Is More Watts Better, w/Everything Else Equal?

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Johny,

You have to understand that THD is a measure obtained under a resistor load with a burst signal or continuous burst or constant, we don't know. Most of the time at 1khz.

This 'value' that compares two different amplifiers, let say 100 and 200 watts.

When you drive real speakers that THD value has NO meaning!!!

In my chart it shows that even how powerful the amp is the THD raise below 1 watt, guess what , this is the power at which your music will play 99.9% of the time.

So this is the first reason, the 100 or 200 watt specified amp power will tell you NOTHING about the THD below 1 watt which is possible to hear... THD can be heard but in big enough quantity :))

the second point is that the sound is a match between the amp and the driver. The inductance, reactance and capacitance of the system is variable with temperature, back EMF, and signal frequency. the THD figure can be quite good on the amp, however it could be a horrible match for some speakers.

THD tells you nothing of the resulting system, how good it will sound.

As mentioned earlier, the more powerful amp should have more power reserve and be more immune to difficult loads, however this is not necessary true, due to more devices in //, which can potentially cause more THD under 1 watt but better figures over 100.

Your question is just too general, you have to get out to audio shows, dealers and explore for yourself.
 
there is a post before that, but this is taken from all about circuit.

IF the higher power amp achieves it by increasing in the other form of perceivable distortion as listed below, it could sound worst than the lower power amp if both are playing within their limits...

Also, sample to sample of amps can vary too, even with same THD, same power. Please read the extract from all about circuit:
Input Pair Differences
The input stage of the classic three-stage amplifier consists of a differential pair of transistors. When there is a mismatch between the characteristics of the transistors or the DC biasing is not matched, distortion will occur. Even with good matching, distortion at higher frequencies shows up due to capacitances looking more like short circuits at higher frequencies; this reduced impedance leads to higher current.

Nonlinearities in Voltage Amplifier Stage
The voltage amplifier stage is a common-emitter configuration. Linear models are used for small-signal analysis of the common emitter configuration, but the transistor, in fact, behaves nonlinearly. This nonlinearity contributes to harmonic distortion, but large open-loop gain along with the use of a negative feedback loop will mostly eliminate this source of distortion.

Output Stage Distortion
The output stage is usually a Class B push-pull type of amplifier. The main distortion contribution of this stage is crossover distortion, and this type of distortion will be discussed later.

VAS Loading Distortion
The input impedance of the output stage is nonlinear. Since this impedance is the load of the voltage amplifier stage, the VAS output gets distorted. Buffering between the voltage amplifier and output stage reduces this distortion.

Rail Decoupling Distortion
Decoupling capacitors on the power rails are always a necessity, but if the current return path (i.e., ground) of these capacitors is shared with the input or feedback circuitry, then the harmonic content of the power supply rails will be introduced to the signal. This type of distortion has an easy fix of keeping the current return path of the decoupling capacitors separate.

Induction Distortion
This type of distortion is caused by an inductive effect between the DC supply and the input and feedback paths. It can be minimized by reducing the ways the supply and input/feedback paths can interfere with each other, i.e., keeping the loop area of the input and feedback signals as small as possible and physically separating the supply and input/feedback circuitry as much as possible.

Negative Feedback Distortion
The output signal and the point where the same signal is fed back to the negative feedback path are theoretically the same, but since wire/track resistance is finite, the signals may not actually be the same. Ensuring that feedback is taken from the correct point in the circuit will eliminate this distortion.

Capacitor Distortion
When used for coupling or DC blocking, electrolytic capacitors tend to distort signals when the AC voltage across them is high. Ceramic capacitors can also be problematic because they have a significant non-linear change in capacitance over frequency. When the frequency of the audio signal changes, so does the capacitance. Ceramics can also pick up mechanical vibrations and convert them into electrical noise (this is a piezoelectric effect). In audio applications, film capacitors are the best choice for AC coupling and DC blocking capacitors. Electrolytics can still be used for DC filtering, but ceramic capacitors should be avoided.



Output (Crossover) Distortion
These sources of distortion, except output distortion, are easy to eliminate using clever but straightforward-to-implement circuit design techniques. Considering these sources of distortion and the means to reduce them, Douglas Self developed the concept of the blameless amplifier. A blameless amplifier is one that is not perfect, but has all easily addressed distortion mechanisms minimized.

A blameless amplifier is therefore left with output distortion (which is mostly crossover distortion), the most difficult source of distortion to eliminate. Crossover distortion is probably the most well-discussed source of THD in audio systems for the very reason that it is not easy to eliminate. Crossover distortion occurs because in a class B amplifier there is a short period when both output transistors are biased off. During this time there is no output signal. The scope captures below show an example of the crossover distortion of a class B amplifier in both the time domain and frequency domain. It is quite clear that the output signal is distorted from the input signal and that there are significant harmonics in that signal.
 
