INTERFERENCE when RECORDING

[rayc]

Hello Folks,
I've been watching the review videos on YouTube for some time. I must admit to having been a fan of the PS Audio videos until I saw the reviews of the Power Regenerator & "cleaning" products AND Paul's responses. I've since unsubscribed from that channel.

I live in South East Queensland, Australia.

I'm one of those home recording dweebs.
I recently moved to another state and upon setting up my gear notice I had some interference showing up in my recordings.
I bought a better power supply for guitar pedals and the other bits & pices that run 9/12/18v gadgets for recording. I swapped the USB cabels connectig the interface to the computer. I bought better shielded guitar cables all to no avail. I did some testing and decided my Focusrite 2i2 was the problem. I tested the set up in other rooms with the same problem showing up.
I replaced it with an SSL2 but the problem persists.
I bought an old "power conditioner" and it made no difference. I bought small Ferrite rings to place at the beginning and and of any/all cables connected to my interface &/or computer and there was no change. I finally did some research on how to test for the problem more clearerly and did some tests based on those instructions.
This 1st image is of a balanced mic cable connected to the interface and being run into Reaper...REAEQ is the plugin that created this representation.
You'll note a bump or four in the bottom end but, more worryingly a big spike around 18Khz

This is the same cable "terminated" - as in a condenser mic attached but no 48v/not switched on.

The spike isn't apparent and the bump has been altered.
ANY/ALL recordings made in the room, (no fluorescent lights, a large TV as monitor but turned off in other tests with no change to the interference) contain the artefacts from the 1st image.

An electrician mentioned that the power lines running along the opposite side of the road have an extra cable carrying a very large load.
we have a solar array & converter as well that might contribute BUT I've tested the set up when the converter was off for checking with no change.

Any suggestions/ideas/diagnosis/cures/recommendations/next steps that might assist would be greatly appreciated.

The 17Khz ish thing is beyond my hearing but I'm aware it's in all finished recordings and some with good ears may hear it & it's not impossible that it causes problems with digital "plugins" within Reaper.

Thanks in anticipation.
Cheers
ray

 

[AnalogSteph]

The parts cannon has been fired, I see.

The levels you show do not at all look problematic, it's all below -100 dBFS... but I guess you're having more severe issues with the guitar recording part?

I would plug the guitar into the interface directly. If you get substantial hum when touching the strings, you may have a faulty electrical installation with PE being disconnected for some reason. (I don't think Australia has had ungrounded outlets in a long time, but no country is exempt from bodgery and old age.) Should be checked out by an electrician then. You can try plugging the computer into another outlet or another room and see whether the issue persists.

A combined power supply for all the pedals only makes sense as long as all the outputs are galvanically isolated from each other, otherwise it's instant ground loop galore - so are they?

 

[rayc]

The parts cannon has been fired, I see.

The levels you show do not at all look problematic, it's all below -100 dBFS... but I guess you're having more severe issues with the guitar recording part?

I would plug the guitar into the interface directly. If you get substantial hum when touching the strings, you may have a faulty electrical installation with PE being disconnected for some reason. (I don't think Australia has had ungrounded outlets in a long time, but no country is exempt from bodgery and old age.) Should be checked out by an electrician then. You can try plugging the computer into another outlet or another room and see whether the issue persists.

A combined power supply for all the pedals only makes sense as long as all the outputs are galvanically isolated from each other, otherwise it's instant ground loop galore - so are they?

