Author Topic: EEVblog #1076 - KRK Textile Dome Tweeter Teardown  (Read 4245 times)

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Online EEVblog

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EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« on: April 18, 2018, 10:14:16 pm »
QUICK teardown of the failed KRK Rokit 6 textile (soft) dome tweeter.

 
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Online langwadt

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #1 on: April 18, 2018, 10:44:24 pm »
I'm surprised that you seem surprised at what inside, it is just like pretty much every speaker that ever existed
 

Offline G7PSK

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #2 on: April 19, 2018, 08:03:46 am »
Usual thing that fails on abused speakers is the ligament connection comes adrift. I have soldered a few back on over the years.
 

Offline b_force

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #3 on: April 19, 2018, 09:31:28 am »
The coil is attached to the dome.
It's a moving piston.
Well, tweeters are an awkward kind of that.

You know what the surprising part is?
Tweeters are all build the same way.
The reason why some cost more than good scope is just something that blows our minds.
I guess the marketing department did their job very well.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

http://www.oneworldconcepts.com/ | http://www.soundprojects.com
 

Online Brumby

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #4 on: April 19, 2018, 01:09:25 pm »
It isn't clear that when the textile dome was removed whether it was still attached to the coil. Was the voice coil already ripped off the dome? It seemed that Dave was looking for a break in the coil.

Would the coil and dome separation be enough to render it kaput?

Absolutely.  The coil creates mechanical movement in the cylinder it is mounted on, but it vibrates longitudinally, with almost no compression of the air.  It is only when this is attached to the diaphragm does this movement create significant air displacement.

Separate the two (by a massive excursion of the voice coil ripping it from the diaphragm, for example) and the volume will drop to practically inaudible.
 

Offline gardner

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #5 on: April 19, 2018, 02:25:15 pm »
Is the coil blown? Where is your multimeter, Dave?  Maybe it would have been interesting to compare the resistance and inductance or AC impedance to a known good one.  Maybe even fiddle around with a sweep generator.

Just ripping the soft dome off is a little disappointing.  I did that when I was 10.
--- Gardner
 

Offline thm_w

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #6 on: April 19, 2018, 08:35:37 pm »
I'm surprised that you seem surprised at what inside, it is just like pretty much every speaker that ever existed

Some people haven't taken a tweeter apart before, or know thats part of their audience.

Is the coil blown? Where is your multimeter, Dave?  Maybe it would have been interesting to compare the resistance and inductance or AC impedance to a known good one.  Maybe even fiddle around with a sweep generator.

He measured open circuit in the previous video.
« Last Edit: April 19, 2018, 08:39:52 pm by thm_w »
 

Offline b_force

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #7 on: April 21, 2018, 10:46:46 am »
I'm surprised that you seem surprised at what inside, it is just like pretty much every speaker that ever existed

Some people haven't taken a tweeter apart before, or know thats part of their audience.

Is the coil blown? Where is your multimeter, Dave?  Maybe it would have been interesting to compare the resistance and inductance or AC impedance to a known good one.  Maybe even fiddle around with a sweep generator.

He measured open circuit in the previous video.
Electro- acoustic engineering in general is not taken much serious anymore these days.
Or "engineers" think they can solve everything with electronics (but they don't always realize physics have its limitations), or it just has a very bad reputation thanks to all the "believer engineers".
People who have been in the field, but never read any decent literature or follow respected society (ALMA, AES etc)
It's to bad, because it's actually a extremely interesting combination of all kinds of different physics.

Even in the Youtube comments someone seems to have a difficult time talking some sense to people.
Debating and discussing subjects is just pretty much impossible when people mix up facts with personal believes.
« Last Edit: April 21, 2018, 10:48:30 am by b_force »
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline GerryBags

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #8 on: April 21, 2018, 02:20:00 pm »
Well, I thought that was a great little tear down. I too have often wondered what was inside one of these hifi tweeters. My old Dad has been telling me to watch his effing tweeters for the last forty or so years So no chance of getting hold of one of his and I've only ever had fairly shitty speakers myself, for some reason.

Also, even if I HAD got hold of a quality tweeter and took it apart there is no way I'd have got as good a look at it. Dave's zoomy cam-work beats any combo of my own eyes and any magnification apparatus I own. Prolly beats his own, too, given his slowness to spot the multiplicity of turns on the voice-coil.

That was good sheep, anyway. :-+
 

Offline artag

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #9 on: April 29, 2018, 01:43:44 am »
Fairly disappointed by the innards of this KRK speaker. I know they're not crazy audiophile territory with gold-plated mains plugs but I thought they were reasonable 'studio monitor' quality for the average musician. Certainly better than you'd get from a high-street box shifter.

From the pcb, and now the tweeter, they look like cheap consumer tat that could have been made in the '70s. I don't see anything in there that looks remotely technically advanced or even decent build quality.
 
 

Online EEVblog

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #10 on: April 29, 2018, 02:18:16 am »
Also, even if I HAD got hold of a quality tweeter and took it apart there is no way I'd have got as good a look at it. Dave's zoomy cam-work beats any combo of my own eyes and any magnification apparatus I own. Prolly beats his own, too, given his slowness to spot the multiplicity of turns on the voice-coil.

Yes, it looked like a solid single turn band to my eyes.
I don't have the best near-field focus any more, but still it's tiny. Things look very different in real life then they do on a full HD monitor recording.
Just x2 magnification is enough to bring it out nicely though.
« Last Edit: April 29, 2018, 02:23:26 am by EEVblog »
 

Online EEVblog

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #11 on: April 29, 2018, 02:22:25 am »
It isn't clear that when the textile dome was removed whether it was still attached to the coil. Was the voice coil already ripped off the dome? It seemed that Dave was looking for a break in the coil.
Would the coil and dome separation be enough to render it kaput?

Yes, the coil ripped off the dome due to the extreme excursions caused by the 40V low frequency square wave. I could physically feel the coil slamming hard against the ends of the travel when it was oscillating.
That is a different failure mode to the open coil itself.
 

Offline gslick

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Re: EEVblog #1076 - KRK Textile Dome Tweeter Teardown
« Reply #12 on: May 02, 2018, 12:15:44 am »
Unrelated side note, KRK is owned by Gibson Guitar Company, which filed for Chapter 11 bankruptcy protection today.
 


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