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Which Amp for 8 Ohm, 1000 watt RMS 18" Sub

Discussion in 'Live Sound [BG]' started by MrLeadFoot, Apr 1, 2013.


  1. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    QSC PLX is out because of the huge handles on the front. Same with Yamaha P7000. I want to be able to close the front door of the rack for transport.

    QSC PLX2 might be a consideration, but not sure I can handle the price!

    Crown XTI4000/2 series is on the radar, but have heard that the new lightweight amps aren't great for sub duty. Is that just internet garbage? But, it would be nice to have something that I could swing into stereo mode in a pinch if the main or monitor amp goes down, and run the sub on one channel and the other speakers on the second channel.

    Also considering Mackie M3000, but like the weight of the FRS2800 better.

    Should I consider Behringer EP4000 for price point? Since I'm only running kick drum and bass guitar through the sub, super clean sound isn't that much of an issue, but I am worried about dependability of Behringer, although they have decent term warranties.

    Any thoughts, or experience similar to the setup I have in mind?
     
  2. If you don't mind the weight, keep an eye on the Classifieds for a used CA 6 or 9. Cheap, huge power.
     
  3. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    What does "CA 6 or 9" stand for? Oops, never mind, found they are Crests. Dang, they are just as expensive as the QSCs, and are quite heavy.
     
  4. modulusman

    modulusman Banned

    Jan 18, 2004
    montana
    What sub are you using? Will it actually handle a 1000 watts or is that "marketing watts".
     
  5. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    Let's put it this way:

    When I push my Mackie M1400 to the point where the kick drum is triggering the overload light (no, I don't push it 'til it clips, or the light is on constantly), which is 850 watts (continuous)/1000 watts (max), that's when the sub starts to really get going and sounds awesome. So even if the 1000 RMS watts/2000 watts peak end up being "marketing" numbers, I'd prefer my amp to at least be 1500 watts, if not 2000 watts.

    More to the point, I'm trying to find out if the lightweight amps I mentioned in my original post, such as the Crown XTI4000/2, QSC PLX3102, Mackie FRS2800, etc. are viable for such a sub.

    If the consensus is that the new-ish lightweight amps really are something to be desired when it comes to subs, then I guess I have no choice but to have to get something with some weight.

    My Mackie M1400 has proven to be quite the workhorse, so if I have to go heavy-ish, I am willing to tote the Mackie M3000 if I have to, but I surely don't want to lug anything heavier, let alone an amp that's 50 lb.+, nor do I want to spend a ton of money.

    And, like I said, I am willing to compromise a bit on quality, as long as it is dependable, because at the frequencies subs emit, I don't think I need something as killer as I would want for mains. This is where Behringer's EP4000 becomes attractive from a price point perspective, but I will only consider it if I know other people have found them to be dependable, unlike Behringer mixers.
     
  6. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    I'm using Crown Drivecore 1500's and 2500's...the 1500 is in bridged mono pushing two lower-end daisy chained Yorkville 18's. Doesn't even break a sweat in the process.

    FWIW, you may want to take a closer look at your gain structure, EQ, compression, and high-pass filtering to recover some head room.

    Riis
     
  7. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    I've got all the headroom I can get from this setup. The amp is just not powerful enough to do the sub justice, as you might surmise by the 1000 watt RMS spec of the sub. In your application, you have TWO 18s, so you have a 4 Ohm load; your Drivecore is sending a potential 1550 watts to the subs. Sure, that wattage is split over the two subs, but you are still experiencing nearly twice the wattage that I am, being that I only have one 8 Ohm sub.

    I don't want to lug two subs around right now, which is why I got such a monster to begin with. I'd rather get a more powerful amp. If I get something between 2500 and 3000 watts, the amp should do me just fine should I decide at a later point to cart around another sub.

    That Drivecore you have is an even lower line than the XTI, which I am not criticizing, because if I can get the performance I need out of a less expensive model, I would be all for it, too!

    I have a couple of questions for you:

    1) Do you think the lighter amps like what you have still produce potent power as compared to the older, heavier amps? I have no problem with bass guitar right now, but I want a strong kick drum punch without having to worry about blowing the speaker because of low amp power.

    2) Do you think that the Drivecores are reliable when you push them through the subs?

    3) I suspect that if you hook up only ONE of your subs to that 1500, you'd still get plenty of bass guitar. But, a kick drum is a whole other animal, because of the potent transient spikes from a kick drum. An amp needs to have enough power to process that signal spike. The specs show that your 1500 is 25% stronger than my 1400 so I assume you would already have more headroom than I do currently. But I would venture to guess that with only one sub hooked up, you'd have to push that amp signficantly harder to feel the kick drum punch in your stomach, than you would if you had both subs hooked up. And, with only one sub, you'd probably be pushing it harder and thus having to watch the amp like a hawk like I am doing now, to ensure you don't blow the speaker or amp.

