My attempt to compare an Outlaw 7500 and a Parasound A51

[RichB]

Time for remedial math, gentlemen. 0.05% is 25 times higher than .002%. Twice 0.05%, which fmv implies is inaudible, is 0.1%, and that's an interesting question, and not so clear-cut as he is implying. 0.1% distortion is equal to -60db. If you are listening at 90db that means the distortion will be at 30db. That's relatively quiet, but if the source was canceled out 30db of distortion would be audible. So the real question in the scenario is, does 30db of distortion in 90db of music affect perception?

It seems to me the frequency of the distortion is important since it may not be harmonics of the source.
Also, some amps may not be as linear as others driving speakers with different loads.

In the first post there was a simulated load where the A51 was down .4 DB with a frequency sweep.
Is this type of deviation from linearity considered distortion?

- Rich

 

[Irvrobinson]

It seems to me the frequency of the distortion is important since it may not be harmonics of the source.
Also, some amps may not be as linear as others driving speakers with different loads.

Agreed. I think the character of distortion affects its audibility. So do a lot of other people.

In the first post there was a simulated load where the A51 was down .4 DB with a frequency sweep.
Is this type of deviation from linearity considered distortion?

- Rich

In the English language, yes, frequency response deviations are distortion, amplitude distortion to be specific. In the audio world, however, distortion typically refers to artifacts in the output signal that aren't supposed to be there, like harmonics of a fundamental, noise, or some sort of waveform distortion, like clipping.

 

[PENG]

Agreed. I think the character of distortion affects its audibility. So do a lot of other people.



In the English language, yes, frequency response deviations are distortion, amplitude distortion to be specific. In the audio world, however, distortion typically refers to artifacts in the output signal that aren't supposed to be there, like harmonics of a fundamental, noise, or some sort of waveform distortion, like clipping.

Waveform distortion is the source of harmonic distortions.

 

[Irvrobinson]

Waveform distortion is the source of harmonic distortions.

Huh? How?

 

[PENG]

Huh? How?

I am sure we can agree that audio amps are designed to amplify the signal linearily but things are not perfect so there will be non linearity issues and that will result in distorted waveform, i.e. the output is distorted from the input, clipping is one example of such non linearities. If there are no distortions relative to the original input signal then there won't be any harmonic distortions because the resulting harmonic content in the output waveform will be the same. Here's a easy read:

Audio Amplifiers

And if you have time, this one:

hearing1

 

[Irvrobinson]

I am sure we can agree that audio amps are designed to amplify the signal linearily but things are not perfect so there will be non linearity issues and that will result in distorted waveform, i.e. the output is distorted from the input, clipping is one example of such non linearities. If there are no distortions relative to the original input signal then there won't be any harmonic distortions because the resulting harmonic content in the output waveform will be the same. Here's a easy read:

Audio Amplifiers

And if you have time, this one:

hearing1

We agree, clipping results in harmonic distortion, specifically because the waveform is getting clipped, but harmonic distortion also has other causes, otherwise at 1W and below powerful amplifiers with high slew rates would have no harmonic distortion, and we all know they do.

 

[RichB]

I am sure we can agree that audio amps are designed to amplify the signal linearily but things are not perfect so there will be non linearity issues and that will result in distorted waveform, i.e. the output is distorted from the input, clipping is one example of such non linearities. If there are no distortions relative to the original input signal then there won't be any harmonic distortions because the resulting harmonic content in the output waveform will be the same. Here's a easy read:

Audio Amplifiers

And if you have time, this one:

hearing1

I am not sure we can, but I can agree

- Rich

 

[PENG]

We agree, clipping results in harmonic distortion, specifically because the waveform is getting clipped, but harmonic distortion also has other causes, otherwise at 1W and below powerful amplifiers with high slew rates would have no harmonic distortion, and we all know they do.

