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Paul R

This I Believe -  

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Ahh- adding in "if they measure the same" I do agree with you. The caveat is that two amps must be virtually identical to measure the same.

 

Two 100wpc Class A amps from different manufacturers are unlikely to measure exactly the same though, and for that reason can sound a bit different. To me this is a case where measurements matter as much as listening. ;)

 

If they measure the same was in there all along. And same does not have to be 100% same cause there are surely slight differences even between identical units. But I would call .0017 THD same as .0015.

Someone asked about internal layout differences. I am not an amp builder and do not know how mich a difference those things make. I assume if you put an output opamp directly on top of the big transformer it is not going to sound great. But it will also measure differently.

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LOL! I met a gentleman the other day with a system similar to yours - including some gorgeous sounding Genelacs. I do believe his opinion was very much in line with yours too. Hard to argue with him too - his system sounded absolutely wonderful.

 

Not enough WAF to get em into my home, but they did sound sweet... :)

 

 

Thanks Paul

 

I usually refrain from such honest and direct statements, but this thread begged for it ?

 

I do acknowledge that many have other aims than the most predictably precise sound at the lowest possible cost.

 

Others may find my USD 15.000 stereo rig for the kitchen gluttony or over the top.

 

It's all fine and valid as long as we keep off the voodoo and 'new speak'.

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They ignore science and knowledge when they argue sound and systems.

Worse: they act as if sound and systems follow unexplainable dogmas of an ancient religion.

 

I would take it one step further -- the individuals you have in mind revel in their ignorance. They don't simply ignore it. In this there is a lot that is logically consistent with evolution-deniers, climate-change deniers and Holocaust deniers (not to suggest these are on the same moral plane -- only that their idiot-logic has similar properties).

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If they measure the same was in there all along. And same does not have to be 100% same cause there are surely slight differences even between identical units. But I would call .0017 THD same as .0015.

Someone asked about internal layout differences. I am not an amp builder and do not know how mich a difference those things make. I assume if you put an output opamp directly on top of the big transformer it is not going to sound great. But it will also measure differently.

 

Yes, I see that you said that now. The exact point at which something becomes audible or not is always open to discussion. I'm not the best person to detail differences in amplifiers, and I seriously doubt I would ever hear a difference between .0017 and .0015 % THD.

 

But I would expect to hear a difference if that .0017% distortion is only at 1Khz on both amps, and the full range (20-20K) distortion figure was much larger on one unit than the other. One of the issues in the audio hobby is - ah - "misleading" measurement results. Do you agree it is a bit of a buyer beware situation? I mean, on the face of it, a $149.99 Walmart Home Theater AIOB special "measures" pretty well. But it sure doesn't sound as good. :)

 

Also, two amps of the same topology but different manufacture, one with a rated output of 50wpc and the other with 200wpc are almost certain to sound a bit different playing at an average of 50wpc. (That is, if you could stand to be in the room with either one playing that loudly.) :) The 200wpc unit will be able to handle peaks in the music that the 60wpc amplifier will clip on.

 

Pretty much, I don't think anyone is disagreeing with you on this. Just pointing out that in the real world, one is unlikely to find two different amplifiers that measure identically. I think this is even more true in the "high end" where equipment is built by hand instead of on a line.

 

-Paul

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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I would take it one step further -- the individuals you have in mind revel in their ignorance. They don't simply ignore it. In this there is a lot that is logically consistent with evolution-deniers, climate-change deniers and Holocaust deniers (not to suggest these are on the same moral plane -- only that their idiot-logic has similar properties).

 

I don't know Bill - that is a lot like saying someone "revels in their ignorance because they don't understand how a hydraulic clutch works." They could well be perfectly good drivers with lots of experience, and not know how a hydraulic clutch works. Or except in the most general terms, how pretty much anything else like the brakes, generator/alternator, transmission, power steering, etc. work. They don't need to know that in order to choose a good car for their needs and operate it safely and efficiently. Or to do simple tasks like change the oil, fill it up with gas, air the tires, etc.

