Kabinet quality issue? Something else?

  • Hi all,


    Would love to get some thoughts from the community on this issue I'm having with a brand new Kabinet.


    I would first like to say, I am new to Kemper, and bought the Profiler Stage about 2 months ago. I ordered from sweetwater, and the first unit I received was defective. The foot switches were intermittent, and after 2 days barely working at all. I peeked inside and saw that the springs were covered in rust. A friend of mine posted about it on this forum. I exchanged it and the one I have now is fine, although I was a bit surprised they didn't put some sort of desiccant inside?


    Anyway, fast forward to now and I ordered a Kabinet and an SD Power Stage 170 to power it (I was previously playing through a home stereo). Played at normal or loud volume it sounds mostly fine if a little gritty, but here's the thing: At low volume (I mean soft playing, not volume knob down), there is a clear vibration (think gritty) that should not be there (low gain amp profile). Also, if you hit a string softly, once the note starts to die out, it suddenly cuts out, almost as if it was affected by a noise gate....but there is no noise gate on.


    Now I tried a few things to troubleshoot:

    - I connected the SD amp to the speaker in my Fender Blues Jr. with the same KPA settings: It sounded fine and did not exhibit the behavior above.

    - I connected the Blues Jr. AMP to the Kabinet.... it DID exhibit the behavior above...

    - I connected the KPA and SD amp to the Kabinet and played at maximum volume (holy S**t!) for a few minutes thinking this might "break it in"....still does it.


    Anyone have any ideas? Did I get another dud from Kemper? Man I will be pissed if so!


    Thanks for your help!


    Brett

  • Hi,


    Just to be helpful - and only to think about once you have determined it is not a manufacturing defect or fault caused by shipping:


    Grittiness: was what you were playing it through before, less detailed/accurate a monitoring system than what you are now playing through? You said hi-fi, so it won't be eq'd to respond in the same way as what you are now listening through - you may be picking up more 'details' in the profile that was always there - but didn't hear before. People hear this typically when they move from cabs to FRFR systems.


    Is it there on headphones?


    Some profiles have a background noise, that you only hear when playing quietly - especially as our actual playing changes dependant on how loud we are...to get reduce it, see what the compressor in the amp block is set to. Lowering this can reduce the background noise/hiss/'grit'.


    Lastly on the vibration thing...anyone with tube amps knows how infuriating trying to track down a rattle is...especially if its a combo. Have you checked every screw on the baffle, handle, speaker to baffle etc for tightness? ALOT of the time though, its something in the room/on a shelf/etc being excited by the note...


    Notes cutting off: there's a noise gate you can insert as a 'stomp', but there is also the global noise gate...have you checked they are both off?


    Cheers,

    Greg

    PRS Custom 22's - Fender Strats - Diezel VH4 - Carol Ann OD2 - Toneking Imperial MK2 - Colin the Kemper - CLR Neo ii.

  • A few years ago I purchased a couple of Celestion speakers, one of them had a similar noise. After looking at it closely I discovered that the dust cap was not glued on correctly, I could pull it up on one side with my finger nail. I carefully applied some glue with a toothpick, let it set overnight and it fixed the issue. Not sure if that's your issue, just a thought...

  • That description sounds like a cooked speaker coil. When the lacquer on the coil windings is overheated due to too much current (DC?) it bubbles. This ‘scrapes’ against the cylindrical metal tube the voice coil is supposed to move freely in. Try gently pressing the cone with even pressure and move the cone in and out. If it feels rough then the voice coil has been cooked. It should move smoothly with no noise.

  • A few years ago I purchased a couple of Celestion speakers, one of them had a similar noise. After looking at it closely I discovered that the dust cap was not glued on correctly, I could pull it up on one side with my finger nail. I carefully applied some glue with a toothpick, let it set overnight and it fixed the issue. Not sure if that's your issue, just a thought...

    A few years ago I bought a nearly new but used Celestion Heritage G12-65 from a seller on ebay. When it arrived it appeared to be in perfect shape, but had a horrible rubbing sound. Being an amateur speaker reconer (have reconed maybe 15 or so Celestions), I guessed it was "crap in the gap", which is debris between the coil and polepiece. The only way to tell this was to remove the dust cap, but I had a replacement that was suitable (dust caps are a huge part of the tone of a speaker BTW).


    Turned out the issue was a sliver of metal that looked like it was left over from when Celestion drilled the polepiece vent. This was probably left loose in the polepiece or motor area, and was held in place by magnetism. The shock of shipping probably knocked it loose, and the powerful magnetic field in the gap pulled it into the gap area. Simply removing the sliver with tape (standard speaker gap cleaning technique) removed the metal, and after replacing the dust cap, the speaker has sounded perfect ever since.


    The point here is that all products can have issues; they shouldn't, but unfortunately it does happen. And the issue here is most likely Celestion's fault, not Kemper's. The Kone is made in China, and the Heritage I have was made in the UK, so it doesn't matter which factory it was made in. If there is an issue with this run of Kones, I bet Kemper will crawl all over Celestion to get them right.


    If the owner does decide to look inside the speaker (not sure if that will void the warranty or not), be sure to look carefully in the area between the spider and where it attaches to the cone. That area has the entire magnetic field of the magnet focused in a tiny gap, and if there are any washers or screws loose in the cab, they could be attracted to that area and cause noises. I once bought a used "defective" vintage G12H-30 Greenback that had a terrible rattle, but the issue was only some metal shavings in that area. Pulling those out with tweezers repaired the speaker in seconds.

  • Hi all,



    Thanks for the great comments. So eventually I decided to open it up and see what I could find.


    I pulled the speaker and couldn't find any noticeable tears or other damage. I did jiggle the connections a little bit.


    In any case, once I put it back together, the issue was gone! Speaker works perfectly now.


    Greg, to your comments, I did verify that this issue was not present through headphones and even a separate speaker. I also ensured there was no noise gate active.


    In the end, I don't think I'll ever know for certain what was causing it, but I do have one speculative theory:


    As mentioned in my initial post, Kemper is, in my opinion, shipping these items overseas without sufficient corrosion protection. No sealed bags, no desiccant, just a cardboard box and unsealed plastic. These likely spend weeks in a shipping container, potentially on open cargo decks. It's possible that it was a slight big of corrosion on the connectors similar to what I found in the first Profiler Stage I ordered...


    Thanks again.