To reproduce realistically clean music peaks, amps need plenty of power and fast response times

[Colin]

To reproduce realistically clean music peaks, amps need plenty of power and fast response times:

most loudspeakers will not reach a level of 100 dB SPL without such severe breakup and distortion as to make the measurement meaningless.

http://www.enjoythemusic.com/magazine/bas/0708/

To reproduce realistic peaks of a rock band, the amplifier must produce 4000 watts of peak power. Nearly the same power capabilities are needed to approximate the realistic experience of a symphonic conductor at the podium.

These projections are accurate only if the speaker in question has purely resistive impedance.

To deal with this phenomenon, Keith Howard ⁽²⁾ introduced the figure of merit he has labeled Equivalent Peak Dissipation Resistance (EPDR).

For example, the estimate for B&W 803D for the same recordings is that its peak power requirement would be as high as 7 kW.

most amplifiers use power supply voltages in the order of +/- 65V or even lower.

We have found that it is common in high-quality recordings to see voltages above 100V peak, with medium-efficiency speakers.

When a musical note is played at the frequencies where the impedance dips, the current demands skyrocket.

musical signals demand hundreds of milliseconds of power burst for accurate reproduction of musical peaks

the heat dissipating capability of the amplifier output stage is paramount in the delivery of required peak voltage and current, frequently over the periods of hundreds of milliseconds

The typical transit time of linear amplifiers is about 2000 to 3000 nanoseconds, which is too slow for effective implementation of global feedback and error correction.

http://www.enjoythemusic.com/magazine/manufacture/0708/index.html

[Bill W.]

Colin,

It is good to see this topic addressed in a publication where readers can give some thought to it. Th author makes several valid points. Too bad he didn't include any Klipsch products in his test list or mention that Klipsch has published distortion vs output specifications for many of its products for years.

Perhaps a letter to the editor from Klipsch can be submitted for publication in an upcoming edition.[^o)]

Bill W.

[jacksonbart]

Please inform as to why you like tubes then?

[DrWho]

I'm afraid most speakers will have quite a lot of distortion with 7,000W going into them.

Is smoke a distortion? []

But on a serious note, the amount of heating from a short high voltage transient is very small. Excursion is still an issue though, which is why we need even more efficient speakers...

[artto]

Please inform as to why you like tubes then?

For me, its simply about the sound quality ~ its more "realistic". But as far as power is concerned, "tubes" are actually and properly called "valves", electron valves. Transistors are called "gates", ie: switches. Valves simply have more "give". They don't just turn to 100% clipping distortion (square wave = DC = direct current = very bad) like transistor amps tend to. Which do you think would reproduce the "waves" (waveforms) of music better, a valve, or a switch? No, its not quite that simple, but thats the basic crux of it.

Example: My 50 watt triode monoblocks sound more powerful than my 275w/ch Crown PSA2. Both are "coasting" 99.99% of the time as far as power output is concerned.

[jacksonbart]

Please inform as to why you like tubes then?

For me, its simply about the sound quality ~ its more "realistic". But as far as power is concerned, "tubes" are actually and properly called "valves", electron valves. Transistors are called "gates", ie: switches. Valves simply have more "give". They don't just turn to 100% clipping distortion (square wave = DC = direct current = very bad) like transistor amps tend to. Which do you think would reproduce the "waves" (waveforms) of music better, a valve, or a switch? No, its not quite that simple, but thats the basic crux of it.

Example: My 50 watt triode monoblocks sound more powerful than my 275w/ch Crown PSA2. Both are "coasting" 99.99% of the time as far as power output is concerned.

so you like the softer clipping then? Why can't we get an amp / speaker combo that won't clip at all. Clipping IMO is not what I want. So basically tubes distort better. Ok with guitar amps I can understand, but amps used in the home/ sound reproduction that are reproducing sound, I don't want them to contribute to the sound.

[artto]

so you like the softer clipping then? Why can't we get an amp / speaker combo that won't clip at all. Clipping IMO is not what I want. So basically tubes distort better. Ok with guitar amps I can understand, but amps used in the home/ sound reproduction that are reproducing sound, I don't want them to contribute to the sound.

