are there common problems with noise supressors?

[mbengs1]

like what if the threshold is not enough to eliminate all the noise and hum? or should i not even consider this problem and all noise gates have enough noise supression in them to cut out the highest gain in any situation. like to distortion pedals with their gain maxed out..

[WRGKMC]

Didn't you read your other thread? Noise suppressors like the boss are improperly named. They have no noise suppression whatsoever. Think of it as a automatic volume control instead because that's all it actually is. Does your guitars volume knob remove noise or does it simply change the gain?

 

The pedal is a gate which automatically raises the volume to max when you hit a string then turn the volume off when you stop playing notes.

 

The knobs adjust attack and decay levels. There is no actual filtering. Its no different then using a volume pedal after your gain pedals except it works automatically. The attack is a sensitivity adjustment. You set it to turn the volume off when no notes are being played. This quiets the background noise. Its not filtering, its simply a volume gate. The decay is set for how long a note can sustain before the gate closes and the signal is shut off.

 

The pedal being called a noise suppressor is what's misleading you.

The pedal is a Gate, no more no less. It comes from the family of devices called compressors except in this case it adds no additional compression. The attack and release work the same was as a compressor does.

 

Autowahs and envelope pedals like a Mutron uses the same attack and release, except in those pedals use a tone envelope to shape the sound instead of producing a simple volume swell.

[mbengs1]

actually, i never asked this before. the problem i'm saying is what if there's too much noise that the gate isn't strong enough to cancel out the noise. even with the noise gate at full, theres still noise. coz if this is a problem, the gate would be useless to me. i assume since engineers designed the noise gates, they would have looked into all situations that a gate needs to be effective.

[1001gear]

Hush tracks the signal and removes anything above it. I've wondered why they can't sample the noise and just cancel it but no dice evidently. That could even be easily done with 60 cycle hum.

 

 

[WRGKMC]

There's plenty of range on the threshold knob. If you adjust it too high it will silence both the background noise and the signal completely and you'll get no sound when you hit the strings.

 

You have to adjust the threshold so it lets the strings through but silences the background noise when no notes are present.

 

If your background noise level is so high that it matches or exceeds the musical signal produce by the strings, then the gate wont trigger. The gate works off of signal amplitude. The sound from the strings must be higher then your background noise in order to trigger the gate.

 

If the background noise is higher then the signal from the strings no gate is going to fix that. You obviously have a major problem with your gain pedals either producing too much noise or failing to pass a strong enough signal. You'd need to resolve that first before the gate will be of any benefit.

[Mr.Grumpy]

Hush tracks the signal and removes anything above it. I've wondered why they can't sample the noise and just cancel it but no dice evidently. That could even be easily done with 60 cycle hum.

 

 

The Electro-Harmonix Hum Debugger does exactly this.

 

It can't do anything for HISS, as that's a more random noise. But hum and buzz that are due to electrical interference are "repetitive" signals so they can be filtered out via the magic of digital signal processing.

 

A standard noise gate just mutes the signal entirely when it falls below a certain level. If it's set too aggressively, it will cut off sustaining notes and can even take away some attack. There are other "noise reduction" pedals that target hiss by rolling off the treble at low signal levels.

[WRGKMC]

Anything done to remove hum is also going to remove some musical information in that same range. The B note is 61hz, and musician instruments produce a wide frequency response not simply a fundamental sine wave. If you notch out the 60hz and its overtones you'll also wipe out musical frequencies which are supposed to be there.

 

If you remove the lowest fundamental of 60hz you probably wouldn't notice it affecting the notes because a guitars lowest fundamental for a low E is 82hz. Its the upper harmonics of the AC wave, 120, 440 etc that are the most bothersome, and any kind of notching of those might be heard.

 

Hum is best handled at the source using shielding before it becomes an audio issue. Same thing with hiss. This way you aren't trying to stick a band aid over it.

[WRGKMC]

Hum notcher's have been around for a while. They usually use deep narrow EQ notch at the power line frequency. The problem is the power company's frequency isn't well controlled and the notch circuit drifts. The ones made for PA's have a frequency adjustment to manually null the hum down. The EH seems to use a DSP controlled notch filter that self adjusts as the line frequency changes.

 

They aren't a perfect solution. From what I've read the pedal works OK with a clean guitar but if you use OD after it adds horrible noise that is completely unacceptable. It make's the signal digital sounding and there are disharmonics on higher notes. That's likely the DSP controlled notch filter readjusting itself. Many say its not so band in the normal mode but the strong mode with an amp cranked has noticeable clicks and artifacts.

 

I suspect many who use it never read the manual. It specifically says to use it first in the chain. If you use it after gain pedals, (where you might need it most) all the extra noise makes the notch lock go nuts. The problem with using gain pedals after it, is any artifacts generated by the pedal will be amplified to extreme levels.

 

From what another described it sounds like it attempts to lock into the hum when you first gain the instrument up. That sounds like its automatically moving the notch around much like my Sabine Feedback eliminators do to kill feedback except it only sees the 60hz and creates notches for it.

 

High volume players are likely better off fixing the problem at the sourse or at least minimizing the problem before putting a band aid over it. There are no magic solutions. Whatever you use to cover up the issue is going to have negative side effects, whether its filters, gates, or smart notch filters like this.

[1001gear]

Anything done to remove hum is also going to remove some musical information in that same range. The B note is 61hz, and musician instruments produce a wide frequency response not simply a fundamental sine wave. If you notch out the 60hz and its overtones you'll also wipe out musical frequencies which are supposed to be there.

 

If you remove the lowest fundamental of 60hz you probably wouldn't notice it affecting the notes because a guitars lowest fundamental for a low E is 82hz. Its the upper harmonics of the AC wave, 120, 440 etc that are the most bothersome, and any kind of notching of those might be heard.

 

Hum is best handled at the source using shielding before it becomes an audio issue. Same thing with hiss. This way you aren't trying to stick a band aid over it.

 

To me the ineffectiveness of hum cancellation is a function of audio resolution; the inability of the algorithm to distinguish between noise and content. Otherwise, inversion and allignment should work 100% - right?