Silly tread - Page 1
Forum section: electronics / projects

author: 001
author_rank: Super Contributor
timestamp: November 25, 2018, 02:28:16 pm
content: Silly tread

author: Benta
author_rank: Super Contributor
timestamp: November 25, 2018, 03:22:04 pm
content: It can be injected anywhere in the amplification chain.The most likely place he should check first is whether the guitar pickups are the culprits. Just unplug the guitar and see if it goes away. After that, the search gets more complicated.

author: diyaudio
author_rank: Frequent Contributor
timestamp: November 25, 2018, 04:49:22 pm
content: Quote from: 001 on November 25, 2018, 02:28:16 pmGround loop problem. use another cable.

author: ebastler
author_rank: Super Contributor
timestamp: November 25, 2018, 04:54:31 pm
content: Quote from: diyaudio on November 25, 2018, 04:49:22 pmBoth, your analysis and the proposed countermeasure, seem a bit arbitrary. Could you elaborate please -- what leads you to those conclusions?

author: Benta
author_rank: Super Contributor
timestamp: November 25, 2018, 05:22:27 pm
content: Quote from: ebastler on November 25, 2018, 04:54:31 pmNot just arbitrary, but seems to pulled out from between the buttocks.As an old rock guitarist and electronics engineer, I've experienced the issues with electric guitars and amplifiers.

author: diyaudio
author_rank: Frequent Contributor
timestamp: November 25, 2018, 06:42:53 pm
content: Quote from: Benta on November 25, 2018, 05:22:27 pm"Not just arbitrary, but seems to pulled out from between the buttocks""I've experienced""As an old rock guitarist and electronics engineer"There is always that guyWTF hahahaha

author: ebastler
author_rank: Super Contributor
timestamp: November 25, 2018, 06:57:48 pm
content: Quote from: diyaudio on November 25, 2018, 06:42:53 pmI wish you had cared to reply to my post first. So, cards on the table please: Do you have any rationale for your earlier "advice"?Ground loops, in my experience, cause induction of power line hum first and foremost. And simply using "another cable" (to make the same connection) has never cured a ground loop; why would it?

author: floobydust
author_rank: Super Contributor
timestamp: November 25, 2018, 06:58:47 pm
content: Not enough info to figure it out.Tell the guy to turn the guitar 90 degrees and try switch to humbuck and see if the noise changes.That will tell if it's VLF coming in at the pickups.I don't know of any ground-loop between a guitar and amplifier- it's one cable

author: Benta
author_rank: Super Contributor
timestamp: November 25, 2018, 07:56:17 pm
content: "There is always that guy" is also interested in the reasoning behind the "use another cable" advice and its relation to ground loops.Diyaudio, please enlighten the OP and us.

author: diyaudio
author_rank: Frequent Contributor
timestamp: November 25, 2018, 08:47:01 pm
content: Quote from: Benta on November 25, 2018, 07:56:17 pmenlighten your behind you so admire.

author: tggzzz
author_rank: Super Contributor
timestamp: November 25, 2018, 09:01:22 pm
content: Quote from: 001 on November 25, 2018, 02:28:16 pmInsufficient information to diagnose.Start with the techniques inhttps://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

author: Buriedcode
author_rank: Super Contributor
timestamp: November 25, 2018, 09:48:36 pm
content: What guitar? Single coils pickup pretty much everything, which is whyhumbuckerswere invented - the clue is in the nameThese use two coils wired out of phase, so common mode noise (that is noise that imparts on both coils) is cancelled out. It isn't perfect but often much quieter - and that is the reason we have high gain rock/metal that simply isn't possible with single coils. The "hum" is often mains (50/60Hz) but it doesn't' have to be, it can be any EMI of sufficiently low frequency.There are other "noiseless" pickups that can be single coil size or use shielding to reduce interference (lace sensors) but none of them completely eliminate noise pickup.Could also be the (lack of) shielding in the guitar itself - as mentioned, broken grounding of the hardware can cause.Moving on to the next bit - the cable. Cables break, most often at the connectors. Although given guitar cables are pretty simple single ended connections, if there is a break - you probably won't get any guitar signal at all. With that said I have had some pickup loud hum due to a dodgy connection at one end.Then there's the amp. Again, ground faults, poor shielding, even broken pots can cause loud hum.Even if you have a humbucker equipped guitar, a decent cable, and a quiet amp, you can still pickup noise from things like PC monitors. Especially if your friends son plays with high gain. Tell him to turn the gain down and volume up - even the heaviest guitar tone is often at a much lower gain than you think, just multitracked several times

author: 001
author_rank: Super Contributor
timestamp: November 25, 2018, 10:12:43 pm
content: Quote from: Buriedcode on November 25, 2018, 09:48:36 pmHuh, I was playing bass in early 70th so it is not silly pickups/wires problemIt is sort of some RF modulation or other process in the ampBut amp is ok at my shop! How to save it from evil computer scream?

