Amp Crackling sound

Discussion in 'Amps and Cabs [BG]' started by BlacksHole, Mar 25, 2005.

  1. BlacksHole


    Mar 22, 2000
    Rockville, MD
    [The following is a rather long explanation - but I need help diagnosing a problem]

    I have a Hartke 5000 that I run in biamp mode with an Avatar 15 and an Avatar 2x10. The other night, after an hour or so of playing, a loud crackling like sound starting coming from my 2x10 cabinet. Fearing that I blew the speakers, I immediately checked them, but the simple push test revealed nothing. I next hooked up the Hartke to a polytone 2x8 & 1x15 cabinet and I still had some crackling sounds, but less. I also tried switching speaker cables to no avail, as well as bass cable and bass. When I switched heads to a Polytone Pro, it seemed to stop, so I figured my amp had something loose inside. A close inspection inside the amp revealed nothing. So I thought I'd have to take the amp in to a pro. However, the next night we had rehearsal, and not only did my amp crackle, so did the PA and one guitar amp and all were on the same extension. Moving the guitar amp to another plug removed the problem from that amp. So my next test was to change the multi-outlet strip - but this didn't work either. So I plugged into a different wall outlet, but still it crackled. Finally, I tried a third outlet and it appeared to be OK. Unfortunately, the crackle isn't constant and I may not have tested long enough at the new outlet. To sum it up, my questions are:

    Can this really be a problem with the house wiring for one circuit?

    Or am I fooling myself, and there really is something wrong with either the amp or the speakers?

    Are some amps more susceptible to such interference?

    And if they are, can they pass along the crackling to other items in the same circuit?

    Thanks for any assistance.
  2. It could be the tube in the preamp ?

    Or more likely, the jack sockets on the bass, or one of the jack sockets on the amp, i think
  3. BlacksHole


    Mar 22, 2000
    Rockville, MD
    Thanks for your suggstions, but I did try using just the solid state part of the preamp and I even removed the tube while I tried this approach. I also had changed basses and cables, so unless I've uncovered several pieces of gear with the same problem(s), this doesn't work either. I've just never heard of an entire circuit (back to the braker box bing like this. But I just had another idea - there may be some device connected to this circuit that generates electrical noise throughout the circuit and kicks on at times that I don't notice. Perhaps the filters on my outlet strips aren't very good.
  4. Steve


    Aug 10, 2001
    I didn't stay at a holiday inn last night but I am an electrician....

    The chances of an entire circuit doing that are VERY remote. The chances of a single receptacle doing that are possible but unlikely unless the outlet is pretty old and pretty well used.

    The chances of the traces on your hartke's circuit board picking up stress cracks from vibration and causing crackling noises is very likely. They're famouse for that very problem. I don't know anyone who's owned a Hartke head for any lenght of time at all that didn't have to have the boards resoldered at one time or another unless they never set it on their cabinet or the only giged once a month.

    It's no big deal. You just go through it and re-flow all the solder joint's. More of a PIA than an expense.


    The fact that it was throwing noise into the rest of the circuit is curious though.
  5. BlacksHole


    Mar 22, 2000
    Rockville, MD
    Hmm - your response puts me back to my original approach - take the amp into a pro to have him look it over. I do have a gig tomorrow night though, and I was thinking about using the Hartke head to see if it crackled there. However, I have had some crackling at some gigs, so it seems that what you suggest is the most likely solution. Since the other amps that crackled were also on the same power strip and after any filters, I'll hazard a guess that my boards are actually causing the electrical noise and affecting them.
  6. Notice that he said the PA and another amp on the same receptacle were doing it!!!

    Loose solder connections on the Hartke would likely NOT go back through the Hartke's power supply then affect the other amps. There's a power transformer, filter caps, and rectifiers that do a fair job of suppressing noise back...

    I suspect EMI/RFI interference...something is on the line, such as an old refrigerator, neon light, or air conditioner; or one of these devices is generating radio waves that are being picked up by the amps in question. Or possibly the power strip itself is faulty!!! You DID say they were all on the same power strip, hmmm!!!
  7. And I've also had a Hartke 5000 for ten years and not had to resolder the circuit board, IMHO it's a little bit of a stretch to claim that all Hartkes develop stress cracks and must be resoldered.
  8. BlacksHole


    Mar 22, 2000
    Rockville, MD
    Thanks for all your help guys, I really do appreciate it. Would it be fair to say that Hartkes are more susceptible to line noise than many other amps? I ask, because the effect seems most promounced on my Hartke - my Polytone is rarely affected and my Hartke has produced these loud crackles at gigs on a few occasions.
  9. +1 Ya buddy.......
  10. Nope!
  11. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY

    I used 2 Hartke heads for a total of 12-14 years of consistent gigging,etc...and never had a problems with any soldering or circuit boards. I've never even heard of this problem. Since other amps are picking up the problem, I'd check to see what else is on that circuit...or maybe what might be producing stray signal that your amp is picking up. Our Keyboard player's older board was cheap and made noise everytime his cell phone rang, so it could be something like that.
  12. Passinwind

    Passinwind I Know Nothing Supporting Member

    A defective power switch in your amp could easily create that set of symptoms, I've seen it happen. Have your tech take a look at that possibility. Bill's scenario of motor interference or something similar could well be the answer too.

