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In Reply to: RE: You keep perpetuating the same BS, over and over again - apparently, in the hopes ... posted by Bob_C on August 15, 2015 at 17:45:36
For the owners and listeners of said new category of Class A equipment.
Too bad we can't have a separate forum for them, too. Wait a second - isn't HydrogenAudio the place they belong to? I mean, the class of equipment used, and the "nothing makes any difference, and if it does, you're a gullible fool" mantra - everything is in place.
The real question then is - why here?
Follow Ups:
I note that you've very carefully never posted loopback response captures of your gear. You must be very embarrassed by the results.
Loopback response checks are OK for quick and dirty functional checks, but do not relate to performance of the equipment as it is used, which is either in input mode (ADC) or output mode (DAC), thereby affecting software and hardware.
In addition to interactions which give different performance, there are other problems as well. If they show a level of performance they do not provide a means to partition the performance between the input side and the output side. Worse, in some cases there is the possibility of offsetting errors. (Example might be jitter if common clock is used for ADC and DAC, depending on delays due to buffering.)
Another problem is that to be trustworthy, measurements require trustworthy test equipment and test equipment has to be fit for purpose and kept in a state of good working order and calibration.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
So quick and dirty that's why when it's easy to spot egregious problems like the OP's 60Hz intrusion you know it's real bad. In fact it really draws suspicion when results are indeed this unreliable and someone is still doesn't want to display theirs for some 'mysterious' reason.
Loopback tests are fantastic for making relative comparisons. Like for example: has may last tweak caused my mountainous 60Hz problems to show up any smaller than the size of mt Everest with respect to the signal I'd like to hear yet?
Some of the posters who are brave enough to have posted their results, and I suspect many who haven't, could obviously benefit from the useful data which can be pulled from tests like this. My question is why would anyone who doesn't have access to the high end test equipment be ignoring whatever valuable data they do have available from the tools they do have access to?
I see no egregious hum intrusion in the charts. Please be specific as to what you are talking about, identifying the particular chart(s) involved.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
When your noise is louder than your signal, there is a problem.
You don't see the 60Hz peak on the IMD+N graphs? Unless that is part of some weird test signal, that is terrible.
The two big peaks are the IMD test signal, as per SMPTE standard RP120-1994.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
You are seriously trying to suggest that low Q peak at 60Hz is part of the IMD+N test signal provided by the testing algorithm employed by this software and an expected part of the sequence????
If that doesn't get a readers BS flag waving nothing will. You are going to need to cite sources from the authors suggesting this is anything more than completely TL generated nonsense.
You are doubly ignorant. First about well known and established test signals that can be used to measure IMD in standardized ways (as can be seen by reading the Wikipedia article) and about reading and interpreting FFT plots such as are produced by audio test instruments, audio test software and audio editors.
Worse, you exhibit a nasty personality by attacking people who have already provided sufficient information for you to figure out what you don't know and how to learn it.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
.... by attacking people who have already provided sufficient information" and so on, and so forth.
To me (and to Bob C., might I add), it was clear from the beginning that we're dealing with dumb and nasty moron, who has clearly defined agenda on his mind - any further scientific, or otherwise, exchanges notwithstanding.
Tony is one of, if not the smartest person here but living in such a beautiful state filled with such nice people may make it harder for him to see the true psychos here...
"You are doubly ignorant."Mostly only since you have failed to establish where there is any evidence this is part of the test. Is there some documentation you've read stating the test conforms to this standard you've linked? The fact remains that is the rattiest looking test signal ever produced if it is intended to be used as a test signal. I am still highly skeptical you are right but we'll see if you can come up with anything.
"Worse, you exhibit a nasty personality by attacking people who have already provided sufficient information for you to figure out what you don't know and how to learn it."
lol whatever Tony. Only because you think you've finally managed to corner me logically for once, you try to pretend that is somehow evidence of poor behavior. I think your dishonor in your debate tactics speak clearly for themselves. Besides, why don't we actually establish you are correct first before you get too carried away patting yourself on the back, mmmkay? Especially since using a 60hz test tone in systems likely to be compromised by energy in that exact band seems like ridiculously poor judgement and I'm still hoping the software authors weren't that clueless.
Edits: 08/16/15
I admit I'm wrong. The thing that shocks me is that the test signal on the authors site looks as ratty as the OP's.
