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Newbie PA Questions...

Discussion in 'Live Sound [BG]' started by BayStateBass, Apr 11, 2014.

  1. First off, I've posted some stuff up here and everyone has been very helpful and informative, so thank you. I've been slowly building and expanding my PA for my band, it's nothing fancy but it works great for us. I'm not very tech-saavy, and I like something simple and easy to use because, well, honestly I'm not too bright with live sound. We play mostly small clubs with no FOH system, so it's up to us. What I am using now;

    Carvin RX1200 powered mixer, 1600W total including mains and monitors
    Livewire power conditioner
    (2) Carvin LS1503 3-way mains
    Anywhere from 2-4 Seismic Audio "Crap" 15" monitors

    Since we recently started mic'ing the drums and our guitarist has been running into the PA, I wanted to beef up the low end support so I ordered a Carvin 18" powered subwoofer. The RX1200 has an XLR output which can be dedicated for a powered sub, using the internal crossover switch on the mixer. Cool, easy to set up and move around, easy to set up. At our last couple shows, I have not run my bass head through the PA because I felt the mains were being pushed just with the drums, vocals, and guitar. Hence the subwoofer.

    Anyway, my question is this; up until now I've only been using my (2)15" cabs for sound, basically my stage amps are the bass with no PA support. It works well and I get plenty of boom, but I would love to be able to bring one cab or use my 210 combo as a monitor and run through the PA (it's also a Carvin and it has the ability to do a direct out). But I've been reading a lot and there seems to be a lot of discussion about how subwoofers don't work well as bass amps. I talked to the guys at Carvin and they told me that the internal crossover in the RX1200 isn't 100%, some of the low end would still go to the mains, the switch will just ensure that the only thing going to the subwoofer will be lows. They suggested using an external crossover but it wasn't in the budget....yet. And all of the diagrams that came with the RX1200 show exactly what I am doing with my setup, like I've totally duplicated it in every way.

    Any suggestions? Please be gentle, I'm learning as I go and again I don't know a lot about live sound, so the more you can "dumb it down" and put it in layman's terms, the more likely I am to understand it.

    Thanks in advance!
  2. What's the question?

    Seems you are short of a crossover my son, not much to do about that but get one.

    From what you're saying, the rig is configured for the sub to low pass but the mains are still full range, not high passed. That's pretty shabby. There may be a way to send the kick to subs only and get some thump without giving your mains death.

    For bass I'd say keep doing it as you were and save up for a crossover. There are plenty for sale cheap.
  3. modulusman

    modulusman Banned

    Jan 18, 2004
    Subwoofers are not designed to be used as bass amps. What they are designed for is to reproduce low frequencies so the main speakers don't have to. You will want your bass guitar in the top cabs or it will sound like crap. You should be able to find a decent used crossover for under a $100.00. A few years back I bought a brand new DBX 223 for $100.00.
  4. tbirdsp

    tbirdsp Supporting Member

    Sep 18, 2012
    Omaha, NE
    I don't know - I'd at least try it with what you have right now (using the sub output on the RX1200). The 1503's should easily take "some low end".
  5. TomB

    TomB Supporting Member

    Aug 24, 2007
    I use essentially the same set-up, more or less. I agree, the mains can take some kick and bass, and the lows will go to the sub just fine. I haven't yet decided whether it's best to engage the 120 Hz x-over or let the sub handle full-range. I haven't noticed a lot of difference either way. I'd also agree that if you're unwilling to serve lows to the mains you'll need an outboard x-over. I wish the sub out was designed to high pass to the mains instead, a more conventional choice.
  6. Lync

    Lync Supporting Member

    Apr 13, 2004
    I had a similar situation back when I used a Yamaha board (sub out was only low pass, but full range still went to mains).

    Try cutting the lows on the PA head. So without the sub you are bass-shy on the bass and kick if you run through the PA. Basically cut 60hz and down, and then cut a good portion up to about 100-120hz.

    Now, turn up your powered sub maybe more so than you originally did. This should compensate for the lost lows at the PA eq. Not the best solution, but does work for the situation you have (not a true crossover).
  7. Does the powered sub have a high pass output? There may be a way to run all signal to it and back before it hits the amp stage in the pa head.

    Really you've got the wrong tool for the job. What you actually need is a normal board with an external amp rack. I'd suggest the dcm2004l (personal experience) and a matching amp for subs and tops (dcm3800). I don't know if the dcm3800 has an internal crossover, either way it's a big step up but also a big up in cost. Powered mixers will only take you so far, this is where it limits growth quickly.

    External crossover will work as long as you can route the mid/high signal back to the powered mixer before e amp stage.
  8. Thanks for all the advice, people. I appreciate it. Great points and sound advice.

