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- Опубликовано: 17 апр 2018
- QUICK teardown of the failed KRK Rokit 6 textile (soft) dome tweeter.
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The foam is to absorb (dampen) the back phase of the tweeter.
And the coil is not burnt, it just has broken wire because of too big excursion. You could unwind one loop and solder it to its contact again.
I only use tweeters while watching Dave's videos... that's all that is required!
I'll pay that.
@@EEVbloglol it’s been 5 years! Just reminding you about this video
You should have pushed the dome in with your finger to get that endorphin rush. Then do the teardown.
The Dollar Guy Haha, I thought I was the only one who dreamed of doing that. Sort of like when round items (water bottles, or cans in cardboard flats.) are heat shrinked, and the plastic covering the space between the cans is begging to be poked with your finger.
Damn, missed it!
Imma make sure to do this🤣🤣 got some roland ds90s on the cheap with blown tweeter coils so its perfect
Thought it was a couch foot on the thumbnail!
he already has a box full of couch feet lol
Great teardown!
pretty much that is how all tweeters looks like and this coil should be connected to the dome
in poland, regeneration of our domestic tonsil brand speakers of this kind is quite popular because coils are avalable as replacement parts for a fraction of the price of new ones. besides they were made in custom colors for some speaker systems. i fixed some in the past and replacing those coils is not that hard, because most of them is self centering design.
The foam dome is used to dampen the sound of the diaphragm. Usually proper tweeters use silk.
The foam absorbs the rear wave of the tweeter. The tweeter emits the same amount of sound from the rear of the diaphragm as from the front, and something has to be done with that acoustic energy before it reflects back to the dome and is re-radiated through the thin dome material, out of phase with the drive signal. Also, yes - tweeter voice coils are very small. I have seen some smaller ones - just 16mm.
The voice coil is likely to be double layered.
Watch out for breaks around terminations, they can sometimes be repaired!
The foam is there to dampen any resonant frequencies between the diaphragm and the flat metal surface of the magnet assembly.
As the distances between the diaphragm and the flat metal surface are within the wavelength of the sound being reproduced, removing the damping will introduce harmonic distortion due to resonances.
When restoring tweeters this fact should always be taken into consideration. Failure to do so will lead to replacements sounding metallic and really rather rubbish, compared to the original.
Human hearing is designed to comprehend and assimilate the most minute phase differences between ones ears, that is how we hear in 3 dimensions.
We are born with 2 ears, both of which are phase correlated to each individual. We all naturally hear the world in binaural vision and can hear direction through 360 degrees in the x and y plane (quite amazing if you think about it). This is achieved by our brain being able to ascertain phase correlation differences between both input sound pressure waves.
Sorry. Geek Rant End :-))
Since it is a tiny little sealed cabinet in there tuned to the frequencies necessary for the frequencies produced, the foam is also used to tune it to the right frequencies. A solid, compressible fill would increase the theoretical volume inside the cabinet.
That is typical construction for a cheap dome tweeter, the speaker may be open circuit where the break may be where the tinsel lead is soldered to the voice coil.
Right at 1:38, you can see were the epoxy is rubbed off the winding and it's darker (heat) is most probably the point of failure.
The foam is not doing nothing, it is for dampening accustic resonances but still allowing movement of the air inside the whole tweeter assembly into the permanent magnet housing. You're compressing and depressing air with any dome movement, so the air inside has to move and deal with that. :)
BTW: almost any speaker modules are "moving coil in permanent magnet" type as you would need special amplifier devices that can deal with the high voltages that electrostatic devices would need to provide the electrostatic forces needed for an electrostatic speaker.
I would agree that there actually may have been some ferrofluid there because you see some brownish gunk on the coil carrier material (the aluminium foil-ish tube). Maybe that's the cause why the coil did not get really dark and did not have black burning marks, because it still did get some kind of cooling as long as there was flluid left. The whole thingy must have seen massive signals that heated up the whole coil carrier which then probably did weaken and rip off the whole coil assy from the dome. That's why the coil assy was still in the slot when you dismounted the soft dome.
Dave trying to understand the black art of acoustics! Excellent :)
The hole is standard, its to equalise the cone pressure to ambient air pressure as its moving. The foam is to prevent the dome crashing against the magnet at high excursions.
Wrong on both accounts; the hole leads to a resonant chamber in the back and the foam is to even out impedance as well as a simple protection for the dome to be caked down from external objects, like your finger pressing on it and the dome gets stuck in a concave fashion.
Vresiberba: No, the hole is not for resonant reasons like a ported box for example, this is an high frequency driver that does not support front pressure reinforced from rear radiation, how could it?, high frequencies are highly directional and would not even make it back thru the enclosure port; they would bounce about in the enclosure much like a ping pong ball.