author: Gyro
author_rank: Super Contributor
timestamp: November 25, 2018, 10:23:56 pm
content: RF demodulation in the b-e junction of the input stage? Maybe try a 100pF cap across the input.

author: 001
author_rank: Super Contributor
timestamp: November 25, 2018, 10:27:29 pm
content: Quote from: Gyro on November 25, 2018, 10:23:56 pmNo wayYou can turn tone knob at guitar to add 0.047uF across the inputIt is not simple problemReallyDo anybody has experience with server EMC?

author: Benta
author_rank: Super Contributor
timestamp: November 25, 2018, 10:42:40 pm
content: OK, so it's not the pickups (you say).Second entry point is the loudspeaker leads. High frequency signals can enter at this point and be "demodulated" in the amplifier stages.A first attempt is passing one of the loudspeaker cables through a ferrite ring very close to the amplifier output.

author: 001
author_rank: Super Contributor
timestamp: November 25, 2018, 10:47:10 pm
content: Quote from: Benta on November 25, 2018, 10:42:40 pmHoney, any RF are killed by output transformer LC it is more complex problem than oldtime AM-radio in the guitarI loose my mind now

author: Benta
author_rank: Super Contributor
timestamp: November 25, 2018, 11:25:39 pm
content: Quote from: 001 on November 25, 2018, 10:47:10 pm"Honey"? I'm male with a full beard. But you're on my "no-go" list now.As you haven't mentioned in one word which amplifier it is, it's no wonder that you get answers that you can't use. Clueless question = Diffuse answer.Just change the cable to avoid ground loops...Jeez!

author: Bassman59
author_rank: Super Contributor
timestamp: November 26, 2018, 12:34:27 am
content: Quote from: 001 on November 25, 2018, 02:28:16 pmIt really helps to know:a) What guitar he's playing, including type of pickups,b) What kind of effects pedals he's using, if any,c) What kind of amplifier he's using.Some older ("vintage") amps are notorious for picking up noise, and since sometimes the mechanism for this noise pickup is endemic to the design and construction of the amp, you're stuck -- replace the amp with something more modern. Check to see if the amp is properly grounded. Sometimes the idiot guitars will cut off the third-wire ground pin on the power cord in a desperate attempt to make noise go away, and that's never good. A high-gain amp setting will also make noise worse.Some guitar pickup configurations are susceptible to noise. These are usually single-coil types (like you find in stock Fender Stratocasters and Telecasters), but some poorly-wired guitars with humbuckers are noisy, too. Sometimes just changing where you stand in the room improves things. Check to see that the strings on the instrument are grounded, and that the cavity with the electronics is shielded.Pedals with high gain, such as fuzz/distortion boxes and compressors, just exacerbate existing noise problems or are actually the problems themselves. The MXR DynaComp sounded pretty cool but damn it made a mess of things.I seriously doubt noise is getting into the amp via the speaker leads.

author: Buriedcode
author_rank: Super Contributor
timestamp: November 26, 2018, 12:40:09 am
content: Yeah I think we need much more info. Also it *sounds* like you're assuming there is a fault somewhere, where-as it seems to me - given that you said he plays in a "data centre" that its simply picking up radiated noise - which is what guitar pickups do really well!1) Is the noise present when the guitar and amp are far away from electrical equipment?2) Is he playing clean, or high gain? As stated, by myself and another poster - high gain will always pick up some noise, either from the amp itself, or cell phones, cars starting .. people underestimate how much gain modern amps and pedals have to satisfy the bedroom-volume playing folk.3) What guitar is this? Even strats (single coils) have a phase cancellation on their selector switch which can dampen or at least reduce by half, any noise.edit: just realised bassman pretty much asked the same stuff.... well I guess I'll just second them!

author: Circlotron
author_rank: Super Contributor
timestamp: November 26, 2018, 12:42:10 am
content: Quote from: floobydust on November 25, 2018, 06:58:47 pm+1

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 26, 2018, 12:55:17 am
content: Quote from: 001 on November 25, 2018, 02:28:16 pmAs noted several times above, the devil is in the details, so all of the information above might be helpful. I also wonder of he has checked all of his connections inside the guitar to see if all of the pickups have intact wiring. This is just speculation, but it seems to me that 1 Khz is not a frequency that would emanate from a data center. I realize this could be a harmonic, as well. What else in or near the room could be leaking at this frequency? Also, again speculation, but it seems that if one side of a coil in a pickup is loose, it could be an antenna?But, again, without all of the details, we are all having a speculation party. With all of the information requested revealed, it will still be speculation, but maybe there are known devices, i.e. pedals, amplifiers that have known issues.EDIT: Wait a minute, he is in a basement, could this simply be feedback (positive) from the amp to the guitar? Does it stop when he covers the strings with his hand?

