Ability to see all electical signatures from every devices in your house with sensors

[microstrip]

I would quite vigorously disagree about the noise floor being less subjective, it in fact is perhaps most controversial of all the parameters, largely because, I believe, it suffers from this misnaming. (...)

I agree with this point. Many people consider that the only meaningful specification in noise is the measured signal to noise ratio and ignore the subjective aspects of noise.

But I am not prepared to rate the importance of this particular versus other subjective aspects.

 

[Orb]

Hey Microstrip,
have you listened to a product that had a noticable noise floor, and furthermore did this affect your listening satisfaction or listening behaviour?
Edit:
Just remembered you use tube products anyway, so possibly this may not be a critical threshold-tolerance issue for you.

Thanks
Orb

 

[microstrip]

Hey Microstrip,
have you listened to a product that had a noticable noise floor, and furthermore did this affect your listening satisfaction or listening behaviour?
Edit:
Just remembered you use tube products anyway, so possibly this may not be a critical threshold-tolerance issue for you.

Thanks
Orb

Orb,
These are the noise specifications of my tube preamplifier : Noise 1.7uV RMS residual IHF weighted balanced equivalent input noise with volume at 1 (109dB below 2V RMS output.) - not bad at all , I hope?

Although it is difficult to explain, in some fine tuned systems noise seems not to affect the enjoyment of music as it exists in a different layer that has a different signature and the music seems to be in a "blacker" background. This happens in vinyl or CD . Changing something that does not affect the measured signal-to-noise ratio can destroy this effect - it is why I call it subjective.

But you are right - if the product has a very noticeable noise floor, nothing can save it. The problem is just how we grade "noticeable" noise floor. Sometime ago, in another thread, I referred to the specifications of the excellent sounding solid state cj premier 350 and a few posters considered it unacceptable.

 

[Orb]

Well that result seems rather better than the ARC Ref 5, what the heck is it
That said, it is the tube power amps that are the real challenge even for the very best.

I see where we differ on subjective, for me the noise floor is quantifiable and for a listener will have a threshold and also a tolerance level, this is easier for a specific listener (and it is personal as each person's threshold-tolerance do not match) to quantify than say imaging, stage depth,etc.
For those that hit their ceiling in terms of threshold-tolerance this results in as you mentioned unacceptable listening, whereas they will not be able to quantify in equal terms of quality imaging,stage depth,etc.
I would say I differentiate between sound quality (those that relate to bass-midrange-texture-etc quality) and those factors that cause an absolute listening response (such as when reaching tolerance-threshold for distortion).
But yes this is not equal in all listeners.

Cheers
Orb

 

[mep]

It's a funny way to list the noise spec. What does volume at 1 mean? Does 1 mean 1 o'clock or does that mean 1 as in the first click from off on the volume pot? It sounds like they are quoting the noise spec at a super low listening level.

 

[Orb]

I tend to look at the measurements listed by Paul Miller that he does for Hifi News, regarding noise they go much further in detail than Stereophile, which is pretty good in itself.
Hifi News measurements are here and need to register for those not aware:
http://www.milleraudioresearch.com/avtech/index.html

Cheers
Orb

 

[stellavox]

clarification?

Microstrip - the MFJ device is not the same as what I was describing. The MFJ device is designed to measure RFI that is radiated (through the ether?) not conducted through house wiring. I believe the original posting referred to conducted radiation.

Typical preamplifier noise specifications are measured over some fixed bandwidth - say 20hz to 20 Khz - in a lot of cases this measurement is then "A" weighted - which rolls off the effects of the lower audio frequencies in an attempt to better match our hearing perception. The results of this measurement are designed to capture the internal noise generated within the unit. Of course something else, like conducted or radiated "interference" could get into the preamplifier either through the power or interconnecting cables (conducted) -or through a "hole" (radiated).

I tried to explain some of this in a posting on the reel to reel thread (I think) under the general category of "grunge". Any interference that can get into, say a preamplifier with a lot of internal gain, can possibly be detected by the circuitry and amplified along with the desired signal - producing who knows what effects. In an urban environment there is a lot of RF (from mobile / portable phones, etc.) running around. As I stated, this may be why, in an RFI-rich environment, some otherwise "far out tweaks" do produce improvements - by actually shunting the "grunge" to ground or at least away from the equipment. It could also explain why some of these tweaks work well in one environment but do absolutely nothing in another.

Levinson (when in CT) did send their new products to a Boston-area testing lab where they could be placed in a "clean room" and subjected to various levels of conducted and radiated interference. Wonder if any other Hi Fi manufacturers do anything like this.

