edwin_rm Posted April 11, 2016 Share Posted April 11, 2016 Similar to electric unicycles, some PC gamings GPUs, such as AMD R9 Nano for example, have that low frequency coil whine. One crt TV and one lcd monitor at my house have it. Whatever all of those have in common with must be the source. Link to comment Share on other sites More sharing options...
Simon Lovell Posted April 11, 2016 Share Posted April 11, 2016 I am not a sound engineer but I think Kingsong could actualy do something about this......by using the amplifier and speakers and adding a sound cancelling program to their app......... A noise-cancellation speaker emits a sound wave with the same amplitude but with inverted phase (also known as antiphase) to the original sound. The waves combine to form a new wave, in a process called interference, and effectively cancel each other out - an effect which is called destructive interference. Could this be the answer? Link to comment Share on other sites More sharing options...
OliverH Posted April 11, 2016 Share Posted April 11, 2016 22 minutes ago, Simon Lovell said: I am not a sound engineer but I think Kingsong could actualy do something about this......by using the amplifier and speakers and adding a sound cancelling program to their app......... A noise-cancellation speaker emits a sound wave with the same amplitude but with inverted phase (also known as antiphase) to the original sound. The waves combine to form a new wave, in a process called interference, and effectively cancel each other out - an effect which is called destructive interference. Could this be the answer? What's the problem? I laught the first time i heard the Gotway sound. I said: I never ride a Gotway. Never say never, today I ride a Gotway and I'm proud of it. Kingsong has the same roots from what I'm heard and it was App/ protocol compatible in the fist versions. Let this sound as is. It looks like to be the best way to drive the mosfets. And you can imagine the load from the sound it generates. Link to comment Share on other sites More sharing options...
US69 Posted April 11, 2016 Share Posted April 11, 2016 For me this is the typical EUC Sound and i like it! As People at all stare at you like you are an Alien from outer Space...you even should Sound like one :-) Link to comment Share on other sites More sharing options...
Jeffrey Scott Will Posted April 11, 2016 Share Posted April 11, 2016 Gotways have this high pitched whine too. I actually like it - I actually wish all wheels had a bit more hum. It's beneficial for pedestrians to hear you coming. Link to comment Share on other sites More sharing options...
dmethvin Posted April 11, 2016 Share Posted April 11, 2016 If I wanted a high-pitched whine to follow me everywhere I go, I'd have more kids. Link to comment Share on other sites More sharing options...
Gunthor Posted April 11, 2016 Author Share Posted April 11, 2016 Now I here are some 'Advanced Spectrum' app snapshots of the KS16. I took my mobile into both hands (approximately 40 cm in front of me) and did not bother to bring it closer to the EUC. I can confirm Jason McNeil observation ( 6kHz, 12kHz & 16kHz) on his KS14 also meet the KS16 one. However, I'd like to point out, that the decibel amplitude levels of the KS16 (between -58 and -40 dbFS) are significantly louder than the KS14 (between -80 and -70 dbFS): As I and propably many others cannot hear 16 kHz let's focus on the 6kHz and 12kHz peaks. @OliverH and Jeffrey Scott Will: Do you mind posting a 'Advanced Spectrum' snapshot while riding your Gotway? I know that each EUC whines, but I'd like to discern the differences between them more objectively. My suspicion is that it is a certain combination of frequencies and their decibel amplitude levels. This evening I traveled another 26 Km and now I have a headache and believe it comes from listening to this whining sound for 1,5 h. Nevertheless I'd like to know if there are other 800W wheels out there that produce less noise pollution before returning the KS16 because of this whining sound... In order for everyone to understand where I am coming from: The Ninebot One only emits 7,8 kHz with barely touching -60 dbFS (and from all 4 snapshots taken I uploaded the loudest one!) when riding with the same speed on exactly the same location and no peaks around 12kHz! @esaj: Thank you for looking into this one. @dmethvin: I agree totally. @All: Thank you for all your input. This is a wonderful community of EUC experts. I have the feeling if I delve more into this forum I soon will be one myself... Link to comment Share on other sites More sharing options...
