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4X10 + 1X15 + LMIII... Whats wrong?

Discussion in 'Amps and Cabs [BG]' started by thebass905, Jan 15, 2012.

  1. thebass905


    Jun 7, 2011
    Hey all, recently I bought an Ampeg HLF 4X10 rated at 400 watts at 4 ohms, which im running with my LMIII (300w @8 ohms and 500w@ 4 ohms) I also connected an old Hartke B900 90 watt combo amp (8 ohms) to the Ampeg for a bit of a fuller sound, the problem is any time the gain or volume passes 12 o'clock, It starts farting! (not literally of course, it's just what I call solid state distortion XD). I'm certain that this is t set up correctly, or maybe the head has too much power or all three ate incompatible ..... But can anyone enlighten me as to possible causes/solutions?
  2. KJung

    KJung Supporting Member

    Your post is a bit confusing. It sounds like you are driving a 4ohm 410 and an 8ohm 15 cab with the LMII. If that is the case, you are running the amp at 2.67ohms, which is below the 4ohm minimum, and the amp will eventually shut down.

    As has been posted many times on TB, the 'wattage rating' of the cabinets has little to do with anything.

    If I am misunderstanding and you are running two 8ohms cabs, then the 15 is getting the same wattage as the 410, and you are simply overdriving the 15 and farting it out... very common with that combination of cabs.

    It is very difficult to drive the LMII to clipping (at the power stage), since it will cleanly compress when it hits its limits (basically not get any louder and start to lose its nice open low end). If you really blast past the limiter, you will hear a small amount of upper midrange distortion.
  3. BurningSkies

    BurningSkies CRAZY BALDHEAD Supporting Member

    Feb 20, 2005
    Seweracuse, NY
    What do you mean by 'I also connected an old Hartke B900 90 watt combo amp"?

    Just the cab to the LMIII, or did you take a line out from the LM to the in on the combo?

    If you're just using the speaker from the combo (8ohm and your 4/10 at 4ohm) then you're running a load that's well below what the Markbass head can handle.
  4. KJung

    KJung Supporting Member

    I didn't even want to contemplate that scenario:D I assume he is using the speaker only, but if not, that would of course, explain a lot!
  5. dog1


    Dec 30, 2008
    I am trying to visualize your set up, but being unfamiliar with either of your amps, it is hard.

    Are you saying that you took a preamp out from the LM and ran it to a power amp in on the combo? If that is the case, then maybe the signal to the combo is too hot, and is overdriving the little 90 watt combo.

    I am curious. The Ampeg is a very full sounding cab with tons of low end. It seems unlikely that the combo could add much.

    Maybe you could try to describe a little clearer how you have them plugged together. Or, maybe someone else has some thoughts and will come to this thread.
  6. BurningSkies

    BurningSkies CRAZY BALDHEAD Supporting Member

    Feb 20, 2005
    Seweracuse, NY
    I honestly can't tell what's going on here. It could be any of a number of situations, or even the basics of 'this amp just has the lows boosted too much for the cab's excursion limits'. :confused:
  7. 'Farting' - if not biological - is not just a function of 'solid state' devices, but it's actually the sound from inside the speaker when it (either) hits the back of the magnet or it overextends from being pushed too hard and exceeds it's designed parameters.

    IOW - you're asking it to go where it's shouldn't go and it's complaining.

    There are also lots of articles (some inflammatory, some not) about mixing different speaker sizes, and this may just be another one of those situations.

    If you turn DOWN the power and the LOWs somewhat, you'll all get along OK and your larger driver will live longer, but it's the differential in power handling that's causing you ( and the speaker) grief.

    EDIT: I may not have understood the OP either - but farting isn't nice in public or for your speakers. I'll stick with that part anyway.
  8. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    +1 for the confusion. OP, please clearly describe exactly what you have, and how you have it connected. There are many possible problems here, not the least of which being running the LMII below it's minimum impedance, as well as mixing a 15 with a 410. NONE of it is good. Please let us know what's connected to what, and how.
  9. thebass905


    Jun 7, 2011
    Alright, sorry for the confusion everyone! I have the Ampeg connected with a speaker cable directly to the markbass head, and from the other port on the Ampeg cab, I have only the speaker on the Hartke (not the preamp) connected to it. I wish I could describe this better, but I'll take a picture to clear things up and post it soon!
  10. Stop trying this immediately, you are about to fry your LM3...

    That lowly little 15" combo speaker has NO CHANCE at all to "help" get more lows then a VERY bass heavy 410HLF will get you.
  11. BrBss

    BrBss Supporting Member

    Jul 9, 2010
    Albuquerque NM
    As others said, you are running the head below its minimum impedance. However, the sound you hear is probably the 15" speaker in the combo "farting" because it can't keep up. Just use the Markbass with the Ampeg cab
  12. And another LMK3, as the 410HLF is 4 Ohms...

    Most likely, he needs to turn the bass down and the mids up...
  13. packhowitzer

    packhowitzer 155mm of pure destruction

    Apr 20, 2011
    Aaaaaaaaaaaannndd this is why I'm skiddish about buying used gear from ebay.... good luck to you though OP. Listen to what these fine TBers are advising you to do (and not do)!
  14. BrBss

    BrBss Supporting Member

    Jul 9, 2010
    Albuquerque NM
    Whoops, that was a dumb error on my part! :bag:
  15. Stop immediately! You'll ruin your amp, if you haven't already- I sure hope not!
    Yr amp can only handle 4 ohms minimum, so only the Ampeg cab by itself as it's 4 ohms.
    You could use 2 different cabs if they're 8 ohms each only.
    Read the sticky in amps forum re ohms etc
  16. dog1


    Dec 30, 2008
    Ya know 905, your Markbass and Ampeg are a ferocious rig. I have wondered more than once why you would even want to spoil the rig with a 90 watt combo. Maybe you should reconsider.
  17. murphy


    May 5, 2004
    Toronto, Canada
    something is very wrong.....
  18. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    ...............or at least it about to go very wrong. :eek:
  19. If you are running a speaker cable from the Ampeg cab to the extension jack of the combo.....you are about to loose both amps!! STOP NOW :)
  20. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Not only is it going to fry your amp (surprised it hasn't shut down on you already), but there is zero point to hooking up the 115 from the combo to the 410hlf. That's a little combo compared to a big cab with a lot of wattage. Absolutely pointless to try to make them work together. The combo speaker will fart out because it's not designed to take the wattage the 410hlf can. I'm quite surprised you haven't had something catastrophic happen.

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