Charles

 

[fas42]

I agree with this point. Many people consider that the only meaningful specification in noise is the measured signal to noise ratio and ignore the subjective aspects of noise.

But I am not prepared to rate the importance of this particular versus other subjective aspects.

The importance of this parameter is that it indeed is a measure of the "holy grail", that is, achieving totally convincing, realistic sound reproduction. As far as I'm concerned, those other elements such as stage-image depth, base and treble quality, silibance-phase-etc are all linked back to the level of the "distortion" noise floor. The standard, easy to measure, signal to noise ratio is just one other element mixed in with the others as a measure of a system's "competence". The latter in fact can be terrible, but if the system has an excellent distortion noise floor, the level of hiss, pops and crackles and other extraneous, purely random interference will be very benign, your mind can easily ignore them, and tune instead into the information of the musical event. That's why people talk of hearing good music buried in the noise floor of tape, not because the medium is any less hissy, but because tape by its very nature does not inject particularly obnoxious low level distortion into the playback sound.

Achieving high levels of "blackness" is a strong indicator of a lowering of distortion noise, not noise in the conventional sense, meaning getter closer to all the other elements falling into place, and the final step, realistic sound ....

Frank

 

[microstrip]

It's a funny way to list the noise spec. What does volume at 1 mean? Does 1 mean 1 o'clock or does that mean 1 as in the first click from off on the volume pot? It sounds like they are quoting the noise spec at a super low listening level.

Mep,
As far as I know Vol 1 just means that it is not in the muting position - ARC preamplifiers usually mute the output a 0 volume. As there are no active elements before the volume control, this way of measuring tries to emulate the conditions of a preamplifier driven by a low impedance noiseless source at any volume.

BTW, I checked it with an audio spectrometer based on a 24 bit EMU tracker - it really has less noise then some solid state preamplifiers.

 

[microstrip]

Microstrip - the MFJ device is not the same as what I was describing. The MFJ device is designed to measure RFI that is radiated (through the ether?) not conducted through house wiring. I believe the original posting referred to conducted radiation.

Typical preamplifier noise specifications are measured over some fixed bandwidth - say 20hz to 20 Khz - in a lot of cases this measurement is then "A" weighted - which rolls off the effects of the lower audio frequencies in an attempt to better match our hearing perception. The results of this measurement are designed to capture the internal noise generated within the unit. Of course something else, like conducted or radiated "interference" could get into the preamplifier either through the power or interconnecting cables (conducted) -or through a "hole" (radiated).

I tried to explain some of this in a posting on the reel to reel thread (I think) under the general category of "grunge". Any interference that can get into, say a preamplifier with a lot of internal gain, can possibly be detected by the circuitry and amplified along with the desired signal - producing who knows what effects. In an urban environment there is a lot of RF (from mobile / portable phones, etc.) running around. As I stated, this may be why, in an RFI-rich environment, some otherwise "far out tweaks" do produce improvements - by actually shunting the "grunge" to ground or at least away from the equipment. It could also explain why some of these tweaks work well in one environment but do absolutely nothing in another.

Levinson (when in CT) did send their new products to a Boston-area testing lab where they could be placed in a "clean room" and subjected to various levels of conducted and radiated interference. Wonder if any other Hi Fi manufacturers do anything like this.

Charles

Charles,
Thanks for the clarification. I do not know how the device you refer, but I would suppose, perhaps wrongly, that they work on the same principles. The noise should be capacitive coupled to the input of the device - approaching the device from the main wires is just a way of doing it, as the radiated noise originates from noise in the wires.

Going along your lines, I remember reading an article that claimed that the main problem of global negative feedback in audio power amplifiers is that it could supply a path to inject all the RF noise captured by the long speaker wires in the input of the amplifier, with the consequences you describe.

 

[microstrip]

Is that the entire spec for noise as published? It is hopelessly deceptive if it is.

Tom

Tom.
Sorry, the full set of noise measurements is too long to quote. If you are interested please follow Orb suggestion - go to the Paul Miller site and look in the HFN: April 2011 tests. You will find there the full analysis of the noise of this ARC preamplifier. I was very pleased with what I found there some months ago.

 

[fas42]

Frank, this noise thing seems to be the latest flavour of the month for you! How is one supposed to be hearing noise when the music is playing at even near normal volume?

