Home recording studio - noise with guitar amps - who to call? - Page 1
Forum section: electronics / general

author: DaveNJ
author_rank: Contributor
timestamp: October 10, 2019, 08:23:58 pm
content: Hi all, great forum here - I came to the forum from watching a few of the YouTube videos...I just recently setup a recording studio in my basement - things are just fine with balanced connections from microphones and other gear, but I'm getting a huge amount of noise through my guitars and amps (things work fine in other locations - multiple amps and guitars are all affected). The studio is on it's own subpanel and the outlets for my gear are the only things on that circuit. I seem to be getting pronounced hum at around 180Hz and this ticking or clicking up between 4k-8k. I've eliminated all compact fluorescent bulbs and dimmers from the house and have had local electricians check my panel and the power company has checked my feed. The power company heard the noise on the ground rod outside at one point, but they haven't come up with any sort of solution or recommendation yet.What I'm trying to find out is who can I call to come in and try to properly identify the root cause and offer suggestions or remediations? I suppose it would need to be someone who can properly measure/analyze my power feed and potentially identify sources of RFI. Short of moving, I'm out of ideas, myself...Thanks in advance - appreciate the guidance!

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 10, 2019, 10:01:53 pm
content: https://en.m.wikipedia.org/wiki/Ground_loop_(electricity)

author: DaveNJ
author_rank: Contributor
timestamp: October 10, 2019, 10:24:18 pm
content: Yup, saw that - read it all, pulled my hair out...I just to find the right kind of contractor to come in, diagnose and address the issue now...

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 10, 2019, 10:29:13 pm
content: Can be a lot of things, such as ground loop.Is it a 60hz buzzing sound by chance? Could be a dimmer, pretty much anywhere in the house. Those make a lot of electrical noise.You could maybe try putting everything on an isolation transformer to see if it helps.

author: fourfathom
author_rank: Super Contributor
timestamp: October 10, 2019, 10:56:37 pm
content: Simplify and eliminate -- this is how you track it down.Your first step is to switch off *all* the circuit breakers in the house, leaving on just the ones you need to listen to the noise. It's likely a local source and those are easier to find, so look there first. If possible, run your recording console from an unplugged UPS and kill the power to your house completely. If the interference goes away, then start switching things on, one at a time. If it doesn't, start looking elsewhereDoes this noise only appear when you have the guitar connected? Is this via a mic'd amplifier, or via a direct (or effects box) connection?

author: ogden
author_rank: Super Contributor
timestamp: October 10, 2019, 10:58:08 pm
content: Quote from: Red Squirrel on October 10, 2019, 10:29:13 pmDisconnect the rest of the house but your studio from mains feed, check noise. Then you will know - source of the noise is in the house or not. It could be insulation failure or neutral/ground wiring mishap/violation. Did power company / electrician checked for grounding/earthing leakage (current)? If not - then they did not do their job properly, especially if told that you have audio equipment hum (?) noise complaint.

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 10, 2019, 11:10:10 pm
content: It could be in the equipment itself. Ground loops can pick up any sort of noise including switching power supplies and RF from digital equipment.

author: DaveNJ
author_rank: Contributor
timestamp: October 10, 2019, 11:50:22 pm
content: Quote from: Red Squirrel on October 10, 2019, 10:29:13 pmIt seems to be higher than 60 - that sound file I put has a large hump at 180, so it's a harmonic. I've removed all the dimmers from the house. The chattering noise is the thing that gets me the most. Yeah, ISO Transformer is my next thing to tryQuote from: fourfathom on October 10, 2019, 10:56:37 pmI've done this once already, and it didn't eliminate the issue. Yeah, it's only when the guitars are plugged in and a little bit of gain is added (not crazy amounts). It happens with single coil or (to lesser extent) humbuckers. All of my balanced gear is dead quiet.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 11, 2019, 01:55:14 am
content: Oh totally random, but if the noise is only really showing up on the recording itself, consider getting one of these:https://www.amazon.ca/Focusrite-Scarlett-Audio-Interface-Tools/dp/B07QR73T66We had issues at my church with the light dimmers (powering 1000w overhead stage lights) and this completely eliminated it. I think because it's USB, by nature it will also have isolation so that helps. I find the overall quality of the recordings is so much better than just recording straight to the aux plug.I also second the idea of trying to run on a UPS just to rule out electrical noise, though you will want to make sure it's pure sine. Those tend to be really expensive so another option is to get a pure sine inverter and a battery. Heck it might be a good investment anyway if you want to setup a power backup solution for the equipment.But yeah it's pretty much a process of elimination to track this down.

author: fourfathom
author_rank: Super Contributor
timestamp: October 11, 2019, 02:03:17 am
content: Quote from: DaveNJ on October 10, 2019, 11:50:22 pmHow are you getting the guitar signal into the recording gear? Are you mic'ing the amp speaker? Is this acoustic noise coming out of the amp? That is a much different problem than what you get from ground loops. Since the humbucker pickups don't give you as much noise, is this a magnetic field problem? If you re-orient the guitar (spin around) does the noise change?Or do you have a line-level electrical output from your amp (XLR connector or phone jack) that goes to the recording gear? Again, two different types of problem.

author: fourfathom
author_rank: Super Contributor
timestamp: October 11, 2019, 02:04:49 am
content: Quote from: Red Squirrel on October 11, 2019, 01:55:14 amEven if it's not a sinewave output, as long as the noise changes he will have a very valuable clue.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 11, 2019, 02:25:03 am
content: Quote from: fourfathom on October 11, 2019, 02:04:49 amYeah that is true. Might still be a useful test and he may already have one handy.

author: BrianHG
author_rank: Super Contributor
timestamp: October 11, 2019, 04:26:57 am
content: Quote from: DaveNJ on October 10, 2019, 11:50:22 pmI analyzed that .mp3, it's 60 Hz on the dot...There are other harmonics due to repeated voltage spikes at repeated intervals along the 60hz sine wave.1) How old is this amp?2) Is it vacuum tube?3) Could it need internal mains filter DC cap replacement?4) Could the amp just be poorly designed being very sensitive to any disturbance on the AC mains?5) Does the Amp do the same thing at another location?6) Has that Amp ever been serviced by an amateur without proper experience with the sensitivities of guitar amps?

author: DaveNJ
author_rank: Contributor
timestamp: October 11, 2019, 07:17:31 pm
content: Quote from: BrianHG on October 11, 2019, 04:26:57 amBrian, good info - thanks! To answer your questions:1. One amp is 10 years old (Suhr Badger 30), the other is 51 (Fender Princeton Reverb). I can also get the noise with a line6 Helix, so its not necessarily due to tubes and electrolytics.2. See above3. I had the Princeton serviced two years ago, the Suhr has not been serviced.4. I don't think so5. No. Even in another room (upstairs in my home)6. No, I only bring them to top folks in the area.I'm going to go through a full debug session on Sunday - turning off all other breakers, running the amps from battery, etc so I can try to narrow it all down... I'll post back with what I see.

author: floobydust
author_rank: Super Contributor
timestamp: October 11, 2019, 08:08:48 pm
content: I've had to troubleshoot oddball noise and hum in two recording studios.It's very difficult because finding the interference source or type of noise, figuring out where on the electromagnetic spectrum it is and how it behaves, is not easy.You may find the interference disappears on weekends and evenings, this is due to pollution from industrial electricity users. Although some welding shops run night shifts, I found some days and times the interference disappeared.Listening to your recording, I hear annoying crackles that are periodic, so likely from some industrial process.You can use a guitar to confirm. Rotating the body 90 degrees and you can at least see what axis the interference is coming in on. Buried power cables, or the airborn power conductors on utility poles are fabulous transmitting antennas.Another technique is using a Walkman (with no cassette inside), the tape head will pick up the same as a guitar pickup as far as low frequency B-fields. That will tell you right away if the noise source is outside your house. A cheapola AM radio also can be used to find an interference source.It's good to first know the (electrical) noise floor of the studio, before blaming the equipment and grounding etc.One studio has arc welding or smelter interference, so the guitar players are oriented 90 degrees and sessions are done on weekends.

author: DaveNJ
author_rank: Contributor
timestamp: October 11, 2019, 08:18:22 pm
content: This is in a residential area - no businesses for about two miles, but I hear you - it’s definitely been extremely difficult to trace the source. I’ve tried the am radio thing, as well, and so many things seem to radiate interference, but I haven’t been able to find that ticking source! That’s what I’m trying to find out - is there a type of service outside of a standard general electrician shop who would be better to bring in? I’ve read about ham radio operators using sensitive equipment to sniff out sources of noise, but I just don’t know who to reach out to.

author: floobydust
author_rank: Super Contributor
timestamp: October 11, 2019, 09:45:23 pm
content: Residential areas do get industrial interference - the substation (big) distribution power transformer can connect to many areas. You have to think a little different, light rail transit, kilns in schools, hospital heaters can be close and affect local power.The interference can come in through the airwaves and/or conducted from mains wiring or the distribution system electrical ground. One studio went all out and installed a large isolation transformer with new isolated ground, which got rid of all noise from the grid. But it doesn't help with the RF.That ticking source, pulsing a few times a second... reminds me of a high power heater that curses the airwaves around my lab. It's about a mile away. That interference gets in everything, all my audio gear picks it up. It changes sound with the heater load.I would ask around who knows experienced techs in the music industry, and find a local HAM club as they will know best how to sniff it out. You will likely get lost between ID'ing the source and shielding the recieving end.

author: BrianHG
author_rank: Super Contributor
timestamp: October 11, 2019, 10:57:06 pm
content: Quote from: DaveNJ on October 11, 2019, 07:17:31 pm1. Same interference on 3 different amps from 3 different eras, all 3 with not input?a) If the hum coming out of the Amp's speaker where you placed a microphone in front?b) Can you hear the hum directly?c) If you took the amp to a different location, like a different house another part of the city, will they still hum?d) Do you have high tension power lines within 2 blocks of your house, or, a transformer power sub station within 6 blocks of your house? (If the answer to this question is yes, you are most likely out of luck, sorry.)e) Do you have access to borrow a (I hate to say this) a high end power line filter and isolation filter like those used by some adiophiles? (These weight quite a bit as they have 2 large transformers in them with huge caps) I'm not talking about those cheap power filter bars or boxes.6. g) Are you saying all of your amps have been serviced?NOTE: A deeper look at your .mp3 file revealed perfectly timed diode switching noise in the waveform. This may be due to light dimmers always on at the same brightness, computer/electronics power supplies, LED/CFL lamps, or, on your power grid, even street lights, or someone has a huge device which internally operates electronically with DC at the full AC mains voltage.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 07:02:40 pm
content: Brian - wow, I can't believe it's been 3 years since I started this thread!In the time since, I had put the studio on hold and just dealt with the noise or recorded elsewhere - I'm ready to dive back into it now and I really do appreciate your input and suggestions.To answer your questions from the last post:1. The interference is the same but, it's only when a guitar is connected. With the amp just turned on, there is some hum, but nothing like what was present in that recording or in the new videos I've posted below;2. The loud buzzing and clicking only happens when a guitar with passive pickups is connected and the volume on the guitar turned up.3. In a music store about 2.5 miles from my house, everything is quiet as it should be.4. Power in my development is underground. but is fed from above ground wires about .2 mi from my house. There're above ground transformer boxes on my block or around the corner.5. I've tried a furman power conditioner and also a Tripp-lite medical transformer, and neither has produced a change.Now, this weekend, I shot a number of videos showing the issue and also a few things I've tried - left field things 0 to suppress the noise. You may find these interesting:First vid - demo of the issue with three different guitars (it also happens with different amps, just didn't want to move them to this room):https://youtu.be/da0JncZyENMThen, a weird update!https://youtu.be/sJuumHCLyikThen, a series I took this evening working through a few things:01 - Guitar Groundinghttps://youtu.be/D3Uv5RvINU802 - Belly Armorhttps://youtu.be/GdfG4vXMc6003 - Further Testshttps://youtu.be/vSpddcZIZW8Lastly, there is this video from another musicians on YouTube who had roughly the same exact issue who was able to get his local power company to solve his problem:https://youtu.be/t6E0O8UtObU

