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Could the cover on the phono jack be to block the air path so it all goes through the bass port on the front?

The gunk is carefully engineered to become conductive shortly after the warranty expires.

Two donkey’s years later and your video just saved me the expense of replacing my KRK Rokit8 Gen2 speakers at a time that I can little afford new toys. Mine suffered from the same issue. Cleaned up and good as a bought-again one! Thank you Dave.

That black gunk is an A/B potting compound, similar to "Smooth-on Smooth-Cast Onyx" I used similar to pot filters back in the day... What tends to happen is that they have a shelf life, and if you use it after its shelf life, it WORKS but the chemicals debind over time because they do not fully cure and when they break down, they break down into a sort of watery soup that you were seeing there, that weird moisture is what is causing the conductivity, and the corrosion. Often times companies will test a little of the expired compound, and if it solidifies and tests fine, they do a run of product with it, and if it meets spec, they ship it.... This kind of unique issue starts popping up after a few years, likely this became a problem with one or two runs of units well after they were off to a new model line.

Just for accuracies sake, the volume is on the back because these are "studio" monitor, "studio" as in "recording studio". The volume is most commonly controlled by a mixing board, either software or hardware driven, thus the XLR and TS inputs. In the world of Studio Monitors, these are quite low on the scale.

Welcome to my world. Conductive gunk is the standard in the industry forever in the CB radio world. Since they started using transistors in CB radios they have been using glue that goes conductive and corrosive. I remove that &%*# almost every day. If I ever meet the guy that invented the original "Sony Bond and Bond Lock" I'm going to strangle them. :-)

Thanks for the video. I have one of the KRK pair sitting disassembled on a shelf for about 2 years - couldn't figure out what's wrong with it, replaced caps, etc. Now I'll give another try by scraping that black gunk first on this one, and then will open the second one to scrape of the gunk as well.

Thank you so much for this video! One of my KRK Rokit 8 G2 speakers started to have issues, it would be ok for about 1 or 2 seconds then the volume would attenuate drastically down to roughly 10% of the original volume. After watching your video I opened up my speaker and saw the same black gunk everywhere. I scraped off as much as would easily chip off where it could possibly have been bridging between two circuits. I discovered one capacitor that was becoming corroded with a rusty colored powder and another with some white powder underneath the black gunk. I cleaned them as best as I could and tested the speaker. It has been running normally since. I imagine I may need to replace the corroded bits, but for now it's working great. Thanks again!

I've got to say these sort of vids are milk and honey in terms of first phase diagnostics - addictive watching, thanks.

Dave, I know you are busy so if you read this....That was an awesome investigation. I love it when you repair stuff. This is the sort of stuff I run into all the time. Lots of conductive glue, Just that most of my repairs where I find this is from the 70's and 80's. Working on a Sony V-21 communication receiver that is full of it now. Thanks for sharing this repair, I truly enjoyed it.

Thanks for posting this video. One of my (pretty old) KRK RPG2 8's suddenly stopped producing bass. After determining it was in fact the speaker's fault I opened it up and found the same conductive black gunk all over. I chipped it all off and gave it a good clean. Luckily no components had corroded yet and I have my bass back :)

Just came back to this video after having watched it when it came out. I bought 2nd gen KRK Rokit 5s like this in 2013, And used them for 7 years straight. I used to turn them off whenever I wasn't using them, and eventually decided to leave them on indefinitely. What I noticed was that after about 5-6 years of daily use, they'd developed an issue where turning them off, waiting for complete discharge of the power supply, then powering them back on would begin buzzing at mains frequency, and would eventually subside back to noise floor. After 7 years, the buzzing would never subside, and leaving them off for any extended period of time, such as my move from South Carolina to Georgia, would cause the lowest level buzzing to rise. Using extra power filtering before the components did nothing, there were no ground faults, and disconnecting signal entirely made no difference. I've finally replaced the KRKs with new main near-fields, but even after just a day of being disconnected, I tested the KRKs again just to see, and sure enough, the buzzing is even louder now, up from an annoying level to an unacceptable, unusable buzz. If I let them sit, I imagine I'll end up with an oscillating amp board. I suppose in about a week or two, I can test again to see if, even in the dry environment of my house, they manage to buzz even louder. If so, then it'll be pretty clear that these will eventually send 50 V to the drivers. Thanks to you, I actually know what this fault is and was informed enough to replace them before running down the line filtration rabbit hole!