 

There is some analogy in that to audio. I don't particularly need to know all the details of how say, an amplifier, works to be able to choose one that sounds good to me. No?

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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I believe a system will sound only as good as it's weakest component.

 

When my primary DAC was away for upgrades it was temporarily replaced by an ODAC - resulting in my system sounding like an ODAC being played through high end amps and speakers.

 

Let's just say I wasn't listening to music much while the DAC was being upgraded....

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Of course 'common knowledge' in a church is not the same as in a physics lab.

As mentioned, I come from an IT background and I very rarely met anyone who doesnt share any of those 'beliefs'. That makes them common knowledge.

I also meant common as in general population, not CA only. If you dont believe I'm right just walk to the next joe on the street...

 

Others would prefer the term common "misinformation". The man on the street who never actually thought about 'cable sound' obviously has no knowledge of the subject. How lack of knowledge can be elevated to "common knowledge" completely escapes me. :)

"Relax, it's only hi-fi. There's never been a hi-fi emergency." - Roy Hall

"Not everything that can be counted counts, and not everything that counts can be counted." - William Bruce Cameron

 

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I would take it one step further -- the individuals you have in mind revel in their ignorance. They don't simply ignore it. In this there is a lot that is logically consistent with evolution-deniers, climate-change deniers and Holocaust deniers (not to suggest these are on the same moral plane -- only that their idiot-logic has similar properties).

 

Would be relatively easy if there were only deniers. Preachers and cable burn in people are however quite affirmative.

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. . .

 

Two 100wpc Class A amps from different manufacturers are unlikely to measure exactly the same though, and for that reason can sound a bit different. To me this is a case where measurements matter as much as listening. ;)

 

Why even bother when 99 out of a 100 feeds straight into massive passive X-overs?

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Measurements (whether for amplifiers or other components) are often just a marketing tool and are a function of what we have the tools to characterize. Are the measurements manufacturers report those that really matter most to what we hear or simply the numbers that are easiest to obtain? There are certainly things that we can and do measure that rarely show up on equiopment spec sheets. How many things can the human ear/mind perceive for which we have no reported measurements (see Barry's post above)?

 

I also believe that just as our tastes in what type of music we like (Rock, Jazz, Classicval, etc.) differ, so do our tastes in what we want a system to sound like. The difference is that while we don't try to convince each other that liking Jazz is "wrong" we often do try to convince each other that liking a certain sound characteristic is either wrong or unfounded.

 

Measurements is most powerful tool for sound improving during development hardware and software.

 

Hearing is unstable tool for it.

 

Full measurements list is very long. For estimating audio apparatus/software need united considering all parameters / responses contained in list (as single complex).

 

For marketing purpoces showed only famous characteristics.

 

If we see THD, we must measure it for different frequencies and amplitudes. It's big table. But THD correctly describe quality of device.

 

Or signal/noise ratio. We can measure it many different methods (as minimum with different frequency bands). This measurement birth graph / table for frequency range. But it also good describe quality.

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Others would prefer the term common "misinformation". The man on the street who never actually thought about 'cable sound' obviously has no knowledge of the subject. How lack of knowledge can be elevated to "common knowledge" completely escapes me. :)

 

Same as flatearth was also 'common knowledge' for quite a while. It only has to be accepted by most people, it does not have to be 100% right :)

That being said however, flatearth and cable-sound do share the same 'truthiness' level in my book. And I assume that is a potential inflamatory remark.

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Same as flatearth was also 'common knowledge' for quite a while. It only has to be accepted by most people, it does not have to be 100% right :)

That being said however, flatearth and cable-sound do share the same 'truthiness' level in my book. And I assume that is a potential inflamatory remark.