author: fourfathom
author_rank: Super Contributor
timestamp: November 20, 2022, 07:21:02 pm
content: Quote from: DaveNJ on November 20, 2022, 07:02:40 pmI previously suggested that you spin the guitar around and see if the noise changes. Have you tried that? This sounds like magnetic fields hitting the guitar pickup, rather than conducted electrical noise. Of course, wiring can radiate magnetic fields, so it could still be ultimately dimmer (etc.) related. But you might be picking up magnetic fields from something like an upstairs refrigerator compressor motor.Since you have already shut off all house electricity save for your studio (?), it's probably not your refrigerator compressor, but at this point I would be looking at magnetic fields.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 07:25:38 pm
content: Yes, it does change when I rotate it but as you can see in the video, it‘s actually the worst when it’s flat on the floor.I just reached out to my power company again to request that they assist with locating the source. I think it’s outside of my house, as well.

author: ebastler
author_rank: Super Contributor
timestamp: November 20, 2022, 07:40:50 pm
content: It seems like that "Bellyarmor" blanket does not act as ashieldfor the pickup, but rather that it grounds the guitar. (You uncover the pickup in the video and the hum is still gone. Only when the blanket loses contact with the last guitar string, the noise returns instantly.)What is your grounding scheme there? Is the amp in a grounded outlet? Does it ground the guitar via the 1/4" plug?It looks to me like one of those connections might be missing. Since you mention that you have seen the problem with multiple guitars and amps, I would check the cables (mains to the amp and audio cable to the guitar) and the power outlet first.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 07:44:20 pm
content: These videos were just filmed in a newly remodeled (and inspected) room - all outlets are properly grounded, the amp has a three prong cord, etc..

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 07:46:07 pm
content: Also, I’ve used multiple cables which all check out with my meter - sleeves have proper continuity…

author: ebastler
author_rank: Super Contributor
timestamp: November 20, 2022, 07:49:20 pm
content: Have you tried grounding the guitar via some other means than the blanket? Just a wire from any of the (to-be-)grounded parts of the guitar to ground at the amp?

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 07:54:24 pm
content: I haven’t. So, are you suggesting that I connect a separate wire from the shield of the guitar cable to the ground pin of the amps power plug?

author: ebastler
author_rank: Super Contributor
timestamp: November 20, 2022, 08:02:17 pm
content: I would go from a metal part on the guitar (the pickup cover, knobs or such -- you had shown them all to be connected) to an exposed metal part of the amp, e.g. the nut of the 1/4" jack on the amp.This is essentially to double-check that the two 1/4" jacks, two plugs and the cord inbetween do actually provide a ground connection. You could also measure continuity between the two mentioned metal parts with your multimeter.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 09:41:27 pm
content: OK, I just ran a piece of 12 gauge wire from the input jack nut to the guitar (try the strings, volume pot, control plate) and there was no difference.

author: ebastler
author_rank: Super Contributor
timestamp: November 20, 2022, 09:56:43 pm
content: Hmm, then maybe the blanketwasshielding the guitar in your video -- but the shielding only works when the blanket is grounded, by making contact with one of the grounded metal parts on the guitar?You could check that by putting the blanket underneath the guitar with the blanket'snon-conductingside facing up; it should have no effect then. But if you connect the ground wire from the amp to the blanket's conductive side, it should shield the noise (if this theory is correct).Not sure what the conclusion would be if you can confirm this. Probably some strong electrical fields coming in from outside; but what would you do about them?One more thought: Do you have a battery-operated amp handy, or can you borrow one? If the noise also shows up with a humbucker guitar and the battery-operated amp, you would have confirmed that it is not coming in via the mains but via radiated immissions.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 10:02:49 pm
content: Yes! We actually did try that (blanket underneath but conductive side down)and it didn’t do anything.I do have a battery powered amp, but I have to go get some batteries :-)