author: ebastler
author_rank: Super Contributor
timestamp: November 26, 2018, 05:43:47 am
content: Quote from: 001 on November 25, 2018, 10:27:29 pmYeah, sure, the solution will be to quench the emissions from all those servers in the data center upstairs. Fat chance...You have not told us much about any systematic troubleshooting you might have done. (Unless I have overlooked it.) Can you even be sure that the problem is in the guitar? Is the same noise also audible with a battery-operated headphone amp, connected to the guitar with a short, shielded cable? What happens if you use the main amp and standard cable, but use a termination resistor in place of the guitar? Etc.

author: 001
author_rank: Super Contributor
timestamp: November 26, 2018, 01:19:29 pm
content: Quote from: ebastler on November 26, 2018, 05:43:47 amit is simple to recive this scream without guitar1M open input is sufficient for thisWe try few amps -- tube peavey 5150, tube fender junior and some solidstate fenderAll of them squeal about 1kHz so it is some outer problemBut what is cause for? Servers? Luminiscent lamps? wi fi routers? Big cooling chillers?What computer or power gear use audible frequencies now?PS -- I see railroad at about 200 yardsIs it use some high power tonal signals in a rails?

author: Simon
author_rank: Unknown
timestamp: November 26, 2018, 01:42:56 pm
content: I used to use a discrete sound card because on motherboard audio was shit as it picked up no end of crap. The motherboard in my new computer has a metal can over the audio chip...... 15 years later they finally got there.

author: ebastler
author_rank: Super Contributor
timestamp: November 26, 2018, 01:49:06 pm
content: Quote from: 001 on November 26, 2018, 01:19:29 pmLeaving the amp input open may be an unrealistically demanding condition. With the amp's high impedance input, that should really pick up any stray fields in the room. But guitar pickups have much lower impedance outputs, don't they? What happens if you terminate the amp input with a resistor, say 1 kOhm or 100 Ohm, to "simulate" the guitar?QuoteRailroads are notorious for strong 16.7 Hz AC fields, from the overhead power lines. I have never heard about strong signals in the higher audio range.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 26, 2018, 04:22:20 pm
content: Quote from: ebastler on November 26, 2018, 01:49:06 pm"Much lower" depends on how you define "much". And obviously depends a lot on the pickups and the presence of an additional internal preamp or not.Most pickups have output impedances in the order of 5 to 10kohm or higher, and depending on the "mix" configuration, they could be in series and further double the output impedance. Even active pickups are usually 10kohm nominal. 1kohm or 100ohm would certainly not be realistic.If dealing with classic single-coil pickups, the pickups themselves are still the most likely culprit. The guitar's internal wiring job can also cause problems as the messier it's done and the more loops you're bound to have. Series humbuckers have usually higher output impedance (around 2x obviously), but they pick up a lot less EMI themselves - you could still have EMI picked up by the wiring.

author: Benta
author_rank: Super Contributor
timestamp: November 26, 2018, 08:20:48 pm
content: Quote from: ebastler on November 26, 2018, 01:49:06 pmAs the OP is in the Antarctic (apparently), the railroad issue does not exist.

author: 001
author_rank: Super Contributor
timestamp: November 27, 2018, 10:01:47 am
content: Quote from: Benta on November 26, 2018, 08:20:48 pmmy soul in antarctic if You understand meno goverments and no customs and taxesBut body is still in human land with EMC problems

author: Zero999
author_rank: Super Contributor
timestamp: November 27, 2018, 12:04:13 pm
content: Quote from: diyaudio on November 25, 2018, 08:47:01 pmThanks for such an intelligent well thought out response.Changing the cable will normally make no difference at all. The only time the cable could be a problem is if it's faulty or completely unsuitable in the first place i.e. a loose connection or no shielding.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 27, 2018, 12:15:07 pm
content: Same response that happens daily in several other audio-centric forums:Post a sample of the signal + noise. A sample is worth 1000 words.The terms people use to describe sounds are not universally understood.Many people use the word "hum" or "noise" improperly because they don't understand.Not saying that is the case here, but still a sample is very valuable for analysis.The instrument and amp can be used as a sensing tool.Does the amplitude (or other characteristic) of the noise change as you move around the room?Or change the orientation of the pickups?

author: 001
author_rank: Super Contributor
timestamp: November 28, 2018, 06:36:30 pm
content: Quote from: Richard Crowley on November 27, 2018, 12:15:07 pmNice ideaThis is a sound sample. Don`t worry about common mains hum and strings. My problem is a wery high-tone squeak, You can hear it.It is same for different guitars and amps

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 28, 2018, 06:59:11 pm
content: Quote from: 001 on November 28, 2018, 06:36:30 pmNo sound in mp3, but now I know that Antarctica is somewhere in a Russian speaking country (maybe Russia?). I always thought that Antarctica was at the south pole...EDIT: Operator error, sound was on mute, sorry.

author: 001
author_rank: Super Contributor
timestamp: November 28, 2018, 07:18:02 pm
content: Quote from: tpowell1830 on November 28, 2018, 06:59:11 pmDo You hear this squeak now?

