Members drenwick Posted May 24, 2008 Members Share Posted May 24, 2008 I know this is probably Live Sound 101 but if I want to run mains and monitors on one amp from a stereo mixer, how should I hook it up so I have independant volume control of the mains and mons? I first assumed that I would use L and R main outputs from a Mackie CFX12 into the L and R inputs of a QSC PLX1804 and put a main (JBL MR925) and a monitor (JBL JRX112) daisy chained to each side output. But then I'd have no independant volume control, right? Then I thought to run mains on one side and mons on the other - but how do I hook up the mixer to the amp? Same way? Does it matter that I'd be running the left side to the mains and the right to the monitors (or vice versa)? I know this is probably simpler than I'm making it - feeling kinda dumb... Oh yeah - is this enough amp to handle the job by itself? Thanks very much for your patience and advice! Link to comment Share on other sites More sharing options...
Members gspointer Posted May 24, 2008 Members Share Posted May 24, 2008 any aux sends on that board? if so, use one of them for the monitor. Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 24, 2008 Members Share Posted May 24, 2008 I know this is probably Live Sound 101 but if I want to run mains and monitors on one amp from a stereo mixer, how should I hook it up so I have independant volume control of the mains and mons? I first assumed that I would use L and R main outputs from a Mackie CFX12 into the L and R inputs of a QSC PLX1804 and put a main (JBL MR925) and a monitor (JBL JRX112) daisy chained to each side output. But then I'd have no independant volume control, right? This will give you a main mix into your monitor(s). You may not like that. Usually, bands members like their own voices/ instruments in their own monitors. Then I thought to run mains on one side and mons on the other - but how do I hook up the mixer to the amp? Same way? Does it matter that I'd be running the left side to the mains and the right to the monitors (or vice versa)? I know this is probably simpler than I'm making it - feeling kinda dumb... This will be the same thing. main mix to the monitors. Come out of the aux 1 output to the second side of the amp and dial in just what is needed into the monitor "mix". That half of the amp then goes to your monitor speaker and then you should be happier! Oh yeah - is this enough amp to handle the job by itself? Don't know without more information. Thanks very much for your patience and advice! Link to comment Share on other sites More sharing options...
Members drenwick Posted May 24, 2008 Author Members Share Posted May 24, 2008 QSC PLX1804 - 600 watts stereo at 8 ohms,900 watts stereo at 4 ohms JBL MR925 - 350W continuous, 1000 peak JBL JRX 112 - 250W RMS, 1000 peak (why can't even the same mfr. speak the same language when it comes to power ratings?) Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 24, 2008 Members Share Posted May 24, 2008 QSC PLX1804 - 600 watts stereo at 8 ohms,900 watts stereo at 4 ohmsJBL MR925 - 350W continuous, 1000 peakJBL JRX 112 - 250W RMS, 1000 peak(why can't even the same mfr. speak the same language when it comes to power ratings?) This is great info, but the part about the room(s) you will be using it in is also very important.Number of people in the audience, approx size of the room, ceiling height, are you micing the drums, stage size, number of seperate mixes for monitors, etc. Link to comment Share on other sites More sharing options...
Members drenwick Posted May 24, 2008 Author Members Share Posted May 24, 2008 We play small to medium bars/clubs - 50 to 200 people max, room size and ceiling height vary - my guess is 1000-2000 sq ft. and usually standard (8-10 ft.?) ceiling height. We're a rockabilly/blues trio and we run vocals and a guitar through the PA and when we add a powered sub (soon) we'll run bass and drums (kick and snare probably all that's necessary) through it as well. I'm a little confused by the "aux sends" suggestion (don't see that config in the mixer manual) but we just want to hear ourselves in the monitors, no need for different mixes for each player. We are decidedly low-tech. Your dealing with the drummer here - and I'm trying to learn to be the on-stage sound man. I really appreciate your help! Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 24, 2008 Members Share Posted May 24, 2008 Okay, now I need to know what mixer you are using. Make and model. The aux send(s) is(are) used for sending signals to monitors or effect units seperately from the main mix. Link to comment Share on other sites More sharing options...
