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  #46  
Old 22-04-17, 09:08 AM
Rockmeister Rockmeister is offline
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Originally Posted by Julf View Post
Yes, the change should be present all the time. A short signal is harder to separate from the semi-random noise. The more data you have (the longer the measurement), the easier it is to pick out the useful signal from the noise.

Imagine a simple sine wave with a random background noise. If you keep averaging out the signal (with a averaging cycle equal to the sine wave), each wave of the signal keeps reinforcing the previous data, whereas the random noise cancels itself out over time.
ah ok I understand that, thanks.

As to the other point(lessness of this concept), I can only re explain that I'm trying to find a compromise between 'I hear, and what I hear is true', and 'I measure, and what isn't measured does not exist'. By replacing the human ear with a microphone we rule out all 'human' emotional responses, which are, are they not, nearly always the basis of much critical humming and haaing on these threads. Removing all human elements, but still measuring what the loudspeaker can output measures what we, were we there, would hear. NOONE listens to an amp. The claim is that cables affect sound output. They may, incidentally be mucking around with the amp, and I can understand how that is far more easily measurable, but my aim wasn't simplicity, but trying to conduct a test that hears what we hear...HEAR, without us present. I might add, that even the most cable pixie of cable pixies will need to admit that if the effects aren't audible, they'd not need to spend money on chasing them...surely???

Editted to add that if Julf and 718 want to go ahead and conduct their test their way, who am I to say whoa, but it's not my test so? I'll need to start a thread on CD deterioration in an ozone rich atmosphere. It's being retired you know...bored. Or what was that suggested...sofa testing? That could be done.
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  #47  
Old 22-04-17, 09:18 AM
mattgbell mattgbell is offline
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Originally Posted by Rockmeister View Post
[...] Removing all human elements, but still measuring what the loudspeaker can output measures what we, were we there, would hear. NOONE listens to an amp. The claim is that cables affect sound output. They may, incidentally be mucking around with the amp, and I can understand how that is far more easily measurable, but my aim wasn't simplicity, but trying to conduct a test that hears what we hear...HEAR, without us present. I might add, that even the most cable pixie of cable pixies will need to admit that if the effects aren't audible, they'd not need to spend money on chasing them...surely???
Sure, but cables could not affect loudspeaker output without affecting amp output.

The advantage of doing the measurement at the amp output is that it makes the test far more sensitive -- and less contentious. By the way, it'll also increase the chances (massively, I think) of returning a positive result, which should please the subjectivists and counter any misgivings they have about not recording the speaker output ('what we hear').
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  #48  
Old 22-04-17, 09:25 AM
Rockmeister Rockmeister is offline
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Well MattG I do understand that, but I have to say that I find it a bitter pill to swallow. I mean this was MY child, MINE. (Rocky exits stage left, sobbing loudly into gaudy hanky).

Seriuosly tho, as I may have mentioned, Art teachers are NOT best qualified, despite my 'O' level grade 4 in both Maths AND Physics, to know how to do these things. Just glad to be doing something and grateful it's moving onwards.
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  #49  
Old 22-04-17, 10:00 AM
Julf Julf is offline
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Originally Posted by Rockmeister View Post
Editted to add that if Julf and 718 want to go ahead and conduct their test their way, who am I to say whoa, but it's not my test so? I'll need to start a thread on CD deterioration in an ozone rich atmosphere. It's being retired you know...bored. Or what was that suggested...sofa testing? That could be done.
I offered to do the analysis of the recorded files - not to do the actual test/recording. But the concern is that going through the speaker and mic, you introduce room noise that will mask any small differences.
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  #50  
Old 22-04-17, 10:05 AM
venton venton is offline
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Assuming reasonable sample rate of 44,100 per second.
10 points per cm on graph paper.
44.1 meters of graph per second!
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  #51  
Old 22-04-17, 10:05 AM
Rockmeister Rockmeister is offline
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I know Julf thanks, and to be honest I'm very glad for it. There's not a lot of light hearted joilty on the Fish, a marked contrast to my previous forum, but whatever, I do really hope that it goes ahead...and thanks again. I mean it
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  #52  
Old 22-04-17, 10:32 AM
mattgbell mattgbell is offline
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Originally Posted by Rockmeister View Post
Well MattG I do understand that, but I have to say that I find it a bitter pill to swallow. I mean this was MY child, MINE. (Rocky exits stage left, sobbing loudly into gaudy hanky).

Seriuosly tho, as I may have mentioned, Art teachers are NOT best qualified, despite my 'O' level grade 4 in both Maths AND Physics, to know how to do these things. Just glad to be doing something and grateful it's moving onwards.
All things considered, you're bearing up well.

As a fellow teacher, I just hope that when the inevitable negative result comes through the subjectivists don't call for you to be burned at the stake.
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  #53  
Old 22-04-17, 12:36 PM
Julf Julf is offline
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Originally Posted by mattgbell View Post
As a fellow teacher
I'm just married to one, does that count?
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  #54  
Old 22-04-17, 02:50 PM
mattgbell mattgbell is offline
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I'm just married to one, does that count?
My wife thinks so.
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  #55  
Old 22-04-17, 05:54 PM
BE718 BE718 is offline
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Originally Posted by Rockmeister View Post
ah ok I understand that, thanks.

As to the other point(lessness of this concept), I can only re explain that I'm trying to find a compromise between 'I hear, and what I hear is true', and 'I measure, and what isn't measured does not exist'. By replacing the human ear with a microphone we rule out all 'human' emotional responses, which are, are they not, nearly always the basis of much critical humming and haaing on these threads. Removing all human elements, but still measuring what the loudspeaker can output measures what we, were we there, would hear. NOONE listens to an amp. The claim is that cables affect sound output. They may, incidentally be mucking around with the amp, and I can understand how that is far more easily measurable, but my aim wasn't simplicity, but trying to conduct a test that hears what we hear...HEAR, without us present. I might add, that even the most cable pixie of cable pixies will need to admit that if the effects aren't audible, they'd not need to spend money on chasing them...surely???

Editted to add that if Julf and 718 want to go ahead and conduct their test their way, who am I to say whoa, but it's not my test so? I'll need to start a thread on CD deterioration in an ozone rich atmosphere. It's being retired you know...bored. Or what was that suggested...sofa testing? That could be done.
I can see where you are coming from but there are a few issues with the concept.

Your objective is to try and see if mains cables affect the performance of the amp. Whilst you are correct in saying that we dont listen directly to the amp, we need a transducer (speaker) to turn the electrical output in to sound pressure, any change in the amps performance by definition has to be contained in its electrical output. Therefore it absolutely is what we hear.

If we put this output through the speaker and then into a microphone via the room, the effects of noise, acoustics and distortion will make it extremely difficult (impossible imo) to see any potential tiny changes in the amps output. Add to this that mics dont really "hear" like we do anyway.

Having speakers and mics dont actually add anything to the experiment and hinder achieving the objective. We still achieve taking the human emotion and biases out of the picture and it still represents what we hear.

Last edited by BE718; 23-04-17 at 12:18 AM.
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  #56  
Old 23-04-17, 08:25 AM
Rockmeister Rockmeister is offline
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I concur 718, but I can already hear the pixie worshippers queing to complain. Still, if they can also complain about microphones and ears, then I have no case, so.
Let's go Jo.
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