I wouldn't say I like "the softer clipping". My amps are never driven anywhere near clipping, valve or transistor.

We already have amp/speaker combos that won't clip ~ so long as the amp/speaker have adequate power output for the situation at hand.

Valves tend to distort not "better", but differently. They tend to exhibit more distortion in the even harmonics (softer, sweeter sounding tones) whereas transistors tend to exhibit more of the odd harmonics (harsher more dissonant tones).

EDIT: Another thing I might add regarding clipping. Do this: Draw a straight horizontal line on a piece of paper. Now draw a "wave" up & down across it, top & bottom equal above & below the line. Now do the same thing, except this time draw a series of vertical and horizontal lines over the wave. The verrtical lines cross the main horizontal line at the same point the wave does. The tops & bottoms of the "sqaure wave" are what hard clipping usually looks like in a transistor amp. These same "flat tops/bottoms" of the (square) waveform bascially represent DC (direct current). It's like connecting the speaker directly to a battery & expecting it to go back and forth. It won't. It will try to move one way or the other. Nice music eh?

Musical instrument amps/speakers are a different animal. Many guitar amp/speaker combos were designed to have colorations and be overdriven. And when overdriven, they don't necessarily have to have the power output section overdriven, just the the driver stage to get that "crunch".

Everything contributes to the sound and alters it, from the very moment the sound wave hits the microphone for recording. It all has distortion. The best we can do is either minimize it, or use it/alter it to our own satisfaction.

[Islander]

None. There is some basic misunderstanding here. ANY amp, even if it has One Million Watts, can be made to clip.

Shouldn't ONE MILLION WATTS be in all caps? It would be pretty loud, after all.

[jacksonbart]

Thank you for the explainations, I have read many reviews that described tube amps as exibiting a more spacious sound/ sound stage, amoung other attributes, which in reading and in some minor degree with listening again with my limited experiance that I can understand why a person would go that route. I understand that even saying "tube amps" is really a wide open statement so excuse me for using such a generic description. I just always found when ones description of the benefits of tubes as its ability to soft clip to be if you will the least if not the worst reason to listen to a type of amp. Most of my listening is done between 80-90 decibels, but again having head room is important and so is the ability to exceed those figures when needed with in reason.

[Colin]

"I have 25W tube amp, and I have a 20W SS amp, and I have no clipping on either one of them. None. There is some basic misunderstanding here."

please explain

The Pass X250 never went into class AB mode on my Corns as far as I could tell, staying in 15-watt class A all of the time, but then the meter surely was not fast enough to show fast musical peaks

[JJkizak]

I guess with "tube amp DC" the speaker will operate but with "SS amp DC" the speaker will not. Nice.

JJK

[Colin]

in toher words Mark, you are using extremely effcient horns to make sure that you are not over drving the amps

[jbsl]

in toher words Mark, you are using extremely effcient horns to make sure that you are not over drving the amps

That is funny Colin!![]

Maybe in his listening room he does not need to have a 250 watt SS amp. So how many watts do you need for the room you listen in Colin. How big is your listening area, Mark, Colin, anyone else?

Mark is using extremly effcient speakers with his amps because in his situation it is all he needs as is the case with his customers and they like the way the amps sound. Which is what I thought all this is about: enjoying the music!

My best friend got me hooked on the sound of La Scalas. He used to DJ parties with them using a 115 watt Hafler SS amp. He played a party that was in a High School gym and filled it up with sound. In that room size the 115 watt amp was required to do the job and sounded damn good! Mark's amps would not have the watts needed. But in my living room I doubt I have used 5 watts. Okay that is not true I have cranked up the volume to 10 on my preamp and it felt like a wall of sound, no not enjoyable loud but just overpowering the room loud. I do not need huge amounts of power in my living room.

Now in my case when I had the 2A3 Moondogs with my La Scalas in my 15 x 15 x 8 living room their 3.5 watts played classical music to levels I found uncomfortable. They were as loud as I would normally play my 35 watt tube amp so I think room size can have a huge impact on how many watts you actually use. Why would I buy a Mac 250 watt SS amp when I only use probably 4 watts in my living room. Would it have a better sound? Maybe or maybe I would think it sounded terrible.