    Tonight was a test, we had a gig at a small club where we didn't have to be crazy loud, but loud enough. I ran the configuration I have with the new sub, the only drum we mic'ed was the kicker. But what I did was to use one of 15" cabs, which would have actually been enough without being plugged into the PA in itself as my main sound, and ran my direct on the head to the PA and kept it fairly low. The system did pretty well, never a hiccup or a problem, and I watched all night to see if any of the clip indicators came on (I know, no the best way to know if it's happening). It was hard for me to tell how well it worked, but everyone seemed to think it sounded pretty good. The mains were able to take the "little bit" I put into them for reinforcement, or so it seemed.

    I agree, this is certainly not the best system money can buy. I'm hoping, over time, to put together a better system using dedicated power amps and a GOOD mixer. The more I use this and the more I play with it, the more I realize just how limited it is. Unfortunately, it's what I could afford at the time and I needed something on a budget that would work without being complicated.
  9. TomB

    TomB Supporting Member

    Aug 24, 2007
    Agreed that the 1200 is limited, but it can be greatly enhanced with an outboard x-over and decent eq in a 2-space rack. Having 4 power amps is a treat. All in all, I like it for what it is and what it cost and what it weighs, and I've come from the world of big PA. Enjoy exploring it.
  10. I have owned this mixer in both powered and un powered versions. Yes they are very limited but a reasonable bang for the buck. I checked on line and I confirmed that each amp has a patch in out port to be used with an insert cable. So buy a reasonable 2 way crossover and use an insert cable for the L and R mains into the crossover. Then use the returns to back to the power amps and take the sub out from the crossover to your powered sub. I truly feel you should dump the lows in your tops if using a sub.
  11. TomB

    TomB Supporting Member

    Aug 24, 2007
    +1 - exactly what I meant as well, but actually explained :)
  12. Lync

    Lync Supporting Member

    Apr 13, 2004
    As I explained with my situation...I also realized that a real crossover was the best solution. So, I went to the Mackie DL1608 and got some powered tops.
  13. I was replying only to the OP's question not other replies, sorry.
  14. Tunaman


    Dec 26, 2004
    I'll be picking up a Carvin TRX2118 SUB today... I'll let you guys know what I think but for the features, price it looks like it can't be beat. The Carvin LS series was just a bit too low end for outdoor use to feel comfortable. The SCX series wasn't bad but for an extra $100 the woofer in the TRX sub seemed way better. Luckily I have some decent mains already.

    BTW... which powered sub did you end up ordering?
  15. Lync

    Lync Supporting Member

    Apr 13, 2004
    Ha-sorry man...I reread my post and it came off kinda short. I was trying to explain it better from my end. Thanks.
  16. I went with the LS1801A. The price was perfect, and it seemed like it would be a good match for my LS1503's.

    I went back and listened to the live recordings from Saturday's gig and I have to tell you, it really sounded pretty good as a whole.
  17. Tunaman


    Dec 26, 2004
    Cool, I just ordered the TRX2118, I'll have a review in a week :)
  18. I have the same mixer - the LS12801 subs too and PM12 monitors/PM15 tops. I also have some JBL 15 and 12s I leave at a small venue I do sound for exclusively. The insert function is great for adding the crossover in line with the existing internal amps.

    I also (usually) use external amps with an old bi-amp brand crossover I picked up from a friend cheap. It works exactly as it should - and I do a mono out from the 1200 into the input of the x-over. highs go to a old crest 1500 watt amp (CLEAN head room) and the lows go to a QSC amp for the subs.

    I use an EQ between the board and X-over sometimes, other times, just use the EQs on the board.

    I know its not a presonus, or mixwiz or the like - but it has been good to me once I figured it out. I use a transformer adapter between the output on front of the board to the x-over and it makes the signal much happier (advice from carvin).

    I am not a real sound guy - just a guy with some sound stuff. I made enough doing it though that I upgraded some of my bass rig, bought most of the Carvin eqpt and am buying two of the Peavey IPR2 5000 amps to step up the headroom. For some reason - I keep getting calls to do this, and it pays better than playing AND doing sound..........I just don't get it.

    Maybe one day - I will step up to a big-boy system.

    I hope some of that info helps - you may find that the system is a little more flexible than some folks may lead you to believe.

    BTW - I use a Genz Benz shuttle with 1-12 cab or my avatar 2-10 and if needed put it into this setup - it sounds huge - not stadium pa setup or MSG huge - but for what we are talking about huge.

    I couldn't find a pic of the entire setup - and this is before it was all tweaked - just getting it cabled one night.....so disregard the settings please......
  19. Not to worry :):bassist: