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KRK Rokit 5 loud transformer hum
Old 3 weeks ago
  #1
Here for the gear
 
🎧 10 years
KRK Rokit 5 loud transformer hum

Hey all,

I have a pair of KRK Rokit RP5's (the first iteration) which are about 15 years old now and still going strong. But one of them has an annoying hum/buzz coming from the transformer. I've already swapped out all the 35v/50v capacitors (which did get rid of some noise) in both speakers, and also soldered the power wires direct to the pins in the problem speaker to rule out a poor quality crimp. But now I've started to think that it's the transformer itself that is making most of the noise. It's much louder listening behind the speaker than to the cone. Has anyone else had this and had success with replacing the transformer? I've seen them on eBay for £30. If I try and replace the transformer I'm going to kick myself so hard for soldering the wires and removing the crimp... that was the most annoying bit of soldering I've ever done! 😂

If anyone is tempted to say "just buy some new monitors"... yep, I could do that, but apart from that noise these are still fine!

Cheers guys!
Old 3 weeks ago
  #2
Here for the gear
Is this the PSU transformer? Press on it with something that’s an insulator (screwdriver with an insulated shaft and handle). If the tone of the hum changes it’s the transformer.👍🏻
Old 3 weeks ago | Show parent
  #3
Here for the gear
 
🎧 10 years
Quote:
Originally Posted by MAXTHEDOG ➡️
Is this the PSU transformer? Press on it with something that’s an insulator (screwdriver with an insulated shaft and handle). If the tone of the hum changes it’s the transformer.👍🏻
Thanks for the suggestion. Yes it's the PSU transformer. It's one of these: https://www.ebay.co.uk/itm/KRK-Rokit...QAAOSwbjde-lmA

When you say press on it, which part do you mean to press on exactly? I did try touching the various parts with an insulated screwdriver but noticed no change in the sound. To be honest, once you take the back-plate out of the speaker, the buzzing is quite quiet, it's just amplified by being in contact with the cabinet. Very little buzz coming through the actual speaker. Putting my ear close, it seems to be coming from a few places... the transformer, the kettle lead plug input, maybe the XLR input (nothing plugged into it).

Thanks
Old 3 weeks ago
  #4
Here for the gear
Hi,
The pic on EBay seems a bit odd. From the angle of the pic it looks like it’s mounted inside an open metal box. I suppose it’s for reducing interference. When I suggested pressing on it I meant press on the laminations( the bit that the two windings are wound round), but it’s hard to see them. They look like very thin pieces of metal stack up against each other. You have to put a bit of pressure on when you press, but if the hum is reduced when you take it out you might not be able to hear any difference. Without hearing and seeing it it difficult and messing with it could be dangerous as it’s got mains voltage on it. I work with mains every day so I’d have probably changed it by now. You seem to know a bit as you’ve already replaced the caps, but you know mains an’ all...
Cheers,
MtD.
Old 3 weeks ago
  #5
Yeah, my KRK RP6 G3s do this too. And it's getting worse.

Between this and the power capacitor issues and the auto-sleep function I can't turn off I've lost my enthusiasm for buying KRK again.
Old 3 weeks ago
  #6
Here for the gear
I nearly bought some KRK RP6 G4’s a few weeks ago until I saw an EEVblog YT vid on some G2’s and the PSU ‘gunk’. Put me right off. I don’t think it’ll be unique to KRK, just a function of the price point and a cheap way to cut down on vibration and microphony.
I decided to refresh on ‘tronics and attempt to fix my broken power amp( were bi-amping so I’m not in complete silence).
Best of luck whatever you decide to do.

Last edited by MAXTHEDOG; 3 weeks ago at 08:43 AM.. Reason: Misspelling
Old 2 weeks ago
  #7
Here for the gear
 
🎧 10 years
Thanks for all the feedback guys. I've decided to sell these on and just buy a new pair. I listened to a bunch of speakers at the same price point, (Yamaha, Adam, RCF), but in the end went with the Rokit RP5 G4's as I just prefer the sound of them. I do hope they don't develop the same buzz, but I will be certainly listening out for it. To be fair mine did last me 16 years!

Re the black gunk inside KRK's - I saw those videos too, in fact that guy's vids helped me do a couple of repairs on mine. The black gunk in mine was nowhere near as bad as the ones he showed, it was all pretty tidy, no gunk on components etc. At the end of the day they cost £280 for the pair, which is crazy cheap, and for a little home studio they are great. I get someone else to do the final mix on my music anyway, so I just need to be able to enjoy the sound while I'm producing and recording and get a feel for the track. The Adam's were pretty great, but the high mids just felt like they would be a bit fatiguing after a while.
Old 2 weeks ago
  #8
Here for the gear
 
I was just about to make a nearly identical post about my pair of Event 20/20bas. They're perfectly adequate monitors for my needs but the hum is a bit louder than I'd like and it doesn't get softer when I turn down the gain trim, so it seems it's likely the PSU. I tried a furman power conditioner to no avail. If there's a solution I'm all ears.
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