  13. Or a defective switch or loose connection in his power strip, since he said the same problem has occurred with other equipment plugged into the same power strip.

    I took apart one faulty power strip and I couldn't believe how cheap it was made, the "connectors" consisted of a V-shaped groove that the wire pressed into--they didn't even strip insulation back, they just pressed the wires into the groove.
  14. Marley's Ghost

    Marley's Ghost Gold Supporting Member

    Feb 9, 2002
    Tampa, FL
    I had the same problem in my basement studio with my Hartke 5000. I connected it to a power conditioner and the problem went away. I am going to have an electrician look at the circuit. I think the 5000 is very sensitive to any power issues. I have a Yamaha emx5000 powered mixer and a Fender Twin Reverb amp which I connected to the same circuit with no problems. :confused:
  15. Passinwind

    Passinwind I Know Nothing Supporting Member

    That's what I thought too, but I re-read this in the top post: So my next test was to change the multi-outlet strip - but this didn't work either.

    I took apart one faulty power strip and I couldn't believe how cheap it was made, the "connectors" consisted of a V-shaped groove that the wire pressed into--they didn't even strip insulation back, they just pressed the wires into the groove.

    Yeah, and some of them just use two 50 cent MOVs for their scary protection mojo.
  16. Okay, I misread his original post, or had a brain fart.... :cool:
  17. My amp sometimes picks up cell phone signals and beeps a bit along with using the remote when im watching tv while just practicing at home. with the cell phone its random and goes on and off. So signal interference could be it. I doubt this helps but I try to make it seem like i know something.
  18. When you had your original 2 cabs plugged in and one one crackled that made me think one of your two power stages in your amp may have a bad capacitor or power transistor. As one cab did and not the other. Biamp mode etc.

    The other gear doing the same then brakes this logic to some degree. One thing I have noticed is thermostats. If your in a place that has large air conditioners or refrigerators such as commercial clubs they may sometimes be wired on same circuit. If anything it's bad for you cabs.

    Whatever it is, it always ends up being something really simple. I must agree with the other guys, getting a tech to look at it may be the best option.

    If it is your amp you could also switch between your preamps to see if it's a dodgy valve?

    Have you tried using it with a single channel? One at a time. A good mains filter would also be worth a try.

    To answer your question as you asked them, yes it may be your amp but as the other gear did the same it doesn't sound like it is. Yes the house wiring sound like the most likley culprit. Also was you amp connected to a mixer with an XLR or DI output. That could explain any one of each of the gear causing the fault. If it was maybe run all the gear seperate for a while and see what happens. Isolation will help with this one and that includes power.

    As for the cell phone stuff, all these power amps we run have many elecrolytic capacitors in them usually for audio coupling and power supply filtering/demand, because they are usually made of aluminium foil rapped up, they act like antennas and again because they are in a monster amplifier they amplify that interferrence being cell phones etc. That by no means make these amps bad, it's just how it is. eg, Even billion dollar aircraft audio/nav gear is not immune from cell phones etc. Also, the leads we use act as antennas as well. They should be grounded at ONE end. This end is at the amp. These leads are one of the most sensitive as they have a very low power signal that can be interffered with before it gets amplified 1000 times.

    Sorry about the windbag, this stuff is an interest.

    Best of luck.
  19. BlacksHole


    Mar 22, 2000
    Rockville, MD
    Thanks for so many responses. I guess noise problems in amps is pretty common. I decided to use my Hartke at a gig I had Saturday night. I also used a better power strip (Furman with filters and surge) and I had absolutely no crackling. On Sunday I ran some wiring from another plug over to the area where I keep my amp for practices and installed a new plug in the wall and I'll use the Furman strip at practice, but I'll leave some other items plugged into the problem outlet/power strip to see if they have problems; or if I ever get crackling through the new plug and power strip with the Hartke. I'm also wondering if the plug on the back of the amp for the power cable is just too loose as it doesn't seem as tight as I think it should be. If it crackles again I may first try switching the power cable but it will probably mean it's time to spend some money and take it to a real tech.
  20. BassyBill

    BassyBill The smooth moderator... Staff Member Gold Supporting Member

    Mar 12, 2005
    West Midlands UK
    I must have been jinxed by reading this thread - I got a crackling noise with my HA5000 last night whilst practising at medium volume. It was actually more a drop in level / intermittent break up of signal, accompanied by a nasty fuzz type sound as it happened. I noticed it seemed to be connected with the vibration caused by a particular note (bottom G on my 4 string). Playing the string harder seemed to make it worse, maybe? The amp is in a rack case at the side of my cabinets, but still picks up some vibration through the floor. When I lifted the amp and put it back down again with just a tiny "bump" (no, really), the problem disappeared. Don't you just hate intermittent problems? They are always the hardest to sort out.

    Am I right in suspecting the problem is a loose connection or joint somewhere, bearing in mind it did SEEM to be vibration related? I have read the earlier stuff about reflowing solder joints - which ones, how's it done, etc, etc? I think I would need to go to a good tech to do this as I have little experience, other than simple jobs like fitting a set of EMGs into my bass. :confused: