Hello Folk,I moved houses/states recently and found, after setting up my recording space, that a sub 50Hz hump, largish 20kHz peak and raised noise floor appear on all recordings made through my Focusrite 2i2.

I swapped all cables, used a different computer, set up in a different room etc. but the problem persisted. I bought a power condition but things didn't change.

I bought a new, more expensive interface, SSL2, and blammo - no change.

The recording space is a rectangular, full brick built room faced with gyprock/sheetrock, timber lines ceiling and about 60 underground. It has cheap tracklights in the ceiling.
Any ideas?

Try recording with the lights off. Those tracklights maybe part of the problem.

...Deb

Could you please elaborate, what do you mean by 20 kHZ peak? Most of us here haven’t been able to hear that high in over 50 years. How does this limit show itself? Your dog knows, but isn’t saying.

Assuming all your cables are the same as in the other location, are they all shielded?

Do mic and speaker cables run parallel to power lines?

Did you get an AC outlet tester to make sure the house is wired correctly (no reversed or floating grounds)?

Is all the audio equipment on one circuit (should be)? Are there other devices like a furnace, microwave, fluorescent lights or refrigerator on that circuit (shouldn’t be)?

Any radio stations or hams nearby?

Where is your router?

Any equipment suffer a beating during the move?

Tons of possibilities. Start disconnecting to try to isolate the problem.

You need to first check that there is a proper ground for the electrical system in your new house. A little two-dollar tester will be enough. Different electrical outlets frequently have a different ground reference value. Plug into one plug. Turn off your cell phone. Turn off the lights. Turn off electrical appliances one by one.

Record just the ambient noise to see what you can hear. I can hear my wife talking on the phone downstairs out in the backyard with the door closed.

I am not sure what you are recording. Guitar DI? Microphone? The lowest string on a four-string bass guitar is around 40Hz. Few people can hear above 20K Hz.

Here is a small amount of info you can read https://www.soundonsound.com/forum/viewtopic.php?f=15&t=64533&start=0.

What sort of floor do you have? Hard or carpet? The high-frequency noise is likely coming from electronics equipment such as a computer monitor.

I have to turn off my AC to record. I have to send my wife to the mall...lol

Billy

Thanks Deb, That is one of a couple of things I'm interested in. they generate heat, they don't generate much light and the wiring of them s always a little suss.

Thanks Matt,
1.the peak and hum are visible on any of a number of EQs graphs within my DAW. MOST folk can't hear 20kHz but what happens up there can be heard by some and can, easily have an impact on audio recording and treatment.
2. All shielded well enough...no parallels.
No outlet tester but do have the power conditioner which would rectify the supply to some degree. I will look into a tester though. On that line the ground loop switch on one of my pedals make the problem worse.
Tested in other rooms down & upstairs and no change so not a single circuit thing. No appliances on the circuit.
Radio station - nope semi rural location - there is a mountain though I don't have a ham radio so wouldn't really be able to tell about other ham radio users.
The machine is offline and the router in the opposite corner of the house AND upstairs. The entire downstairs is brick built walls interior and exterior as well.
Nope no damage, new interface has same problem.
Everything has been isolated, swapped. moved and tested in various modes - including with my hand on them.
Yes tons of possibilities many of which I've addressed and the reason I asked...thanks.

I've checked the ground spike is properly connected and well buried but haven't plugged anything into a socket/power point, (as we call them in Australia), yet.

We live in a quiet pot where a car driving down the road is remarked upon. The bush turkey, crows and magpies sing a lot, the trees sussurate a bit and any conversation in the house can be heard throughout...phones...I'd need to send my up the street not to hear her talking into one.
The hump & spike come with balanced and unbalanced cables, dynamic & condensor mics, DI or mic'd guitar. Not being able to hear 20kHz (considered excellent hearing in a youngster,) of the 20Hz doesn't mean they don't have an impact on audio production though - a sub hump can often be the result of DC offset problems and cause a mass of issues.
The monitor is the same as I used in NSW, all gear in the same relative position too, as is all the gear but the new interface, power conditioner and pedal power supply - all bought in an attempt to alleviate the problem.
We don't have AC - yet.
Thanks for the outlet tester suggestion - I'll follow it through.

You are right, a 20K Hz signal won’t be heard except maybe by grandchildren, but it will affect plug-ins attempting to analyze and process sound.

I just looked up and discovered 50 Hz is your power frequency in Australia. It’s 60 Hz in the US. That doesn’t change any of my answers.

The tester I use now is a $20 tester at Home Depot made by Klein Tools. It has a text readout in addition to the light pattern found on the $7 version that used to be all that was available. I have no idea if the one sold here for 60 Hz works in Australia but check Klein Tools. I carry a tester in every gear bag and won’t plug in any gear to an outlet before testing it first.

This 240 Volt power socket tester is a handy piece of kit to make sure active, neutral and earth are all correctly connected.
It's locally available and setup for Australian power outlets.

Here is what I have to deal with...lol




Billy

The 2i2 is USB powered. It doesn't plug into anything but the USB port.
Are you sure the noise is coming from there?

Thanks for asking. As explained above, I'm certain it's NOT coming from the 2i2. As mentioned above the new interface presents the same issue so it's not based on the interface or preamps.

Thanks for the response folks.
The power point tester is my next purchase...possibly the cheapest and easiest of the process though it could lead to some expensive modification.
Thanks Noel, that's a cheap one that can be had fairly locally.

Do you have a laptop? Might be a bit overkill, but try running a laptop from battery with the Focusrite powered off it, and shut off the power to the whole house from the mains. If you're still getting the high-frequency noise coming in, then it's something environmental to the area you live in, and if it goes away then it's something powered by your house and you can hunt it down by turning on breakers one by one until you find the culprit. Once you've found the circuit it's on you can experiment with any noise filters or the like that others have mentioned.

I'd suggest using a receptacle tester on EVERY outlet in the house, not just for the noise issues but for safety. Some older equipment (old guitar amps in particular) connect the neutral line to the chassis, where if the live/neutral wiring gets swapped it'd be connecting the live 230v to the chassis!

Thanks Simon,
I've an outlet tester coming in the post and will do that part 1st then try the laptop blackout process. yes, it sounds drastic but where I lived for the previous 24 years power outages were so common that we had torches and candles at hand in all rooms as well as a camping stove and matches always at the ready. Resetting clocks is the only thing that annoys me...so many clocks need to be reset now almost any/every electronic device has a clock.

Good to hear Ray! Yeah the blackout process is drastic but it's the quickest way to determine if the noise is something you can control or not - and if you can't control it, then I suppose buying cables with better shielding is in order. Hopefully the power at the new house is a bit more stable than the last one!

Interestingly, that doesn't appear to be 50Hz mains interference. The frequency is quite variable, verging on white nose perhaps.

Nope, not 50Hz interference. The response isn't particularly variable...a relative straight line could be extrapolated between the the low hump and the high peak.
I was told, today by a sparkie, that in Qld, a carrier freq. is used for signals to solar panel inverters. Also that the inverter may be producing interference. I'll start with a wiring check via the power outlet meter.

Does your house have any intercom system that utilizes the mains wiring to communicate data. Perhaps a neighbor has a system?

This could get tricky...

Quite tricky. No local intercoms and the distance between dwellings is rather larger than suburban NSW too boot. The power point tester arrived today, thanks for the link & recco, all points in the room have been tested as well as any power boards. All are AOK.
I've ordered ferrite beads as the next step...oddly largely O.O.Stock in many places in Oz and LOTS of bad reviews for most online sellers (mainly masquerading as local but actually in mainland China).

Ok, at least if your outlets pass with the tester then they should be safe to use!

Good thought on the ferrite beads - they might help, as long as the noise is coming in through the power lines.

I kind of lost track of this thread, but

1. It’s good your outlets test ok
2. I thought somewhere it was established the the frequency was not limited to your power at 50 Hz.

By the way, the power can be fine but still cause a problem if connected audio devices are plugged into different circuits. It’s best to have all your studio equipment on one circuit by itself. Lights, phones, routers etc. and especially AC should be on another.

Thanks Matt,
No ground loop that was an easy and early check..all the audio gear is on one circuit and that comes through a power conditioner.
Ferrite beads can/may reduce EMI & RFI picked up by cables from the environment...so it's a small investment that MAY be of benefit.
Robustly shielded cables may also have to be considered.