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 28, 2018, 07:19:12 pm
content: Quote from: 001 on November 28, 2018, 06:36:30 pmHave you measured this frequency, it sounds much higher than 1 khz.

author: floobydust
author_rank: Super Contributor
timestamp: November 28, 2018, 07:20:08 pm
content: It sounds like SMPS whistle, my wild guess is from the data center's power supplies (wiring) or UPS. Does it use a 380VDC bus?I use a battery-powered audio amp with a pick-up coil, or an AM radio and look for the noise source. Do a walk around and see what can be found.

author: 001
author_rank: Super Contributor
timestamp: November 28, 2018, 07:22:07 pm
content: Quote from: tpowell1830 on November 28, 2018, 07:19:12 pmI can`t do this since signal is muddy and squeak is masked by othersIt include some HF harmonics too

author: 001
author_rank: Super Contributor
timestamp: November 28, 2018, 07:25:47 pm
content: Quote from: floobydust on November 28, 2018, 07:20:08 pmCan You say about some standard ways to eliminate it?Quote from: floobydust on November 28, 2018, 07:20:08 pmYea whistle is everywere

author: chris_leyson
author_rank: Super Contributor
timestamp: November 28, 2018, 08:41:12 pm
content: Damn, I AM old, I really can't hear the squeak. Floobydust has the right idea. A pickup coil and a battery powered audio amp might offer a few clues, I would sniff the mains cables first and if an audio amp doesn't pick up anything then try using an AM radio. Common mode interference coming from your mains supply will find a way across any transformer at some frequency or another.

author: 001
author_rank: Super Contributor
timestamp: November 28, 2018, 08:54:36 pm
content: Quote from: chris_leyson on November 28, 2018, 08:41:12 pmI`m not a boy too. But I feel it as headache. I cant say how it high but I know what it existUPDafter about hour of squeak audition it seems to me what I can hear it directly, without any electronics now

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 28, 2018, 09:18:05 pm
content: Just listened to your sound sample. (Yes the recording is very low volume, so we need to crank up the volume to actually hear anything.)To me, it sounds like noise coupled from some switching power supply. Could be something like a computer monitor, or maybe LED lighting, or a lot of other possible sources. It's very possible it's coupled to the guitar pickups or its internal wiring as I suggested.It could also be coupled to the guitar amp itself. You could try plugging in a jack with something like a 10k resistor to the amp's input, crank up its volume and see if you hear the same noise.You could try and locate the noise source itself (by switching off any surrounding device one by one) until the noise disappears.

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 06:41:24 am
content: Quote from: 001 on November 28, 2018, 07:22:07 pmI took a quiet section of the signal, which mainly has the high-pitched noise, and Fourier-transformed it via Audacity. The dominant tone is pretty exactly 5 kHz.Edit: Found the level control in Audacity's spectrum plot and attached a clearer version of the spectrum...

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 06:45:06 am
content: Quote from: 001 on November 28, 2018, 07:25:47 pmJust to be very clear: Is the signal audible (at similar levels) when you use a battery-powered amp only, without any mains connections? That's very relevant, since it allows you to distinguish whether the noise is coupled via the power line or via radiated emissions.

author: Buriedcode
author_rank: Super Contributor
timestamp: November 29, 2018, 06:51:16 am
content: Quote from: 001 on November 28, 2018, 06:36:30 pmSo its most likely radiated EMI. Just to rule out the cable - have you shorted the end of the cable? Does the interference disappear?Quote from: chris_leyson on November 28, 2018, 08:41:12 pmWell he already has a pickup (the guitar) and amp. Does it change in amplitude depending onwherethe guitar is? My guitar seems like a pretty directional pickup to me - I have to face the window to not pickup the noise from the large collection of power bricks I have plugged into a multiway.

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 07:10:17 am
content: Quote from: ebastler on November 29, 2018, 06:41:24 amThanx! Awesome helpWhat about this 5kHz peak nature?

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 07:17:42 am
content: Quote from: 001 on November 29, 2018, 07:10:17 amThe signal looks pretty sinusoidal in the time trace, and the spectrum does not show significant harmonics at 10 or 15 kHz. Can't get more info from the recording, I'm afraid.Others have mentioned switch-mode power supplies as a likely cause. Possible -- although I thought that these are mostly designed to use a switching frequencyabovethe audible range? (To avoid problems like the present one, and also directly audible transformer squeal?)

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 08:33:39 am
content: Quote from: ebastler on November 29, 2018, 07:17:42 amIs it some internet wire or other communication gear?