Thanks for the indepth response AnalogSteph,
Excellent points and questions.
I did have an electrician in for other matters & asked, he said the wiring is fine. He was also the source regarding the extra power line. We had had concerns about wiring as the 30 year old house was a "self build" and quite a few eccentric things were done but the sparkie said the wiring, whilst odd in some respects, was fine.
I don't get any hum or drop of hum when touching the strings except in one guitar which I know has faulty internal wiring & don't use.
When tracking properly I "mic" a speaker cabinet and plug into a guitar amp.
If I go in directly with a guitar, bass or keyboard I've taken to using a balanced DI box as the last piece before the interface. The "visible noise" takes quite a jump straight in the peak increases quite a bit and a new one is introduced though smaller but the DI reduces it a bit. Any effects pedal, as designed, adds much more to the signal.
As mentioned I've set the gear up in different rooms and even used an extension cord to plug some parts of the chain into a different circuit.
I rarely use more than one pedal at a time and always check the response to the ground loop switch, most have them, before recording. I bought the new, supposedly better isolated power supply because the little 9v one I already had was the sort that runs on a "rapid cycle" or something & introduces a high pitched whine with some pedals and amps. To answer that question directly - no, there's no ground loop problem.
Recording vocals with a condenser microphone is the most problematic task as there's nothing but a vocal in that signal.
I acknowledge that this problem may only be a problem becasue I can see it. My hearing, as a 65 year old male, isn't brilliant so I can't rely on it too closely for assessment. Here's a relatively clean sounding song from the gear...I've done all that I could "in the box" to address the peak etc. sample of completed audio It's streamed which doesn't help but was uploaded at 24 bit and within the streamers specs so may not have been too mangled before streaming.
Stay safe
Stay well
Cheers
ray

 

[Matthias McCready]

A few things:

1) "Power conditioners" are little more than over-glorified rack mounted power strips, they are handy at getting power into a rack or roadcase, but I have never found them to magically fix power issues.

2) What type of DI are you using? Over the years I have found cheap DI's to cause all sorts of fun noise issues; you may already be using a decent one, but it is worth a check. At minimum a Radial Pro DI series is a good starting place ($100 per channel). I am partial to Cable Factory's Pro DI (Lundahl Transformer) or a Radial J48 (Jenson). For recording electric guitar (unamped that is) it may be worth recording it via a DI, and then using a Radial SGI system to reamp it or run it through pedals. You may also find that you can achieve higher quality results by using plugins vs the guitar pedals (guitar pedals often have noise issues; some of my favorites are terribly noisy!).

3) As far as problems at frequency extremes, this is usually a good place to be using high-pass or low-pass filters anyways.

4) I would say don't worry about this stuff! A lot of brilliant recordings have been made with less than stellar equipment and setups. If you can't hear something don't worry about it; worry about the stuff you can hear/learn. In that vein thing that make a large audible difference, roughly in order of importance

A) Playing Ability
B) Source instrument quality
C) Mic/DI Locker
D) Room Acoustics
E) Skill with compression and dynamic processing
F) Skill with EQ
G) Quality Monitoring Setup
H) Available processing tools

 

[goat76]

Have you tried reducing the noise on the tracks you have already recorded?

In Reaper, you have a plugin called ReaFir.
In the plugin, you can change the Mode setting to "subtract", tick the box "Automatically build a noise profile" and play a recorded part that only got the noise (a quiet part when the guitar is not playing or when you're not singing), untick the "Automatically..." box and you have a profile that will take away the noise. You can then lower the whole reduction floor by holding Ctrl and dragging it up or down a bit to your liking, probably down so it doesn't affect the sounding part of the guitar or your voice.

 

[rayc]

Have you tried reducing the noise on the tracks you have already recorded?

In Reaper, you have a plugin called ReaFir.
In the plugin, you can change the Mode setting to "subtract", tick the box "Automatically build a noise profile" and play a recorded part that only got the noise (a quiet part when the guitar is not playing or when you're not singing), untick the "Automatically..." box and you have a profile that will take away the noise. You can then lower the whole reduction floor by holding Ctrl and dragging it up or down a bit to your liking, probably down so it doesn't affect the sounding part of the guitar or your voice.

Hello goat76,
Yes, I use ReaFir to address the problem - it's good, not brilliant and does come with the problem all removal/subtractions programs do. It's really good though. I have it set as part of my project template all all tracks that will be recorded into via cable - I just select the count in section as the sample after recording and let ReaFir do it's thing. It's also, to a degree, a bit of a band aid but it does work as you describe.
Thanks for confirming the value & Ctrl part of the process.