I am not wrong about high excursion protection; that is the primary reason, to protect against someone pressing the tweeter? no thats why speakers come supplied with grills!.
Did you know a lot of woofers also have this hole?, do you think they use it as a resonant port too? LOL.
Yes, it's a resonant chamber, it's obvious seeing that it has a cup behind the pole piece and it's a closed cavity, just like a NON-ported speaker because otherwise it wouldn't work due to the relatively small membrane. Just google it. Dynaudio and Scanspeak uses this technology in a lot of their tweeters including the ancient D-28 I'm holding in my hands; it has a hole through the pole-piece and a plastic cup behind the magnet with a small dampened chamber.
And there's no such thing as a "high excursion protection" on a tweeter, that is something you completely made up.
www.stereo.net.au/forums/uploads/monthly_12_2015/post-154025-0-34455500-1449297557_thumb.jpeg
Vresiberba: I suggest you read a book like 'Loudspeaker Cookbook' or the many other publications out there that describe why drivers have this hole, really no point trying to convince you. I have been working with speaker design for a couple of decades. You completely ignored my reasons why the hole could not work as a resonant port like a ported speaker, just doing a basic port calculation would prove my point, look it up.
KRK Rocrap :)))replace the tweeter with couch feet! Will sounds the same....
which one is good for cheap?
artifactingreality Dave holds a lot of couch feet ...soooo the couch feet? :)
back in the 70's i took apart "woofers" (note quotes) that had magnets about that big! lol
There is indeed a lot of design that goes in to making these things work well. The magnetic field linearity, the suspension linearity, resonance in the cavity, dome profile and doping agent. The list goes on.
Simon Ashton Plus whatever can be compensated in the filter!
“I believe the coil was glued to the dome”...come on, you surely KNOW this!
oh god. there it is... thousands of these buggers i've replaced... literally THOUSANDS... one of the connecting wires to the coil becoming disconnected before the blue dab of glue was common....
The thing lies guts out : ladies and gentlemen, I don't where it's blown. Is it ?
How do I attach my wires back on to terminals from the coil. They are now too short. Can I unwind some of the winding from coil? Solder heat? I assume very low? What guage is this coil wire and who sells it?
come on dave, where is your adventurer spirit? lets have some fun repairing this tweeter
this
I'm curious to know how it would sound compared to the original
Better pro audio tweeters can be reconed, you can order the entire thing (all moving parts) as a kit. I done that many times when i was in the pro audio rental biz.
1:39 you can see the blowout as white shmoo with a bit of darkness in the middle. that'd be where it'd blown out
1:44 you can see the black spot next to the light reflection off the coil
the foam on the magnet is a damper for the sound at top end
How long before Dave starts selling speakers out of the back of an unmarked white van?
How do you know I don't already?
Multiple sources of income
Jazz Rock You can't set the prize too low or they won't buy it. And you obviously need special audio grade ferrofluid
I'm such an idiot for going to work every day..
Okurka Maybe not kickstarter but indiegogo absolutely is the new white van
Please help me. I have a problem Speaker KRK ROKIT 6 GEN 2. Bass / Subwoofer sound is very audible from the sound the original. Sometimes a tweeter dies and lives again, dies again, so over and over again. I think what parts should I fix?
Hey EEvblog. On the Tweeter diaphragm right where the solder is for wire to pigtail is cut right there you could not see it with your Naked Eyes you have to put that under a microscope I do a lot of repair for these things back in the day now I prefer change them.
Wow, after that thrashing the coil actually survived well, the driver failed mechanically.
Yeah, surprising.
So happy i never got one right now :3
Foam helps to damp out
the resonant frequency of the dome itself , all vibrating objects have their own resonant frequency !
If you do a multimeter test between the actual tweeter terminals and the coil wire you'll probably get non conductivity on your DMM.
There is a rear chamber on this tweeter. The hole in the pole piece is there to vent the air generated from the rear of the dome into the rear chamber. This lowers the fundamental resonance frequency. The foam is there to help absorb reflections off the surface of the pole piece. Design of this tweeter is standard, but the rear chamber is something of an enhancement. Build quality looks shoddy from here.
Don't know what "fancy" Dave expected to see, this is how a dome tweeter works, even $2500 Dynaudio dome tweeters are identical in construction.
Chineseium
Speakers usually consist or a coil, spider, magnet , cone (if its bigger) and dustcap. The film or foil or metal the coil is wrapped around is shot, coil didnt look to bad itself, if its unusually dark the coil is blown, fck rewinding a coil btw
I didn't know you tweeted!
hi dave you its not top shelf so how much different would a top shelf tweeter be?
those are silk soft dome tweeters and can be replaced very easy, they on sale on EBAY for a small price
www.ebay.com/itm/KRK-Rokit-5-6-8-Generation-2-Tweeter-Part-TWTK00012-For-Studio-Monitor-Speaker-/151596761678
reconingspeakers.com/product/krk-rp568-rp568-g2-rp6se-tweeter/
Do you know what exact textile the tweeter material is? I have one that’s deteriorating. The other is not. Maybe 2 different suppliers.
have you found out?