I'll reference the pass articles to support as Pass is more articulate and considerably better informed

Many thanks for that. I'm reading it, tho not necessarily understanding all of it.

you need to multiply the output devices to get sufficient current drive.

Confused. I thought FirstWatt is about reducing number of devices.

There's evidence to suggest that the higher current through the Fet = reduced distortion, so you're 'moving out of the sweet spot' as I characterized it earlier.

Unclear. Isn't reduced distortion sweeter?

With multiple devices come multiples of input capacitance, meaning increased drive requirements, and ultimately a different front end to deliver that drive/deal with the higher rails, and lower bandwith.

For the purpose of my question, I'm fine saying more devices in an otherwise similar design is fine for comparison with a lower watt device.
If you're genuinely interested in learning more (and not just trolling us all here),

Not trolling. Tbh, people are making this whole thread overly complicated. I'm asking, in a generally similar design, what are the general pros and cons of low vs high watt. If somebody said, "high watt is, usually, louder", that's a fine answer.

Presumably, there must be advantages to different powers, or all amplifiers would be one standard wattage.

Thx for links!
 
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IF the higher power amp achieves it by increasing in the other form of perceivable distortion as listed below, it could sound worst than the lower power amp if both are playing within their limits...

That's a useful insight of low vs high watt.

sample to sample of amps can vary too, even with same THD, same power.
No doubt, but I'm comparing different power, similar amp, not same power, dissimilar amp.

The rest of your post lists types of distortion, which is very useful info! But, again, doesn't discuss those types of distortion as they relate to high vs low watt.

Thx!
 
Your question is like... is there an advantage of using a bigger aircraft?

Is there an advantage to using the Boeing 747 , the Airbus or the Cessna?

I have a grand piano of modest size, however is there an advantage to using a 9' ?

Yes, however in my living room the 9' would be too big and play too loud. So my 5'8 is a good compromise.

Your amp is 100% speakers + room dependent, it is a tool, nothing else.

The more power, usually the more dynamics. Less dynamics is not a bad thing, distortion is not 'bad' searching for lower distortion is meaningless.
 
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is there an advantage of using a bigger aircraft?
A reasonable question with answers.

Pro: A bigger aircraft can transport more people.
Con: Uses more fuel to travel same distance.

Not that complicated.
in my living room the 9' piano would be too big and play too loud.

You mean a 9' is louder? So, there's a difference!. See, not so hard :)

Your amp is room dependent
You mean, your selection is room dependent. Tru nuff. Because they are different.

The more power, usually the more dynamics.
Now you're getting the hang of it!

Less dynamics is not a bad thing, distortion is not 'bad' searching for lower distortion is meaningless
.
You're still confusing difference for selection. I'm not asking for amplifier recommendations here.
Oh well.

You just posted a list of like 10 different kinds of distortion. Why? If distortion is irrelevant...

Plz explain how more dynamics isn't better than less dynamics.

Cheers!
 
Ah thanks,

Less dynamics is associated with a warm sound, more dynamics associate with party music.

Party music is good to make people dance. In rock concerts distortion is a must, the more the better.

We go back a few steps into the speaker realm to understand dynamics.

The drivers are primitive devices which tends to do some things better than others.

Music is already concocted into a potion that will release the illusion of music when played on your loudspeakers.

The best thing I can say to vulgarize the subject is that it is like making a cake with cake mix.

The baking powder would be the amp.

The amount of mix = the speakers.

Maybe the room your oven or your plates?

Too much powder is bad, not enough is bad, you want just enough.

Less dynamics will show you another face of music, intricate texture, details.

A powerful amp will maybe only show you a sterile picture of the music contours without much shape.

Your perfect super power amp will maybe be tiresome to listen because it handles more than the driver can produce, it becomes angry at you.
 
Plz explain how more dynamics isn't better than less dynamics.

Compromise.

If you have 30W amp, can you increase the power by only changing one part? Yes you can. Increase the value of feedback resistor. Now the amp's voltage gain is greater and maximum power is bigger.

Now if the low gain amp is compared to high gain amp at the same (low) watt, what is the difference? The high gain amp will usually be more dynamic, the low gain one will usually have lower distortion.

Now, which one is better, lower distortion or more dynamics? Key word is 'threshold'. Everyone may have different taste and priority. I know my thresholds with many parameters in audio. In general, compared to most people, I value dynamics more than distortion.
 