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 08:47:05 am
content: Quote from: 001 on November 29, 2018, 08:33:39 amWhat I have not tried yet is to bandpass-filter your recording, to see whether it is a 5 kHz carrier modulated in some way. I can give that a try when I am back home tonight. But it does not seem likely; 5 kHz is just too low a frequency for information transfer in today's world...

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 29, 2018, 02:57:58 pm
content: Quote from: ebastler on November 29, 2018, 07:17:42 amYes, but switching PS emissions are usually modulated by the current draw of the powered circuit, and that modulation itself can be in the audio spectrum. That's very common.The fact there is not significant harmonics of the 5 kHz signal may be explained by the fact that most guitar preamp stages low-pass filter at between 5k and 10k usually.

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 03:37:47 pm
content: But why 5kHz?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 29, 2018, 06:12:21 pm
content: Quote from: 001 on November 29, 2018, 03:37:47 pmWhy not?You can design an SMPS to operate at ANY sub-sonic, sonic, or super-sonic frequency.If you were designing some non-audio product, there is no reason to avoid sonic frequencies.Just your bad luck to be within the field of something that wasn't designed for audio environments.That is why it will require more extensive detective work to identify the source with some sort of portable "probe".

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 06:37:28 pm
content: Quote from: Richard Crowley on November 29, 2018, 06:12:21 pmIs some spetial grounding can help me?I rotate pickup and now I find "quiet" positionBut now I can hear some chirping and new HFhum(dont worry about mains buzz)Hear it:

author: tggzzz
author_rank: Super Contributor
timestamp: November 29, 2018, 06:53:45 pm
content: Quote from: 001 on November 29, 2018, 06:37:28 pmHave you read the reference I provided here:https://www.eevblog.com/forum/projects/need-help-with-emc-problem-and-audio/msg1990748/#msg1990748Full of good theory and practice

author: ogden
author_rank: Super Contributor
timestamp: November 29, 2018, 06:57:03 pm
content: Quote from: 001 on November 29, 2018, 06:37:28 pmYou shall find issue first, only then fix it.I would switch off anything in that house except guitar+amplifier+recording_laptop_on_batteries and check that interference is gone or not. If not then find it. After all it is *audible* frequency, you have "EMC receiver" in any device with microphone input. Find some solenoid or build one and go hunting.To find junk SMPS, I usually suggest LW/AM radio. Pure 5KHz sine w/o harmonics is strange interference, dunno if radio receiver could help, yet you can try if have such in your toolbox.

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 07:48:55 pm
content: Quote from: ogden on November 29, 2018, 06:57:03 pmYea! What gear use it?

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 07:57:19 pm
content: Quote from: ogden on November 29, 2018, 06:57:03 pmGood idea in principle; but you probably missed the post where 001 explained that this is in an basement below a data center (server room?). If he meant that literally, I don't think they would be supportive of the "switch it all off" approach...

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 29, 2018, 08:14:29 pm
content: Quote from: 001 on November 29, 2018, 06:37:28 pmThen you have an "accidental" direction-finder.You can rotate the pickup to find the null (*) and maybe even triangulate to the source.(If it is a point source, which it may not be)And you should be able to move around and get a stronger signal as you move closer to the source, etc.* Remember that when using a coil for direction finding, when you have a null, the source is perpendicular to the coil axis.

author: coppercone2
author_rank: Super Contributor
timestamp: November 29, 2018, 08:18:47 pm
content: if you play those backwards you hear some stuff about spilling the blood of the innocent and burning crosses

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 08:39:45 pm
content: Quote from: 001 on November 29, 2018, 06:37:28 pmThat's still the same 5 kHz frequency. (With mains buzz in the first clip, without in the second.)

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 08:52:24 pm
content: Quote from: ebastler on November 29, 2018, 08:39:45 pmi mean some modem-like hum

author: ebastler
author_rank: Super Contributor
timestamp: November 29, 2018, 09:07:52 pm
content: Quote from: 001 on November 29, 2018, 08:52:24 pmBesides the dominant 5 kHz, there are also pronounced harmonics (mostly the odd ones) of 50 Hz.

author: 001
author_rank: Super Contributor
timestamp: November 29, 2018, 10:14:10 pm
content: Quote from: Richard Crowley on November 29, 2018, 08:14:29 pmIt is strange thing"Quiet" position is for horisontal pickup direction

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 29, 2018, 10:30:05 pm
content: Quote from: 001 on November 29, 2018, 10:14:10 pmThat may indicate that the source is on your floor (not the data center above).Ref:https://en.wikipedia.org/wiki/Loop_antenna#Direction_finding_with_small_loops

author: ogden
author_rank: Super Contributor
timestamp: November 29, 2018, 11:32:58 pm
content: Quote from: ebastler on November 29, 2018, 07:57:19 pmYes, I missed it. If audio equipment itself is not actual source of "5HKz" (setup tested in other place), but EMI is present even when whole test setup powered form single wall plug - run. Rent another place.

