What is this "Noise" so many Audiophiles are talking about? Anyone really Understand?

[morricab]

Great post up above from Brad, the breakdown of different electrical noises was interesting and comments in general on feedback as a noise as well.The amounts of feedback and whether it is global is always something I look for in amps and definitely a less is more approach often seems to be a good one.

If you live in a constantly noisy environment and then have gear that is generally obviously noisy with hum or fan noises, or if you have horns at 100+ db sensitivity I suppose at some level your perception seems to give in and tend to filter and cancel out some of the components of this noise floor and it becomes a bit like very mild tinnitus where you try and manage and listen through by focus. What this requires of our brains and if this comes at a cost or teaches us how to focus better I have no idea really but generally desensitising is helpful to some degree if there was a hypersensitivity to these things in the first place but certainly too much desensitising comes at some cost.

The differences between noise and distortion can maybe also come down to more about definitions and context. In the end noises and distortions are only an issue if you don’t like them. If you view these things holistically both mask the true signal which for me is the performance rather than the recording. There are clearly going to be distortions all along the chain from recording through to replay and finally in the perception. Noises can occur anywhere along the chain and also be captured in the recording.

For me noise and distortion both mask signal. There are more audible levels of each and also levels where they are barely audible but still have significant bearing on how we perceive the true signal... the performance and the music.

I worry about them primarily out of concern for them masking the low level signals that are responsible for so much ambience retrieval and the carving of true 3d spaces and correct timbre of instruments etc.

Take an old (1950s) Jazz recording like the famous Kind of Blue and you will hear a significant amount of tape hiss on this recording...however, it doesn't affect the ability to hear very soft cymbal brush strokes, inflections in the horn playing etc. In fact, with really good systems it seems to exist on a plane outside the music itself, detached if you will. This is because this tape hiss is not correlated with the music so our perception of it is different and more interestingly to me we can hear BELOW this noise signals that are correlated to the music...our brains are amazing processors this way. Same thing with clicks and pops on a record.

I am worried about noise in my system more for issues where it is being intermodulated with the signal to create new signals, which are now distortions, that are modulated by the signal but are now related to outside influences AND the signal. These will be non-harmonic multiples and will most likely be rather unpleasant to hear even at very small levels.

It seems nearly universal that when one cleans up the power with a regenerator or a power cable the first thing people usually notice is "blacker" backgrounds but while music is playing not statically. RFI/EMI is insidious and seems to "dirty up" the electronics output. As I said, I have seen this firsthand in a more obvious manner on an oscilloscope of mass spectral traces. We had to do a lot of work to minimize these effects so that we had cleaner spectra. Now, this is in the high MHz to Ghz range but with intermodulation you can get a lot of "fuzz" on the signal possibly from this. Block this from entering your system and you will probably immediately get cleaner output from your gear.

 

[morricab]

Great post from Morricab et al.

If removing/reducing noise is the goal, given the different types, it would suggest a multi-pronged approach.

The big issue (??) seems to be stripping out the signal (or at least current) along with the noise - doing more harm than good. Gryphon repeatedly suggest not to use power conditioners and the like.

Solar power is becoming more ubiquitous these days which raises other questions. Are the PV panels polluting the grid with harmonics? If you have your own PV system, does an inverter add more noise than normally expected via the grid?

David

Inverters are pretty noisy I think.

 

[morricab]

Great post Morricab (Brad?) - a great outline of the various noise forms & their results.

Totally agree that noise which modulates with signal is probably the most insidious of the noise categories & probably the last one to be identified.

Also totally agree that modulated noise is perceived far differently to static noise. This difference, I believe, is down to one of the quirks of auditory perceptions which has a difficult name "co-modulation masking release" (CMR). It describes a phenomena that we can hear a signal which is below the noise floor when there are signals at other frequencies which are modulating in unison with the buried signal. This is a common feature of natural sounds & it appears that our auditory processing has evolved to take advantage of this fact & to be able to hear sounds which would normally be inaudible as they are buried beneath the noise floor. The actual mechanism underlying this ability of CMR to hear beneath the noise floor is still not resolved even though the effect has been know for a very long time.

One of y premise is that noise floor modulation which is generated in the electronics & signal related generates a non-natural perception of the sound in some way. I suspect that the correlated noise create din the electronics is not of the same form as found in natural soundscapes but our auditory processing still latches onto it (as it is the way auditory processing works) & as a result, is confused by it?

