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Second hand GT16, interesting mix of highs and lows


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10 hours ago, Hunka Hunka Burning Love said:

Gonna post up some ride videos?  :popcorn:  You know we want to see 'em.

Man this Korean guy is going pretty fast on one forwards and backwards... this is from November of last year too!

 

Jees... I can barely go backwards at all yet. Let me become a bit cooler first, then I can start thinking of shooting videos :D

 

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Man that whining noise is horrible! I was drooling after the GT16 as an upgrade for my Lhotz, but it seems I couldn't handle the noise. My choice might now be limited down to the Gotway ACM.

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On 6/14/2017 at 6:51 AM, Scatcat said:

Jees... I can barely go backwards at all yet. Let me become a bit cooler first, then I can start thinking of shooting videos :D

 

That is very cool.  And I also got a kick out of the little girl whizzing along on her own cute pink EUC!

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2 hours ago, mrelwood said:

Man that whining noise is horrible! I was drooling after the GT16 as an upgrade for my Lhotz, but it seems I couldn't handle the noise. My choice might now be limited down to the Gotway ACM.

Yes because we all know the ACM is whisper quiet.  :whistling:  :efee8319ab:

I think all these higher speed, higher wattage wheels emit their own distinctive hum.  I think people get used to it, but as a plus at least it warns people to get out of the way as they can hear you approaching?  I bet at higher speeds you probably won't notice it as the wind noise would be louder.  Maybe think of it as the sound of the future, and you'll get used to it... 

 

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1 hour ago, Hunka Hunka Burning Love said:

Yes because we all know the ACM is whisper quiet.  :whistling:  :efee8319ab:

You should hear my ACM Hunka! Super quiet! :P

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2 hours ago, mrelwood said:

Man that whining noise is horrible! I was drooling after the GT16 as an upgrade for my Lhotz, but it seems I couldn't handle the noise. My choice might now be limited down to the Gotway ACM.

I hardly notice the sound anymore. Especially not when going beyond 20mph :) 

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The GT16 sounds pretty annoying in the video, but the ACM does as well Marty's video, and in reality it's not nearly that bad.

Can anybody compare the GT16 whine with that of a Gotway? Is there a notable difference?

Btw, if you want a silent powerful wheel, the KS16S seems amazingly quiet and whine-free. Check out the review video posted by @Lukasz. Either his camera is very different than the others, or the 16S really is remarkably quiet.

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3 hours ago, mrelwood said:

Man that whining noise is horrible! I was drooling after the GT16 as an upgrade for my Lhotz, but it seems I couldn't handle the noise. My choice might now be limited down to the Gotway ACM.

I've ridden the GT16. It is louder than any other wheel I've used (ACM & MSuper for sure). That being said, you still can't really hear it much as the rider because of the wind noise in your ears.

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It's definitely electrical. You can hear, and it can't be mechanical anyways as it happens when the wheel is perfectly still. Made a video but you can't really hear it there, so I guess it's not that bad. I mainly noticed as my first ACM motor didn't do that (or I didn't hear it).

But some arcing is definitely there when the wheel is still or nearly still, sounds like the Gotway magic gnomes have a tiny tumble dryer full of tiny rocks;) Interestingly, it gets notably louder when you switch on the light (heard that with my old ACM too), so if you ever come across an ACM, you can try.

edit: as per the light thing, it may or may not be the actual motor itself doing the sound.

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1 hour ago, Hunka Hunka Burning Love said:

Really?  I haven't heard of anyone mentioning that the ACM does that.  Do you have any video?  :popcorn:  I wonder if it's arcing or maybe noisy bearing ball bearings shifting around or something else.  Is it definitely electrical sounding?

You missed the follow-on thread where we discussed this. @captainwells shot a video demonstrating the crackling sound, and that it got worse when the light was on. Than I went to my ACM and sure enough I can hear the crackling sound, but only when I stick my ear close to the case. And when I turn on the light the loudness of the crackling sound increases dramatically.

So all of these powerful wheels make the sounds. It's not coming from arching.

