 db on peaks. Using a 100 watt amp that is a peak of 10 watts with 90 watts to spare. I know Roger Sanders work and I know he makes a very power amplifier for his speakers and I have no doubt he uses its full power listening at very high levels (which I don't). The big difference is not in the speaker and amplifier but in the listener and his desired levels.

I do agree with Sanders that you can see your headroom with the most basic oscilloscope which can be had on eBay for under $100, (just make sure the seller promises that it works, is reasonably accurate and will take it back if not). I do not agree "that most audiophiles are not aware that they are using underpowered amplifiers that are clipping and distorting most of the time".

There are several easy ways to check accuracy which I will be happy to write about if asked. Most scopes have a built in calibrator and even if the accuracy is 10% off, its plenty good enough to determine peak power and clipping and further determine if your amp is putting out what it should or if it is being limited by speaker impedance dips, cable losses, low line voltage or any number of things.

All this being said, with a 90 db speaker I do not see clipping at my average listening levels with even the 15 watt EL-84 Class A version of the RM-10 that I am currently working on. Furthermore the standard 35 watt per channel RM-10 satisfies most listeners and they often comment on how loud it will play their speakers and how much bass impact this little, light weight amplifier has.

Sanders further states: You will find that conventional, direct-radiator (not horn-loaded), magnetic speaker systems of around 90 dB sensitivity, require around 500 watts/channel to avoid clipping.  More power is needed in larger rooms or if you like to play your music more loudly than most.

I would say from the above that Mr Sanders likes to play his music more loudly than most. Due to what I cannot say, though I hope he has not severely damaged his hearing. I routinely check mine, often in a group of several people at once, it's not hard to do. I connect an oscillator to a speaker, set a moderate level like 70-80 dB start at 400 Hz, everybody raises their finger and drops it when they can no longer hear the tone. You could do the same at several frequencies and lower the level and watch fingers drop. It's a very interesting test and you can use CD with a sweep and tones or get them off your computer with free software. Get a group together on a Saturday and see where everyone is at.

Another thing I do when playing my system for others is to routinely ask if the volume I set is higher or lower than than they usually listen to. I find a fairly equal number who like higher and lower and the same as I listen to.

The room size matters little as most of our rooms are relatively dead (by choice) and the reflected energy is thus low and not material. What does matter is how far you listen from the speaker as most speakers fall off 6 dB as you double the distance. At 4 meters (13 feet) the 90 db speaker is now 78 dB per watt but two of them are 84 dB which is a level most people listen at, which means one watt per channel. We can argue for large peaks in live music but with music as compressed as it is these days on CDs 10 dB peaks are about all you can expect unless it is a very quiet CD on the average. Ten dB above 1 watt is 10 watts and you still have headroom. In my experience occasional clipping on the scope is not heard by even the most golden eared listeners. However if you do see clipping on the scope, just turn it down a bit.

Another thing you may see on the scope even with well recorded vinyl like Willie Nelson's Stardust is clipping in the recording on rim shots on the ALL of Me track. We used that record extensively at Beveridge  and I never noticed it till I saw it on the scope. So in many cases, the source material is going to clip before your amp.

One thing that Sanders does not address is the "First Watt" principle that Nelson Pass, myself and many others feel is more important than unused headroom. Granted some headroom is a good thing but for a listener who is using one watt, 99 watts of headroom are not needed. People listening at 70 dB (and there are many) are using far less than that.

[Roger A. Modjeski]

Good points made about gain vs. power.  The First Watt F4 has an output of 25 watts @ 8 ohms, but 0 db gain.  In fact, many systems have a preamp/power amp combination which throws away quite a bit of gain.

I have a little different take on this.  I do not subscribe to the view that one needs 800 watts with 100db speakers to get the best sound.  My experience over the years has caused changes with my systems to employ lower power amps with more efficient speakers. 
From the First Watt website:
{ Dick Olsher famously remarked that “The first watt is the most important watt.” This sentiment has also been expressed by others as “Who cares what an amplifier sounds like at 500 watts if it sounds like crap at one watt?” }

I have found this to be closer to the truth than the high power wattage approach.  For example, an 800 watt amp  in Class B with a lot of feedback just does not very musical to me.  So, the answer to the question is: It depends on several factors:
1.  The type of speakers used
2.  The listening environment
3.  Preferred listening levels
4.  Type and quality of amp used

Amen....and here's to the memory of J Gordon Holt who knew and wrote more audio truth in one issue than a year of what we get these days.

[JLM]

Beyond the importance of the 1st watt, back EMF, and handling peaks (which I fully agree with each) there is also the issue of control/command.  Having "enough" power also allows the amp to maintain a firm grip of the drivers.  Without keeping a solid choke hold, the drivers "wobble" like loose wheels on a car going around a curve.

BTW speakers with passive crossovers lose much of this potential control by wasting energy, adding phase mix ups, and masking the electrical/mechanical feedback between amp and driver(s).

[BobRex]

Amen....and here's to the memory Dick Olsher who knew and wrote more audio truth in one issue than a year of what we get these days.

Olsher's dead?????  Far as I know he still writes for TAS and occasionally for Enjoy the Music. 

[Roger A. Modjeski]

sorry, my bad... i meant J Gordon Holt. Dick is a good writer too. Wish we had more like him.