author: fourfathom
author_rank: Super Contributor
timestamp: November 20, 2022, 10:38:58 pm
content: Back to the magnetic fields, remember that a guitar pickup is *supposed* to convert magnetic fields to electrical signals. Grounding, shielding, aren't going to fix that, nor should they. Humbucker pickups (think Les Paul) are less sensitive to these external fields, but are not completely insensitive. Single-coil pickups (Strat, Telecaster, etc.) are particularly vulnerable. Transformers, motors, some lighting, some wiring can generate these fields. If the hum changes when you change the guitar orientation then this is not a grounding problem -- you are picking up these fields. Perhaps there are additional sources of noise, but you do have to address the magnetic field problem.

author: DaveNJ
author_rank: Contributor
timestamp: November 20, 2022, 11:00:28 pm
content: Agreed. Which brings me back to my topic title - are there any specialists I can work with to try to identify the source (in addition to the electric company)?

author: fourfathom
author_rank: Super Contributor
timestamp: November 21, 2022, 12:35:42 am
content: Quote from: DaveNJ on November 20, 2022, 11:00:28 pmSorry, I'm no expert and I don't know anybody who is. Just speculating wildly, but you might try hooking a solenoid coil (or guitar pickup?) to a battery-powered headphone amp and walk around the area trying to locate the source(s). A solenoid coil can have a fairly sharp null which might help in triangulating the offender. If you can deal with this at the source that has to be way easier than paneling your basement in Mu-metal.

author: BrianHG
author_rank: Super Contributor
timestamp: November 21, 2022, 01:06:47 am
content: Quote from: DaveNJ on November 20, 2022, 07:02:40 pmQuote from: fourfathom on November 20, 2022, 07:21:02 pmQuote from: DaveNJ on November 20, 2022, 07:25:38 pmI am so sorry, but it looks like to me that you are to close to the transformers in your area as I had a similar problem at my old address. (Even worse, with all power turned off at my old location, you could hear my ducts humming/vibrating during the coldest winter days.) I do not know if there is much you can do other than metal shielding your entire room where you play your guitar, and even that may not work if your pickups are responding to a raw magnetic field.I wonder if you should look into electric guitars with piezoelectric pickups. They will probably be immune to magnetic fields, however, they might have a different sound characteristic.

author: DaveNJ
author_rank: Contributor
timestamp: November 21, 2022, 01:36:05 am
content: Quote from: BrianHG on November 21, 2022, 01:06:47 amIt could be, but I’m holding onto hope. If you look at the video I posted from that other guitarist, his power company in Canada was able to address it. I’ve reached out to him asking for any detail he can provide.Non-magnetic pickups certainly sound different - the EMGs I have in that one guitar are not susceptible to interference, but they aren’t regarded as “the best sounding”. Now, vintage guitars with old p90 pickups are some of the best sounding, but also the most susceptible.I’ll definitely circle back if I find more details or a solution to close the loop. I really do appreciate you all looking over this and offering suggestion and insights.

author: BrianHG
author_rank: Super Contributor
timestamp: November 21, 2022, 01:39:20 am
content: Looking at my old location:You can see that I lived 175 meters / 0.1 miles from the high tension power lines feeding part of the city of Montreal, supplying a population of 1.8 million people. Worse, I was 500meters / 0.3 miles from the booster station at the bottom left.Believe me when I say, all the really sensitive analog electronics I worked on has measurable interference on my oscilloscope. My 75Hz 21inch studio grade CRT computer monitors would also vibrate the image like mad on some days unless I used a 60Hz, 90hz, or 120Hz video modes. There is nothing the power company can do as the transformer station and power lines when heavily loaded will radiate out. The field was strong enough to illuminate a white LEDs just by touching 1 side to a long metal beam part of my workbench table with the other wire contact held in my hand.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: November 21, 2022, 01:44:38 am
content: Can you add a filter to the mains supply for the guitar amp?A balanced EMI filter might be worth trying to eliminate conducted noise on the mains.