Jason McNeil Posted April 11, 2016 Share Posted April 11, 2016 Nice! That's some sexy data It's difficult to see what can be done to reduce the resonant harmonics inside the motor hub (?) without undesiered complications. If they add a thin barrier on the hub plate, it's going act as insulation. Still, could be worth investigating... Link to comment Share on other sites More sharing options...
StreetMeatNYC Posted April 11, 2016 Share Posted April 11, 2016 I had assumed most of it was coming from the electronics and board, not the motor itself? Link to comment Share on other sites More sharing options...
Simon Lovell Posted April 12, 2016 Share Posted April 12, 2016 Voila! Link to comment Share on other sites More sharing options...
Keith Posted April 12, 2016 Share Posted April 12, 2016 On 11 April 2016 at 10:32 PM, StreetMeatNYC said: I had assumed most of it was coming from the electronics and board, not the motor itself? Don't forget that, actually, there is very little real difference between a motor and a speaker, they both have electromagnetic coils and magnets. The speed controllers I use for model aircraft all emit loud beeps through the brushless D.C. motors they are connected to using them as speakers, during controller set-up or to indicate an unsafe condition (powering on with the throttle on full, etc.). I was assuming that the tone that is being heard here is possibly the pulse frequency (PWM) that the controller is sending to the motor being of high frequency? Do we know that is not the case with these? If I'm understanding @Jason McNeil correctly though, do I take it is a believed to be a frequency caused mechanicly writhin the motor itself? in which case it must be similar to the way an air raid siren works I.e. Chopping the air at high frequency. If it is an electronic PWM frequency the tone will be the more or less the same frequency at any speed, but may change in volume with speed. If it is mechanical it ought to change frequency significantly with the speed the wheel is moving - in much the same way as an air raid siren does. BTW, I cannot hear any sound at all (or it is a frequency above my 60 year old range) on my KS-14C, it has always amazed me just how quiet it is. Link to comment Share on other sites More sharing options...
StreetMeatNYC Posted April 12, 2016 Share Posted April 12, 2016 6 minutes ago, Keith said: @Jason McNeil BTW, I cannot hear any sound at all (or it is a frequency above my 60 year old range) on my KS-14C, it has always amazed me just how quiet it is. 60 years old and riding an EUC... I love it!!! I'm gonna guess it's not as quiet as you think Link to comment Share on other sites More sharing options...
Tim Haden Posted April 12, 2016 Share Posted April 12, 2016 @StreetMeatNYC Would be great to see some video of you on a roll! Link to comment Share on other sites More sharing options...
Jason McNeil Posted April 12, 2016 Share Posted April 12, 2016 25 minutes ago, Keith said: If I'm understanding @Jason McNeil correctly though, do I take it is a believed to be a frequency caused mechanicly writhin the motor itself? in which case it must be similar to the way an air raid siren works I.e. Chopping the air at high frequency. Ha, I probably should have been more clear: I imagine the dozens of meters windings in the motor housing amplify the PWM frequencies to create the acoustic sound that we hear? Falling back to my infallible "Electric Motors & Drives- Fundamentals, Types & Applications" 3rd, Guidebook, pp. 75: "though when the converter is used to feed a motor, the sound from the motor is usually a good deal louder than the sound from the converter itself. These sounds are very difficult to describe in words, but typically range from a high-pitched hum through a whine to a piercing whistle. They vary in intensity with the size of converter and the load, and to the trained ear can give a good indication of the health of the motor and converter." Link to comment Share on other sites More sharing options...
dmethvin Posted April 12, 2016 Share Posted April 12, 2016 37 minutes ago, Jason McNeil said: Ha, I probably should have been more clear: I imagine the dozens of meters windings in the motor housing amplify the PWM frequencies to create the acoustic sound that we hear? Am I the only guy around here old enough to remember flyback squeal from TVs and monitors? When you're young you can hear the noise, usually around 18KHz, and it's grating. The solution is usually coil dope, basically a glue or paint you put on the coils to prevent them from moving. Link to comment Share on other sites More sharing options...