Hey Dave, Tried to log into the EEV Blog forum today.
Got the following message "
Please try again. If you come back to this error screen, report the error to an administrator."
I Tried again and I came back to that same error screen. This is the only way I know of on how to 'report the error to an administrator'
Have you seen oil in the power transformers, if so do you know what it is
Is that coil printed on a flat flex?
in most pro audio PA systems the voice coil isnt too dissimilar. The replacement part for my EV DH1 horn/tweeter which is worth a few hundred dollars is basically the same just a titanium i think domeand a few more windings. My thoughts with most products is the difference in cost between cheap crap and expensive stuff is bugger all the rest of the money is marketing.
The product that cost $2 and sells for $5 vs the product that costs $4 and sells for $200
Nice video, needed more couch feet!!!
You can buy recones on Ali for a couple of dollars, they look similar.
I have tweeters and the coating on the soft dome has flaked away. Can I use some sort of paint to recoat the dome.
have you found a solution?
You should do a teardown of that PS4 controller you got.
I think you are right. The voice coil isn't blown. It just came unglued from the speaker cone.
It's actually broken, I measured it.
When you measure it with a DC Ohms meter, it'll surely be broken afterwards. Tweeters do not like DC.
Errrmm, are you suggesting that a digital multimeter is putting out enough power to destroy a tweeter?
DMM has no enough current to blow a voice coil
Too bad you can't find replacements anywhere now, rumor is going chapter 11 and all replacements are out of stock.
I will bet if you glue the diaphram back on to the coil and stop destroying the coil... I bet it would work
Dave,
Any interest in doing a video on LoRa Wireless Communications? Im working on a project at work designing around a LoRa network and i find it to be beneficial for the frequency range to be utilized in industrial applications
Get Medevil on it Dave! 😁
hi do you have voice coil for pt6a pioneer tweeter
Totally standard way to construct a dome tweeter.
Tweeters generally blow at the connection of the lead to coil wire. The black glue shit iow.
Mailbox soon?
has not blown its detached from the dome & is not repairable as it needs to be 100% central between the magnet & outer casing
I fried my old speakers on purpose, it had ferrofluid tweeters and man, that smelled bad :D
Nice KRK plastic quality drivers...
Given the flame on the logo, I think they are supposed to be the 'Rocket 6'. Or am I being trolled
Maybe you can teardown an AMT or folded ribbon tweeter
In the background I heard a Canon camcorder timing out and shutting itself off. :-)
A generally naff speaker intended for audiophools..the modular amplifiers are a long, long way from any sort of quality and the drivers are cheap.
+405line I literally can think of 0 audiophools who would buy these. These are monitors, mostly marketed towards bands and engineers that deal with bass-heavy music
When I say audiophools I mean people who don't believe that some things can and do sound better than others and that "it all makes no difference" whatever the equipment is. An audiophool is the opposite of an audiophile in my universe.
Oh ironically :) yeah I can get behind that:)
I am not surprised. The KRKs sound awful even compared to cheaper monitors. They only have a slight advantage at the low end. Probably why they are used for hip-hop and the like. But imho the advantage is not enough to justify the crappy mid-highs.
Now I am curious to see what Yamaha and JBL are using
Hey can you do a teardown of my mother in law? She's constantly overexerting and sounds horrifically distorted Maybe she's blown
What did Dave mean with "it's a moving coil type"? Aren't all speakers "moving coil"? (Except for piezos). I know "Moving magnet" only from turntable pickups.
Ribbon tweeters aren't moving coils, heck they don't have a traditional coil at all but surly that was evident by simply establishing that it's a dome tweeter.
Good point, thank you!
Most audio equipment is wank. I'm surprised you were surprised at the design.
You could probably find a basic calculator equation for voice coil design with a few Google's.
1:40 "It's been *blowen* " - Funny Australians 😆
Blown. Not 'blowen'.
Not many turn's and a flimsy coil former. The old Kef and Seas tweeter's were a lot better built, no wonder it died so easily.
I'd love to see such KEF or Seas teardown here.
Me to- But they´re hard to find and it would be a shame if they are destroyed by the teardown ;.)
I'm less than impressed with the KRK Rokit 6 powered studio monitor at around $300au each, I'm sure it does the job but the parts are cheap, amplifier module is very ordinary, you don't get much for you're money. I prefer to make my own speakers.
I took apart my headset, somehow broke one of the two speakers in it while doing other repairs, only to discover that I could get nearly identical replacement speakers for $1.80. The headset costs $270 new. (I bought it used.)