 

Myth of the Flat Earth - Wikipedia, the free encyclopedia

Sometimes it's like someone took a knife, baby
Edgy and dull and cut a six inch valley
Through the middle of my skull

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Yes, I see that you said that now. The exact point at which something becomes audible or not is always open to discussion. I'm not the best person to detail differences in amplifiers, and I seriously doubt I would ever hear a difference between .0017 and .0015 % THD.

 

But I would expect to hear a difference if that .0017% distortion is only at 1Khz on both amps, and the full range (20-20K) distortion figure was much larger on one unit than the other. One of the issues in the audio hobby is - ah - "misleading" measurement results. Do you agree it is a bit of a buyer beware situation? I mean, on the face of it, a $149.99 Walmart Home Theater AIOB special "measures" pretty well. But it sure doesn't sound as good. :)

 

Also, two amps of the same topology but different manufacture, one with a rated output of 50wpc and the other with 200wpc are almost certain to sound a bit different playing at an average of 50wpc. (That is, if you could stand to be in the room with either one playing that loudly.) :) The 200wpc unit will be able to handle peaks in the music that the 60wpc amplifier will clip on.

 

Pretty much, I don't think anyone is disagreeing with you on this. Just pointing out that in the real world, one is unlikely to find two different amplifiers that measure identically. I think this is even more true in the "high end" where equipment is built by hand instead of on a line.

 

-Paul

 

I would bet that a 200w and a 50w amp do not measure the same at 50w. But they may at 10-20w. Someone else also mentioned that two amps with the same 1% THD may sound quite different because they distort different harmonics. In my book that is a case of different measurements.

My initial statement is indeed somewhat fuzzy and it is not easy to define what exactly 'measure the same' means. But I think the meaning is clear now for everyone and it is also true. Or maybe you do know a countersample?

 

As about buyer beware I guess that is always the case. And I also agree that the published specs are almost always misleading. You mostly just see some best case numbers. Would be great to have an enforced standard for published specs. But hifi is a luxury industry and those usually do not have any standards.

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Two amps that measure the same will sound the same, as shown by Bob Carver.

 

The Carver Challenge | Stereophile.com

 

 

That's not exactly what the "Carver Challenge" was demonstrating. I was in attendance at one of the Carver Challenge demonstrations and it wasn't about specs, it was about nulling-out nonlinearities in two disparate amplifiers (a Carver SS amp and a conrad-johnson tube amp) to the same degree of audibility (or rather to the same degree of silence) to show that an amplifier's signature sound was a product of it's nonlinear behavior. Carver's point was that if you make two amplifiers' nonlinearities equal in volume when all but the nonlinearities are removed from the signal, then the two amps will sound the same. I don't recall Bob measuring anything. He just used a comparator of his own design to invert the original signal and mix it with the non-inverted amplifier product in equal proportion so that only the difference between the original and the amplified signal remained.

George

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I would take it one step further -- the individuals you have in mind revel in their ignorance. They don't simply ignore it. In this there is a lot that is logically consistent with evolution-deniers, climate-change deniers and Holocaust deniers (not to suggest these are on the same moral plane -- only that their idiot-logic has similar properties).

 

The very strange thing is that on science forums the folks arguing with the experienced degreed people are usually thought to be the science deniers, whereas on this forum you can find any number of people telling Gordon Rankin, John Swenson, etc., to stuff it and claiming they are the science *defenders*.

 

Edit: As I have said before, I think this is because *both* the "subjectivists" and "objectivists" yearn for a certainty we haven't yet attained in audio, partly for the very good reason that no one is going to waste the kind of money determining audio questions that is spent on science research into evolution and climate change, or historical research into the Holocaust.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

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I would bet that a 200w and a 50w amp do not measure the same at 50w. But they may at 10-20w. Someone else also mentioned that two amps with the same 1% THD may sound quite different because they distort different harmonics. In my book that is a case of different measurements.

My initial statement is indeed somewhat fuzzy and it is not easy to define what exactly 'measure the same' means. But I think the meaning is clear now for everyone and it is also true. Or maybe you do know a countersample?