author: Circlotron
author_rank: Super Contributor
timestamp: November 30, 2018, 03:45:11 am
content: Quote from: Richard Crowley on November 29, 2018, 08:14:29 pmWith an AM radio the null is when the loopstick axis points directly at the source. Is there some difference between an air cored loop and a ferrite loopstick in this regard?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 30, 2018, 04:40:59 am
content: Quote from: Circlotron on November 30, 2018, 03:45:11 amIt appears to be exactly the same....Quote

author: Circlotron
author_rank: Super Contributor
timestamp: November 30, 2018, 05:41:59 am
content: Quote from: Circlotron on November 30, 2018, 03:45:11 amIf a source is perpendicular to the coil axis for a null that means it is at 90 deg to the coil axis. If a loopstick axis is pointing at the source for a null then it is not perpendicular to the loopstick axis.

author: 001
author_rank: Super Contributor
timestamp: November 30, 2018, 06:16:18 am
content: Quote from: Circlotron on November 30, 2018, 05:41:59 amIn fakt guitar pickup look like this.It eliminate 50Hz quite good. But not a 5kHz (Why?)How to identify problem direction?

author: Buriedcode
author_rank: Super Contributor
timestamp: November 30, 2018, 02:55:31 pm
content: The image you posted is for a "humbucking" pickup - as explained previously, these use two pickups wired in series, but placed anti-parallel to eachother, so that "interference" creates the same signal in both pickups, but at opposite polarity, so it cancels out. This should be the case for a wide range of frequencies. The clue is in the namehum- mains hum, andbuckingto oppose or resist.These do not completely eliminate mains hum interference (or any other interference), merely attenuate it - often enough to make life easier for recording situations.once again, I have questions, I think I have posted these before and others have asked:What guitar is it? What kind of pickups does it have? single coils? or humbuckers?Does changing the pickup switch on the guitar change the amplitude of the noise?Is the amp set to high gain? (overdrive) or "clean" ?Are all the guitars you've tried shielded internally? Normally this doesn't' matter a great deal since most people don't experience a lot of EMI with their guitars. But in very noisy places it can make a significant difference.I'm afraid, if you've tried different amps, with different guitars, on "clean" and still get interference, then there isn't much you can do about it. There are noise-gates which are designed to cut the guitar signal out when it falls below a threshold, so that when one isn't playing it is very quiet, but these only work with low-level noise, and the noise can often be heard just before it kicks in.It just sounds to me like your friend needs to find another place to practice :/

author: 001
author_rank: Super Contributor
timestamp: November 30, 2018, 04:14:18 pm
content: Quote from: Buriedcode on November 30, 2018, 02:55:31 pmHoney. You don`t want help me since Your questions are silly. You didn`t read my previous postsI posted three clean samples from humbucking guitars beforeIt is not "guitar for beginners" treadI`m just looking for engineer who had deal with strange 5kHz sine wave

author: ebastler
author_rank: Super Contributor
timestamp: November 30, 2018, 04:40:42 pm
content: 001, I don’t understand your reaction to Buriedcode’s post. He has a lot of valid questions, regarding the sensitivity of different pickups, shielding inside the guitar etc. If you want to „deal with the 5 kHz signal“, you will probably have to deal with those questions.

author: 001
author_rank: Super Contributor
timestamp: November 30, 2018, 05:30:14 pm
content: Quote from: ebastler on November 30, 2018, 04:40:42 pmNo. Now we know that all guitars feel this wave. So question is about strange 5kHz source and direction, not about guitar and amps (guitar gear is a toy for ee)

author: ogden
author_rank: Super Contributor
timestamp: November 30, 2018, 05:34:57 pm
content: Quote from: 001 on November 30, 2018, 04:14:18 pmYour attitude may backfire and give undesired results.- I do not like to receive rude answers to my posts, so this is last one here in this thread. Also next time I will think twice.QuoteSeems, you did not find any.

author: tggzzz
author_rank: Super Contributor
timestamp: November 30, 2018, 06:27:42 pm
content: Quote from: 001 on November 25, 2018, 02:28:16 pmMany people freely gave their time and effort to help you.Deleting the original post and changing the thread title is both rude and anti-social.

author: ebastler
author_rank: Super Contributor
timestamp: November 30, 2018, 07:14:30 pm
content: 001, I don‘t know how this thread deteriorated so quickly. You seem to be in a bad mood tonight. I recommend that you stay away from the keyboard, get some sleep and think it over, and come back tomorrow.

author: floobydust
author_rank: Super Contributor
timestamp: November 30, 2018, 07:41:35 pm
content: OP deleted his original post and renamed it, so the thread is full of blues guitar nowTroubleshooting EMI takes lots of patience and a formal method. You can't just guess and mess around trying to make sense of it, until you first know what it is from, what is causing it. It takes discipline or else you get frustrated and lost.

