That's the funny thing about "noise floor" - it's not like you hear REAL noise, like static or hiss; usually you don't realize it's there until it's gone. But it IS real.

It's like this: at a certain level in sound (where transients and a lot of acoustic details reside) noise level, maybe call it resolution(?), just seems to suck up that detail. Or perhaps it's like all those details just sort of mush together. You just don't hear all of what's there- so it's not something you'd immediately notice, if at all.

But! then you add a dedicated power line, a line conditioner, a better amp, an upgraded phono pre-amp, etc... Bingo! All that low level detail and ambiance, and those ultra fast transients, just appear as if out of nowhere! And then you realize- they were always there, but weren't getting through the "noise."

That's my definition, based on my experience, and a little from what I've gathered around here. Hope that helps some.

In the days of old (1970's) noise was a very key factor in amplification (anything with gain) and something of a pain to engineer out of the system.

These days the designers are trying to deliver ever more channels (DTS - Dolby - THX) and noise again gets attention and hammered by designers with a keen ear. Though the component capability today is much better than we had then.
If you have already engineered noise beyond human hearing - noise is no longer an electronic problem.

Just stand in a silent room for a moment and listen to the noise your ears make - especially if you have been doing something strenuous -- like having copious amounts of sex. Your own internals cause a certain amount of noise and ears are very sensitive to the "Thermal" -- so you have an S/N ratio too

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That's the funny thing about "noise floor" - it's not like you hear REAL noise, like static or hiss; usually you don't realize it's there until it's gone. But it IS real.

Yes and you can measure it. With my system on and volume set to normal listening levels, it adds 2-3dB to the noise in the room. OTOH, I cannot hear the difference since it is still in the NC-20 range and the relay noises get in the way of a subtle A/B comparison.

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But! then you add a dedicated power line, a line conditioner, a better amp, an upgraded phono pre-amp, etc... Bingo! All that low level detail and ambiance, and those ultra fast transients, just appear as if out of nowhere! And then you realize- they were always there, but weren't getting through the "noise."

Yes, again, but that assumes the room noise will permit it.

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Yes, again, but that assumes the room noise will permit it.

Excellent point.

I have a friend how lives in a wonderful condo in the city, up many floors, view of the river. Unfortunately, while he has a great system a good deal is lost in the basic noise of the condo and the city. While quite subtle until you listen to it, there is a surprising amount of noise.

I also believe that this ambient level messes up his TacT's ability to properly compute room correction - but this is simply my pet theory as to why I don't like the sound with the TacT in active mode.

If you ever get a chance to go into an anechoic chamber, do it! We humans are incredibly noisy - breath, pumping blood, quiescent nervous system noise. I had no clue what a sonic mess I am.

Speakers sound really liefless in anechoic space also. But the detail and smooth response!

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I have a friend how lives in a wonderful condo in the city, up many floors, view of the river. Unfortunately, while he has a great system a good deal is lost in the basic noise of the condo and the city. While quite subtle until you listen to it, there is a surprising amount of noise.

Yes. When I was apartment shopping, I rejected many that had wonderful views because of the noise. My present apartment 'sounded' quiet as soon as I walked in.

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I also believe that this ambient level messes up his TacT's ability to properly compute room correction - but this is simply my pet theory as to why I don't like the sound with the TacT in active mode.

Very likely. Most such devices are very sensitive to extraneous noise.

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Not sure I understand reviews and discussions of how a lowered noise floor helps so much. That is, of course it helps, but, typically, isn't a given reviewer's (or forum poster's) system pretty doggone free of background noise to start with?

Sounds to me like you actually do have a pretty understanding.

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I also believe that this ambient level messes up his TacT's ability to properly compute room correction - but this is simply my pet theory as to why I don't like the sound with the TacT in active mode.

Noise floor has really nothing to do with ambient noise.
I would think that a Tact would compensate for ambient noise at the time it was calibrated after all it is comparing what it hears (what the room add/removes) with what the system reproduces. I also would think that it may just get it wrong if at the time of calibration the was a constant source of real noise e.g a generator, jack hammer or party nearby.

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Noise floor has really nothing to do with ambient noise.
I would think that a Tact would compensate for ambient noise at the time it was calibrated after all it is comparing what it hears (what the room add/removes) with what the system reproduces. I also would think that it may just get it wrong if at the time of calibration the was a constant source of real noise e.g a generator, jack hammer or party nearby.

In principle. However, ambient noises (refrigerator 2 rooms away, HVAC, plasma monitor buzz, etc.) vary so the EQ wastes resources compensating for something that (1) cannot really be eliminated and (2)may be subjectively inaudible. Also, significant ambient noise reduces the S/N ratio during the measurement process.

Systems such as MRC, REW, Audyssey, etc. will discard measurements and may even abort if the ambient noise level is high enough. In such cases, they did not seem subjectively significant but, when alerted by the measurement system, I could hear them.

Kal

"Yes, again, but that assumes the room noise will permit it."

Yes- you're right there too. In the winter it's quieter in our house since we have no windows opened (with double pane windows). All out appliances are pretty new so that helps too. LG by the way make incredibly quiet appliances!

But assuming your listening room is indeed quiet, "noise floor" then becomes a discussion largely about system resolution and sonic detail. That's what I believe the original poster's question was referring to.