author: BrianHG
author_rank: Super Contributor
timestamp: November 21, 2022, 01:45:00 am
content: Quote from: DrGeoff on November 21, 2022, 01:44:38 amNot a mains issue, read his post.Quote from: DaveNJ on November 21, 2022, 01:36:05 amYour chances have diminished.If it were mains interference, the amp's input and wiring would replicate the same 60hz hum on his EMG guitars as the magnetic coil guitars. It is truly a magnetic field transmission like what I had at my old location where even computer monitor electron guns where being pushed in and out over-driving the deflection 'YOKE' due to the 60hz magnetic field.Only 360 degree, below and above copper plate shielding might clean this up.

author: DaveNJ
author_rank: Contributor
timestamp: November 21, 2022, 03:22:12 am
content: Quote from: BrianHG on November 21, 2022, 01:39:20 amYou know, looking at the image you posted, I may have misstated something - I’m not .2mi from high tension wires, I’m .2mi away from above ground, residential power lines. The towers are a good 10 miles or so away…I’ll let you know what the power company says…

author: BrianHG
author_rank: Super Contributor
timestamp: November 21, 2022, 07:46:55 am
content: Quote from: DaveNJ on November 21, 2022, 03:22:12 amSee what your power company can do. You should not be having the problem I was having as those transformers in my attached image 0.3mi from my house power ~25% of a city. I'm not talking about the tiny telephone pole style transformers which only power a few houses. (I feel sorry for those houses whose back yards are just across the street from that booster station, within ~0.05miles.)The only other thing I can think of is if somebody right next door, or withing the same building has some big ass machine with a huge AC motor or giant transformer running 24/7.

author: jonpaul
author_rank: Super Contributor
timestamp: November 21, 2022, 01:38:10 pm
content: See library of Jim Brown and Don Davis, at SynAudCom, excellent papers and tipshttps://www.prosoundtraining.com/Jon

author: magic
author_rank: Super Contributor
timestamp: November 21, 2022, 07:11:25 pm
content: I have no experience fighting with low frequency magnetic fields, but people say that they are a bitch to block, basically requiring thick solid steel or stuff like that.OTOH, the behavior you show is perfectly consistent with (perhaps unusually strong) electric field. These fields are stopped simply by surrounding the sensitive circuit with any reasonable conductor connected to the circuit's ground. It looks like something internally at the back of the guitar is receiving the noise. I guess that sticking a layer of aluminium foil to the back (maybe even a small patch in a particular location) and grounding it would be all you need. This should have been done internally by the manufacturer, I suppose, and still could be done if it's possible to take the guitar apart and access whatever electronics are inside.You tried an experiment with putting the blanket on top of the guitar and it was found ineffective, you may want to try the same with the guitar upside down. This would confirm if it's the particular side of the guitar or separation from the floor that makes the difference. I expect the former.No idea why your location is so bad. The source of electric fields is voltage, and the source of strong AC electric field is high voltage AC.

author: DaveNJ
author_rank: Contributor
timestamp: November 22, 2022, 02:23:08 pm
content: Quote from: magic on November 21, 2022, 07:11:25 pmThanks - you're correct, flipping the guitar over does not provide a full cancelation until I wrap the fabric up over the top (back of the guitar) as well. I think I show this in one of the videos...

author: jonpaul
author_rank: Super Contributor
timestamp: November 22, 2022, 03:21:25 pm
content: get a better guitar pickup, hum buckingj

author: DaveNJ
author_rank: Contributor
timestamp: November 22, 2022, 03:49:09 pm
content: Quote from: jonpaul on November 22, 2022, 03:21:25 pmIt is.

author: fourfathom
author_rank: Super Contributor
timestamp: November 22, 2022, 05:42:44 pm
content: Quote from: jonpaul on November 22, 2022, 03:21:25 pmBetter? Better in the hum department, but I personally love the sound of the single-coil Strat and Tele. That's why the piezo pickup may not be *the* solution, although you can do amazing things with modeling boxes these days.