author: Simon
author_rank: Unknown
timestamp: November 30, 2018, 08:21:34 pm
content: Quote from: 001 on November 25, 2018, 02:28:16 pmI'l be the judge of that thankyou very much. If we all do that this will be a silly forum. Thanks for being an antisocial thug.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2018, 08:34:03 pm
content: why would you delete a thread about EMCits not beer bong dick pics

author: ogden
author_rank: Super Contributor
timestamp: November 30, 2018, 09:37:33 pm
content: Quote from: Simon on November 30, 2018, 08:21:34 pmRight. We shall learn from our mistakes and have guts to admit them without overreaction.

author: Simon
author_rank: Unknown
timestamp: November 30, 2018, 10:25:53 pm
content: Quote from: ogden on November 30, 2018, 09:37:33 pmThere do seem to be users that are too scared to admit they ever asked "that" question or so arrogant they think they own the thread and their posts. I have asked many a simplistic question in the past, often to get a hunch confirmed or just because I am curious and think a discussion may help others. That is the whole point of the forum.

author: ogden
author_rank: Super Contributor
timestamp: November 30, 2018, 10:33:30 pm
content: Quote from: Simon on November 30, 2018, 10:25:53 pmIt's not about "i am scareD to ask" but "fck off this is not what I am askeD". You (OP author) shall know what I mean.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2018, 11:13:36 pm
content: I think its work related because people are scared its going to make them seem less qualified as a engineer, because we have some serious know it alls here (not the bad kind but some people here probably have like 50 years experience). And some times the different languages and translations make people come off as extremely stiff.

author: ogden
author_rank: Super Contributor
timestamp: November 30, 2018, 11:42:30 pm
content: Quote from: coppercone2 on November 30, 2018, 11:13:36 pmRight. You better do everything to *not* be on any side of that thought.

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2018, 12:32:37 am
content: Quote from: coppercone2 on November 30, 2018, 11:13:36 pmIn reality the good engineers know the limits of their knowledge and arecompletelyopen about it. Ignorance is curable, whereas stupidity and arrogance aren't.When interviewing candidates, I always tried to get them to simply say "I don't know, but this is how I would find out".When interviewing companies to see if I wanted to work there, I always tried to get them to say "no, that's not how we do it" - because then I could believe them when they said "yes".

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 08:22:26 am
content: I pride myself in knowing my limits and am always happy to get a second opinion. It stops me making a mistake that would make me look even more silly.

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2018, 09:35:43 am
content: Quote from: Simon on December 01, 2018, 08:22:26 amPrecisely.Such attitudes engender trust in engineers - but is detrimental for politicians and religious hucksters and their ilk.

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 09:48:53 am
content: As I have said before I had to deal with an "engineer" at a subcontractor and he was a nightmare as he was not very clever and would not take advice whilst spendiyng a lot of energy on denying things were his fault. We don't use them anymore. Our current subcontract designer whilst being very knowledgeable and experience will seek my advice particularly in areas where he knows I have experience like connectors and how easy it would be for us to make "that". I in turn seek his advice and as a result we get the best results we can and of course I am always on here asking for advico on mission impossibles.

author: Ian.M
author_rank: Super Contributor
timestamp: December 01, 2018, 10:18:32 am
content: Frankly I'd rather have to skip over ASCII dick pics than to suffer posters vandalising threads they started, or throwing a 'I'll take my ball and go home' hissy fit by deleting all their posts as they leave the forum.Its not as if '001's nym is easy to link to their real identity, so the 'not wanting to appear foolish to work colleagues' excuse doesn't fly.@Simon, do the mods have any options here, less nuclear than restoring the post and putting '001' on a week's ban?

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2018, 10:20:49 am
content: Quote from: Simon on December 01, 2018, 09:48:53 amJerks are omnipresentI've mostly had a great relationship with technicians and devops etc, because we have a mutual respect for each others' strengths. jerks are omnipresent

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 01:47:59 pm
content: Quote from: Ian.M on December 01, 2018, 10:18:32 amI don't think a post can be restored if it is modified. Basically if someone is going to keep doing that I will just ban them. this is an adults place, children are not permitted!

author: 001
author_rank: Super Contributor
timestamp: December 01, 2018, 04:30:02 pm
content: SorryI was so drunk for this saturdayIt looks for me what someone bully me with not sufficient "guitar" posts, since we know now that problem is not guitar

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 05:00:20 pm
content: sounds like you are still drunk

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2018, 06:01:07 pm
content: Quote from: 001 on December 01, 2018, 04:30:02 pmI think there are two lessons for you in this episode. The second lesson is "if you are in a hole, stop digging".

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 06:27:53 pm
content: the second lesson is stop digging also.

author: Ian.M
author_rank: Super Contributor
timestamp: December 01, 2018, 06:50:42 pm
content: The third lesson is, if you do stupid stuff when drunk, don't drink!