Faraday Cage anyone?

If it's caused by 50Hz mains, then the interference would be delivered as a continuous low-frequency hum.

It also may be that something has become dislodged as part of your relocation effort and is delivering the static. Perhaps an edge connector or other internal connector?

To rule out your home environment, can you take the gear to another location and connect it up to test?

It partially depends on how "clean" the 50hz is for him. In some places I've seen AC as a nearly pure sine wave, and in others it's got all sorts of spikes and other nasties. Some of that noise can present itself way up into the khz range or even mhz range, which can cause all sorts of weirdness when that's being sampled at the regular audio sample rates.

One thing I've done in the past that can help with situations like this is to use balanced cables with the ground lifted at the receiving end. This can often produce lower noise than having the ground connected at both ends. If you're handy with hand tools and/or a soldering iron it's fairly trivial to lift the ground at the end of a cable, provided it's a jack that can be disassembled.

I agree that some internal connector somewhere could've shifted, which could cause this problem.

Rayc, did you try the blackout test?

Good points Simon, and definitely worthy of consideration. The area the Ray is in should be expected to have reasonable electricity supply. My brother lives not far away from there and has never experienced an issue. That is not to say that any external interference could be quite local to Ray, which is why I suggested a trial of the same gear at a different location. I understand that his gear apparently worked OK at his previous location.

If you have access to an oscilloscope, you can put it on the mail lines and see if anything is riding on them that would be causing this. You mentioned the solar panels as possibly having a carrier. Sweep the freq up and down and you'll see what's hiding there.

I'd certainly do the laptop powering the interface and see if it's still there. If it is.... I'd then carry that setup a good distance away to the local pub or something that gets you away from any local noise sources.

This certainly sounds like a detective job for you.

Since you are in AUS.... any aboriginal graveyards nearby?

Do keep us posted when you finally figure it out.

I'm back with an update.

I turned the lights off,
I put Ferrite beads on both ends of each related cable into or out of the interface and computer,
I have the power conditioner set & running properly,
I have the gain at noon on the preamp,
I created a Faraday Cage for the interface, (as best could be expected given cables in n out ), using a foiled lined freezer bag,
I turned the monitor screen off,
AND
I used a "terminated" XLR cable.

Net result a TINY drop in the level of the problem.
I tried to filter the noise out using ReaFir...
it takes a block at -108dB to filter out the sub hump and a block at -102dB to do the same for the peaks.
Those dB levels are according to ReaFir.

With those settings there's quite a bit of "noise" between the hump & peak when the line & HiZ buttons are engaged and quite a bit more when the 4K button is brought in...all expected as a matter of signal increase and colour (interesting to "SEE" the colour of the Heritage 4K thing...a low mid through to upper mid curve and harmonics after the peak). basically some EQ and distortion.
a) bass before Reafir
b) bass IN ReaFir &
c) bass post ReaFir

I filtered the noise from the guitar bus and the bass as they had the most pronounced readings - caused by the HiZ preamping the vocal wasn't as severely affected.

I turned my system on one day and had a really bad hum.... 60hz. I was thinking something had blown up or whatever.... bad cables.... etc.....

After spending more time than I should have spent.... I realized I had left my POD2 output turned up from the last recording session and the guitar cord was in the input and the guitar was not connected.

Some times it's just the simple stuff.... be sure you check those things too.

Do to my personality and how I think....I try to analyze from the hardest things first.....as a result, I often spend more time and effort than necessary.... if I had only checked the simple things first.... such as.... yep... is the switch on the side turned on? No? Oh S%#&!

Got it folks,

I call this baby the "Herb Hartley."

See this post:

https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=674005&#Post674005

Thanks for the encouragement HH,
As my most recent post makes clear, the only input for the recent test was a "terminated" XLR cable.
The images were taken with a bass D.I.'d as I needed some signal to show the variation.
The fairly extensive list of variations and changes include using a laptop computer running on battery and in a different room to the problem spot.

There are two steps I've not yet taken..one is to repeat the laptop & interface test but after blacking out the house AND taking the laptop and interface into the street.
There're two BIG questions - 1. What's causing this problems? and 2. Does it have an audible impact on my recording, processing & mixing?