I almost always hear if you are going to use SS and tubes go tube preamp and SS power amp. Well I use the preamp section of a SS Luxman int amp with the amp section of a Cayin tube int amp. I like this combo better than anything I have heard. It does not mean that it is the best combo available but to my ears and my room it is the best I have tried so far.

I know there are forum members that use powerful SS amps that sound great. Do they even come close to using that total watts available from the amp? Maybe if they have a large room or listen at concert levels.

As always it just depends on the person, room size, music taste.

[boom3]

Klipsch used to have an ad called "Yawn or Goosebumps?" It showed a triple floor-to-ceiling stack of bookshelf speakers and lots of amps versus two K-horns & a Belle, powered by one amp (with that phantom circuit, natch). Klipsch needs to revive that (with updates) to try to educate the HT masses as to what they are missing.

[Don Richard]

Valves tend to distort not "better", but differently. They tend to exhibit more distortion in the even harmonics (softer, sweeter sounding tones) whereas transistors tend to exhibit more of the odd harmonics (harsher more dissonant tones).

You have given a good example of some of the differences between single-ended circuits and push-pull circuits. Tubes or solid state may be used in either.

[Islander]

My Yamaha Class D power amps are described in their literature as SEPP (Single-Ended Push-Pull). Does that make any sense or is it even possible?

[sheltie dave]

As far as speakers go, I want to listen to music reproduced in superb fashion.

If I want to hear clipping, I'll plug in an electric guitar. It is always fun to hear people expound on soft clipping. Don't like, don't want it, and won't listen to it. Many Klipsch speakers allow the luxury of almost any amp we want. Life is good.

[oldtimer]

My Yamaha Class D power amps are described in their literature as SEPP (Single-Ended Push-Pull). Does that make any sense or is it even possible?

Versus single ended triode?

[Don Richard]

My Yamaha Class D power amps are described in their literature as SEPP (Single-Ended Push-Pull). Does that make any sense or is it even possible?

In the marketing department, all things are possible.

[DrWho]

But as far as power is concerned, "tubes" are actually and properly called "valves", electron valves. Transistors are called "gates", ie: switches. Valves simply have more "give". They don't just turn to 100% clipping distortion (square wave = DC = direct current = very bad) like transistor amps tend to. Which do you think would reproduce the "waves" (waveforms) of music better, a valve, or a switch? No, its not quite that simple, but thats the basic crux of it.

What you are describing is a common misconception and very far from the truth. All transistors have a linear mode of operation which is extremely similar to the linear operation of tubes

Also, a square wave does not have any DC whatsoever. The flat top to which you refer is actually not flat - even under the most extreme of clipping. It has all sorts of crazy high frequency content mushed together to produce a wiggly line. For more information, wikipedia has a good explanation (and a cool animation that makes it more clear):
http://en.wikipedia.org/wiki/Square_wave
Note that the lowest frequency present in a square wave is not 0Hz (DC), but rather the fundamental frequency of the square wave itself.

The reason that a clipping amplifier is so detrimental to speakers is because the crest factor goes to 0. Normal music has a crest factor of about 10-30dB depending on the mix. That is to say, the short-term peaks are about 20dB louder than the RMS levels. The heating of the speaker is a function of the RMS, not the peak (since the peaks are very short term). So when you go from a 20dB crest factor to a 0dB crest factor, the speaker is essentially dissipating 20dB more power...so if you were barely lighting up the clip lights at 10W, then your speakers would be soaking up about 9.9W of power (since speakers are about 1% efficient). Crank it up so that the clip lights are solid red and now your speaker is dissipating an extra 20dB, or 990W of power (assuming of course that the amp doesn't blow up first).

Wikipedia has a good article on crest factor too:
http://en.wikipedia.org/wiki/Crest_factor

The reason tweeters tend to blow up when an amp is clipping is because most of that 990W of power comes from the higher harmonics of the square wave. A quick common sense check to make sure there is no DC in a square wave is that all tweeters have high pass filters... If there were indeed a DC offset introduced by clipping, then it would get filtered out by the filter, and therefore would not be the reason for the tweeter failure.