 

Not in amplifiers, no. Even in sighted comparisions, I can rarely tell the difference between two amplifiers that are similar, much less measure the same. I can tell differences between amplifiers that are measurably different - sometimes. Like between a NAD amp and the little Outlaw 2200 mono blocks I use.

 

As about buyer beware I guess that is always the case. And I also agree that the published specs are almost always misleading. You mostly just see some best case numbers. Would be great to have an enforced standard for published specs. But hifi is a luxury industry and those usually do not have any standards.

 

And therein lies a real PITA problem. Since it is a hobby (or luxury) industry, getting someone to pay for the extensive testing needed to find definitive answers for *why* this or that sounds different is a real chore. Two things that should sound the same often do not. Worse, differences seem to vanish when the listener is put under even mild stress.

 

It's a trifle annoying sometimes.

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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I would bet that a 200w and a 50w amp do not measure the same at 50w. But they may at 10-20w. Someone else also mentioned that two amps with the same 1% THD may sound quite different because they distort different harmonics. In my book that is a case of different measurements.

 

You are right. Usually, THD tests are made at either 400 or 1000 Hz and only the amplitudes of the THD are measured, not the spectral content. Sometimes odd and even harmonic distortion content are characterized and differentiated in the specs but not often.

 

 

My initial statement is indeed somewhat fuzzy and it is not easy to define what exactly 'measure the same' means. But I think the meaning is clear now for everyone and it is also true. Or maybe you do know a countersample?

 

Depends on to what degree two amps measure the same. Obviously two identical amps of the same model from the same manufacturer are going to measure and sound identical because every measurement possible will be identical between them. But the chances of two disparate amps measuring identically everywhere, are pretty slim, no matter how similar they are topographically.

 

As about buyer beware I guess that is always the case. And I also agree that the published specs are almost always misleading. You mostly just see some best case numbers. Would be great to have an enforced standard for published specs. But hifi is a luxury industry and those usually do not have any standards.

 

It's not that published specs are misleading, it's just that, for the most part, they don't tell the prospective buyer much that is actually useful to him. Other than power output, what do the specs tell us? Well, distortion at some power output (usually the amps "rated" power), for one. But that's pretty useless and ambiguous if you think about it. I've seen subjective reviews of amps with what I would consider unacceptably high amounts of THD, where the amp was hailed as among the best sounding amps on the market! Clearly that's a useless specification. Frequency response? Show me a modern solid-state amp that doesn't have "DC-to-daylight" frequency response specs? Do these correlate anything that will give the buyer even a clue as to how the amp will sound? NO. Specs can be interesting, and they can give savvy engineering types some insight into the design decisions made by the manufacturer (depending on how comprehensive the published specs are), but the specs won't even tell these people how the amp sounds reproducing music. The only way to find that out is to listen.

 

Now, in this day and time, it is unlikely that any amp on the market is going to sound bad, specs or no specs. What you will get is distinct, subtle "flavor" differences between different amps. Sort of like tasting a bunch of different premium bourbons. Van Winkle's, Knob Creek, Woodford Reserve, they all taste different, but all are within the overall taste profile of being a pretty good bourbon. The same is true of modern amps. Go up in price (with both bourbon and amps) and you can expect more "refinement", but the whiskies still taste like bourbon and the amps still sound like clean, modern amplifiers.

George

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*In the spirit of the thread* (by which I mean curiosity about what others think and not as fodder for argumentation), I'd like to know, if you, Dennis, and you, trithio (and/or anyone else who feels like replying) are thinking of particular measurements in this context. Any of the less common ones not named by Dennis above, such as slew rate, response at higher frequencies than 20kHz, etc.? Or is this more of a general category, essentially "whatever the common measurements are that are generally thought to be significant"?