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30 minutes ago, meepmeepmayer said:

It's definitely electrical. You can hear, and it can't be mechanical anyways as it happens when the wheel is perfectly still. Made a video but you can't really hear it there, so I guess it's not that bad. I mainly noticed as my first ACM motor didn't do that (or I didn't hear it).

But some arcing is definitely there when the wheel is still or nearly still, sounds like the Gotway magic gnomes have a tiny tumble dryer full of tiny rocks;) Interestingly, it gets notably louder when you switch on the light (heard that with my old ACM too), so if you ever come across an ACM, you can try.

edit: as per the light thing, it may or may not be the actual motor itself doing the sound.

It can't be the actual motor. Must be the electronics. maybe @esaj has a theory on what's generating the crackling sound (which is in addition to the whine from the motor as it's running)?

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Yes I did miss that video!  Found it.

My theory is that there are small Tesla coils emitting mini-lightning strikes on the magnets!

Here's an interesting article on the subject:

http://www.jimhendershot.com/Jim_Hendershot/Articles_files/causes%26sources of audible noise in elec motors.pdf

 

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36 minutes ago, Marty Backe said:

It can't be the actual motor. Must be the electronics. maybe @esaj has a theory on what's generating the crackling sound (which is in addition to the whine from the motor as it's running)?

I believe the mosfets would die far before the voltage can go high enough to actually cause arcing in the motor. And even if the motor would cause internal arcing, it would likely burn through the insulation lacquer or whatever they use and ruin the motor. Maybe the step-down coils "whine" with the frequency at which they're being pulsed (or some lower fundamental of the step-down frequency, likely the actual frequency is much higher than audible)?

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37 minutes ago, Hunka Hunka Burning Love said:

Yes I did miss that video!  Found it.

My theory is that there are small Tesla coils emitting mini-lightning strikes on the magnets!

 

Tesla coils are awesome, there was one at a museum that you could charge and fire but it had something like a 45 minute time between firings.  It was pretty large, and when it went off the smell of ozone was everywhere.  Read a book on Nikolai Tesla, he was a genius but tested x-rays on himself and some think that caused his health to fail.  He sold a lot of patents for very little money and died a pauper, what a shame, while Edison made a small fortune with his inventions.

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22 minutes ago, esaj said:

I believe the mosfets would die far before the voltage can go high enough to actually cause arcing in the motor. And even if the motor would cause internal arcing, it would likely burn through the insulation lacquer or whatever they use and ruin the motor. Maybe the step-down coils "whine" with the frequency at which they're being pulsed (or some lower fundamental of the step-down frequency, likely the actual frequency is much higher than audible)?

Coils tend to give of harmonics of the frequency they run on, don't they? Even the toaster does it...

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12 minutes ago, Scatcat said:

Coils tend to give of harmonics of the frequency they run on, don't they? Even the toaster does it...

Yeah, if you have a spectrometer (I don't, they're really expensive :D), usually you see spikes at higher harmonics of the fundamental frequency, but it can work in reverse too, there are spikes in lower fundamentals of the highest spike. Many step-down switching mode voltage regulator control chips use frequencies in the 100's of kilohertz frequencies or even megahertz, but they can still cause lower frequency components to emerge and/or the coils to start mechanically moving (very slightly) at lower frequencies and emitting a sound.

Image result for switching voltage regulator frequency spectrum

 

 

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4 hours ago, Hunka Hunka Burning Love said:

It's been too quiet these past months!  Get riding that thang!  (and post up some videos! :popcorn:)

I was so close yesterday! Everything is wired, side panels back on, turned it on and the ACM came to life:w00t2:and then I turned on the fan.:crying:I mounted the damn thing upside down and it was sucking in air as opposed to blowing it out. Discouraged I left and headed to the lake. What's a few more days? Maybe GW will have some answers by then. :confused1:

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23 minutes ago, Rehab1 said:

then I turned on the fan.:crying:I mounted the damn thing upside down and it was sucking in air as opposed to blowing it out.

Hey, either way it's going to give a cooling effect.  And you can always turn it the other way and compare cooling efficiencies!

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