    What I want is PLENTY of headroom for the kick drum punch, so I don't have to worry about it. That said, I'd appreciate hearing your comparison findings of a kick drum through your 1500 to only one sub as opposed to your 2500 to one sub. I suspect you'd get way more punch and WAY more headroom with the 2500. Care to do a test for me?;)
     
  8. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    Holy Smoke. I just looked at the Drivecore specs and it's a Class D amp. Could that also contribute to them not "breaking a sweat" in your application?
     
  9. seamonkey

    seamonkey

    Aug 6, 2004
    This will get a lot of hate, but "subs" don't need a lot of Hi-Fi
    Power amps, if they have the same actual rated watts, all sound the same.
    You'll do great with just about any "name brand" power amp rated 500 to 1000w into your load.

    What distinguishes one amp from the next is build and quality. And it will be reflected in the warranty term, and how easy it is to get warranty service. I can't see any power amp not having a full warranty for at least 5 years. The longer the warranty, the more the manufacturer is standing behind their quality.

    Really, pick on the features you're looking for, and warranty terms.
    Easy to bridge is a nice feature, but not needed if each channel puts out full power into your load.
    Light amps ship a whole lot easier if any return to depot service is ever required.
    I like shallow amps.
     
  10. what does that even mean...this is pro audio, not a home theatre system...Hi-Fi doesn't even come into this world...
     
  11. Jazzdogg

    Jazzdogg Less barking, more wagging!

    Jul 29, 2006
    San Diego, CA
    Don't forget the basic math. Using two identical 8-Ohm subs provides a theoretical 6dB increase. To provide a 6dB increase using one sub, assuming it can handle the output, would require a power increase of approximately 400%. To make your sub sound twice as loud (10dB) would take ten times the power.
     
  12. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    I don't necessarily need double the volume, as subs are omnidirectional, so to speak. But, you're on to my point: Just because Zooberwerx said his Drivecore 1500 is plenty good for his two subs does not mean it's good for my one sub. I'm simply looking for an amp that will do my sub justice.
     
  13. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    I think his use of the term Hi-Fi meant that I don't need anything super-clean since it's a sub and it won't produce frequencies in which one would hear something super crisp anyway. But, I think already said I didn't need anything like that. I'm just looking for feedback on the amps I mentioned in conjunction with my 18" monster sub.
     
  14. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    On my way to work but formulating an answer(s). In doing so, I'm laboring along the lines of two possibly-fatal assumptions:

    #1) Your volume demands are greater than mine. Very likely.

    #2) A Mackie 1400, or any other "1400" power amp in bridged mono, should be capable of doing justice when matched with a single 8 ohm 18" subwoofer enclosure. If I'm off-base on this one, please chime in fellow TB brethren!

    Riis
     
  15. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    Like I said, it does sound great, but I'm trying to dial in a kick drum. The bass guitar is PLENTY loud and the meters are perfectly happy. In fact, we have to cut the bass level to keep our sanity. :)

    But the clip light illuminates on hard kicks, which I would rather not see. Being that the sub is 1000 watt RMS, it can handle more than the amp can put out, which is 850watts continuous in bridged mono into 8 ohms. And, therein lies the danger: If the amp ends up clipping for real, squaring off the sine wave, I'm going to blow that speaker.

    Now that I think about it, I do have the limiter engaged on the amp. Maybe I should disable it to see what difference that makes. I mean, with it engaged, maybe the amp is "predicting" a clipping level, and is designed to illuminate the clip light when it goes into limiter mode, even though I don't hear any clipping.
     
  16. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Yes, the clip limiter is designed to attenuate and illuminate below a given threshold...that's protection, do not defeat. You may also want to consider inserting a compressor / limiter in the kick drum channel to handle the transient spike you referenced. I can see upgrading the power amp but doing so with the intent of adding a second 18" enclosure. I'm as frugal as the next guy but this would be money well-spent.

    Still at work...

    Riis
     
  17. No no no. Not a chance. You've fallen for the clipping myth. It's almost impossible to blow a woofer with clipping, unless you're playing continuous tones through it at well above the clipping threshold, continuously.
     
  18. Jazzdogg

    Jazzdogg Less barking, more wagging!

    Jul 29, 2006
    San Diego, CA
    +1 With woofers and subs the risk of damage is from overpowering, not distortion.

    If you can't harness the bass drum with a limiter, try a high-pass filter or parametric EQ.
     
  19. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    The 1400i has a high pass filter on the reverse. 12:00 = 35 hz. I'd recommend a bit higher @ ~50 hz. The manual has a rather convoluted (or so it seems at first) procedure for running subs exclusively but that ties in the use of the onboard crossover...or is it a low pass filter?...to process a full range signal.

    To the OP: what are you using for a crossover, if anything?

    Riis
     
  20. MrLeadFoot

    MrLeadFoot

    Mar 4, 2012
    California
    So, are you saying that it's perfectly fine to see the meters peak in time to the kick drum? I don't know if that's a good idea, but like I said, I hear no distortion of any kind when that happens with this sub. Now, the two subs at a church I play at WILL sound like cardboard if pushed too hard, but they are only 400watts RMS each powered with its own QSC RMX1450 bridged mono.
     

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