Increase the value of feedback resistor. Now the amp's voltage gain is greater and maximum power is bigger.

ahhh no this is not the way things work. Without power supply change , without output transistor heat sink change , the THD at clipping will remain the same.

Maximum power is same, only hard clipping / while the other is softer clipping, higher distortion earlier, with a less pronounced peak.

Feedback doesn't do anything about peak power!

And BTW, many High-end manufacturers are ABANDONING Class D !!! why ? I have no idea, but there must be a reason beside customer aversion to listening to another round of ADC / DAC transformation of your music.

Rock/Electronics, promoted by stereo actually 'killed' hifi lowering the standard of perceived distortion to oblivion, destroying the capacity of any system to produce even the likeliness of real instrument sounds.
 
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Increase the value of feedback resistor. Now the amp's voltage gain is greater and maximum power is bigger.

ahhh no this is not the way things work. Without power supply change , without output transistor heat sink change , the THD at clipping will remain the same.

Maximum power is same, only hard clipping / while the other is softer clipping, higher distortion earlier, with a less pronounced peak.

Feedback doesn't do anything about peak power!

I know how it works. The answer to the OP question is in my first answer. If he can't understand the answer, he needs simplifications. I didn't need to add required conditions in order for the statement would become true. Some people even think that this is a troll.
 
Sorry johnego, I am seeing things, feedback increases can lower specified THD, true, not maximum absolute power.

I think johny is learning by reading this. It is not a technical discussion, I am unable to talk about technical stuff without referring and copying from known sources.

It is such a pity that one resolves to post on a forum to look for answers he can only find himself by going out in the world.

I truly like class D, Class AB transistors and class A transistors. I have nothing against any means or power of amplification. I respect everyones path and budgets. DIY is the objective of this forum and it should be kept this way.

I only have a technical degree in electricity, and a degree is discrete math and economics with specialization. However I am passionate about learning electronics and read avidly each day 5 hours of technical books from master thesis to doctorate. I don't understand everything and audio is mostly a mystery to me. Learning the tubes is most interesting and appropriate to the Point to Point soldering, due to simplicity. However I started with high power Class A tube amps, I built transistor amps of respectable power and sold them. I love the compression and honesty of tube amps, I found the best source of schematics which were beyond my understanding, and built them, compared them with audition and tests. There are unknown diamonds and so many stereotypes like power, thd, someone has to raise against it. I do.

Like ranges, like clothes washers, so many lies pushing people to buy inferior products with higher profit margins. Glass top is the worst kind of heat conductors. Commercial front-load wash machines have nothing in common with your appliance store machines. You end up with wearing toxic clothes full of strong soap. And now the USA banned motion of old school agitators for public use. This is madness.
 
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Hi gabdx,

I think johny is learning by reading this. It is not a technical discussion, I am unable to talk about technical stuff without referring and copying from known sources.

I think I know how i would discuss technical things with you. Anyhow, my posts have been addressed to the OP, original poster. I knew exactly there would be two major things that would be 'questioned' by some engineers: this gain-power relationship, and gain-dynamics.

Sorry johnego, I am seeing things, feedback increases can lower specified THD, true, not maximum absolute power.

The supply voltage (and available current) is the main parameter determining maximum power, P=VI. With some requirement in input sensitivity, the next important parameter is voltage (and/or current) gain.

We cannot make the output voltage to swing above supply voltage, but we can decide not to allow clipping with the given input sensitivity by lowering voltage gain.

So the restriction is the input voltage. For some current power buffers or low voltage gain amps, when connected directly to source, the normal 2v input will not bring the maximum power. What happen if the input is more than 2v? Its up to the designer, he can restrict the maximum input if he wants.

The above will then lead to things questioned by OP, i.e. is thd important? is more dynamics good? It is hard to make things completely equal as required by OP, but many decided to say that with high power you get more 'dynamics' and this is my way to explain it.
 
Less dynamics is associated with a warm sound
How do you define "warm"? Is this a common view? Or just your opinion? Can you give a technical explanation for why this would be?

more dynamics associate with party music.
I believe your statement is 100% wrong. Party music is characterized by less dynamics, not more.

Is this just your opinion? Based on what? How do you define "dynamics"? How do you define "party music"? Is that a genre?

This graphic shows the amount of dynamic range in different genres. The "party" music has the least dynamic range of all. Jazz, Pop, Rap, Rock and Schlager (German pop music):
10.1177_2331216516630549-fig1.jpg

Dynamic Range Across Music Genres and the Perception of Dynamic Compression in Hearing-Impaired Listeners
In rock concerts distortion is a must, the more the better.
You listed many types of distortion. Which type? Is your statement based on your personal experience running sound systems at rock concerts? Something you read? How do they add this distortion in rock concerts?