Though I'm not sure my laziness to do digging into the things I didn't realize, when I first mistakenly assumed this was a noise signal and still mistakenly assumed the author of the software would go with a more reasonable and common TMD test such as CCIF or DIN, necessarily qualifies as nastiness or ugliness considering the apparent quality of this so called test signal appears in the test.
It is hardly what I'd call a pure and solid, high Q 60Hz signal. What is that all about? Does that actually even conform to SMPTE? It's a weird an unexpected choice implemented in an even weirder manner.
I don't know that any of that weirdness could reasonably be argued to be obvious to the level I'd be reasonably accused of nastiness or ugliness for having questioned it.
It took me a few posts to understand that you were confusing the test signal @ 60Hz with a hum problem. I thought you were commenting on the power supply spuria at -110 dB, which are a problem IMO for someone trying to measure the performance of digital sources.
The SMPTE IMD test is a legacy test that's been around for many decades. Like I wrote to Tony, I didn't realize anyone was still using it. My ignorance. I don't think it's a good choice of frequencies. I also don't think it's being implemented properly by the RightMark software, otherwise the reported level would be much lower.
But I don't understand what your complaint is with the 60 Hz component of the test signal. I'm confident that the test signal is a pure 60 Hz tone mixed with a pure 7 KHz tone, and the way the peak looks in the FFT is determined by window type. It looks like a flat-top window to me. If your complaint is the width of the peak, that's mainly due to the log frequency scale, and secondly a function of the window type.
"I thought you were commenting on the power supply spuria at -110 dB,"
I mentioned early on -110 dB is a level I wouldn't want to put up with and again in another response. Bad enough I think that it may even be a data point supporting my original assertion...that noise challenged systems are the most affected by software/OS tweaks when there is no difference between the data being sent to the DAC.
"My ignorance. I don't think it's a good choice of frequencies."
I also made the point it's a bad choice of frequencies and gave my reasoning.
"I don't understand what your complaint is with the 60 Hz component of the test signal."
I haven't spent much time staring at pure tones generated by sound cards at high resolution. And while I get the log scale can be tricky for some I am fairly used to looking at it and have am just expressing my surprise that a decent soundcard can't pull off a more pure tone. Having significant energy + or minus 10Hz is a surprise to me...almost as if it were something much less controlled than an D to A updating at 96kHz or whatever. Id expect most modern soundcards could presumably create very low distortion and time accurate sine waves at that frequency. As I say not an expert, doesn't seem right to me.
However that still doesn't answer how this line of question , ie my not understanding 60Hz is part of the RMAA IMD+N test, actually matters for something. What was the point of any of this??? Tony does this often. Picks some irrelevant point to argue for fifteen posts then disappears without ever actually making his any relevant point. Was he just here to prove he is the smartest person in the world that only knows things that don't actually matter?
Seems like a troll to draw attention away from subjects he and others here are don't want to address for some reason...hardware noise issues. They become militantly opposed to any sort of discussion about anything related. I'm guessing the discussion all hoits to close to home and forces them to ask themselves unfavorable questions about gear that cost too much. but that's only a guess. Surely will draw great ire from some but we will see if it actually draws out some relevant, on topic point of discussion. I doubt it. It's all part of the game.
Tony, I don't think you being right on this last point makes any sort of statement or argument one way or the other about my original point that the more compromised systems are perfect for the experiment.I'm sure you'll at least agree only -110 dB down on the 60Hz signal is still not great noise performance if that truly is an accurate representation at the gain setting the IMD+N test is run at. If that's true that's one piece of evidence not contradicting my original claim to SBGK in this thread.
If you feel me knowing the smpte standard was obviously being used, this test actually conforms to that standard, and what frequencies are in the standard when I am not even ambitious enough to have gone beyond looking at OP's pictures and reading his article, you have a funny idea about what comes as obvious for me.
As much as I appreciate your setting me straight on RMAA I'm hoping this last long string of posts had some actual point to any of it other than again diverting attention from the point I made to something apparently irrelevant? I'm not seeing the bigger picture you are trying to paint if there is one.
If there is some point you are planning to make, now would be a good time to make it.
Edits: 08/16/15 08/16/15
Who would do an intermodulation distortion test with 7KHz and 60Hz as the test frequencies? That's a very odd choice of frequencies given that any +/- 60 Hz sidebands are going to be too close to 7KHz to really identify on a log plot.Not sure what Archimago was trying to achieve with that one.
