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Help with buzzing speaker?

Discussion in 'Amps and Cabs [BG]' started by H_Wordsmythe, Mar 13, 2010.


  1. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    I picked up a new GK MB115 combo a few weeks ago. Love the tone, the weight and the features. But shortly after I bought it, the speaker started buzzing (I don't mean the grill was rattling). It increased as I turned the amp up and was more noticeable on the deeper notes. I double-checked all the screws on the speaker and made sure they were all tight. Eventually I just went back to Guitar Center and told them I wanted a new unit. So they ordered it for me and I just made the trade last night. Playing the new one in the store and after I got it home, I was thrilled that there was no buzz. I assumed the first model I got was slightly defective and looked forward to many hours of buzz-free playing. Well... Got up this morning, turned it on and what do ya' know? The buzz is back. Just as bad as it was on the first amp. I haven't even pushed it hard yet - kept the volume at about 9 o'clock and both the gain and boost at 2 o'clock. The only thing I can think of is that leaving it my slightly moist and humid basement overnight did something to the speaker? Please help me, guys! I'm going to leave it upstairs in drier air for a few days and see if that helps, but if not I'm guessing I'll have to take it apart and look at the guts. If anyone has any expertise they'd be willing to share, I'd appreciate it!
     
  2. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    I think you're expecting more than a single 15 can give, and pushing the gain and boost to 2 o clock has damaged now 2 speakers. Just my opinion, but I'm guessing that's it.
     
  3. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Seriously? Why design gain and boost circuits that will damage the speaker without even being maxed? If that's the case, it's ridiculous. They could have set it up right to begin with and limited them to the point that no damage would be done. I can see that happening with a head, but with a combo? The unit should be completely capable of withstanding any setting it allows. Well, that's my opinion anyway... Maybe I should call GK and get their two cents.
     
  4. butchblack

    butchblack Life is short. Do good. Find and do what you love.

    Jan 25, 2007
    Waltham Massachusetts
    Try taking it somewhere else and plug it in and see if you get that buzzing. If not it might be a problem with the wiring in your house. I seem to remember reading on a thread somewhere that the MB's were a bit fussy about the quality of the power they receive. I went out and bought a Furman power strip with the RF conditioner as some of the clubs have less then stellar wiring around here.
     
  5. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Will do. I'm actually taking it to a church service tonight, so I guess we'll find out...
     
  6. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    Gain circuits need to compensate for a wide range of input levels. A passive bass needs a higher gain setting than an active bass, for example.

    If a designer limited gain so you could never damage a speaker, most instruments would not produce enough volume from the amp.

    The use of excessive bass EQ can overextend a speaker (causing it to fart out); overexcursion will damage the cone. Would you like designers to eliminate the bass control on amps? How about on instruments?
     
  7. butchblack

    butchblack Life is short. Do good. Find and do what you love.

    Jan 25, 2007
    Waltham Massachusetts
    Keep us informed
     
  8. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Well on an amp with separate passive and active inputs and a limiter (which I always leave on), I certainly wouldn't expect damage to a speaker at a 2 o'clock gain setting. I've cranked the gain higher on Peavey and Behringer combos and not done any damage to the speaker. I expect even more durability from GK. And no, I wouldn't want designers to eliminate the bass control on an amp, but that's not what I'm talking about in the first place. Also, 2 o'clock is hardly excessive - if that were an unsafe gain/boost setting for this amp, the manual should indicate it. By your reasoning I should just be content to do without the GK growl I bought the amp for in the first place.
     
  9. The amp was not designed specifically for YOU and YOUR bass, so they would have no way of knowing your particular situation and what would constitute excessive for YOU.

    The amp is designed to work with everything from weak passive basses, up to super hot 18V actives and beyond.

    They simply build an amp that is designed to work in the widest range of situations.

    It is up to the user to know and understand what they are doing with those tools.

    Do you fault a car manufacturer when someone blows an engine or their clutch because they constantly redline the motor and don't shift properly ?
     
  10. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    Remember, the gain setting simply sets the point at which the amp generates full power. Even at a low gain setting, if you slam the input hard enough, you'll get full power. The gain is not a limiter.

    They're not the same as yours, so we don't know their gain structure.

    They can't prevent you from overdriving the speaker; don't blame them. Would it be GM's fault if you went off the road? Should they make it impossible for you to make a mistake steering?

    The 2-o'clock position is reasonable depending on the input signal. If you provide a hotter-than-normal input signal, then 2-o'clock is too much. There's a clip light to warn you.

    No, my point is that you have a responsibility to use the equipment carefully and to pay attention to how it's working. It isn't a microwave oven where you hit "2" and walk away.
     
  11. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Holy cow... Take it easy guys! You sound like your taking personal offense to my expectations of this amp, and unless you work for GK, I can't understand that. If I had a super hot active, or if I was "redlining" with my single humbucker passive, you'd have a point. But when a knob goes all the way to 5 o'clock, and I leave it at 2, and when the volume is as low as I set it, a bass like mine shouldn't overload it. It takes more than boost and gain to blow a speaker. I've played on enough amps, both bass and guitar, to know that strain is put on the speaker by the master level as well as by the gain and the boost. In my experience, it takes a combination of all three to overdrive to the point of damage. And 9 o'clock on the volume isn't so much.

    But, as I stated earlier, I took the amp to a church event this evening, and I did notice a difference. I only got the buzzing when I turned the contour switch on. So I tried it upstairs on a couple different wall outlets, and found notable differences between each of them. On one, I got the same buzz I've been getting in the basement, with and without contour switched on. On the other I got the same result I had at church tonight. So it looks like the dirty power theory has something to it after all. I'll keep experimenting. And thanks to all of you who responded with your input, even if you were scolding me for pushing the amp "too hard". Attitudes aside, I appreciate your willingness to offer your opinions, guys. So thanks again... ;)
     
  12. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    You make some valid points, but the problem is your assumption that I don't know what I'm doing in the first place, dude! As I said, I've left the limiter on. Also, there is NOT a clip indicator, unless the light on the power button doubles as one, in which case I never clipped. Lastly, I know what kind of input signal I'm supplying to the amp. And it's not high, hot and heavy. Give me some credit for not being completely ignorant of what my bass is or is not capable of...
     
  13. wideyes

    wideyes

    May 9, 2007
    Eugene, OR
    IME no normal bass should be able to supply the kind of output that would blow a combo with gain at 2 o'clock and volume at 9 o'clock. That's just not very much volume. I'm with the OP on this one.
     
  14. Since it is looking like a power problem, have you tried it in different outlets around your home ?

    If it really is a problem with that particular amp being picky about power supply, you may just have to rey another direction in amps.
     
  15. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    My last post in this thread.

    1. The limiter protects the amplifier; it doesn't necessarily protect the speaker, because you don't know how much power is being delivered when the limiter limits it. The speaker can still be overextended.

    2. As for knowing the input level, without measuring output power you don't know how much is hot and heavy.
     
  16. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Thank you!! Finally! I was starting to feel like I'd taken crazy pills or something... But you have validated my sanity. May you have a long life filled with whatever it is that you dig. Peace.
     
  17. H_Wordsmythe

    H_Wordsmythe

    Feb 22, 2010
    Michigan
    Okay? If that was your last post I won't bother to address it other than to say... Have a good one, dude. And thanks again.
     
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