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Audibility thresholds of amp and DAC measurements

andreasmaaan

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The table that @andreasmaaan posted from the 1980 study is indicative of this in that it appears solo piano music was more revealing of the distortions than "pop" music (I hope the original article listed the actual recordings for reference).

FYI:

1545092204416.png
 

RayDunzl

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One of my more memorable audio experiments:

Create a file with 400Hz in the left channel, 405Hz in the right.

Listen with speakers, hear 5hz beating (in the air).

Listen with headphones, hear the same beating (but only in the brain).
 

restorer-john

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For my room it measures about 45 dB SPL broadband noise with a rise at the low frequencies. If my critical listening level is 83 dB SPL, at what level can I hear below the noise floor of my room before the noise masks the signal?

Either move to the country, or get a kW or two on tap, or in my case both.

It's so quiet here at night, all you can hear is the blood in your head/ears, or occasional creature in the bush (koalas at the moment). Friends of ours who stay, sometime say they can't sleep because it's too quiet. With any conceivably sensibly recorded music, I don't have an issue losing low level detail, it runs into the fuzz of lack of bits and at the bottom end, I haven't really run out of power at the other end either.

As for your question- ask Amir- he's got a ton of knowledge in that area. We can perceive way into a noise floor depending on a whole lot of things.
 
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restorer-john

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Listen with speakers, hear 5hz beating.

Listen with headphones, hear the same beating.

Wow, five times a second! I'll have to get my mistress to step up her game, she's probably only at about 2 hurts (hz)

1545095061430.png


(random internet mistress for effect)
 

andreasmaaan

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I don't think DIM and TIM are the same thing. As I understand it, TIM is what happened to a transient of greater slew rate than the amplifier can accommodate. As such, it should never happen in any amplifier if the bandwidth, both open and closed loop were correctly designed. Even if the amplifier was badly designed, a simple filter at the input would stop it. It seemed to be an issue with unfiltered preamps that had MHz bandwidths and power amps that didn't. In any event, no normal signal off an LP or tape would trigger it, and CDs are band limited. I suppose a record click or unfiltered tape recorder bias might be sufficient, as might an unfiltered NOS DAC, but frankly, why worry about badly engineered sources when there are plenty of well engineered alternatives?

I've never been convinced that TIM was ever a real problem that needed fixing, or indeed, measuring.

S

Fair enough. Like I said, I'm not an expert on this. However, the AES considers DIM and TIM to be the same thing in their Pro Audio Reference.

But my perspective is: whatever the cause of the distortion in this study, I can't see how that could invalidate the finding that distortion (of whatever kind) was reliably detectable by two subjects at 0.003% RMS. Do you see a problem with my logic here?

I do think there are other reasons to wonder about the validity of any study in which the reproduction equipment produces a higher level of baseline distortion than the levels of distortion being tested for (i.e. any distortion audibility study), of course. I just don't see any particular additional problem in this study.

Or perhaps you'd be interested in reading it?
 

mitchco

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Either move to the country, or get a kW or two on tap, or in my case both.

It's so quiet here at night, all you can hear is the blood in your head/ears, or occasional creature in the bush (koalas at the moment). Friends of ours who stay, sometime say they can't sleep because it's too quiet. With any conceivably sensibly recorded music, I don't have an issue losing low level detail, it runs into the fuzz of lack of bits and at the bottom end, I haven't really run out of power at the other end either.

As for your question- ask Amir- he's got a ton of knowledge in that area. We can perceive way into a noise floor depending on a whole lot of things.

I live off the grid too, but house noise is house noise, did you measure yours?

Re: perceive into the noise floor... I meant to put a winky, as it is a trick question ;-) Do you own JRiver? Care to take the bit depth test? If not, try Ethan's links - the answer is there too...
 

Wombat

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Either move to the country, or get a kW or two on tap, or in my case both.

It's so quiet here at night, all you can hear is the blood in your head/ears, or occasional creature in the bush (koalas at the moment). Friends of ours who stay, sometime say they can't sleep because it's too quiet. With any conceivably sensibly recorded music, I don't have an issue losing low level detail, it runs into the fuzz of lack of bits and at the bottom end, I haven't really run out of power at the other end either.

As for your question- ask Amir- he's got a ton of knowledge in that area. We can perceive way into a noise floor depending on a whole lot of things.


I, too, have encountered city/suburban folk complain that my rural locations(at different times) were too quiet and too dark(baddies?) for settled sleep. They also complained that residents walked too slowly in town and that the shopkeepers and customers held them up, time-wise, by chatting.
Talk about being on a self-caused stress treadmill.
 

Blumlein 88

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I, too, have encountered city/suburban folk complain that my rural locations(at different times) were too quiet and too dark(baddies?) for settled sleep. They also complained that residents walked too slowly in town and that the shopkeepers and customers held them up, time-wise, by chatting.
Talk about being on a self-caused stress treadmill.
The USA, being the greatest country, has all that figured out. Anywhere remote enough to be too quiet to sleep is also somewhere riders of Harley-Davidson motorcycles show up. So with their loud syncopated exhaust note and lack of mufflers there is noise for miles around.

PS-don't mention this to Sal. Though I do remember sleeping on the beach in Florida listening to the waves pounding the shore, and being awakened by damned H-D motorcycles. I took my revenge though. A friend loaned me an Aprilia and I dusted all their asses in stoplight races until they were afraid to try anymore.
 

Wombat

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If one has to try very hard to 'think' there is a difference and endlessly discuss it with like-minded individuals does it really matter, in real-time, when listening to music in a problematic consumer environment?

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RayDunzl

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A side note:

When attempting to measure speaker distortion here, the noise floor seems to dominate the reading, until the SPL set exceeds the levels at which I would listen.

SPL, from 50 to 91 at 1kHz. Ambient "noise" intrudes here at the bottom left...

1545117417777.png



And the THD for the same measurements. Only at the highest SPL (traces at the bottom) does the measured distortion seem to start rising out of the noise. The top six traces, I interpret as ambient noise being mistaken for harmonic distortion.

1545117564718.png


Anyway, makes me wonder about the tiny amounts produced by various DACs.

Which would be waaaaay down here someplace:

1545119482186.png
 

solderdude

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add to that we hear in Phon and not in dB which makes a lot of difference in lower frequencies. (not in the midrange)
 

Blumlein 88

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add to that we hear in Phon and not in dB which makes a lot of difference in lower frequencies. (not in the midrange)
Oh, so now we are going to talk about Phons. Not this Fonze. That is actually Fonzie.
1545120013889.png


I find the phons concept very helpful. Yet it is almost completely ignored.
 

Wombat

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Microphons as distinct from microphones.
 

restorer-john

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Come on now. I've got more class than to pass out drinking Bud Light.....................

Fair enough, my mistake. But you had finished off that entire Vodka watermelon before you used it- hadn't you?
 
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