Same problem here with pair of KRK RP8 G2. Removed all the gunk from both boards on both speakers, replaced all caps on both boards with high quality Japanes caps Nichcon, Rubycon, and sound is now incredible. Also there is no more buzzing or strange noises coming from speakers when they are silent or when music is playing.

The "volume knob" on the back of proper studio monitors isn't a volume knob, it's a trim pot to adjust your reference level (-10dbv for consumer equipment, +4dbv for professional sources, etc). This is why their range is very small. You control volume with the device that's feeding the speakers, usually a USB or FireWire interface like a focusrite Scarlett etc, or in larger studios, an actual mixing console

I've been so happy with my RP8 G2's, they have been powered on 24/7 for almost 10 years now here. And the back of 'em is facing the sun when it's up, so I haven't been kind to them. If they fail at any time I'll be sure to see if theres some black-gunk-removal needed. Thanks for the vid! (For the price I think they are really good studio monitors, and from the 8's onward you really really don't need a sub with them.)

Exact same problem with one of my KRK 6" gen2's: woofer stopped functioning after being powered off for a few weeks - So incredibly grateful i found this video - I have absolutely zero experience repairing things like this, and was able to find the black goo and scrape it off the pcb with a mini screwdriver / paperclip + some rubbing alcohol - Most needed to be chipped away, but some of the goo was "wet" - (wonder if the potting material melts down due to the generated heat, and then starts to grab and hold water vapor?) - Fortunately, the goo was only in a few isolated areas, and took me no more than an hour to clean up - Didn't seem to work at first, but about a minute later, the bass faded back in to its normal level - This video saved me not only ~$150 on a matching replacement, but more importantly, it opened my eyes to that very replacement would have also been potentially problematic down the road - THANK YOU.

KRK RP5 G2 owner here, had my speaker go deaf around 2 years ago. I was troubleshooting it for whole days until I ran out of tools and patience and sent it for repair. Of course it was the black plague gunk in the end.

Great video! In infinite-baffle (closed/sealed) cabinets, certain frequencies will cause buzzing sounds through any small orifice as the air gets huffed back and forth. That's why the maker seals up all jacks and any other through-hole components accessible from outside the cab.

Good video, Dave! It was fun watching you experience the black gunk! I've repaired many KRK monitors with the black gunk of death and I have come to love hating the stuff. KRK studio monitors are notorious for using the black gunk but I have also seen it on others including Pioneer studio monitors. I wonder what it is made of, a blend of something with recycled rum and coca-cola? I always scrape and clean it off thoroughly and typically replace all those garbage capacitors with high-quality Panasonic or Nichicon caps as well as replace any poor corroded resistors. I then use a good replacement for the black gunk like Dow Corning 738 or 736 electrical sealant. :)

Wanted to Thank You for your detailed video! I got lucky, my tweeter vibrated badly when I stared it up! Shut off immediately, found your video, cleaned my gunk around all speaker connections. Looked for any swollen ( whatever they are ) but looked good! Put it back together! Sounds like new! You are very much appreciated! Keep up the good work for the people who try!

This video helped me to repair a speaker for a customer of mine! Thanks for the help, I would never have guessed the goop was to blame.

Well, I guess Ill stop looking for used KRKs online then!

This is an extremely common issue on all kinds of powered speakers. I usually just wire wheel it off with a dremel by default, and replace it with solid setting white heatsink compound.

Yeah, I've had basically the same journey down the rabbit hole on a Teufel subwoofer (german brand), the gunk was originally yellow, but turned orange and corrosive. A poor 10 ohm resistor had gotten one of his sides chewed off, had to replace him with a wire, since I had no spare resistor. Worked a treat!

I've been cleaning that conductive gunk off circuit boards since the 80's. Yes, they're STILL using it! Amazing. Harman Kardon used to love squirting it all over the inside of their cassette decks. They would stay in mute or oscillate. Scrape off, replace corroded parts and jumpers, and voila! I've fixed plenty of these speakers too. Other brands are not immune, unfortunately.

I've repaired a number of these with exactly the same issue. Scrape it off, replace anything that looks corroded, replace with a better compound if required. Issue is the same with the RP5's too.

krk are GREAT!!!!! love studio use of them they sound incredible !!

Thank you, Dave! You just confirmed my theory! I've recently repaired one of these myself. But it was in it's initial state, it only had static, random noise in the drivers. At first I thought the filter caps were the problem, but nope. I couldn't believe that is was the gunk! The entire day I was speaking to myself: "It cannot be from the gunk...". But aparently... So...lo and behold: gunked removed, everything worked! Actually they are 2nd gen. And no, they didn't called them back.

Both my KRK Rokit 6 speakers have been affected by this..its so frustrating as these things aren't cheap. Thanks for the video.

Yep, planned obsolescence. I've seen a ton of these. If left long enough, it actually eats through the component leads!

It's a very old problem. My 1980s Yamaha gear had white glue holding large caps that turned brown, went conductive and ate resistors and wire links off the board. The PCB (that single sided brown version they use) also changed colour and bulged wherever it was in contact with it.

Thanks Dave, Yes the black gunk is all over on my KRK boards also. There should be a recall on these. Too much work to start scraping away only to possibly have them fail again. Thanks for your time finding this problem.

My KRK rokit 8 same issue with the black gunk, instead of the tweeter being affected, my woofer would randomly pop. So ended up replacing a failed resistor, and while I was in there I also changed out all the capacitors to some Nichicon Muses and Fine Golds on the preamp board, and higher quality caps for the power side of things.

Someone chose that material based on its ability to dampen vibration.....my guess is it was chosen outside of the view of the EE's that designed the circuits and PCB's. Oops.

I never would have fathomed that selastic would become conductive over time. I'd look at it and say "hmm, nothings broken. Must be dead".

I've used a pair of gen 2 Rokit for 10 years, absolutely no problems (other than mixes that don't translate!). My Yamaha NS-10m's blew a tweeter, and deformed the paper woofer cone in just a few years. I didn't expect this much out of the Rokits, but seriously been rock solid, one of those things that I just expect to work when powering up the studio. No thought given to them. I can't say the same for the 80's analog synths, or the 90's virtual analog synths. I, and many other people would love to see a repair of an Access Virus B, a high end German synth at $1,200 new in '99 - the B version used cheap caps (supposedly) in the power section, and apparently all the B's are going down now, or have gone down. A's and C's and so forth are okay, just the B's! There is one poor repair video on RU-vid, and that is it. I'd really like to know what is going on. Mind doesn't boot now, I'm a real hack when it comes to electronics, but I have to repair it myself, I can't afford a repair tech!

I think I have the same problem with one of my Rokit 6 speakers. I bought them back in 2010/11. Great speakers I think. Done me a great job with my video editing. It started playing up a few weeks ago. So that's about 8 years of good work out of them. Thanks for the video. Going to try and fix it myself and see how I go!

Sounds like a chance to build a passive volume controller and explain impedance and cable inductance? And maybe compare it to active volume control?

Wow, that's great. This is propably what's causing one of my Rokit 5 to crackle and loosing volume all the time. Gonna try to clean some gunk away soon.

Love my Alesis MK1 Active Mk2 powered monitors, had them since 2007 and still putting in the work today.

I just picked up a rokit 6 for $5 at the recycle centre. Non functional bass amp. Spent about an hour scraping off black gunk of death, and it works again!

POC (planned obsolescence compound)

That was a RP6G2. I have been using a pair of RP5G2 for probably close to 10 yrs now and I have no problems with the black gunk. I replaced all the JRC to BB OPA2228 the moment I got them. If you have a chance to lay your hands on a pair of Eve SC207, they sound really good but the power supply died on me after 4 years. Got one board completely replaced and the other piece died with a pop sound and I managed to fix it by just replacing a TinyMOS regulator.

I love this video. I have a pair of Gen2 5'' KRKs and one of them has a strange distortion at certain frequencies. A friend of mine also has the same ones as me and she also has one of them with faulty response. We're going to get together tomorrow and scrape together this gunk of death like a support group. This video was very informative, thanks a lot, you're awesome, you're always awesome!

