Faraday tent? Noise-cancelling headphone NC circuit?

[MattZilla]

Compulsive backstory, two paragraphs. Please skip them. I can’t allow myself to delete them.

I’m not totally Electronics Illiterate, but my education hit a wall at the Water In A Hose analogy and it all devolved into very convenient and necessary magik and wizardry.

I kind of have just accepted hum in working with my favorite instrument, the DAW, but chatting with an acquaintance who’s early in their career doing sound for TV/film about their recent gig doing a documentary in a well-lit stadium fired up the old puzzle solving engine and it’s hot and spinning entirely too free now that I’m home. Checked a few pages worth of threads in this sub, hoping that I’d missed something in the last half decade about a BDDI/Fender P or Klon/Noble level essential or unobtanium but effective Buzz Buster being on the market, and it looks like there’s nothing new. Shut off the fluorescents, LED’s, variable light/fan switches, get on a different circuit from the AC & fridge, yadda, yadda.

Two dumb hum-cancelling for the purpose of sound recording ideas that must be dumb because they’re not commonly talked about or seen being used:

1) the noise-cancelling circuit in old analog telephones and in modern NC headphones that doubles and inverts the noise signal thus cancelling it… I think that’s <20% incorrect in how it works? A DAW plugin that does this seems like a petty task for anyone who’s already developed any plugins… and even more Easy As Pie for a circuits/hardware designer.

1.2) Is this not what De-Essers are?

1.3) do studio techs not already just, like a lumberjack sharpening their axe, record a song-length track of hum from each mic to then invert and match to the performance tracks of each given mic?

———

I did find this comment exciting: “that noise disappeared as fast as I closed the venetian blinds on the window. They're made of light metal. Aluminium“ This commenter has disappeared, but…

2) Party Tent / Construction Rain Tent frame with the tent material made, at least one layer, of a highly conductive but re-foldable-for-storage-and-re-use material… The Faraday Tent? Possibly with a single-conductor (wire) disconnectable Faraday Rug? “Simply” (as Idea People like to say) make a budget version of the tent frame easy to erect in a room with 7’ ceilings and “simply” make the conductive tent material durable and loose-fitting enough to handle a few hundred-to-thousand foldings & unfoldings, depending on consumer pricepoint? Probably/definitely have at least mediocre sound damping material on the inside of the tent? Hopefully a <$200 thing big enough to surround a power trio in a not-too-cozy way?


If they were The Answer, they’d be as common as XLR cables, yeah?

I feel so dumb for every single word in this post. I’m so sorry for my ignorance, Wasnex, Silky, Horse, Beans, and other EE’s (professional and/or highly experienced hobbyist) whose names I’m forgetting. I’m sure both of these have been proposed at least five times per year. I haven’t seen it though, even with a cursory google>”site:talkbass.com…” search.

I’m stuck overthinking the tent, imagining the rug having an almost labyrinth seal thing going on with the tent. Please tell me on a scale of 1 to 1di0tic how dumb it is.

I think I’m not the only ignorant DAW hobbyist who would love to read why all of these over-caffeinated proposals are as beneficial as heated seatbelts in a car.

 

[silky smoove]

1) the noise-cancelling circuit in old analog telephones and in modern NC headphones that doubles and inverts the noise signal thus cancelling it… I think that’s <20% incorrect in how it works? A DAW plugin that does this seems like a petty task for anyone who’s already developed any plugins… and even more Easy As Pie for a circuits/hardware designer.

It's not as simple as you'd think, which is why Izotope RX's Spectral De-Noise function exists. Noise tends to be complex and difficult to remove without also removing critical information from the source signal that you want retained.

1.2) Is this not what De-Essers are?

It is not what a de-esser is or does.

1.3) do studio techs not already just, like a lumberjack sharpening their axe, record a song-length track of hum from each mic to then invert and match to the performance tracks of each given mic?

None that I've ever worked with. My studio doesn't have excessive noise, hum or other forms of interference, so I just record and never think about it. If a piece of gear is faulty and causes some form of noise then an analysis of value must be conducted. Is the piece of gear so special that we can't live without it on the session? If no, then I'll replace it with something not-noisy. If yes, I'll use it and then either apply RX after the fact, or find some other means of obscuring the noise in the track.

 

[MattZilla]

@silky smoove thanks a ton for all of that!