Yes, harmonic distortion is flucutating with the music signal so a "noise floor" composed of a myriad of very small harmonic distortion components will be correlated with the signal in a way true noise is not and it would confuse the ear/brain and make a kind of hard perception floor that we cannot hear below.

 

[jkeny]

Yes, harmonic distortion is flucutating with the music signal so a "noise floor" composed of a myriad of very small harmonic distortion components will be correlated with the signal in a way true noise is not and it would confuse the ear/brain and make a kind of hard perception floor that we cannot hear below.

Nicely stated but I think it may perceptually have a more encompassing effect than the phrase "hard noise floor" may suggest?

This 'noise floor' composed of the sum of the many distortion products from each music note, is itself fluctuating but this fluctuation is not directly tracking the music - it is an amalgam of all the IMD products from the electronic processing of the music. Again, this 'fluctuating' noise floor is very much more perceptually insidious than a "hard noise floor"

My thinking is that it blurs our perception of the initial attack of sounds which is perceptually a hugely important area for timbre, soundstage i.e.more accurate perception of the start of sounds = better location of each sound object within the soundscape = more solidity to the soundstage, more definition to each sound object.

 

[morricab]

Nicely stated but I think it may perceptually have a more encompassing effect than the phrase "hard noise floor" may suggest?

This 'noise floor' composed of the sum of the many distortion products from each music note, is itself fluctuating but this fluctuation is not directly tracking the music - it is an amalgam of all the IMD products from the electronic processing of the music. Again, this 'fluctuating' noise floor is very much more perceptually insidious than a "hard noise floor"

My thinking is that it blurs our perception of the initial attack of sounds which is perceptually a hugely important area for timbre, soundstage i.e.more accurate perception of the start of sounds = better location of each sound object within the soundscape = more solidity to the soundstage, more definition to each sound object.

Agreed.

 

[Empirical Audio]

I worry about them primarily out of concern for them masking the low level signals that are responsible for so much ambience retrieval and the carving of true 3d spaces and correct timbre of instruments etc.

Take an old (1950s) Jazz recording like the famous Kind of Blue and you will hear a significant amount of tape hiss on this recording...however, it doesn't affect the ability to hear very soft cymbal brush strokes, inflections in the horn playing etc. In fact, with really good systems it seems to exist on a plane outside the music itself, detached if you will. This is because this tape hiss is not correlated with the music so our perception of it is different and more interestingly to me we can hear BELOW this noise signals that are correlated to the music...our brains are amazing processors this way. Same thing with clicks and pops on a record.

When I listen to "Kind lf Blue", the hiss is centered and recessed and everything else is stereo. Easy to ignore.

I am worried about noise in my system more for issues where it is being intermodulated with the signal to create new signals, which are now distortions, that are modulated by the signal but are now related to outside influences AND the signal. These will be non-harmonic multiples and will most likely be rather unpleasant to hear even at very small levels.

It seems nearly universal that when one cleans up the power with a regenerator or a power cable the first thing people usually notice is "blacker" backgrounds but while music is playing not statically. RFI/EMI is insidious and seems to "dirty up" the electronics output. As I said, I have seen this firsthand in a more obvious manner on an oscilloscope of mass spectral traces. We had to do a lot of work to minimize these effects so that we had cleaner spectra. Now, this is in the high MHz to Ghz range but with intermodulation you can get a lot of "fuzz" on the signal possibly from this. Block this from entering your system and you will probably immediately get cleaner output from your gear.

Here are things that can cause correlated or signal-related noise:

1) digital jitter
2) ground-loops
3) leakage or bleed-through
4) intermodulation distortion
5) crossover distortion between signals

Ground loops, once eliminated at least allow for really black backgrounds. Noise due to them can be both correlated and uncorrelated. Balanced signaling helps, but is not 100% effective. Eliminating all ground loops does not necessarily get you there either.

I recently put an isolator on an Ethernet feed to my DAC. The Ethernet input was already galvanically isolated, so this shouldn't help, but it did. It's evidently due to leakage of noise through the interface which is reduced by the isolator.

Steve N.
Empirical Audio

 

[caesar]

Bravo!!! Excellent thread. Thank you!!!!!!!!!!!!!!!!!