The way you speak while doing all this is ....goooood...I am just lovin that..😂🤗

LOL at "and my voice is usually very high frequency."

Mine was popping and clicking from the tweeter and low level sound I followed this video and now it's working again amazing I really thought I had a blown cap or some sort thanks again mate

I was seconds away from making my Rokit 5's redundant as one monitor had a capacitor discharge sound coming from it. I have enough limited electronic engineering knowledge to investigate. Found nothing obvious after a general check over. Typed discharge from speakers into youtube and found your video. Problem solved!!! How many KRK's have been thrown away because of this black gunk!!! Thank you for your video.

I considered a pair of these once. Glad I went for non-driven KEF Q300s instead.

Hey, they are probably the best studio speakers at their price point. Buy the tweeter! Repair good stuff before someone throws it away plz!

I've had my series 1's Rokit 6's since release, in my studio, never had a problem. I do however have a theory that leaving powered speakers running continuesly all day causes so much internal heat that this type of melting is, I suppose, inevitable in these. Badly designed yes, but like most things they're given a shelf life. Depending on how you take care of them, I would imagine matters a lot with KRKs.

Love your enthusiasm!! Replaced some faulty caps to get rid of buzzing, but now can notice some persistent loud white noise on a single speaker. Hoping that some gunk cleanup does the trick.

A really cool video Dave! I've shared it amongst my musician communities - as this sort of product is discussed quite a lot. It is really interesting that the black acoustic anti-vibration "gunk" as you call it is conductive! WoW! Good pickup!

That gunk seems to be the same as that nasty yellow gunk that turns dark orange and becomes conductive over time. I'm amazed the stuff has not yet been banned in products.

HP had a run of computers with power supplies that used gunk that went conductive over time. I worked at a school that had some of these. Every fall a couple would go bang when powered on due to the conductivity.

Great video Dave! Really eye opening. I've owned a pair of these exact models for about 6 years now and they've performed greatly for my purposes. I use them as general purpose pc speakers as well as for DJing; where I've pushed them quite hard for extended periods of time (6+ hours of high volume, bass heavy music in party settings) on multiple occasions. I haven't had mine succumb to the fault in the video, although one has developed a low volume crackle on start-up as well as occasional clicks and crackles that can only be heard in silence which from some forum browsing I've found can be attributed to the crap quality large caps on the amp board. But otherwise I'd say they've served me very well for what I paid for them. However I think I'll be checking out some higher quality brands if I ever plan to buy new monitors now that you've uncovered the dirty secret that is the conductive gunk all over their boards. p.s. Somewhere in the video you said this was a gen 1 model, however it is actually gen 2, designated by the "G2" in RP6 G2. Currently the latest model is gen 3. Also in the conclusion you voiced concern about the speakers being sold as matched pairs but they are in fact sold individually, as are most studio monitors to my knowledge, so no worries there!

that high pitch thing you do when you' get excited broke my beer glass mate.

Am I the only one that spotted at least 4 bad solder joints between 12:07 and 12:17 ? As an "aficionado" this is the second thing I check (after the bulging caps of course).

Laying in bed one night watching a NRL game on a small portable colour TV. Then all of a sudden the TV set goes off. I get out of bed and look in the back and through the back grill I could see flame. Now as most of you guys would know, in those old CRT sets the main board was always mounted at the bottom of the set, so all I could do to put out the flame was to start blowing it out out from the top. Luckily it eventually extinguished. The next day I open up the set to see what had happened and I found that a dry joint on a transformer had ignited the glue they had blobbed around the base of the transformer. I re-soldered the dry joint on the transformer and cut all the glue off and TV was working again. However, it was a real eye opening moment just how a TV can start a house fire. I just could not believe they would use a flammable glue to hold down a component.

The convenience of having volume and headphone jack on the front of the speaker? That's what a USB audio interface is for. I got the Mackie Onyx Artist 1-2 right in the middle of my desk. Got a nice big volume knob, separate volume for my headphones, headphone jack right on the front, and separate volumes for the XLR and TRS inputs on the front as well. Then USB goes to my PC and TRS goes out the back to my two Behringer Truth B2031A's. But if you didn't want to get into all that, the USB monitors are nice to have. You should see the inside of the B2031A's. Really well done in there. Beautiful bi-amp setup.

corrosive, conductive black gunk of death! How awful is that.