The Faraday Tent with or without the floor pan… something for only the most insane of home DAW enthusiasts?

 

[silky smoove]

The Faraday Tent with or without the floor pan… something for only the most insane of home DAW enthusiasts?

I mean… I’m all for overkill when time and budgets allow

 

[silky smoove]

I should mention that your idea of recording the noise, inverting phase and then combining the signals isn’t without merit. Try it. If you like the results then it was the right solution and it cost you nothing but time.

 

[MattZilla]

@silky smoove the shielding/faraday enclosure to be used in an RF-noisy home studio… it’d need to be grounded to have any significant benefit?

 

[silky smoove]

@silky smoove the shielding/faraday enclosure to be used in an RF-noisy home studio… it’d need to be grounded to have any significant benefit?

I’ve never built a faraday cage, so I’m not entirely certain. My assumption would be to not only ground it, but to utilize a common ground to everything attached to it to avoid loops. Someone more knowledgable will have to weigh in.

 

[smoothbrain]

This may be an imperfect analogy but think of this: try shielding a cell phone [when it's close to a tower] so it won't receive or send calls or text messages. It's not as simple to do as one might think. Once you get that done, consider that shielding a cell phone against the signal it was designed to receive is is in some ways similar to shielding audio equipment against the interference you'd like to prevent it from receiving.

 

[markjazzbassist]

I’ve had a lot of success with ebtech humX. It has helped on a lot of stages where there is ground loop hum from amp, pedalboard, shared power outlets, etc.

they are cheap under 100 dollars and I always gig with one in the bag.

 

[ardgedee]

1) the noise-cancelling circuit in old analog telephones and in modern NC headphones that doubles and inverts the noise signal thus cancelling it… I think that’s <20% incorrect in how it works? A DAW plugin that does this seems like a petty task for anyone who’s already developed any plugins… and even more Easy As Pie for a circuits/hardware designer.

1.2) Is this not what De-Essers are?

No, that's what guitar humbuckers are. Also balanced signal lines, such as used for microphones.

2) Party Tent / Construction Rain Tent frame with the tent material made, at least one layer, of a highly conductive but re-foldable-for-storage-and-re-use material… The Faraday Tent? Possibly with a single-conductor (wire) disconnectable Faraday Rug? “Simply” (as Idea People like to say) make a budget version of the tent frame easy to erect in a room with 7’ ceilings and “simply” make the conductive tent material durable and loose-fitting enough to handle a few hundred-to-thousand foldings & unfoldings, depending on consumer pricepoint? Probably/definitely have at least mediocre sound damping material on the inside of the tent? Hopefully a <$200 thing big enough to surround a power trio in a not-too-cozy way?

A proper Faraday cage is only going to be as effective as the equipment inside it. If you have a noisy computer monitor in your studio (or iPad with wifi turned on), the Faraday cage you built around the studio won't protect the equipment from that noise.

 

[logdrum]

I've seen a real Faraday cage rooms. The cell modem folks when I worked in San Diego occupied 3/4's of the campus and we had a small lab in one of their labs. There is nothing foldable in those cages.

 

[Engle]

Compulsive backstory, two paragraphs. Please skip them. I can’t allow myself to delete them.

I’m not totally Electronics Illiterate, but my education hit a wall at the Water In A Hose analogy and it all devolved into very convenient and necessary magik and wizardry.

I kind of have just accepted hum in working with my favorite instrument, the DAW, but chatting with an acquaintance who’s early in their career doing sound for TV/film about their recent gig doing a documentary in a well-lit stadium fired up the old puzzle solving engine and it’s hot and spinning entirely too free now that I’m home. Checked a few pages worth of threads in this sub, hoping that I’d missed something in the last half decade about a BDDI/Fender P or Klon/Noble level essential or unobtanium but effective Buzz Buster being on the market, and it looks like there’s nothing new. Shut off the fluorescents, LED’s, variable light/fan switches, get on a different circuit from the AC & fridge, yadda, yadda.

Two dumb hum-cancelling for the purpose of sound recording ideas that must be dumb because they’re not commonly talked about or seen being used:

1) the noise-cancelling circuit in old analog telephones and in modern NC headphones that doubles and inverts the noise signal thus cancelling it… I think that’s <20% incorrect in how it works? A DAW plugin that does this seems like a petty task for anyone who’s already developed any plugins… and even more Easy As Pie for a circuits/hardware designer.