Edits: 08/16/15
Test software computes the result so there is no need to look at a display. However, if you want to, my software (Soundforge 10c) can scale the display window for any desired range, e.g.blow up the entire horizontal scale to go from 6900 to 7100 Hz. The FFT itself has more than enough frequency resolution with 65K points and Blackman Window.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Sorry, I should have explained what I was getting at yesterday but was running out the door.
The test software is reporting what it calls "intermodulation distortion + noise" using the SMPTE frequencies but if you look at the IMD+N level reported in the summary (0.0019%) it seems obvious that the software is neither using the SMPTE analysis method nor some other method of quantifying the IM sidebands. Or at least it's not doing it correctly. If it were, the result would be more like an order of magnitude lower.
Given the reported level of IMD+N (0.0019% = -94 dB), I suspect the software is including THD + IMD + noise + anything else not the signal. If I'm right, it's a useless test because all it's really measuring is the level of power supply hum in Archimago's test rig. In fact, I think 5 of the 8 metrics reported in the RightMark summary appear to be just measuring power supply hum: Noise level, Dynamic range, THD, IMD + N, IMD + N (swept).
But in order to know for sure whether I'm right or not, you would need to blow up the display to see what's going on near 7 KHz. Maybe you would see +/- 60 Hz sidebands at the -100dB level, but I doubt it. And I suspect the spectral leakage around the 7k peak in an FFT plot would obscure any lower level sidebands.
I think Archimago has a problem with power supply hum in his test setup which is above the level of any distortion products and it results in inaccurate metrics being reported by his software. And the only way to really separate the power supply related components from distortion products is via FFT analysis, in which case choosing a very low f1 for the IMD test isn't helpful.
Also, I really do think the choice of 7KHz and 60Hz frequencies is dumb. I honestly thought that the SMPTE IMD test was a legacy test that nobody used anymore, but after searching around I see that some people are still using it. The problem I see with it is twofold: First, the choice of a very low f1 will make it hard to interpret the result via FFT because low level sidebands could be buried in the spreading of the peak at f2. Second, choosing an f1 that coincides with the power supply frequency could potentially lead to confusing results in systems with a power supply hum problem. I think the DIN method with 8KHz + 250Hz is more useful, as is the HF intermodulation test.
If I were doing the tests, I would have used a wide variety of IM test signals. One needs to look at all the stages of signal processing and look at the effect likely defects and limitations have on the signal output by the system, choosing particular tests to catch each possible problem area.
Measurements are useful for engineering purposes when they are used interactively by an engineer. They are completely useless (if not dishonest) when used as marketing tools to non-technical customers. Even where they are directed at technical customers they are suspect, because the lack of interactivity makes it impossible to do hands-on testing to understand what is going on, which includes at least understanding the accuracy of the measurements and their significance. To use measurements to prove a "religious" point is the equivalent of counting angels on the head of a pin. (Especially as in this case some of the plots did show that operating system changes affected measurements.)
I was not commenting on the intelligence in the selection of IM test signals. However, now that the point has been raised, I suspect that there may be some merit to use of a low frequency test signal if one is looking to see low level non-linearities in a DAC's output. However, it might be even better to use a DC signal if there is a DC path from digital to analog to digital. This will show up a lot of converter artifacts as a change in noise floor. Sometimes one can infer this behavior by looking at published curves, e.g. DAC spec sheets.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Pretty much agree with all of that, particularly measuring being part of interactive, iterative process.
My impression of Archimago's blog is that he's just having fun experimenting like a kid with a chemistry set and not serious about digging into what's going on.
2 agendae points.......
1. He's angry that he can't afford higher performing equipment.
2. Therefore: he's creating a "straw man" to "prove" an objective position in a subjective field.
"Asylums with doors open wide,
Where people had paid to see inside,
For entertainment they watch his body twist
Behind his eyes he says, 'I still exist.'"
How do you know that the problem you create, apparently being gain calibrated to the 60Hz peak since it is by far the largest, doesn't totally confuse the algorithm and invalidate any IMD+N result? If nothing else you've limited the IMD test signal level to IMD artifact signal level ratio by having the gain set where the IMD test signal is lower than it could be under more ideal circumstances and so limited the resolution of any results that are attained.
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