 

[Folsom]

Actually looking at data published by Stereophile and Soundstage does not bear out what you are saying. Many modern amps today have significant high order distortion components and not only at higher frequencies like 1Khz or the 19+20Khz IMD test but also at 50Hz. It is the nature of feedback that this is so and has nothing to do with the deisgner's wish. It is clear that the total THD is reduced but the order is increased and based on the work starting back in the 1940s and 50s it is also clear that higher order harmonics are far more detrimental to the sound than 2nd order. Also, as Jena Hiraga and Cheever have pointed out, the pattern is also important and that it be monotonic, ie. exponentially decreasing with increasing harmonic order. The rearrangement, as you put it, IS the problem. The myriad of components making the new "noise" floor is also a big problem with low level resolution and spatial representation.

What it does with IMD is also interesting and distressing.

You push this all the time but... I have no idea what trash you're looking at. It's just a dead horse I can't even fathom what the interest even is... Here's a modern amp. There are plenty out there. Maybe I'm just missing something and Stereophile reviews amps by total idiots that live under rocks? I don't know. FACT IS there's too many published circuits and measurements that don't have squat for harmonics past the 3rd, without cutting out feedback. Feedback is highly adjustable, it doesn't have to cover a frequency spectrum with the same properties across it. Furthermore it's not a "noise" floor when it's -100db. Can you hear the difference in amps? Yes, but it isn't the "noise floor" from THD. Name dropping isn't useful because everyone designing if familiar with all those people - assuming they aren't whatever weirdo total hacks you keep talking about.

In the 70's low distortion sounded bad. Today it sounds good among many devices. We are not in the 40's and 50's - nor the 60's, 70's, etc.

IF you really want to fight an enemy then start looking at complex impedance. Probably most of what you assume is problematic stems from it; as does so many audiophiles.

Nicely stated but I think it may perceptually have a more encompassing effect than the phrase "hard noise floor" may suggest?

This 'noise floor' composed of the sum of the many distortion products from each music note, is itself fluctuating but this fluctuation is not directly tracking the music - it is an amalgam of all the IMD products from the electronic processing of the music. Again, this 'fluctuating' noise floor is very much more perceptually insidious than a "hard noise floor"

My thinking is that it blurs our perception of the initial attack of sounds which is perceptually a hugely important area for timbre, soundstage i.e.more accurate perception of the start of sounds = better location of each sound object within the soundscape = more solidity to the soundstage, more definition to each sound object.

Blur is more accurate of a term for what noise does, since it's nearly impossible to actually hear the noise itself except in rare circumstances. I actually agree that attack can sound wrong with too much RF noise, for example. But many gladly trade the heightened spatial cues and detail that RF provides for attack and timbre. On that same note soundstage is not a good example because they don't read nearly as well without a lot of noise being thrown in. The reason is the high frequency information simply isn't loud enough until you pump it with RF, and that information is the spatial cues (that recording engineers often try to remove, so it's often very low). Now if you're talking imaging, then lower noise tends to improve that as the clarity climbs.

 

[Empirical Audio]

Blur is more accurate of a term for what noise does, since it's nearly impossible to actually hear the noise itself except in rare circumstances. I actually agree that attack can sound wrong with too much RF noise, for example. But many gladly trade the heightened spatial cues and detail that RF provides for attack and timbre. On that same note soundstage is not a good example because they don't read nearly as well without a lot of noise being thrown in. The reason is the high frequency information simply isn't loud enough until you pump it with RF, and that information is the spatial cues (that recording engineers often try to remove, so it's often very low). Now if you're talking imaging, then lower noise tends to improve that as the clarity climbs.

What I have found is that many go down the garden path of correlated noise, usually sibilance, believing that it is "airiness", particularly jitter-caused distortion. Jitter can easily cause "halos" or "echoes" of the music track, giving the illusion of airiness. Sometimes, there is no airiness in the track and this makes it sound like there is.

The best indicator that you have low sibilance is razor-sharp focus, a 3-D presentation and that the venue of the recording is easily visualized. If it's a studio recording, the vocalist sounds different than the instruments, because they are singing in a booth or dubbing in later in a different location. These things are obvious in a truly resolving system. Most systems are not.

Steve N.
Empirical Audio

 

[Folsom]

It sounds like jitter and RF cause similar functions. I guess that's no surprise since both tend to elongate voltage response.

Razor-sharp focus with outlines? That is what I think of... if you say razor-sharp. The fundamental should still dominate the "outline", because of simple physics, where the loudest part of the music should be the most attention grabbing. For designing a DAC I can understand those goals, but I'd be tempted to use a bad amplifier to be able to read those changes. A great amp will keep the fundamental dominate.

In the same gesture I prefer an amp that doesn't like complex impedance issues in drivers & crossover, for diagnosing how to correct a speaker. Amps that just force too much feedback make it too hard to figure out the adjustments needed (while always falling short to thrill).

Steve where in the PNW are you?

 

[the sound of Tao]

I worry about them primarily out of concern for them masking the low level signals that are responsible for so much ambience retrieval and the carving of true 3d spaces and correct timbre of instruments etc.

Take an old (1950s) Jazz recording like the famous Kind of Blue and you will hear a significant amount of tape hiss on this recording...however, it doesn't affect the ability to hear very soft cymbal brush strokes, inflections in the horn playing etc. In fact, with really good systems it seems to exist on a plane outside the music itself, detached if you will. This is because this tape hiss is not correlated with the music so our perception of it is different and more interestingly to me we can hear BELOW this noise signals that are correlated to the music...our brains are amazing processors this way. Same thing with clicks and pops on a record.

I am worried about noise in my system more for issues where it is being intermodulated with the signal to create new signals, which are now distortions, that are modulated by the signal but are now related to outside influences AND the signal. These will be non-harmonic multiples and will most likely be rather unpleasant to hear even at very small levels.

It seems nearly universal that when one cleans up the power with a regenerator or a power cable the first thing people usually notice is "blacker" backgrounds but while music is playing not statically. RFI/EMI is insidious and seems to "dirty up" the electronics output. As I said, I have seen this firsthand in a more obvious manner on an oscilloscope of mass spectral traces. We had to do a lot of work to minimize these effects so that we had cleaner spectra. Now, this is in the high MHz to Ghz range but with intermodulation you can get a lot of "fuzz" on the signal possibly from this. Block this from entering your system and you will probably immediately get cleaner output from your gear.

Yes, it was such an eye opening experience over the years to go through the system working through upgrading pc cables and that evolving greater sense of underlying quiet and dynamics that became increasingly evident in the sound that a better the level of PCs brought. RFI/EMF is sooo insidious... insidious is the perfect word for what these subtle noises rob you of both in the sound and then the experience of the music. That grainy greyness that just drops away when you shield out some rfi is not something easily or obviously audible beforehand but then when it is taken out becomes most evident in how the listening experience becomes more natural and more purely connected. The bigger system noises like hum are annoying and obvious but the subtle noises have as much impact on our listening in more fundamentally as you say insidious ways just holding you back from an easier and deeper involvement in the music.

After going through and upgrading all my PCs, power conditioning and signal cables and then using additional shielding with entreq connector wraps and WA connector shields (because rfi just seems to love getting in via any exposed connection points) there was just one lonely 12v dc cable on an external linear psu that was as originally supplied with the psu. I had some carbon fibre tech flex shield that I put around it and the shift was large for one short length of seemingly decent gauge wire. Every cable is important and the better the rest of the cables are the more significant the impact of any remaining rfi archilles heels become.

When I see guys digital setups with a dozen various add on boxes like regen units and all the additional clocking boxes all with additional power supplies and all the additional connections and various leads and wires I wonder how many points for more noise and all the complex soup of additional higher order cocktail of distortions are layering in to the outcome. Simple one source systems rigourously dressed and carefully wired can contain a natural direct musical magic that can allude some very wonderfully complex setups with many, many electronic boxes, a plethora of associated transformers, seeming kilometres of cables strewn throughout and all the sundry connections.

Sometimes a more complex system approach or an addition of a device may buy us an initially sonically obvious benefit like say more obvious bass or greater frequency extension or whatever and we buy in but underneath other more subtle qualities may also be lost or insidious layers of noises added just because there’s just more electronics in the room and cables in the loom. I sometimes look at pics of people’s rooms with piles of electronics and boxes and heaps of cables strewn from connector to connector and wonder what kind of rfi soup the music is actually trying to come through...

 

[Empirical Audio]

It sounds like jitter and RF cause similar functions. I guess that's no surprise since both tend to elongate voltage response.