I have to say, apart from that nasty conductive glue and other design problems, they are a great value for the money compared to other monitors in the market, possibly the best deep BASS. Sharing this video with all my Sound Engineers, DJs and musicians network =]

thanks, same problem, different resistor (R100 had gone). All working again now!

Yep, got a set of rocit 5's here with bad corrosion around all the black goo. Got some corroded through resistor legs too. R100 is burnt out. It was covered in crap. Also got mechanical hum due to transformer / port coupling even though there is a damper strip on port edge. Now to phone the customer! Thanks Dave.

This is not new. I repaired consumer electronics from 1987 to 2009. I've fixed a fair number of devices by simply chipping that conductive glue out. I think it's hygroscopic thus promotes corrosion. As the metal corrodes the metal ions impregnate the material. That's my theory anyway.

you would never need to change volume for studio monitors directly on the speaker, most users would change volume and plug in headphones on their daw interface or mixer.

The same thing happened to my cheap Audiomoods 10'' amplified subwoofer at home! And it happened while i was at work, so you could imagine how freaking loud it was! I heard it from the driveway! Good thing it didn't catch on fire! So remember guys: turn off your amps before leaving home...

I'm a retired TV / VCR / Audio / Computer Tech. I serviced all types of home entertainment gear for almost 40 years and have seen this black gunk many, many times. It's extremely hard to remove without damaging traces and component leads. It turns metal green. It's hard to believe they still use this stuff.

Got to wonder if the heatsink might work better on the outside of the box!

Managing to strike my electrical engineering and music production nerves simultaneously

I’m impressed that the tweeter hasn’t fried, it very much sounds like the HF amp section has gone DC. I’ve repaired countless DB Technologies Opera cabs where an LM3886 chip has failed and it often takes the (rather expensive) B&C compression driver with it... that speaker will have an active crossover which may be at fault. (commenting at 15.00)

8:31 You don't see that too often, but i for one, quite like the bottom copper "silkscreened" on the top. That stuff's real handy for troubleshooting / probing / tracing the circuits (not having to flip the board over all the time).

Evil conductive gunk! - FFcossag had quite some videos on this subject.

Love repair vidoes!!!

Exactly same issue happened on Mine. Had to get a repair as it was doing this awful sound and then done a weird thing where it sounded like a frequency sweep. Technician that fixed it also stated the gunk became conductive. So this is definitely a known issue!

"That'll blow the snot out of your driver" - Wonderful. You Aussies are a pack of pranksters, love it.

*[serious]* please go around the lab and talk about/describe the most satisfying knob indents you have.

Some one needs to be fired over this! There is a lot to be said for hot snot!!! AND, I bet it would have been cheaper than that black stuff!!! The 1980's called and said "use our shit!" Hot snot FTW!!!! Excellent diagnosis Dave! Shame no-one would pay for for this repair / diagnosis because you can't replace the tweeter! Thanks Dave! Yes your voice is a perfect test martial (nice one!). I'm sure ebay sales of these faulty speakers have just sky rocketed!

I used to be the service centre for KRK, that black gunk affected various makes and even the glues Roland, Yamaha and Korg used to secure large electrolytic caused problems.

In an audio amplifier in a speaker enclosure, there is a definite possibility of microphonics causing feedback. Unfortunately the "solution" is to immobilize anything that MIGHT be in the feedback loop. Thus the "goop" (probably liquid gliptal or some such ("liquid tape"?). The cheap components (design to price) are susceptible to microphonics (ceramic caps seem to be vulnerable) and you are witnessing a "shotgun" approach to attempt to solve the problem. To further diagnose the problem you might start tapping components (on both boards) to see if there are components susceptible to the problem. The real solution is to have the amplifier in a separate box so it won't be effected. You might have it functional when in pieces, but when you put it back together, and sweep out the response, you might trigger a problem somewhere. Very good diagnosis. Visual inspection, then power supplies. #1 and #2 in the test list!