 

I don't know what the answer is myself, having never made a "blind" survey of amps of the same class with similar measurements. I can say (sorry, trithio, an audio anecdote - but I tell it for purposes of showing my bias) that when I was in the process of putting together my DAC and tried out different brands of caps with identical specs on the left and right channels, what came out of the left speaker sounded very different to me than what came out of the right speaker, even with the mono recordings I was using to test. So this admittedly subjective experience biases me to think that different components with identical specifications/typical measurements might sound different, and thus that two amps with the same typical measurements but with different componentry might well sound different. But as I say, I have no way of knowing whether my bias might be true.

 

Speaking for myself, I would say any two amps that null to better than -60 db will sound the same. This with the actual speaker loads mind you. Which might mean two amps sound completely indisthinguishable with some Magnepans and completely different with an odd load like my Soundlabs.

 

As for the measurements, the THD, IMD (especially the 19 + 20khz version) along with noise and frequency response will get you most of the way there if the results are similar enough or if the results all fall below the threshold of what can be heard. In other words if two amps had 2% distortion with similar harmonic structure they would sound the same. If two amps had less than .01% with different harmonics they would sound the same too. The goal would be getting everything below audible levels so you don't care which amp after that point. Or to make the audible distortion one you like. Two opposite goals there.

 

This idea that measurements are just what is easy not what is needed is somewhat misguided. Yes, the measurements have to be possible or we can't do them. And yes we don't pick especially difficult measures if we can avoid it. But that isn't quite the same as saying those became standard because they were easy, and no other reason.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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I believe that a low jitter front end in a system with an overall high dynamic range coupled to low distortion speakers will result in a system you can live with for a long time. In my experience if you focus on these three variables the rest will follow.

 

How do you focus on jitter?

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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This I believe...... Unless you've properly dealt with the acoustics of your listening room, you're listening to it, and not your rig.

Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not." — Nelson Pass

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Depends on to what degree two amps measure the same. Obviously two identical amps of the same model from the same manufacturer are going to measure and sound identical because every measurement possible will be identical between them. /QUOTE]

With modern high sensitivity test equipment, not even this is true. There will always be some very small differences.

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That's not exactly what the "Carver Challenge" was demonstrating. I was in attendance at one of the Carver Challenge demonstrations and it wasn't about specs, it was about nulling-out nonlinearities in two disparate amplifiers (a Carver SS amp and a conrad-johnson tube amp) to the same degree of audibility (or rather to the same degree of silence) to show that an amplifier's signature sound was a product of it's nonlinear behavior. Carver's point was that if you make two amplifiers' nonlinearities equal in volume when all but the nonlinearities are removed from the signal, then the two amps will sound the same. I don't recall Bob measuring anything. He just used a comparator of his own design to invert the original signal and mix it with the non-inverted amplifier product in equal proportion so that only the difference between the original and the amplified signal remained.

 

Well, I wasn't there, but the article told a different story about him not measuring things. I mean how would he make changes without measuring. He was described as having 15 cartons of parts and measuring equipment in his hotel room. Here is a paragraph from that article:

 

The hotel room was a shambles! Across one end was a long table buried in oscilloscopes, distortion analyzers, voltmeters, the two amplifiers, a soldering iron, a white noise generator, two unidentifiable chasses full of inductors, resistors, and capacitors, a large table fan (there was no air conditioning), a half-dozen partially-drained Diet Coke cans, and perhaps 50 feet of audio cables, test leads, and clip-lead interconnects. The adjacent sofa and table were covered with countless little plastic bags of resistors and capacitors, several schematic diagrams, and sheets of paper crammed with arcane numbers and calculations. On the floor under the table was a Rogers LS3/5a loudspeaker which appeared to be connected to both amplifiers at once.

 

I believe it later said he managed a 70 db deep null between the devices. The final tweak needed to get that being to diminish the low end response of the Carver amp.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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How do you focus on jitter?

 

Take a SONOS connect as an example. Known to have high jitter. When inserted in a high end system it sounds like crap. Connect it to a say a Synchro Mesh by Empirical Audio which is designed for the sole purpose of reducing jitter and you have a world class transport.

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