Tom, only because people speak of reducing the noise floor of their system, and being able to hear blacker silences and backgrounds. It's still the same distortion I'm talking of, the same old thing I've been rabbiting on about for yonks, that's why I "invented" the term "distortion noise floor". Reduce that, and everything gets better, including what people call noise. Of course, the real noise does not change one iota, but subjectively it does, which is what the whole point of improving your system is. Take a very "noisy" recording, hissy, rumbling, crackly, etc, etc, put on a good system: bliss. Same recording, on an edgy, classic "hifi" setup: every tiny defect, every minute problem will scream at you, draw attention to its presence and well and truly get in the way of enjoying the "show" ...

Frank

 

[Orb]

Micro, thanks. The main thing is you are happy, but these kinds of games by manufacturers in spec'ing thier gear is tiresome to me these days....the standard spec is simply something like signal to noise, A weighted, 98 db or max output noise, 100 microvolts, A wighted, etc. Not that hard, really.

Tom

Micro has made me smile, no wonder his product has rather good measurements, not only is it a reference model ARC preamp (some of the best that are measured), it is the freaking Anniversary 2-box setup with a seperate mains
Nice gear Micro.

But as mentioned in a post not far back, these ignore the affects of as said grunge that is potentially on the mains that then affects these figures, furthermore we have the example of the grounding solution being uprated in someone's house that anecdotally also improved the noise floor.

I have heard a 6-way extension add a lot of noise (we opened up and could not see much wrong visually but could not test it at the time).

Also I feel some need to consider listening distances, not everyone can listen 4m and over away from a speaker and this is especially true in many European and Asia houses.
Seperate to the noise floor, I can hear the transformer core saturation buzz of my CD player just under 3m away (in our quietest room) due to our mains (also can hear PC monitor and Pioneer TV screen "sing its pretty sinewave"), as mentioned this may not bother some but it comes back to a listener's threshold and tolerance to such noises.
Furthermore as I mentioned earlier not all products are designed-engineered-built to the same level, or have the space to implement and so cope with the various demands of mains characteristics,etc.

Edit:
With all that said, the OP showed a concept that enables seeing all the electrical signals on the mains, and maybe just maybe this would be useful to test the practicality of mains filtering products (could see signatures both sides of the filter-regenerator) and could be used in such scenarios as the described ML controlled environment.
It is a great and well thought out concept-product.
It may be best if we all agree to disagree on the importance of such a product and the potential affect of mains grunge and potential benefit of mains related products and grounding solutions.

Cheers
Orb

 

[Orb]

Hi Guys,

A few years back I happened upon a device on Ebay called a power line noise monitor. It was apparently made for one of the audiophile cable companies and because of no sales was being offered "surplus".

Turns out that the device was made by Alphalab in Salt Lake City. This company makes all kinds of conducted / radiated, electric / magnetic field detection / measuring devices. This little "black box" has a speaker and an LED display on the front panel and a power cord that can plug into any 115VAC outlet. Think of it as a little AM radio that "listens to" power line noise extending from 60hz up to maybe 500Khz or so. Depending on the situation you might hear a hum or a crackle or ... the undead...

Using it was very interesting. Plug it into a 115VAC outlet and you may hear something or not. You can adjust a control on the front that sets the display to an arbitrary reading which you can now move around the house and "look for / hear" DIFFERENCES. Both at my house and a few others we could hear an AM radio station "above ground" but not in the basement. Fluorescent lights could be very "noisy" but easy to find and turn off or replace. Certain areas in a house seemed to be much quieter than others for no obvious reason. Most significant thing I learned was "listening" to the output of a few different "balanced power" units at mine (a "simple" 1KVA toroid) and a few friends locations. In every instance, the "noise" at the output of the unit - as measured by the meter - fell to the lowest level - in some instances by more than an order of magnitude versus the input level.

The result of this whole exercise convinced me that power line "noise" sure exists and can vary quite a bit throughout a house. Also, a balanced power type of conditioner does significantly lower this noise. In none of the cases did we try any A/B listening tests to see if any change was "audible". Also I performed all the tests during the day. Will have to ask whomever has my meter (can't remember who I lent it to) to try a few measurements in the early AM.

Charles

Good post, and similar product I feel is this:
http://www.audioprism.com/noisesniffer.html

This blog does some interesting work with that sniffer; check from September 21,2009 to begin with:
http://hifi-unlimited.blogspot.com/search/label/Power Line Conditioner

And another blog I read sometimes:
http://audioinvestigations.blogspot...-max=2012-01-01T00:00:00-08:00&max-results=50

Cheers
Orb