I haven´t noticed any change in audio quality with the new spealers. They are of similar construction as the ones in the video.
Beats?
Just because it looks similar, it's not the same.
Prehistoricman no, Sound Blaster Evo ZxR. You do get more than just a couple of cheap drivers for your money, but I still wouldn´t recommend them anymore.
Frank Gormanns I took them apart further than dave did. Other than the dimensions and impedance, mine were practically the same.
Basement ScienceE Prices for this thing are absolutely crazy.
You can get these here for anywhere between 140 down to 37 euros new.
Frank Gormanns do you mean this exact headset? there are a few variants. Anyway, I got it probably around 3 years ago for 150€ almost unused. Wireless headsets always seem to be in this kind of price range, at least if you want any kind of build quality.
The real problems with this thing are design problems:
1. it uses an internal Lithium battery that charges over micro-USB. That usb port has broken the first time maybe 2 years ago. It´s simply not a good connector for something you have on your head while plugged in. I have since replaced it with a round connector. (not perfect either.) Of course the battery has lost more than half of its capacity by now. I will replace it in the near future, which means taking it apart again. A replaceable battery system would be much better.
2. Bluetooth. Do I have to say more than that? It´s simply not properly implemented in any OS. In Linux I am yet to get any sound out of it, in windows I cannot use the microphone and speakers properly at the same time. On android it sort-of works. At least it doesn´t lose its connection and has a decent range.
Diamond tweeter domes FTW! check out www.bowers-wilkins.com/Discover/Discover/Technologies/Diamond_Tweeters.html ..leaves that crappy "textile" dome for dead!
Is 'cactus' a new Australian term for f'ed up? ;)
2:19 he must sit in a room and think of Australian things to say during his videos
Thats a quality for ya lol :D
foam is covering a vent hole
I used to call these "screamers" when I was young.
The dome is caled a diaphragm btw
Actually, no, KRK call it a dome, and "soft dome" is a common industry term for it.
A diaphragm and a dome, because not a cone.
Wicked
High end audio...where the cheapest looking piece of junk can sound better than something that looks made in a Swiss lab. Half dark magic, half ridiculous engineering.
thechosendude yeah it's sad
... And 100% marketing...
Khron's Cave true high end is not usually the stuff you hear about
On one hand, depends what circles you hang around in. And on the other hand, what actually is "true high end"?
There is actually some truth to this. Some of the most mundane looking speaker drivers actually have incredibly good performance. Others from 'boutique' manufacturers with very unique designs, exotic construction materials and insane tags turn out to be mediocre performers.
Whenever you say "cactus," I think you're getting ready to eat the thing.
You don't even have cactus in Australia, do you?
Not natively, but see...
en.wikipedia.org/wiki/Prickly_pears_in_Australia
quite possibly the origin for the Australian slang terms; In the cactus: In trouble. Back to the cactus: (Back to) the boondocks. Cactus: Broken or ruined.
Have a nice day.
No ferrofluid? edits:lol right before the video said it.
40 volt square wave
Here's a tear down video
ruclips.net/video/CpCrkO1x-Qo/видео.html
Yes. Eyesight fades out with time.
Hi Dave.
I’m almost sure that the reason why the tweeter failed is because the dividing network failed and the tweeter thereby was overloaded with low frequencies which the tweeter was’nt designed to reproduce.
Your comments are very welcomed and appriciated 😉
Thx your vids🙏🏻
Best Regards
Whisky Hotel Yankee "Oscar" & Alpha Lima Sierra Oscar "One"?
@ Caalamus:
My radio amateur Call sign is
OZ1OS
😉
Oscar Zulu OneOscarSierra Victor Kilo Three Hotel Alpha Uniform
Yankee Echo Alpha Hotel, Bravo Uniform Tango... "Oner" November Oscar Tango "One" :]
Oscar Zulu OneOscarSierra Actually the amp after the filter shorted out and pumped high volume self-generated hum into Tweety Bird. Filter did nothing.
Michael Faraday 😃
Black gunck of deth..... Jezzz... 😂😂😂
Thats a tiny tweeter for a pro speaker.
I mean the magnet assembly.
PsYcHZ It obviously needs to be minimum weight to handle the frequency.
People often overestimate the requirements on tweeters and subwoofers in terms of perfect reproduction. The human ear is nowhere that accurate in those ranges, so you can get away with much less effort than the mid-range speakers.
Music producers need that in order for your mid-range speakers to sound good.
HIGH
Could they not have used a ceramic or Piezo transducer for the tweeter.
Lol blowen
You should get glasses or contacts.
Err, the resolution of the camcorder LCD screen is limited, it's not full HD.
I'm early! :)
Dave face realty you need glasses mate
Hmmm - you know nothing about speakers :-(