Dave, could you bust some audiophile myths? I'd love to see that! I mean, if you aren't too busy busting solar roadways... :)

Luckily it's a single sided board, so you can dig right in to scrape that crap off!

Awesome videos. Intelligence - High. Voice- Ultra- Super High. Painful on the ear drums but worth it.

My first ever teardown was a Rokit 5 gen2 that started playing up within 2-3 years. Nothing obvious (no burnt out components) but the black goop was slathered everywhere. Just moved on and bought a second hand replacement cheap. If ive still got the old faulty unit floating around ill send you the tweeter, its probably the same!

Gotta love these comments about ‘planned obsolescence’! It’s absolute nonsense. No manufacturer is going to deliberately introduce something into their product that will break down randomly and cause reliability issues. It’d be suicidal business practice. They simply made a mistake and picked the wrong adhesive for the job. That’s it, no conspiracies or mischievous intent.

Rokit stands for RottenKit

Dave hi I was with you all the way I used to work for farnell instruments learned a lot from this

Funny, a few years ago I had a similar issue with my (well, now like 15 year old) JBL SCS 135 5.1 set - conductive gunk on one of the subwoofer boards. It started "motorboating" once I turned it on. Scraped it all off, works like a new one again!

I have a pair of these, they’re awesome.

Guessing it should be pronounced "rocket". :)

Funny. About a year ago I was on a service call at a restaurant, troubleshooting their little soft serve Ice cream maker/server, the standard one with two flavor bins and 3 levers in the front for either flavor or mixed in the middle. The mixing motor shaft key had sheared off due to someone sticking something in there while running probably, but what dropped my jaw a little was the 2 inches of MUCK pooled up on the bottom of the enclosure, engulfing everything due to no drain hole apparently, including the wiring harness for the stirring motor, which used a belt to run a drive wheel with the mixing heads axle shaft (where the key had sheared). Of course I always check motor stats out of service call courtesy (and it's sparky-fun), so I was measuring some weirdness and decided to grab a big spoon from the kitchen and shovel out some of the semi-dry brownie mix filth to see if maybe it had somehow eaten through the motor leads. Found the harness, stuck my meter probes into the much and wow! The resistance was bouncing around in the 1k range, plus or minus a couple hundred ohms...! And I would definitely not say the ummmm, "batter" was "wet" in any significant sense, too....! Needless to say I wasn't afforded a lot of time to play with it, and also since the day manager was kinda looking on and saw the ummmm, "ruiner of soft-serve ice cream for me" and wanted to clean it right away, I didn't get to play with my megger that I was hoping to get out, throw some 1000v through it, see what the needle does, lol. Oh well, still strange conductivity from things that probably shouldn't have such properties, especially thinking about eating it...!!??!! HA! BTW, good work!

I've had several KRKs come in to my shop out here in Caracas, the BlackGunkofDeath is the main issue, but I always put in new higher voltage power caps, had many come in with strange popping and crackling noises from these cheapos going bad. Great video, hope you are well dear bro !

*ahem*, if I may: Connor's Law: rarely should one ascribe to incompetence what can more easily be explained by profit motive. (I know I'm being a little paranoid, but still. :-) )

What a junk! This ticking bomb is called “monitor” speaker? Hahahahaha:)

The spliced tweeter cables are factory too 😀 Nice diagnoses and job I’ve done a few of these, have to replace all caps, remove all that glue and sometimes the resistors and zenner diodes below the glue need replacing.

An interesting repair. Looking at the components that just fell out of the board. Is it possible that the liquid is able to dissolve the tin from either the solder or the component wire. At about 18:55 there are two resistors and two diodes. looks like the gunk has peeled from all 4 components and one of the diodes looks to have corrosion on the right hand lead.

its 4:35 am in india and still not feeling sleepy 😂😂

probably carbonized due to heat

Krk seems to be a good company. I think this was just some type of a human error quality control mishap. They happen. I know I make mistakes sometimes. Maybe they learned their lesson, and eventually built them better than before, hopefully. Cheers and God bless. Peace!

I was looking at buying KRK but ended up "cheaping" out and buying nEar (ego-sys) for about a quarter of the price. My nEar's are still going strong 15 years later. I never turn them off, they are on 24/7 and have been for all those 15 years :D