Members lonotes Posted May 25, 2008 Members Share Posted May 25, 2008 I'm a little confused by the "aux sends" suggestion (don't see that config in the mixer manual) but we just want to hear ourselves in the monitors, no need for different mixes for each player. We are decidedly low-tech. Your dealing with the drummer here - and I'm trying to learn to be the on-stage sound man. I really appreciate your help! On page 10 of your manual, item #10, shows the location of the aux 1&2 outputs. Page 12, item #25 shows the location of the aux controls on each channel strip. This will give you two independent mixes. Each mix will require it's own amplifier channel, and preferably, it's own dedicated eq for feedback control. Optionally, a third mix can be obtained by using efx1 in the same manner as the two auxes, if you are content with using the internal efx only. Link to comment Share on other sites More sharing options...
Members GCDEF Posted May 25, 2008 Members Share Posted May 25, 2008 We play small to medium bars/clubs - 50 to 200 people max, room size and ceiling height vary - my guess is 1000-2000 sq ft. and usually standard (8-10 ft.?) ceiling height. We're a rockabilly/blues trio and we run vocals and a guitar through the PA and when we add a powered sub (soon) we'll run bass and drums (kick and snare probably all that's necessary) through it as well.I'm a little confused by the "aux sends" suggestion (don't see that config in the mixer manual) but we just want to hear ourselves in the monitors, no need for different mixes for each player. We are decidedly low-tech. Your dealing with the drummer here - and I'm trying to learn to be the on-stage sound man. I really appreciate your help! The monitor mix is sent out an aux send rather than from the mains as it's unlikely you'll want the same mix for both. In your case, you'd run one of the pre-fade aux send outs into one side of the power amp and either the left or right main out to the other side. Make sure you keep all the channels panned either left or right depending on which out you use. Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 25, 2008 Members Share Posted May 25, 2008 On page 10 of your manual, item #10, shows the location of the aux 1&2 outputs. Page 12, item #25 shows the location of the aux controls on each channel strip. This will give you two independent mixes. Each mix will require it's own amplifier channel, and preferably, it's own dedicated eq for feedback control. Optionally, a third mix can be obtained by using efx1 in the same manner as the two auxes, if you are content with using the internal efx only. I missed the name and model of the mixer somewhere. Where is this info? Or, do you know him? Link to comment Share on other sites More sharing options...
Members GCDEF Posted May 25, 2008 Members Share Posted May 25, 2008 I missed the name and model of the mixer somewhere. Where is this info? Or, do you know him? First post, first line of the second paragraph "I first assumed that I would use L and R main outputs from a Mackie CFX12" Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 25, 2008 Members Share Posted May 25, 2008 First post, first line of the second paragraph "I first assumed that I would use L and R main outputs from a Mackie CFX12" oh, brother. Link to comment Share on other sites More sharing options...
Members lonotes Posted May 25, 2008 Members Share Posted May 25, 2008 oh, brother. No worries, it was printed awfully close to the screen :poke: Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 25, 2008 Members Share Posted May 25, 2008 Yeah, and there was some whiteout left on the screen from where I made a mistake earlier. Link to comment Share on other sites More sharing options...
Members lonotes Posted May 25, 2008 Members Share Posted May 25, 2008 I hate it when that happens. Link to comment Share on other sites More sharing options...
Members drenwick Posted May 25, 2008 Author Members Share Posted May 25, 2008 I thought the "oh brother" was in response to my choice of mixer - seems folks here are not big Mackie fans. Anyway - I understand the aux send deal and the advice on panning to one side, etc. - now it's making sense - thank you! Is my power adequate for the rooms we play and the speakers I have? (I know my speaker choices don't thrill either, but it was a budgetary thing and for what I paid (used) I think I did OK. Link to comment Share on other sites More sharing options...
