Ooooh... Charts and Graphs

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yeky83 said:
What? This dude struggles to get one measurement right because of his lack of basic knowledge in the subject. Summary of his verbose, badly communicated article: He chronicles how he keeps getting the measurement wrong because of his equipment and technique, until the very last graph.

The only graph worth a salt is the very last one which goes to prove Cliff's finding, high-ish aliasing noise in the Helix across its amp models.
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He's doing something very wrong because his very first graph comparing to the Fuchs has aliasing on the real amp and real amps don't alias. Those spikes at 4 and 6 kHz are aliases as are the two around 14 kHz.

Actually, now that I think about it, I know exactly what he did wrong. There's a little quirk (one of several) in TrueRTA in that it will alias (a LOT) if you don't set it's sample rate to equal the sample rate of your interface. IIRC the default sample rate is 44.1. If you leave it at 44.1 and your interface is running at 48 it will alias and vice-versa.
 
FractalAudio said:
He's doing something very wrong because his very first graph comparing to the Fuchs has aliasing on the real amp and real amps don't alias. Those spikes at 4 and 6 kHz are aliases as are the two around 14 kHz.

Actually, now that I think about it, I know exactly what he did wrong. There's a little quirk (one of several) in TrueRTA in that it will alias (a LOT) if you don't set it's sample rate to equal the sample rate of your interface. IIRC the default sample rate is 44.1. If you leave it at 44.1 and your interface is running at 48 it will alias and vice-versa.
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Correct. I struggled with this till i upgraded my audio interface. If you read the entire post you will see that the only real relevant data is the last graph where it confirms your findings. I did my best to draw no conclusions, and I think you will also admit that this is a difficult test. 60 db is a high bar. That said. Helix failed I am a helix owner, and wasnt particularly happy to post this but it failed plain and simple. I wasn't going to hide my results. As to the story and drama... Its just a blog post, i try and make it amusing. I'll give you the signal to aliasing ratio of any amp in helix if you ask.
 
This article is a nice example of internet knowledge in blogs ;) I'm not saying that all blogs are as wrong as he is, but there's a lot of bullshit information out there.

But at least he's honest telling the readers that he has no idea :D
 
axifist said:
This article is a nice example of internet knowledge in blogs ;) I'm not saying that all blogs are as wrong as he is, but there's a lot of bullshit information out there.

But at least he's honest telling the readers that he has no idea :D
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As I said, Its just as blog, I do it for my own amusement. I document my successes as well as my failures. I followed this process because it intrigued me. No other reason, no agenda, or i wouldn't have posted it at all.
 
GeekeryGeek said:
As I said, Its just as blog, I do it for my own amusement. I document my successes as well as my failures. I followed this process because it intrigued me. No other reason, no agenda, or i wouldn't have posted it at all.
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Mistakes and all, it doesn't appear you are claiming to be an authority, clearly, with all that bungling. I say give credit for showing the path you took and eventual knowledge gained, however many mistakes along the way.
 
I respect your process from no understanding to a basic understanding! I have no idea how to do this stuff, I also didn't read your whole post, because at some point the images didn't load...

To be precise, what I meant was simply, that many people writing blogs obviously have no idea what they are writing about, e.g. food and what not, without being honest that they are no experts. You at least are honest enough to make this very clear :) In that sense it's a GOOD blog post!
 
I imagine that one of the consequences of higher levels of aliasing noise in a signal is a cumulative listener fatigue. Are there any studies on this subject that establish thresholds and durations of what most people will tolerate?

And when I say "studies", I mean even simple ones conducted by FAS with users or employees?
 
GeekeryGeek said:
Correct. I struggled with this till i upgraded my audio interface. If you read the entire post you will see that the only real relevant data is the last graph where it confirms your findings. I did my best to draw no conclusions, and I think you will also admit that this is a difficult test. 60 db is a high bar. That said. Helix failed I am a helix owner, and wasnt particularly happy to post this but it failed plain and simple. I wasn't going to hide my results. As to the story and drama... Its just a blog post, i try and make it amusing. I'll give you the signal to aliasing ratio of any amp in helix if you ask.
Click to expand...

Thank you for you honesty and candor.
 
I understand the theory here. I also started to internalize the struggles at work of setting up instrumentation, understanding its limitations and started to develop a stomache ache in the process. That’s when I dropped an Alka-Seltzer in a glass of water and heard the fizz.
 
FractalAudio said:
Perhaps. I believe it's also a contributor to the "fizz" that people say they hear.
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Fizz, I think I know what you mean, though the only negative quality I regularly detect in my high gain sound, more on the Cornford less on the Orange 50, is a graininess in the upper mid/presence range. Seems to be variable, perhaps with where I am on the neck.

I look forward to some critical listening between the 2 and 3 of the same models.

Is there any possibility of diminishing aliasing further in future firmware updates?
 
GeekeryGeek said:
If you read the entire post you will see that the only real relevant data is the last graph where it confirms your findings.
Click to expand...
I would ask you to write more clearly so that it's well understandable from the beginning that the other graphs are meaningless. Your readers will have less of an understanding than you do, and not be able to sift through the junk from real data unless you're very clear about it. You make several conclusions along the way, and aren't clear about communicating that they're the wrong conclusions.

GeekeryGeek said:
As I said, Its just as blog, I do it for my own amusement. I document my successes as well as my failures. I followed this process because it intrigued me. No other reason, no agenda, or i wouldn't have posted it at all.
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And if I may, "it's just a blog" seems a little unforthcoming. You're an admin in the huge Helix facebook group, and seems to me distributing your blog and graphs out for many to see. So again, I would ask for clear communication.
 
yeky83 said:
And if I may, "it's just a blog" seems a little unforthcoming. You're an admin in the Helix facebook group, and seems to me distributing your blog and graphs out for many to see. So again, I would ask for clear communication.
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To be fair, he never claimed to be an authority on the subject, was fairly clear that he’s trying to do things he has no idea about, and his style of writing wasn’t suggesting academic rigor or authoritative conclusions anyway.

These days, that’s more forthcoming and up to standards than your average Washington Post piece...
 
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FractalAudio said:
Thank you for you honesty and candor.
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You are more than welcome. One small thing tho... Ya see there's this small complication.... when I reproduce the test and alter the gain settings on my Helix the same way you said that you did on your AxFxIII i come up with this. Which shows 78dB "peak signal to aliasing" To be 100% clear your unit as you tested it only came up at 68dB. k2uaZRR%SCeGyS1h8QAEXw.jpg
 
GeekeryGeek said:
You are more than welcome. One small thing tho... Ya see there's this small complication.... when I reproduce the test and alter the gain settings on my Helix the same way you said that you did on your AxFxIII i come up with this. Which shows 78dB "peak signal to aliasing" To be 100% clear your unit as you tested it only came up at 68dB. View attachment 45174
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I'm assuming the green trace is the DUT in which case it's only 30 dB. At 5 kHz there's a small spike that touches -30 dB.

Oh, and nice title on your project...
 
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