1.2) Is this not what De-Essers are?

1.3) do studio techs not already just, like a lumberjack sharpening their axe, record a song-length track of hum from each mic to then invert and match to the performance tracks of each given mic?

———

I did find this comment exciting: “that noise disappeared as fast as I closed the venetian blinds on the window. They're made of light metal. Aluminium“ This commenter has disappeared, but…

2) Party Tent / Construction Rain Tent frame with the tent material made, at least one layer, of a highly conductive but re-foldable-for-storage-and-re-use material… The Faraday Tent? Possibly with a single-conductor (wire) disconnectable Faraday Rug? “Simply” (as Idea People like to say) make a budget version of the tent frame easy to erect in a room with 7’ ceilings and “simply” make the conductive tent material durable and loose-fitting enough to handle a few hundred-to-thousand foldings & unfoldings, depending on consumer pricepoint? Probably/definitely have at least mediocre sound damping material on the inside of the tent? Hopefully a <$200 thing big enough to surround a power trio in a not-too-cozy way?


If they were The Answer, they’d be as common as XLR cables, yeah?

I feel so dumb for every single word in this post. I’m so sorry for my ignorance, Wasnex, Silky, Horse, Beans, and other EE’s (professional and/or highly experienced hobbyist) whose names I’m forgetting. I’m sure both of these have been proposed at least five times per year. I haven’t seen it though, even with a cursory google>”site:talkbass.com…” search.

I’m stuck overthinking the tent, imagining the rug having an almost labyrinth seal thing going on with the tent. Please tell me on a scale of 1 to 1di0tic how dumb it is.

I think I’m not the only ignorant DAW hobbyist who would love to read why all of these over-caffeinated proposals are as beneficial as heated seatbelts in a car.

Before getting into building a Faraday cage, have a licensed electrician check the grounding and bonding of the electrical system in your house.

 

[seamonkey]

Here's an old article with some interesting information
Audio Filters -- Theory and Practice
He goes through hum cancelling by generating a signal to use it to null out hum in the recording.

Izotope software can do something similar.
Amazing audio tools.

Almost Everyone has one Faraday cage in their house. It's call a Microwave. You can shield RF with it, especially that pesky 2.4Ghz band. Put sources of RF noise like power supplies or cell phones in one, but just don't turn it on. You need the ground wire connected to the plug ground lug for the cage to work the best.

Maybe that's what Geddy was doing

 

[Hoochie Coochie Man]

I used to work in a lab associated with circuitry used in medical diagnostic imaging systems, and some of the testing we did was performed inside a Faraday Cage.

Here is what a Lindgren RF Enclosure looks like.

I don't think an aluminized tent would solve noise problems the OP is asking about.

 

[Bassamatic]

If you are truly getting RF noise - One of my engineers had worked for a local radio station and would respond to residents' complaints and go out and install filters to help keep the RF out of their TVs, etc. Maybe a call to the provider of the RFI causing systems might help.

Making a Faraday cage around your room will be very difficult. Even the tiniest opening will allow RF to enter, and could, in fact make it worse by becoming part of a tuned circuit, amplifying the RF at that frequency. As RF frequencies go up, the wavelengths get smaller and smaller, and harder to deal with.

 

[MattZilla]

Re: hum source-

I honestly think most of the noise I have left, and my acquaintance is also fighting is coming from being close to the road and its High Pressure Sodium lights and/or Mercury Halide lights.

But I do also have a Voly Fire house a block up with a bitchin antennae on a mini tower which I’d be surprised if it weren’t attached to a mean old repeater rig.

I’m not hearing any chatter, just the something not hugely different from a Big Muff cranked with the instrument’s vol off… but this is on each sm57 pointed at just a drum and there’s no amps on. It’s not overpowering, it’s just annoying like John Bonham’s squeaky kick pedal.

When I record at someone else’s with my laptop-interface-mics rig, sometimes it’s worse enough that I’m a bit embarrassed that I’m even doing the recording at all and not just sending them to a pro studio.

It keeps sending me back to only recording the drum kit with three mics so as to minimize how many tracks are combining to elevate the noise floor. Same with trying to get fancy and room-mic the guitar amps.