7
As heard within amplifiers, the frequency can be 100/120Hz (2nd harmonic of 50 or 60Hz) because of the rectification process when converting AC to DC to power said amplifiers. There can also be a component that is the third harmonic of 50/60Hz as well and this is magnetically "coupled" from the AC transformer inside an amplifier.
There are all sorts of ...
7
That is the result of bad isolation of either the DAC or the ADC. If the internal circuitry of the interface and the actual capture or playback circuitry share a common power supply, the operation of the electronics itself cause a distortion to the power being supplied to the capture or playback circuits.
Capture and output both rely on a fixed reference ...
7
I'd be inclined to think it would be from scratches/dust in the optical medium that sound was carried on in cinema film, up until 1976.
See this image from Wikipedia…
Edge of a 35mm film print showing the soundtracks. The stereo optical sound strip is located on the right, with waveforms for left and right channels.
To the far left is the SDDS digital ...
6
Is AC current fundamentally better as a working current when it comes to amplifying audio signal?
No. If anything, using an AC power supply makes it more difficult to have low noise.
The circuits that handle audio are all powered by DC. So any amplifier that has an AC power input has to convert this to DC internally. The AC cabling inside the amplifier ...
5
They missed out one vital piece of information - at what frequencies?
They'd need to be made of lead to stop anything below 100Hz…
I wonder whether their mosquito-repellant curtains work when they're open too ;-)
5
Short, honest answer: nope, forget it.
In principle it's possible nowadays to separate any part of a signal, using software like iZotope RX or the (rather dated, by now) Algorithmix Renovator. These are expensive heavyweight products; unfortunately I'm not aware of any more affordable or even open-source alternatives that get close to their performance.And ...
5
The type of current is actually completely irrelevant as all transmitted power is AC. Unless you are driving your amplifier from batteries, everything has to be converted at some point to DC.
The end result all boils down to the amount of power you need to draw from the supply in order to amplify the audio to the level you require.
The main reason why AC ...
4
Yes, they do wear out eventually. As pointed out already, the life time depends greatly on use and quality. Even with a cable that seemingly works sound quality may get drastically reduced. See below.
The type of defects you will start to see over time, can be categorized into three main areas:
mechanical damage
corrosion
dry out/cracking
Mechanical ...
4
I used to have a tone sweep from one of the convolution plug ins as my ring tone. It worked really well because it was a chirp, followed by a few seconds of silence, and then a tone sweep low to high. The chirp and pause gave me time to answer it if i was in a room, and the tone sweep cut through when i was in noisy locations. The only caveat is that the ...
4
Balancing! All your lines should be balanced. What this does it splits the signal in two and flips one half of it. Then the side that is flipped is flipped back at the end, and added to the first one, therefore cancelling the noise induced in the cable out. You need a DI box, especially since your cables are long and then something to unbalance the signal at ...
4
Izotope rx is the industry standard. But any fingerprint style noise reduction should be able to improve it.
4
How much money have you got to spend & would you consider replacing the floor entirely with a new one made of solid concrete, not connected to the current walls or floor?
That is not as frivolous a question as it may seem.
Audio separation, especially at low frequencies, can only be achieved by mass & air-gapping.
You could generate a bit of an ...
3
It's a 50 or 60hz sine wave (depending on power frequency). You aren't going to get more accurate than that. The harmonics are going to depend on the particular power generation and will vary based on uncontrolled variations in both the grid and how the hum is actually being introduced in to the signal.
3
The fastest way to solve this problem is simply sample a mains hum / ground loop and work with that. I would start by recording 5 minutes of ground hum. Then find a section of about a minute long that loops nicely (make sure that the start and end points are aligned to either both a rising or falling zero-crossing). Then progressively shorten the sample ...
3
You should look into feature extraction from audio signals. Audio is being analyzed, as a result you get numerical values that more or less correspond to the perceived qualities of the sound. The values are called descriptors, and you will probably find the result you are looking for by combining some of them. You could then observe the impact of ...
3
That looks like one of the most severe cases of DC Offset I've ever seen. I can't really make out the scale, but it looks pretty out-zoomed to me, and if so, I would return that card if I were you. It doesn't necessarily mean the audio is screwed though. Most editor-programs I've seen have the option "Remove DC Offset", which SHOULD fix this completely.
I ...
3
This is most likely an issue related to microphone cable, connectors or wireless receiver. Try the following to determine the source of the error:
Test amplifier
Connect amp and speakers only - NO input cables connected at all, and turn it on with the volume a bit up.
Try gently shaking/pushing the power cable.
Try gently pushing the main volume fader ...
3
To fully discard the option of the method you tried make sure that before you invert the phase of the left channel you bring both channels to the center field; then you invert the phase and judge if its working or not.
However, your best bet will be an audio repair/restore plugin (or hardware), perhaps Izotope - RX de-noiser, spectral repair or Waves x or ...
3
All audio electronics create noise, including your interface itself. It's actually pretty good that the self noise of the interface is at around -100 dB.
Even when all other sources of noise are eliminated in an electronic device (e.g., leakage from the power supply, EM radiation from outside the device, etc.), there is no way to eliminate thermal noise. ...
3
There are automated algorithms like those you tried in iMovie, the ones in Audacity might be worth a try but if you want better results you should individually edit phrases.
Software like izotope RX can help in the restoration process.
3
Firstly, do any and all processing in WAV files. If your source material is on CD, then rip to 44.1kHz/16bit WAV and process at 24-bit in your software. Do not transcode via mp3.
Tracks like 104b should be discarded. There is nothing you can do with files like this. The studio has not done their job properly. They have recorded the transfer with input ...
3
A very High-Q notch EQ filter can do the trick, although I would probably recommend spectral cleaning to nail this. Izotope RX Advanced Spectral Cleaner is the way to go.
3
This is a broad sweep at the issue, some guesswork & experimentation required.
First of all, if you have an alternative DAC try it, no matter how basic, just to eliminate the simplest explanation.
Secondly - if anything has batteries, replace them.
Up at 5k, it's unlikely to be directly related to 'mains hum' itself, grounding issue etc.
A very simple ...
2
First of all I don't think there's an easy solution to these kinds of noises.
Although RX3 is great product, it's not a magic pill (nor any other product.
It totally depends on how loud/continuous/'wide' it is. Since this is a flyby
it could mean that the sound evolves dramatically over the course of a few seconds.
This is much harder to reduce (with any ...
2
I recommend doing it the same way a dialogue editor would - manually edit them out, small crossfades in between. Then try a noise supression tool after the fact as icing on the cake. It's a great way to learn how to edit in practice. Take dialogue for instance. anyone editing voice must learn the intricacies of inflection, rhythm, and cadence - and ...
2
If you really needed to get rid of them I would try Izotope RX3 spectral repair. It can be extremely time consuming especially if your inexperienced with it. The tough thing about dish sounds is they are in the same frequency range as the parts of the voices that you want to preserve. It can save lots of time and money to get a good recording in off the ...
2
I realize this comes a bit late, but what the heck....
I've run into this same phenomenon. What's happening is a natural result of using the Denoiser audio plug-in in Adobe Premiere. Unfortunately, it takes about 4 seconds for Premiere to "learn" the noise print of a clip. That is why you're hearing about 4 seconds of static and unwanted background noise ...
2
Have you considered investing in a power conditioner? They are used in most studios and also live venues. It's basically like a rack mounted power bar, but it does so much more than just basic surge protection. Looking at the Furman PL-8C, it offers noise filtration for delivering cleaner power, and also isolated banks which reduces inter-component ...
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