author: jmelson
author_rank: Super Contributor
timestamp: November 22, 2022, 05:46:53 pm
content: In video 03, it was VERY obvious the noise got louder when the guitar was flat on the floor. Is that room the lowest level of the house? IE, a poured concrete floor? If so, there could be electrical conduits buried in the concrete. If not the lowest level, there could be unshielded Romex wires in the space below the floor. Holding a guitar with magnetic pickups next to electrical wiring would be a SURE way to pick up noise.I'm QUITE impressed by that "belly armor" it is one of those tinfoil hat products that ACTUALLY does what it is supposed to! But, magnetic pickups are really terrible receivers of magnetic interference. try some PZMs, they should be a LOT less sensitive to this stuff. Where is the main breaker panel for the house? If near where you made these videos, there will be HUGE bundles of Romex branching out from the panel, either in ceilings or floors near there.Jon

author: DaveNJ
author_rank: Contributor
timestamp: November 22, 2022, 06:00:14 pm
content: Quote from: jmelson on November 22, 2022, 05:46:53 pmJon,The room is the video is an extension over a crawl space. There is no wiring that runs under there - all outlets for that room run through the 2x6 framing in the walls. This room is also on the opposite side of the house from the breaker panel.Using the EMG pickups did what they're supposed to do - they're totally silent. but, they really don't sound as good as standard mag pickups. I'm certainly not going to put one in my 59 Junior!I was amazed that this blanket worked as well! I saw some teardown of these supposed EMI blockers which look like they're just three pronged plugs with some electronics inside, but they're just filled with epoxy! Haha!

author: magic
author_rank: Super Contributor
timestamp: November 22, 2022, 06:42:47 pm
content: Quote from: jmelson on November 22, 2022, 05:46:53 pmNo, it does something else. If you want to know how effective it is for its stated purpose, put a phone under your shirt, wrap yourself in that blanket and try to call the phone.I bet it will ring

author: ebastler
author_rank: Super Contributor
timestamp: November 22, 2022, 08:18:44 pm
content: Quote from: jmelson on November 22, 2022, 05:46:53 pmBut it can't be magnetic interference if it is shielded by a sheet of grounded metallized fabric, right? Must be electrical fields?

author: jonpaul
author_rank: Super Contributor
timestamp: November 22, 2022, 09:00:37 pm
content: Dave NJ Guitar pickups and hum buck are a big topic, not all are equal.Suggest to test near a strong 60 Hz mains field eg near large power transformer or tape head demagnetizer to see the hum susceptibility.Then us a battery powered amp to eliminate ground loops etc.Jon

author: BrianHG
author_rank: Super Contributor
timestamp: November 22, 2022, 09:11:36 pm
content: Try a grounding wire between the bottom of the pickups and the square metal plate at the back of the entry to the neck of the guitar.

author: BrianHG
author_rank: Super Contributor
timestamp: November 22, 2022, 09:14:50 pm
content: Wouldn't it be funny if all this problem is due to the'Hot' and 'Neutral' being wired backwardson DaveNJ's wall outlet.(Also potentially dangerous depending on how some old tube amp and radio designs do have a degree of coupling between one of the AC outlet pins and their chassis GND, but this would explain a lot. Some old AC chords don't even have a polarity on these old designs. You would need to get your amp re-furbished by a pro like Mr. Carlson who knows how to correct for this stuff.)

author: magic
author_rank: Super Contributor
timestamp: November 22, 2022, 09:45:40 pm
content: Not sure what you mean?In any decent equipment, the secondary of the transformer should be grounded to protective earth, and that's separate from neutral even in America, right?And if the amp is grounded to neutral, there's going to be mains AC on the guitar and everything. I think that would be hard not to notice pretty soonBut it is indeed an interesting question: is the problem a field in the air picked up by the guitar, or ground bounce in the amp and the guitar "picks up" the static ambient field of earth which looks like noise with respect to the noisy "ground".