Well I hope there is no real disagreement. I stated the fact that harmonic distortion is caused by distorted waveform, clipping is just one form of distortion. Distorted waveform (not being amplified perfectly linear) can be caused by many things such as cross over, transistor mismatches (characteristics not being exactly the same), and other imperfections in circuitry and componentry that result in non linearity even at low output level. I just don't think you can look at distorted waveform and harmonic distortions as though they are two different causes for why amps sound different as the two are directly related such that one implies the other.

Then you asked how, and I tried to respond, but maybe without a clear understanding of your question. Well I hope this is confusing enough that I can now watch something on Neflix.

 

[PENG]

I am not sure we can, but I can agree

- Rich

Thanks for being so agreeable, for a change..

 

[Irvrobinson]

I just don't think you can look at distorted waveform and harmonic distortions as though they are two different causes for why amps sound different as the two are directly related such that one implies the other.

Then you asked how so, and I tried to respond, but maybe without a clear understanding of your question. Well I hope this is confusing enough that I can now watch something on Neflix.

Oscillations and reflections can cause harmonics that don't distort the original waveform, they are simply additive. The fundamental is still there in all of its glory, there's now just other frequencies along for the ride. Right?

 

[RichB]

Thanks for being so agreeable, for a change..

Sure, it is easy to agree when we discuss the reasons amp can sound different and it is more interesting too.

- Rich

 

[PENG]

Oscillations and reflections can cause harmonics that don't distort the original waveform, they are simply additive. The fundamental is still there in all of its glory, there's now just other frequencies along for the ride. Right?

Right, IMD is an example too, it is not harmonically related to the fundamental but additive as you called it. Just can't find too many watchable 5.1 DD+ movies on Netflix.ca. Getting better but still miles away from Netflix in USA from what I heard.

 

[Irvrobinson]

Right, IMD is an example too, it is not harmonically related to the fundamental but additive as you called it.

Why are you so difficult to agree with?

 

[PENG]

Why are you so difficult to agree with?

Not me, you guys are a real challenge all the time.

 

[Irvrobinson]

Just can't find too many watchable 5.1 DD+ movies on Netflix.ca. Getting better but still miles away from Netflix in USA from what I heard.

Maybe, but Netflix in the USA is no prize either, at least for ones included in the base pricing, if that's what you're discussing. If you want to watch something you haven't seen before, or isn't pure junk, it's $5 or $6 per movie, and pricing is better on Amazon, generally.

 

[PENG]

Maybe, but Netflix in the USA is no prize either, at least for ones included in the base pricing, if that's what you're discussing. If you want to watch something you haven't seen before, or isn't pure junk, it's $5 or $6 per movie, and pricing is better on Amazon, generally.

I guess I can't complain then as I paid the base price of CAD 7.99. Watched Battle Los Angeles, didn't sound too bad.

 

[PENG]

So Rich, you think you can hear a difference going from A51 to 5 JC-1 (250W consumption idling)?

 

[RichB]

So Rich, you think you can hear a difference going from A51 to 5 JC-1 (250W consumption idling)?

I have an idea, bring two over and let's find out
if you believe the John Curl design to reduce artifacts produces a less fatiguing SS sound, then at low levels it is unlikely.

My Salons might like the power at concert levels

- Rich

 

[RichB]

Most of us don't buy into that sort of nonsense.

By definition, no one would buy into nonsense.

it is interesting that Emotiva has added balanced input stages (like Parasound) to their XPA 2 series and an option for very high class-a bias.
Of course, they do this to sell product, but I am not prepared to say this is nonsense.

There are measurements that show that Parasound amps have less artifacts when operating in class-a mode.
is this audible, well, that is debatable but I believe it is.

- Rich

 

[fmw]

All you need to do is conduct a properly done bias controlled test to find out. Personally, I wouldn't go through the hassle, having gone through it years ago but that's the way to find out. Pesonally, I'd rather just listen to the music rather than obssess about whether some artifacts are audible or not. Let me know if you need some advice on how you should conduct the test.