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 06:56:38 pm
content: Just don't drink, i mean really what do people get out of it. Drinking is wasted on me, no matter how much i have I won't do anything silly

author: 001
author_rank: Super Contributor
timestamp: December 01, 2018, 07:59:41 pm
content: Quote from: Simon on December 01, 2018, 06:56:38 pmTry vodka with beer

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 08:01:44 pm
content: you didn't mix grape and barely did you?

author: 001
author_rank: Super Contributor
timestamp: December 01, 2018, 08:12:43 pm
content: Quote from: Simon on December 01, 2018, 08:01:44 pmI can`t understand itmy english is not so good for humor

author: Simon
author_rank: Unknown
timestamp: December 01, 2018, 08:23:14 pm
content: barely based drinks like beer do not mix well with grape based drinks like wine.

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2018, 08:31:40 pm
content: Quote from: Simon on December 01, 2018, 08:23:14 pmBarley. Spull chuckers are onederful.

author: ebastler
author_rank: Super Contributor
timestamp: December 02, 2018, 01:20:19 pm
content: Quote from: 001 on December 01, 2018, 04:30:02 pmI'll try one last time to get this thread back on track, and on topic.001, there may indeed be nothing wrong with the guitars you tried. (I.e. in a more typical environment, they may work just fine.) But in the challenging environment next to the server room, improving the shielding on the guitars and amplifier, and maybe selecting a particular type of pickup for the guitars, my be the only realistic solution to the interference problem. More likely than not, you can't change things at the source (assuming the signal comes from the servers).So, unless your friend wants to find a different room for practice, the questions others have asked about the guitar(s) and their shielding are valid. -- On the plus side, the servers will probably not mind your friend's acoustic noise much; so this practice room has its merits.Why don't you get back to troubleshooting, and restore the thread's title to something more meaningful?

author: 001
author_rank: Super Contributor
timestamp: December 02, 2018, 02:44:51 pm
content: Quote from: ebastler on December 02, 2018, 01:20:19 pmI drunk a little yetThe idea is to find problem direction and add steel plate to wall or to build a Faradey cell

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 02, 2018, 05:10:52 pm
content: Taking measures to add some shielding to your equipment will be much easier than trying to shield the whole room.Note: It's probably best to try and avoid drinking while playing with electricity. Just saying...

author: Simon
author_rank: Unknown
timestamp: December 02, 2018, 05:13:24 pm
content: Quote from: SiliconWizard on December 02, 2018, 05:10:52 pmi am a firm beleiver in judicious natural selection.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 02, 2018, 05:39:55 pm
content: Quote from: Simon on December 02, 2018, 05:13:24 pmTell that to Photonicinduction.

author: Simon
author_rank: Unknown
timestamp: December 02, 2018, 05:43:07 pm
content: Quote from: Cyberdragon on December 02, 2018, 05:39:55 pmSure, he is obviously smart enough to pass natural selection. He is accepted into the sensible sector of humanity - did i really just say that?

author: 001
author_rank: Super Contributor
timestamp: December 03, 2018, 08:51:57 am
content: Quote from: Simon on December 02, 2018, 05:13:24 pmWhat hell with You? I`m 65 now and drink beer every day.Does anybody has experience with Faradey cell at 5kHz?

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2018, 04:51:37 am
content: most real labs I have seen feature a no liquids policy unless its dangerous ass hydraulics that can spray you with water connected to 3 phase from 50 feet away. Thats fine but no water bottles or beer.open enclosures and stuff were fine with all the cooling water,but for god sakes no beer or water bottles.working in a big puddle on the floor with exposed mains in a chassis on a metal cart? no worries. not even about the alligator clips. no one will bat an eye. weird unknown chemicals come pouring out of a tank when you open it.. who gives a fuck. dust from god knows where? (probably from los alamos plutonium cabinet), who caresPossibility of alcohol: serious fucking situation.ahh workplace logic, easier to try to understand black hole surface physics then figure out the insane policies out (trick, you cant figure them out, their literally insane).

author: 001
author_rank: Super Contributor
timestamp: December 05, 2018, 07:10:14 am
content: Quote from: coppercone2 on December 05, 2018, 04:51:37 amcool story bro

author: TurboTom
author_rank: Super Contributor
timestamp: December 05, 2018, 02:52:00 pm
content: IIRC, the OP mentioned AC / cooling devices somehwere. The 5kHz can well be the PWM frequency of a variable frequency drive (VFD), powering a substantial induction motor. If not properly filtered and no screened cables are used, this noise may radiate anywhere. Will be difficult to eliminate it at the guitar/amp's site, rather have a look at the source and see what you can achieve there...

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 05, 2018, 06:40:53 pm
content: This thread is full ofand

author: Gyro
author_rank: Super Contributor
timestamp: December 05, 2018, 09:54:55 pm
content: Agreed. With the OP content deleted, it is indeed very silly to continue it. Somebody up there should have locked it by now.