Sampling noise reduction/elimination pedal
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Posted: 23 February 2019 05:55 PM

When I suggested this on another forum , for some reason, I was accused of having already made one and trying to market it even though I don’t have any of the required skills to do so, although I do have a distant background as a radio mechanic but that was on aircraft and nothing to do with music.

Basically, because I was having some problems with amp noise which may very well be due to the idiosyncrasies of my house, I wondered if it might be feasible to create a pedal which samples the noise on a noisy signal and then subtract it from the output signal.

I used a bit of software (and VST plugin, I think) which used to do this pretty effectively called SoundSoap but that was mainly for processing recorded audio and I was thinking of a pedal being used in a live situation where there might be problematic noise, perhaps due to the electrical environment or some rig incompatibility, which cannot be fixed and rather than spending hours of frustration, simply put this hypothetical pedal at the end of the signal chain when there is no signal and sample the noise to be eliminated.

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Posted: 26 February 2019 02:37 PM | Link to this reply (#1)

EHX already makes such a thing:

https://www.ehx.com/products/hum-debugger

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Posted: 26 February 2019 02:50 PM | Link to this reply (#2)

That is not what I am suggesting.

The Hum Debugger might eliminate noise but it does not do so by sampling the noise and subtracting it from the signal - it just uses two levels of noise reduction.

I suspect that you only read the title of the thread and not my post.

gvelasco - 26 February 2019 02:37 PM

EHX already makes such a thing:

https://www.ehx.com/products/hum-debugger

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Posted: 04 March 2019 04:02 PM | Link to this reply (#3)

No. The Hum Debugger does NOT just have two levels of noise gating. It uses a SPECIAL ADAPTER to sample the power and anything attached to it. Then it uses noise cancelling technology to eliminate the noise.

From their web page:

“Not a noise gate, and not a noise suppressor—but a real hum extractor.”

The NORMAL/STRONG switch controls whether only odd numbered harmonix are eliminated in low setting, or both odd and even harmonix in high setting. From the manual:

“NORMAL/STRONG TOGGLE SWITCH - Sets the amount of Hum Elimination.  In NORMAL mode the Hum Debugger removes only the odd harmonics from the hum present in your signal. In STRONG mode the Hum Debugger removes both odd and even harmonics from your signal’s hum content.”

Also from the manual:

“WARNING: Use only the 7.5VAC/400mA AC adapter the Hum Debugger comes supplied with.  Do not use any other AC adapters. Using other AC adapters, even those made by Electro-Harmonix, could cause harm to the unit, the adapter or your drummer. The Hum Debugger does not use batteries.”

The reason that you must use the AC adapter that comes with it is that the special adapter is part of the circuit that samples the power signal.

This is, in fact, exactly what you were proposing.

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Posted: 04 March 2019 05:36 PM | Link to this reply (#4)

But I’m not.

What if the noise was not caused by AC current?

What if the noise is not a hum?

I get interference between certain pedals when they are on certain settings.

The fact that EHX recommend that the Hum Debugger be placed at the beginning of the effects chain shows that it it only works on a dry signal. If the kind of device I had in mind was produced, it would be placed at the end of the effects chain so that a sample of the noice throughout the signal path could be taken.

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Posted: 04 March 2019 05:47 PM | Link to this reply (#5)

FYI:

https://www.antarestech.com/product/soundsoap-5

https://www.youtube.com/watch?v=LedI5BxKHcc

Edited: 04 March 2019 05:50 PM by Okulo
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