Members jwlussow Posted May 25, 2008 Members Share Posted May 25, 2008 Mackies are OK. Some Mackies had a ribbon problem. I believe they are fine now. One side of the amp for monitors and the other side for FOH. 200 might be pushing it with JRXs. Should be adequate for small rooms if you don't need to blow people away with sound. You might consider another amp for monitors when you get the cash. Link to comment Share on other sites More sharing options...
Members agedhorse Posted May 25, 2008 Members Share Posted May 25, 2008 Yeah one monitor accident and there may be a puff of magic smoke. Be sure the limiter and 50Hz HPF are engaged and be careful. Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted May 25, 2008 Members Share Posted May 25, 2008 I thought the "oh brother" was in response to my choice of mixer - seems folks here are not big Mackie fans. I also have a Mackie 2404VLZ mixer. I have been thinking about the TT24, too. They are finally coming down in price, so Mackie, IMHO, makes some alright stuff. Link to comment Share on other sites More sharing options...
Members drenwick Posted May 27, 2008 Author Members Share Posted May 27, 2008 Yeah one monitor accident and there may be a puff of magic smoke. Be sure the limiter and 50Hz HPF are engaged and be careful. Can you elaborate agedhorse - be careful how? What kind of monitor accident? Were you referring to using one amp for both mains and mons or just in general cuz of the JRX's lack of quality? Thanks! Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted May 27, 2008 CMS Author Share Posted May 27, 2008 Can you elaborate agedhorse - be careful how? What kind of monitor accident? Were you referring to using one amp for both mains and mons or just in general cuz of the JRX's lack of quality?Thanks! Be careful because you are putting 900 watts into a pair of 250w speakers. That's close to double their rated RMS power handling, and an accident like feedback or bad clipping at high volume could damage a driver, or more. The limiters in the amps won't be of much good because the amps are so much higher power than the speakers can handle....limiting them to 900w is not a big help here, but use them anyway. A limiter and the knowledge to set it up, and a dual 31-band EQ and the knowledge to ring out the system would be very helpful additions to your rig. Link to comment Share on other sites More sharing options...
Members agedhorse Posted May 27, 2008 Members Share Posted May 27, 2008 Craig correctly defines the potential for failure in the event of an accident like feedback or a dropped mic or just driving the snot out of them. Link to comment Share on other sites More sharing options...
Members drenwick Posted May 27, 2008 Author Members Share Posted May 27, 2008 Thank you very much for the feedback. Instead of starting another post, what is a good rule of thumb for determining the appropriate power amp for a particular set of speakers. (That is, when finances allow me to get a separate amp for the monitors - and maybe different monitors as well). I'm alway confused by RMS, program, peak, FTC, EIA. My manuals say the following: JBL MR925 - Cont. Pink noise - 350W, Peak pink noise - 1000W JBL JRX112 - Power capacity - 250W, Peak Capacity - 1000W, recommended Amp power - 250-500W @8 ohms Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted May 27, 2008 CMS Author Share Posted May 27, 2008 Thank you very much for the feedback. Instead of starting another post, what is a good rule of thumb for determining the appropriate power amp for a particular set of speakers. (That is, when finances allow me to get a separate amp for the monitors - and maybe different monitors as well).I'm alway confused by RMS, program, peak, FTC, EIA.My manuals say the following:JBL MR925 - Cont. Pink noise - 350W, Peak pink noise - 1000WJBL JRX112 - Power capacity - 250W, Peak Capacity - 1000W, recommended Amp power - 250-500W @8 ohms For a beginner, stick close to or just above the value given for RMS, continuous pink noise, continuous average power, etc. which are all different ways of stating, for our purposes, the same thing. Ignore the "you'll do more damage underpowering than overpowering" statements, especially since it'll be people selling amps that will push this with the most zeal. Link to comment Share on other sites More sharing options...
Members drenwick Posted May 27, 2008 Author Members Share Posted May 27, 2008 OK, so it sounds like my qsc plx1804 (600w @8ohms) is even a bit much for the MR925s (one box per side when I get a 2nd amp for monitors). Can I just run the amp around 1/2 to 3/4 and be safe? Link to comment Share on other sites More sharing options...
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