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problem with Ampeg B2 combo

Discussion in 'Amps and Cabs [BG]' started by DirtySocks1379, Nov 22, 2002.


  1. I have an ampeg B2 combo with a 15". When I play the combo alone it sounds fine. But when I run it through an ampeg 4x10 cab at 350 watts (as opposed to 200 out of the combo alone), the 15 makes a buzzing noise when played at a high volume. I tried tightening the speaker and it seemed to help for a short period, but now I here the buzzing again. Any suggestions?
    Also, the 4x10 cab has a knob on the back of it that has -16dB on one side and a 0 on the other, it can't be for volume because it doesn't become louder when I rotate it, it just sound more trebly as I approach 0. Does anyone know exactly what this knob does? Sorry about the lenghty questions, if anybody gets this far.
     
  2. That mystery knob is the attenuator for the horn. -16 means a 16db cut and 0 means no cut so the horn is on full.

    I think the problem you're experiencing has to do with the 15" not being able to keep up with the 4x10. This is the problem with running mismatched speakers. The 15" is going to reach it's limit long before the 4x10 cab does.

    ...or, it could be that the cab simply buzzes at high volumes. Combos have been known to do that.
     
  3. thelastofus

    thelastofus Guest

    Jul 3, 2002
    Bakersfield, Ca
    i have a b2 also and mine would buzz sometimes. i was able to minimize it by tightening the grill and the head. stopped them from vibrating, minimized buzz, every now and then the screen would come loose but two seconds and it'd be fixed again for a few weeks. for what it's worth.
     
  4. tim4003

    tim4003

    Apr 30, 2002
    Dawsonville , GA
    DirtySocks,
    What 4X10 cab are you using? How many ohms?
     
  5. it's the SVT-410HLN it runs at 4 ohms. the combo alone runs at 8 ohms but switches to 4 when I plug the 4x10 in. sorry it took so long for the reply.
     
  6. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Ooops. If you plug in a 4-ohm cab along with the 8-ohm, you're now at 2.67 ohms.
     
  7. What Munji said. Looks like you are driving the amp too hard.
     
  8. what? now I'm confused, I thought since the amp is running at 4-ohms then would be alright. Does this mean I can't hook up another cabinet with the 4x10? what ohms should the 4x10 be to be able to hook it up to the combo? You'll have to excuse me, I never needed this much power before so I am new to this whole ohm business. thanks.
     
  9. thelastofus

    thelastofus Guest

    Jul 3, 2002
    Bakersfield, Ca
    2 8ohm cabs brings the impedance of the amp down to 4 ohms. One 4 ohm and one 8 ohm like munji said brings it to 2.6 ohms. the ampeg wasn't intended to run that hard and you're probably running a chance of damaging the head by doing this. sell the 4x10 and get an 8ohm 4x10 then you can run both cabs safely and effectively.
     
  10. So I can't connect another speaker to the 4x10 unless the amplifier I'm using drops down to 2 ohms? That's a bunch of crap.

    Anybody want to buy a 4x10, hardly used...
     
  11. also, I pulled the head out of the combo and made a cover for it some thime ago(long story). There's no way I could hookup just the head to the 4x10 and have it run at 350 watts, is there?:confused:
     
  12. This is why it's important to do some research before buying.

    1 4 ohm cab = 4 ohm load

    1 8 ohm cab = 8 ohm load

    2 4 ohm cabs = 2 ohm load

    1 4 ohm and 1 8 ohm = 2.67 ohms

    2 8 ohm cabs = 4 ohms

    4 8 ohm cabs = 2 ohms

    You have to match your amp to your cabs. Some amps can do 2 ohms, but I don't know of any that can go lower. I also don't see why you would need to.
     
  13. Oh, and yes, you could just pull out the head and run 350 watts into the 4x10.
     
  14. Any advantage to running your amp at 4 or 2 ohms as opposed to 8? Sorry to be such a pain in the #&*!:D
     
  15. Nope. It just produces more power the lower you go. Generally, an amp "works harder" at lower impedances, but if it's rated for a certain impedance it should be fine. The B2 is rated for a minimum of 4 ohms.
     
  16. Thanks for all the info everybody
    :)
     
  17. One more question, is there any way I could have somebody change the ohms in the 4x 10 to 8? I just bought it about 3 months ago for $500 and I don't feel like selling it for $250 now.