I follow the reviews Tyll does on innerfidelity and I concur that there is some remarkable value available now. I use Etymotics for work which I held off justifying for about 15 years. I do need some nice sealed over-ear units to complete the set.
I'm saying that listening on laptop 1" speakers at 1m distance, I am hearing faint background noise that is not correlated with the main music, unlike excess noise which is signal dependant.
Dan.
sorry.... was just cruising thru the forum..... HF can get into audio systems and produce higher distortion - possible audibility. Thought you might be talking about that HF's audibility in the more sensitive hearing range.
THx-RNMarsh
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Excess noise is current dependent noise, ie signal dependent noise, as opposed to Johnson or thermal noise which is solely related to absolute temperature.
Excess noise forms are otherwise known as flicker noise, popcorn noise and RTS noise.
Thermal noise is white, consistent and readily ignored by the ear.
Excess noises are signal dependent and therefore dynamically varying and therefore readily heard either directly, or more commonly heard indirectly by the modulation/intermodulation products caused by constantly changing operation conditions of electronic circuits.
Manifestations of excess noise subjective damage include loss of image positional stability and localisation (focus), non harmonically related distortions throughout the audio band (harshness), loss of perceived resolution, and musical 'wrongness'.
In digital systems excess noise can cause timebase instability, which further modulates the above mentioned sonic faults.
I find it quite intriguing that when excess noise is reduced in el-cheapo and mid-fi systems, just how musically satisfying these systems can become.
The maths and measurements describing these systems are perfectly correct, but fall down when dynamic variables such as excess noise are present.
Dan.
I figure it's quiet but not anechoic? I've been in the now gone chamber at Harvard, not someplace you would want to be for more than a short period. Unless of course one is very eccentric.
Excess noise can be non-signal/current dependent and extremely temperature dependent too. But once in the signal only Maxwell's demon can part them, sorry that's just the way it is.
Excess noise related to current flowing in a resistance is a well accepted term/principle, I have posted the LIGO survey of SMT resistors several times. But more to the point it also is a material property and can not be removed after the fact.
The LIGO guys will be here on the 16th to give a presentation. I'm looking forward to that one!!
John
Scott,
Now you are definitely over my head here but I have a couple of questions. With this excess noise caused by a material such as a resistor is that noise a fixed noise, does it have a specific fixed frequency response or is it a random noise? If is was a fixed noise product and could be measured would there theoretically be a way to measure it and counter it such as is done with noise cancellation in the audio spectrum? I'm just asking this as a curiosity, I have no idea how you would do any of this.
Now you are definitely over my head here but I have a couple of questions. With this excess noise caused by a material such as a resistor is that noise a fixed noise, does it have a specific fixed frequency response or is it a random noise? If is was a fixed noise product and could be measured would there theoretically be a way to measure it and counter it such as is done with noise cancellation in the audio spectrum? I'm just asking this as a curiosity, I have no idea how you would do any of this.
I thought excess noise is any component noise which is over and above thermal noise. The noise heard at the output of a circuit is a mixture of thermal noise and excess noise (and amplified input noise).Max Headroom said:
All noise is random. Noise can have different random properties, including frequency response/statistics. Resistor noise runs from a frequency approximating to 1/(age of resistor) to somewhere in the UV spectrum of light?Kindhornman said:
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Excess noise is a standard term in the industry. What it is composed of can be vague, but if you measure a resistor for example and it measures 1Kohm, you must expect 4nV/rt Hz of noise at the MINIMUM at room temperature! Everybody knows and expects that, but IF there is more than 4nV/rt Hz of noise from a 1Kohm resistor, then the excess is EXCESS NOISE. It is usually in the form of 1/f noise and it can be generated by the resistor itself, especially with dc current flowing through it, if it is not 'perfect'. Popcorn noise is a separate mechanism, but just as real, and must be considered as excess noise as well, if it is present. Quantum noise? Who knows, but it has been measured as well. What are we quibbling about?
Excess noise comes from the current flowing in the resistor. No current and all you get is the thermal noise. There is a mil spec for measuring and quantifying excess noise. Smaller parts will have more and metallic conductor resistors will have less. It is random. If you get deterministic noise you have different problems.
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