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Cab options...need help with load rating too

Discussion in 'Amps and Cabs [BG]' started by Sigurd, Feb 20, 2006.

  1. Sigurd

    Sigurd Supporting Member

    Oct 27, 2004
    I'm having some problems figuring this out. I just joined a 12-piece band (2 guitars, keys, drummer, 2 trumpets, t-bone, 4 vocalists and me) and I'm afriad that my Mark VI isn't cutting it.

    It overdrives easily at the volume of the band. The head is rated at 400W in 2 ohms and 250 in 4 ohms. I play through a 15" Black Widow rated at 350W continuous at 4 ohms. I have pre and post at 6.5 and 4 respectively and something is overdriving. At those settings and the listed gear, what is maxing out here?

    Second issue. I'm thinking of adding this. 400W at 4 ohms(won't buy until I learn some more)

    If I add this to my existing setup, total load will be 2 ohms, correct? Would this then open up the 400W into 2 ohms that is rated on the head? When do I have to take into account the individual speaker ratings of the 1820?

    I hope this doesn't sound silly. I'm trying to learn a little more.

    Thanks in advance.
  2. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    I would try to get a larger amp first. one that can go down to 2ohms and also have at least DOUBLE the power ratings you have now.

    if you get the other cab and push both to the limit and the amp you'll more likely still have the same problem.
  3. Sigurd

    Sigurd Supporting Member

    Oct 27, 2004
    So basically a new 800W rig? That's what I was hoping not to hear. What about a single 2 ohm cab to replace what I have? If a 2 ohm bass cab even exists...
  4. jamminbassguy


    Mar 31, 2005
    I wouldn't buy another head until you've looked at everything. Did you check to make sure that your overdrive isn't a torn speaker? or that you're not pushing the low frequencies too high? A good website to check out is, www.glennletsch.com. You'll find in doing some research that anything below 50-60Hz is a waste of air. If you attenuate anything from 60Hz to 1kHz you might find some or all of the 'overdrive' sound will go away and that you may be able to hear yourself better. Mids are your friend, well, that's at least what I've learned and tried and found to be true. You have enough head room with that amp, however, adding another 4ohm cab will give you that extra space. My personal belief is that all cabs should be 8ohms. After you add two 4ohm cabs together, you won't be able to add anything else without a power amp. (by the way, if you add an 8ohm cab to your current rig, you'll drop to 2.66ohms, still within the parameters of your head). Hope this helps!
  5. Sigurd

    Sigurd Supporting Member

    Oct 27, 2004
    I just got done reading all those articles on the Glenn Letsch site. Wow, awesome information! I will be playing in another live room this weekend, so I will try rolling off the bass a bit.

    I did notice last weekend that my sound wasn't good where I was standing, but for the few songs that the second guitar player played bass on (I'm new, don't know them all yet), he used my rig and it sounded really nice halfway out in the room. He also has a Hartke vx3500 which is a 4x10 that he said he would let me borrow, so I might try that too.

    So you say that by adding an 8 ohm cab to what I have will give 2.66 ohms? I understand that...I had physics. Will that open up the 450W (or close to it) of my head? I gotta find a way to get some more gas. I'll try boosting mids first though.
  6. jamminbassguy


    Mar 31, 2005
    8ohm cabs allow you the opportunity to add more 8ohm cabs to the system without mixing up the the ratings. The 2.66 isn't a nice even number, so you're not getting the full output from the head, just more then you have been. Also, in addition to loading down your amp to get the maximum output, you'll be able to monitor yourself, the speaker will be closer to your head (get it, ha ha, uh hum), I mean, ears. Always, Always load your amp down to the lowest rating, you'll get better performance out it. That could be why 2x10 cabs are 4ohms instead of 8. Anyway, 450W can go along way, especially with a decent house sound system, so there would be no need to buy another head!

    Make sure when you add the mids that you start with everything flat or at zero. Move the low mids, then the high mids, then the highs. Use the Lows (not the low mids) to fill in the 'umph' when you're done. This will keep your amp from overworking your speakers.

    Let me know how it turns out, I'm curious.
  7. Sigurd

    Sigurd Supporting Member

    Oct 27, 2004
    Let's say I have an 8ohm 200W 2x10 cab hooked up with my 115 existing cab. This makes my resistance 2.66, but what does it do to my wattage? Because my head is 450W, what will blow first, the 115, which handles 350, or the 210, which handles 210? How does wattage split?
  8. jamminbassguy


    Mar 31, 2005
    Neither. Believe it or not your amp will know where to send the the signal. Have you ever heard of the phrase, 'electricity/current takes the path of least resistance'? Well, that's whats happening. Keep in mind, the 4ohm speaker will sound louder than the 8ohm speakers, because of this pathway. More importantly, you have a total of 550w with your speakers and 450w output at 2ohms, you have 100w of headroom. Nothing is going to blow, unless you don't EQ properly as you turn up. If you have the 'lows' on 7, let's say, while your volume is on 3, you're good. However, if you turn up to 5, you should turn the 'lows' down to 4 or 5 to ease the speakers. Anyway, as long as you don't go below the lowest ohms rating of the amp, you're fine.
  9. Sigurd

    Sigurd Supporting Member

    Oct 27, 2004
    Well, for my gig tonight, I'm using a Hartke VX3500 410 combo. I've never used anything but my Peavey half-stack, and when I was playing the Hartke in my living room, it sounded incredible. So we'll see. I'll use my stack next week for comparison. More to come...gotta leave for the show!
  10. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    You dont get headroom from cabs that can handle more power than they are getting that is a terrm for amplifiers you do not have to load down your equiptment to the least impedance rateing. More speakers = more air moving = good But more amp power for those additional speakers and not having to run your amp wide open= headroom. That blackwidow 15 inch @4 ohms with a peavey Firebass head and the extra cab would be a killer rig if you can afford it. you will get more voltage to the 4 ohm speaker so it will be louder. you should keep speaker impedances the same so both cabs get the same power/volume but this is no hard and fast rule just imho. :cool:
  11. Herman


    Dec 25, 2005
    Lynchburg, VA
    This isn't necessarily true. How loud each of the cab's sound depends on how much power they're taking and their sensitivity. Perceived loudness also depends on the cab's placement in a room and its frequency response - there are probably other factors as well. Just because a cab's impedance is lower than another's, doesn't mean it's going to be louder than the cab with higher impedance.
  12. You should consider just adding one of Peaveys TVX or older TX 210 cabinets.They are 4 ohms and would give you some added punch and mids so you could hear yourself.There are lots of used ones around so they go pretty cheap and sound good even by themselves.That would be a lot lighter option than the 18"monster.If you like the punch of the Hartke 10s the Peavey 15 and 210 would be a good choice.
  13. jamminbassguy


    Mar 31, 2005
    Yes, you're right, headroom is a term typically used for amps, however, if you have a 600w amp and a 400w cab (found in the Carvin RC210) you're not going to be able to turn it up, at all, without doing some damage....so, 'headroom', generically, can be used to describe having enough 'room' to turn it up without clipping the amp or the speakers. There are two points or 'rules of thumb' maybe, you should follow,
    1. Always have more power than you need, and 2. Always have speakers that can handle the power with some watts left over so as not to over work them. Try it...you'll see. Loading down your amp to its lowest ohms only brings out the best quality from your amp. That's all. You don't have to do anything really!

    Another thing, it's true that 4ohms will sound louder than 8ohms. Why? Less resistence draws more power, therefore, louder. Why do think that Sigurds head, along with mine, and every other amp, puts out 400w @ 2ohms and 250w @ 4ohms? Read any FAQ on any cab manufacturer website... All other factors are trival, really, because they change with every room, the conditions of your strings, etc.

    Anyway, thanks for yellin' at me, this guy is going to have some good stuff to think about!