Noise in guitar amplifiers

[abbey road d enfer]

Or if post processing / mixing ITB then noise gate / filter plug ins (preferably with 'look ahead' so all the attack of a note gets through). It's all hassle and compromise though.

Although my setup is pretty clean, there's always some hum & buzz on gtrs. I use Samplitude's De-noiser, that uses a print of the noise and convolutes it with the signal. No look-ahead necessary, but only post-processing.

 

[Zander]

Thank you.

Yes I could always fix it in post (RX, gating, editing...) but I would rather make the source reasonably quiet.

http://www.pedalsnake.com/blog/2016/09/noise-series-dealing/
Point 2 in this article suggest that noisy ac lines can induce antenna like behaviour. I don’t know the quality of this article but could my problem be a combination? The studios are 5m removed from the ac units...

It’s a commercial studio so it’s unpractical to only use shielded guitars...

 

[abbey road d enfer]

http://www.pedalsnake.com/blog/2016/09/noise-series-dealing/
Point 2 in this article suggest that noisy ac lines can induce antenna like behaviour. I don’t know the quality of this article but could my problem be a combination?

The answers given there are a confirmation of what I wrote earlier. Th efact that turning down the volume pot turns down noise eliminates conducted interference. S/C p/u's are notorious for picking hum, that's why humbucking p/u's were invented. It should not come as  a surprize to experienced guitarists, who generally know they have to find a spot and orientation where hum is minimized and not move from there.
Now you really have to find what is the dominant source of hum, by "sniffing" as suggested in the article.

The studios are 5m removed from the ac units...

  I would not think the a/c to be the dominant source of hum; they generate mostly acoustic noise, but their motors are pretty quiet, electrically speaking, except when switching on or off.
Transformers are the dominant source of magnetic hum, and transformers are everywhere, in guitar amps, in console PSU's, in power amps, in rack gear.

 

[MagnetoSound]

Are you close to a railway line perhaps?

A faraday cage (otherwise thought of as an isolation booth, but for the players, not the amps) and screened with mesh or copper wire, might be one solution.


[I do not expect this idea to be popular, but if all else fails ...]

 

[abbey road d enfer]

A faraday cage (otherwise thought of as an isolation booth, but for the players, not the amps) and screened with mesh or copper wire, might be one solution.

Faraday shield protects against electrostatic fields, but is almost useless for low-frequency magnetic fields.

 

[MagnetoSound]

Most noticable is a 6k noise with it’s harmonics. I’m used to regular guitar amp noise but this is something else. I need to edit out noise in between notes, more than normal.

Zander

Sounds a lot like the railway signalling that used to break through at my old place. You never know.

 

[Newmarket]

Sounds a lot like the railway signalling that used to break through at my old place. You never know.

I've experienced railway related noise but it was a short and sharp burst / transmission.

But it was / is very strong - it was being picked up in a "full on" screened EMC test chamber.
But the building is adjacent to one of the UK's busiest railway routes !
Very specific fixed frequency so easy to identify 

 

[Zander]

I’m at least 100m removed from railway lines. I had no problems before on this location.

 

[MagnetoSound]

I’m at least 100m removed from railway lines.

Perhaps not the cause of your problem then, but that's not really very far.

I had no problems before on this location.

Until ...?

 

[Zander]

Until I built a new studio on the same place

 

[Newmarket]

Until I built a new studio on the same place

New Studio = New Electrical Installation ?

 

[Zander]

Yes, indeed. New electrical installation AND new hvac...

 

[MagnetoSound]

Maybe have a chat with your spark?

Supply characteristics and earth impedance would be good points to raise.

 

[Zander]

Maybe have a chat with your spark?

Supply characteristics and earth impedance would be good points to raise.

I have 3x230V coming in. Impedance to earth (measured with a special device which has two pins placed in the surrounding earth @10&20m) is 15ohm.

 

[MagnetoSound]

You have a 3-phase supply.

15 ohms is HIGH ...

Is your earthing system TT (provided by a groud spike)?

 

[abbey road d enfer]

15 ohms is HIGH ...

Does it really matter? A plane has almost infinite impedance to earth.
Earthing does not change a thing about magnetic fields.

 

[Monte McGuire]

If the noise is being picked up by a single coil guitar pickup, have the player rotate to reposition the axis of the coil, essentially so that it's parallel to the net interference field. You will find a null spot (actually a pair, 180 degrees apart). Make the guitar player stand in that orientation. Problem solved!

 

[Zander]

It needs to be under 30ohm here...
I hammered three pins down (150cm).

 

[MagnetoSound]

Does it really matter? A plane has almost infinite impedance to earth.
Earthing does not change a thing about magnetic fields.

It helps to keep the building's earth cabling free from noise - motor currents and the like, even capacitively coupled, will radiate throughout the building if the earth impedance is high enough, effectively turning the ring main into a kind of induction loop.

 

[MagnetoSound]

It needs to be under 30ohm here...
I hammered three pins down (150cm).

So 30 ohms is what the regs require for safety. A recording studio has rather more stringent requirements.