Jason McNeil Posted April 12, 2016 Share Posted April 12, 2016 I don't know if the coils are actually physically moving, since they're wound pretty tight. It might be worth opening my demo 16" Wheel up when it finally arrives & trying that glue stuff—today I learned my freight-forwarder screwed up with my long awaited KS18s & 14Bs, that didn't get loaded onto the train, so are still in LA after nearly three weeks FutureWheel.nl posted some interested photos of inside the KS14 800W today. Link to comment Share on other sites More sharing options...
Chriull Posted April 13, 2016 Share Posted April 13, 2016 8 hours ago, Jason McNeil said: Ha, I probably should have been more clear: I imagine the dozens of meters windings in the motor housing amplify the PWM frequencies to create the acoustic sound that we hear? ... The coils/winding themselves should not really move and produce the sound. Imho that would be quite a wear for the insulation of the windings, which is some form of varnish/paint. This also could wear down the whole structure (magnets, rotor) if there is something resonating/moving with 6 and 12 kHz.... When googling for "bldc pwm noise" i found http://ww1.microchip.com/downloads/en/AppNotes/00771b.pdf - which states as source for the pwm noise the torque ripple. So it should be the (moving) wheel itself which acts as resonator since it is not driven smoothly, but has torque ripples with the frequency of the pwm signal. So the 6kHz whistle could come from the pwm frequency itself (main torque ripple), the 12 kHz from the "slopes of switching" - so that with every (up and down) slope of the pwm signal a second "torque ripple" is produced. Could be that the Kingsong/Gotway controller boards have quite some overshooting when switching the inductive load (motor coils), or just use higher slew rates (faster switching times) - which is on one side advantageous in regard of overheating (less switching losses) but could produce more of the high frequency sound?! Also, if you look at https://en.wikipedia.org/wiki/Equal-loudness_contour at 6 kHz the ear is still quite "sensible" - at around 10kHz there would be a perfect spot for the pwm frequency with quite low "sensibility" of the ears... So in comparison with the Ninebot the main differences should/could be: - The KS motor has 800W instead of 500W so there is more (hearable) effect of torque ripples - The PWM frequency of KS is at 6kHz instead of 8kHz - so the same "sound pressure" is heard better - The slopes of the PWM signal of the KS could be steeper/contain more overshooting so they produce more (additional) torque ripples? ... additionally there are many different "nuances" of how to controll the driver for a BLDC which also could have quite some influence of the PWM noise produced. Link to comment Share on other sites More sharing options...
Gunthor Posted April 14, 2016 Author Share Posted April 14, 2016 @Chriull T h a n k Y o u for your input and the links. Now I know another bit how the EUCs work and what e. g. acoustic PWM noise is... @Jason McNeil You are correct: The fan turns on at 50°C! The "broken ball bearings" sound is coming from the engine and are torque “bursts” causing minute flexings within the wheel resulting as audible “ticking” noise!!! My dealer told me this tonight and said that he tried to get the fan running on opened up KS16s but the fans don't move (he didn't manage to produce the 50 °C!). Concerning the mal functioning odometer: This is related to the firmware and a bug all KS16 have at the moment. Kingsong knows about this and should roll out a bug fix in the hopefully near future. Link to comment Share on other sites More sharing options...
StreetMeatNYC Posted April 15, 2016 Share Posted April 15, 2016 Anyone else think some of this info should be pinned? Link to comment Share on other sites More sharing options...
StreetMeatNYC Posted April 15, 2016 Share Posted April 15, 2016 Fascinating thought on this: Riding around in NYC, I pass A LOT of people. I began noticing that some people had an uncanny ability to know I'm coming from a distance. I've noted it many times and began to pay attention to factors that may give me away, such as shadows, onlookers, etc... I was perplexed until @Keith said "BTW, I cannot hear any sound at all (or it is a frequency above my 60 year old range) on my KS-14C, it has always amazed me just how quiet it is." This is when I realized that its all younger males and females. Just thought it was interesting. Link to comment Share on other sites More sharing options...
EUCMania Posted April 15, 2016 Share Posted April 15, 2016 2 hours ago, StreetMeatNYC said: This is when I realized that its all younger males and females. Just thought it was interesting. Yep, you only need the frequency that is audible and attractive to this age group Link to comment Share on other sites More sharing options...
Chriull Posted April 15, 2016 Share Posted April 15, 2016 Since i just wrote this in another thread regarding the PWM noise - i think that could also be an addition to this topic:" The loudness depends imho on the "state of some wheel parts" somehow. I presume that mine got louder after an exhaustive (for the wheel - not for me ) hill climb including quite some offroad riding..." If this permanent loudness change is not pure imagination from my side, it could mean that there are still some other factors involved, or just some "loosening" parts resonate and amplify the torque ripple? Link to comment Share on other sites More sharing options...
Gunthor Posted April 18, 2016 Author Share Posted April 18, 2016 10 days later: Now here I am with a noisy but stronger EUC and an odometer that is not working. Or maybe it does so now...? A minute ago I updated the firmware to 1.16 - same illogical behavior as when I updated to 1.15: This time the firmware 1.17 is offered but after the upgrade the app shows that 1.16 got installed and offers again to download 1.17! And like Ninebot the Kingsong team also doesn't bother to communicate the bugfixes the upgrade offers! The following days will show if the odometer will work correctly or not. Oh - one more thing: Within the app you are asked to reboot once the firmware is installed. I think they don't mean to reboot your mobile or to restart the app but to restart the EUC in order to get the new firmware going... Two days ago I was riding my 9b1 again and I felt like an inept EUC beginner again. This was surprising because 10 days ago I'didn't even have to think what to do - I only had to look into the direction I wanted to "go" and my body was doing the all the necessary flowing motions automatically without me thinking anything... ...I believe it is because the 9b1 and the KS16 are differently equilibrated and you need to stick with one and the same wheel for some time without switching them. in comparison to the 9b1 I really love the power of the KS16. I don't feel like the engine will stall any moment when climbing a 17% incline and when gliding with 26 Km/h the wheel still conveys the confidence that it was designed for more. So what do I do? I decided to get engaged with the KS16 because of the fun it offers knowing that there is a high pitched whining noise especially downtown where it reverberates very well from the walls of the adjacent houses and hope that in the years to come there will be a noiseless EUC that I will replace it with. BTW: I added another good point to the list I started off this thread... Link to comment Share on other sites More sharing options...
Chriull Posted April 19, 2016 Share Posted April 19, 2016 Just got an idea regarding the PWM Noise: the speakers of my KS16 play quite some electrical noise (hearable in quiet surrounding).Could be that they also "play the PWM Signal" and are one of the/the main source of the high pitched noise? Maybe someone here, who knows how to open ths ks or already has it open by accident could try to disconnect the speakers and hear if there is any difference? edit: or its maybe enough to turn sounds (?speaker?) off with the new app? Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted April 19, 2016 Share Posted April 19, 2016 On April 15, 2016 at 7:33 PM, StreetMeatNYC said: Fascinating thought on this: Riding around in NYC, I pass A LOT of people. I began noticing that some people had an uncanny ability to know I'm coming from a distance. I've noted it many times and began to pay attention to factors that may give me away, such as shadows, onlookers, etc... I was perplexed until @Keith said "BTW, I cannot hear any sound at all (or it is a frequency above my 60 year old range) on my KS-14C, it has always amazed me just how quiet it is." This is when I realized that its all younger males and females. Just thought it was interesting. Link to comment Share on other sites More sharing options...
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