author: BrianHG
author_rank: Super Contributor
timestamp: November 22, 2022, 10:20:28 pm
content: Quote from: magic on November 22, 2022, 09:45:40 pmIn North America where the 120v outlets have one contact to the fuse box GND (called Neutral) and the other side connected to 1 phase of a 240v supply (called Hot) to give us 120v. This ground is also Earthed to the ground with a spike as well as plumbing and ducting in a house. Normally in consumer equipment, there should be a class Y cap connected to the Neutral line to the amp's/device's chassis GND. Some older equipment from the ~1940's had it directly wired, no series cap. Though, in older equipment, AC plugs used to have no polarity direction meaning you rotate them 180 degrees and still plug them in. This means the 'Hot' 120v would have a 0.1uf to the amp's chassis. This means the guitar's pickups should hum if the plug's polarity is backwards and the guitar is placed on the ground as the amp's GND may be it's 0v reference, but, the ground below would look like a 120v oscillating electric supply. (Placing the guitar in that conductive blanket, as in his videos when you hear that blanket make electrical contact to 1 or more metal surfaces on the guitar, having the noise vanish, means everything inside would reference the frame GND and isolate the pickups from the surrounding true earth GND.)If you are un-aware of the North American power system, and you didn't know you can rotate the AC plug around 180 degrees on older plug which which didn't have a thick bulge on one side to polarize them, then I would not expect you to know this and about the class Y cap tying the AC plug directly to it's chassis or GND.Also as the standards have changed back in the ~1970s, some electricians doing work in that period may have wired the AC outlets backwards and we have some AC outlet testers which specifically have an LED to tell you if you have this problem with your outlet. If the amp was serviced with a new polarized outlet, it may have also been wired backwards as some old designs had the AC power switch on the wrong line and the serviceman didn't want to go through the hassle of re-wiring the AC input stage to fix the problem properly as it entails some additional work as Mr. Carlson Lab's electronics vacuum tube radio/amp restorations have demonstrated this exact problem with shoddy third party restores. (Mr. Carlson Lab's is here in Canada, so he pays particular attention to the AC power and power switch issue with his restorations for safety reasons... Without the re-wiring, turning off the radio/amp may mean energizing the chassis of the radio with 120v.)

author: magic
author_rank: Super Contributor
timestamp: November 23, 2022, 10:59:00 am
content: In such case the secondary is never really effectively grounded at 60Hz and noise will couple through the transformer no matter which way you plug it in, although one way will be worse than the other depending on where the Y cap goes. It seems that shielding the hell out of the circuit to hide true ground from it is a necessity with such installations.But IIRC OP said that the sockets have been tested by an electrician and that the same amp works fine in other placesAnyway, shield the hell out of it, problem solved.

author: BrianHG
author_rank: Super Contributor
timestamp: November 23, 2022, 12:47:49 pm
content: At my old home, a functional solution was a thick grounding cable tied between all my AV hardware's chassis (usually any screw on the side of my equipment) after all being tied together, they finally went to an earthed point separate of my house's earth wall outlet earth. This got rid of my 60hz buzz throughout my AV hardware. (Though, I still needed 2 home made split bobin isolation transformers for my AV recorders and preamp to completely get rid of the buzz.)This means preamps, PC, digital AV sources, monitors, and power amps. Doing so killed all buzzing.

author: jmelson
author_rank: Super Contributor
timestamp: November 23, 2022, 06:16:55 pm
content: Quote from: DaveNJ on November 22, 2022, 06:00:14 pmWow, VERY strange! So, the only thing under the floor is the earth? That seems to indicate that the electrical "ground" is not at ground potential!Maybe there is some issue with the service entry grounding, like the ground rods have corroded away or the earth around them is too dry to be conductive.Also, in one of the earlier videos, you lay the guitar cord on the floor with no guitar, and there is strong hum. This indicates the shielding on that cable is quite suspect. Either the shield braid is very loose or not well-connected to the barrel of the connector. That should be investigated. Maybe you need to make your own cables, it is not difficult, and you will then KNOW how the shielding has been done. For the ultimate, get differential to single-ended transformers and put at each end of the guitar cable.Jon