Less dynamics will show you another face of music, intricate texture, details.
WHAT? I believe the exact opposite is correct. MORE dynamics show the intricate texture and details of music.

A powerful amp will maybe only show you a sterile picture of the music contours without much shape.
"Maybe"??? Ok, when would it? When wouldn't it? "Maybe" doesn't say anything.

Your perfect super power amp will maybe be tiresome to listen because it handles more than the driver can produce, it becomes angry at you.
True, if an amplifier overdrives the speaker, it will sound bad. My question at the top of this thread describes playing both amplifiers at the same amplitude, within the capacity of the loudspeaker.

You don't seem much interested in addressing the original question. Seems you're just going off in your own direction here. You seem to make statements without any basis. You seem to make completely false and incorrect statements.
 
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Seems you're just going off in your own direction here.

I took some of the other directions before, and they were all wrong.

One wrong direction was to take the higher wattage amplifier, everything else equal.

If you don't know that some less powerful amplifiers can bring special textures to music and some softening of it that other powerful amp cannot, they you are on a long road to learn more.

Btw , what does impaired listeners have to do with dynamic ranges graphs? What does this has to do with music at all???
 
some less powerful amplifiers can bring special textures to music and some softening of it that other powerful amp cannot
i believe that's true. Can you share which types of amps? What kinds of textures? What does "softening" mean? If you can't explain your meaning, then i'm on a long road to understanding your comments.

what does impaired listeners have to do with dynamic ranges graphs? What does this has to do with music at all???

The chart i posted has nothing to do with impaired listeners. It's a chart of dynamic range of different types of music.

The IEC standard was used as the method of analysis in this experiment. It uses window lengths that correspond with the time resolution of loudness perception (Chalupper, 2002; Moore, 2014) and provides a frequency-dependent analysis. It is therefore possible to analyze the dynamic range of any kind of acoustic signal including music. All stimuli were RMS equalized prior to analysis to allow for averaging across segments within genres. The results of the dynamic range analysis for each genre (100 samples) and speech (28 samples) are depicted in Figure 1. The percentiles are reported in dB SPL and shown across frequency in kHz.
 
softening = slightly compress, in an enjoyable way (not like a digital compressor, terrible).

The easiest comparisons I could make was with changing output tubes on my amps and re-bias to optimal point. Well there was not really a difference in sound if I could say of the different tubes performance point, they sound different like EL34, EL34, KT77, and 6L6, but they are same power.

So, to change output tubes to more powerful ones and make the amp 50 to 100 watt, there was less difference in sound than swapping EL34 and KT77 (same power) in another amp.

I think it was caused by the fact I wasn't using the extra power.

So this is what could happen at best with your 300W amp. I cannot predict what power you will need although.

All the listening experiences I had with commercial gears were that the more power usually the better built the amplifier. This is contradictory to what I said before.

I listened to many types of class D and I preferred the mono block of 300 - 600 watts each. I found enjoyable the 20, 40 so others class D but they were too warm and easy on the ear.

With hifi transistor AB I found almost every time the highest power amp sound better, I doubt it is because of the max power, but because the power supply is better and that makes the sound a lot better than it is measurable.

To be honest, my system is built so far on Harbeth, I liked them driven by a 3500$ amp and I didn't wanted to invest in 5K tube amps that could sound better, so I kept that in mind and tried to achieved the same sound with my diy amp than the 100 Watt amp I liked a lot.

However the tube amp will never sound like the transistor amp, they have their own characters because of devices used in them. Upping the feedback level in the tube amp just to get the 'transistor' sound would not make any sense.

So these are just a few design considerations.

Jonny, please don't take as 'wrong way' what I said in my other post, I said objectionable warnings to getting more power = better sound quality.

The proof of that is if you have the chance to listen to Accuphase Class A transistors amps.

Some of them are 20 watts but they do sound very good and preferable to more powerful amps.

And please remember, that the 1000W advertised could be a burst maximum output, but the bandwidth could be very poor as well as continuous output.
 
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Perhaps a definition of terms is relevant here? We're now neck deep in the objective vs subjective part of the audio world...

What do you mean by...

Dynamics?

Sweetness?

Distortion?

I believe the question has already been answered sufficiently. ie the 'ideal' amp is one with infinite ability to deliver voltage and current, whilst accurately amplifying the signal in - a wire with gain essentially. SO yes, all things equal, a higher power amp is 'better'.

However this is an engineering space as much as anything else, and all engineering is an exercise in compromise... so pick the compromise you like the most and go for it.

Or best of all, build a bunch of amps and enjoy the fruits of your labors. :)
 
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