Razor-sharp focus with outlines? That is what I think of... if you say razor-sharp. The fundamental should still dominate the "outline", because of simple physics, where the loudest part of the music should be the most attention grabbing. For designing a DAC I can understand those goals, but I'd be tempted to use a bad amplifier to be able to read those changes. A great amp will keep the fundamental dominate.

In the same gesture I prefer an amp that doesn't like complex impedance issues in drivers & crossover, for diagnosing how to correct a speaker. Amps that just force too much feedback make it too hard to figure out the adjustments needed (while always falling short to thrill).

Steve where in the PNW are you?

Central Oregon, Black Butte Ranch.

When I say razor sharp, I'm talking about focus, like a pair of binoculars. Putting the binoculars in precise focus allows you to see detail and easily differentiate items. Likewise, focus in stereo allows one to pinpoint locations and minimize spreading of sound sources. It also allows for deeper and wider imaging, if it's in the recording.

Steve N.
Empirical Audio

 

[Empirical Audio]

When I see guys digital setups with a dozen various add on boxes like regen units and all the additional clocking boxes all with additional power supplies and all the additional connections and various leads and wires I wonder how many points for more noise and all the complex soup of additional higher order cocktail of distortions are layering in to the outcome. Simple one source systems rigourously dressed and carefully wired can contain a natural direct musical magic that can allude some very wonderfully complex setups with many, many electronic boxes, a plethora of associated transformers, seeming kilometres of cables strewn throughout and all the sundry connections.

Sometimes a more complex system approach or an addition of a device may buy us an initially sonically obvious benefit like say more obvious bass or greater frequency extension or whatever and we buy in but underneath other more subtle qualities may also be lost or insidious layers of noises added just because there’s just more electronics in the room and cables in the loom. I sometimes look at pics of people’s rooms with piles of electronics and boxes and heaps of cables strewn from connector to connector and wonder what kind of rfi soup the music is actually trying to come through...

Whether or not more electronics adds or subtracts distortion depends on what is added. If it's a reclocker with galvanic isolation, this will usually lower jitter, and therefore distortion.

If it's a line transformer that eliminates a ground-loop and creates a truly balanced signal, it will generally improve sound quality, depending on the quality of the transformer.

I'm also a believer in the KISS principle. My own system comprises : Any computer I like sending music to my router, where it is sent WIFI or Ethernet to my DAC where it is volume controlled, then sent balanced to an isolation transformer and then to my SET tube monoblocks and then to speakers. Its basically a DAC connected to amps to speakers. However, I do use isolators on the Ethernet, and I do use a LPS to power the WIFI adapter.

Steve N.

 

[the sound of Tao]

Whether or not more electronics adds or subtracts distortion depends on what is added. If it's a reclocker with galvanic isolation, this will usually lower jitter, and therefore distortion.

If it's a line transformer that eliminates a ground-loop and creates a truly balanced signal, it will generally improve sound quality, depending on the quality of the transformer.

I'm also a believer in the KISS principle. My own system comprises : Any computer I like sending music to my router, where it is sent WIFI or Ethernet to my DAC where it is volume controlled, then sent balanced to an isolation transformer and then to my SET tube monoblocks and then to speakers. Its basically a DAC connected to amps to speakers. However, I do use isolators on the Ethernet, and I do use a LPS to power the WIFI adapter.

Steve N.

Steve, I’m also simple as, but a different kind of simple probably, I go Sotm ultra 200 via Ethernet but will always have a preamp in the chain because of the potential benefits a great preamp can provide to musical structure, I prefer the music via single ended over balanced in general and I know that that everything has to be reviewed in context of whether any choice ultimately works for us either sonically or musically or some mix of both.

I thought about adding a sotm Ultra tx USB after the Sotm 200 which has linear psu already but that means another linear psu, another Shunyata PC and even more stillpoint ultra5s just to then ensure that I’m then not also adding another pickup point for some other mechanical or electrical input being brought in to complicate the setup any further just to win some other sonic attribute or detail. In the end everything is a choice and potentially a compromise.

In the final mix tho it’s not just about the sum of distortion or noise, but about balances and how we experience the nature of interrelated harmonic effects from the interaction of all these kinds of noise and whether we just like the effect or not that ultimately preclude any one universal or single best approach. Every system and listener are different but yes KISS as a guide if not a rule is generally my default strategy for sure.