 

[rayc]

A few things:

1) "Power conditioners" are little more than over-glorified rack mounted power strips, they are handy at getting power into a rack or roadcase, but I have never found them to magically fix power issues.

2) What type of DI are you using? Over the years I have found cheap DI's to cause all sorts of fun noise issues; you may already be using a decent one, but it is worth a check. At minimum a Radial Pro DI series is a good starting place ($100 per channel). I am partial to Cable Factory's Pro DI (Lundahl Transformer) or a Radial J48 (Jenson). For recording electric guitar (unamped that is) it may be worth recording it via a DI, and then using a Radial SGI system to reamp it or run it through pedals. You may also find that you can achieve higher quality results by using plugins vs the guitar pedals (guitar pedals often have noise issues; some of my favorites are terribly noisy!).

3) As far as problems at frequency extremes, this is usually a good place to be using high-pass or low-pass filters anyways.

4) I would say don't worry about this stuff! A lot of brilliant recordings have been made with less than stellar equipment and setups. If you can't hear something don't worry about it; worry about the stuff you can hear/learn. In that vein thing that make a large audible difference, roughly in order of importance

A) Playing Ability
B) Source instrument quality
C) Mic/DI Locker
D) Room Acoustics
E) Skill with compression and dynamic processing
F) Skill with EQ
G) Quality Monitoring Setup
H) Available processing tools

Hello Matthias,
Yes, I know about conditioners now. I bought it before having the sparkie comment on the wiring. I did follow up research and testing after speaking to him.

As to DI, I have a passive one and two active ones. The one I'm using definitely improves the situation the best of the three and certainly doesn't make it worse...I did before & after tests to ensure that was the case.
I have looked into reamping but, to be honest, a cranked Marshall Superbass buries an awful lot of noise so recording clean, getting the spike and rumble included in the signal and then sending that to an amp means potential for more noise.
Using ReaFir to clean that DI tone before reamping may be beneficial. I use reverb, delay and modulation plugins after tracking in Reaper rather than as pedals - the only pedals I do use are one amp in box for electric 12 string into a clean amp and, occasionally, an EQ/boost.

High & Low pass filtering - yes, I use them when needed but not as a matter of course - depending on the bass guitar & kick drum. Most digital EQs don't do a very steep/hard cut off and that spike does get reduced a bit but doesn't disappear. High passing at 100Hz thins my already reedy voice quite a bit but it makes sense for some guitars when the bass & kick are sorted.

Audibility is a niggle for me because my hearing begins its decline at 8Khz. It's not a case of what I hear but what others hear. I need other ears/perspective as well as a potential solution to the problem, (or a diagnosis that I can't use to tell myself it can't be addressed/isn't a problem). I use a proper M.E. in part to address that need.

as to the list:
a) I'm rubbish
b) cheap to mediocre - from a late 80s Fender 12 string acoustic to a Harley Benton electric 12 string with also sorts in between. See a) for why this is so
c) a relatively quiet AudioTechnica AT2020 and other quirky & often noisy mics.
d) currently only modestly treated as I'll be moving into a larger room and doing a complete re set - hence the desire to address this issue before doing so.
e) I get by and try not to use it unless needed...I've "been there done that" mashing things and getting the noise floor lifted to be a noise mezzanine.
f) I'm from the cut before you boost school
g) it's not bad but I'm currently looking for new 7 or 8 inch woofer monitors.
h) as far as possible I stick with Reaper native plugs as they are decent, if unspectacular, but do have a couple of things I like to use such as Voxengo Span, and a particular compressor for 12 string.

It's a good list and edifying to work through. I was able to do some detail reflecting whilst reading your post.
The main issue remains - what is causing the rumble & spike?
If they can't be heard, by good ears, in the sample recording, which is mainly DI stuff, then I may be fretting over nothing.

Thanks again