Members spottyaudio Posted April 28, 2012 Members Share Posted April 28, 2012 i've been asked this questian by a club owner, not quite phrased like that..he has two ev tour x subs the tx2181 with the evx180b drivers, and just bought a third. he wants to find a way to power this without adding more amps, only four spaces of rack available. i know old ma5000vs crowns could be bridged into quite low impeedence loads and run for hours like this, but can anything out there today do this safely? failing that, are there any stereo amps, that are four rack spaces or less, that'd power three of the evx drivers per side at 2.67 ohms? qsc makes the 5050, but i dont know if he'll go for it as qsc and him had a bad run when he was first starting out, his fault, but try and convince him of that.. i know this isnt really the right way to do this, i should just add a third crown macrotec 1200 but he really strongly doesnt want to redo the pretty dj booth/amp rack to acomidate it. Link to comment Share on other sites More sharing options...
Members MJastrzebski Posted April 28, 2012 Members Share Posted April 28, 2012 if you run everything off one amp and that amp goes down, you don't have subs. Just get a second amp. If one amp fails, you still have the other to get through the night. Link to comment Share on other sites More sharing options...
Members spottyaudio Posted April 28, 2012 Author Members Share Posted April 28, 2012 could do that, run something like a qsc 2450 for four, and a 1450 for two..however, i think i found a sollution. the crest cc4000http://www.fullcompass.com/product/235979.html any experience with these? i can keep one of the macrotec 1200s in the rack with it as a spare if the worst happens. Link to comment Share on other sites More sharing options...
Members gspointer Posted April 28, 2012 Members Share Posted April 28, 2012 what about single space amps? Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 29, 2012 Members Share Posted April 29, 2012 1. No, I know of not a single power amp (with any credibility) that will run a 2.6 ohm load safely. To tryhis would be irresponsible and shortsighted. 2. A MAJOR flaw in your reasoning running 3 drivers on one channel and 3 driver on the other channel is that you will be splitting drivers in the same cabinet AND (assuming the drivers share airspace) if you were to have an amp channel fail, or if somebody happens to turn down one channel of the sub amp, the cabinet with the unpowered driver will destroy itself under any significant power as the cabinet tuning will be so far off as to be essentially out of bounds. Additionally this will be made worse as the remaining unpowered driver will operate essentially out of phase or with reverse polarity REDUCING the sub output even more causing the unbsuspecting DJ to turn it up more. 3. Put 1 cabinet on one side and the other 2 cabinets on the other side and be done with it. 4. If you wanted to use the QSC solution, use 2450's for all cabinets, or try 2 subs on one channel (2 ohm) and 1 sub on the other (4 ohm). 5. If you use 2 amps, they need to be the same. The 1450 is not an adequate choice under the conditions you propose. Look at the 4 ohm power and choose based on that (do NOT bridge the 1450 as then you have polarity and gain issues to correct as well as making anybody troubleshooting the sysyem after you are gone curse you like the devil incarnate. Link to comment Share on other sites More sharing options...
Members spottyaudio Posted April 29, 2012 Author Members Share Posted April 29, 2012 all valid points, and i agree with them, however i am just trying to get someone off my back that was foisted on me by a friend while keeping everybody happy. i didnt think about the two drivers in same airspace on different channels, thats actually the strongest argument against this whole idea. i'm still learning lots, and while i think i have a good grasp on most concepts, those who've been doing it for many years have a quicker off the mark logic that i just dont have yet. i'm going to go see if there is room to hide another macrotec 1200 in there because if there is, his costs go down, he thinks i'm a genius lol, and all amps are the same. this is all behind a ventelated door so i'm not to worried about tampering but i do want the third amp to be secure somehow so thats going to be the next hurdle. Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 29, 2012 Members Share Posted April 29, 2012 The biggest point is that you do not want to get somebody off your back by gining them a bad solution that you may down the road REALLY wish you hadn't done. Once you do something like this, you are married to it if you gave bad advice or were not forthright. Link to comment Share on other sites More sharing options...
Members spottyaudio Posted April 29, 2012 Author Members Share Posted April 29, 2012 thats kind of why i asked first, i would rather do a three amp set up but he wants to use the sale of the crowns to get a bigger amp for all six drivers. he knows just enough about sound to know nothing. its a sticky situation i'd rather not be in, and like i said the third crown would be my first choice. i want to be honest, and i want to be done, in that order. Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 29, 2012 Members Share Posted April 29, 2012 A bigger amp with 2 subs on one channel and one sub on the other would be fine as well. Just not what you proposed, that would cause issues. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 29, 2012 Members Share Posted April 29, 2012 1. No, I know of not a single power amp (with any credibility) that will run a 2.6 ohm load safely. To tryhis would be irresponsible and shortsighted. Out of curiosity: as far as the amp is concerned, it there a difference between 2 ohms and 2.6 ohms? I ask, because it's always been my understanding that amps are generally safe driving loads with an impedance higher than what the amps' rated for, but not lower. By this logic, an amp rated for 2 ohms would be ok running at 2.6 ohm. Is this correct? -Dan. Link to comment Share on other sites More sharing options...
Members spottyaudio Posted April 29, 2012 Author Members Share Posted April 29, 2012 dan, most amps are designed to run, if not totally happily, at two ohms stereo. however, bridging the amp, and here i may be a bit off but i dont think so, halves that impeedence as it combines channels, meaning that most amps can only safely bridge to four ohms or higher, and some cant do that without risk of damage. Link to comment Share on other sites More sharing options...
Members Rezrover Posted April 29, 2012 Members Share Posted April 29, 2012 Call EV, they'll tell you their Tour Grade amps are perfectly suited for this set-up, if you can afford them. That's what they told me and I had the PX-2181's. Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 29, 2012 Members Share Posted April 29, 2012 Call EV, they'll tell you their Tour Grade amps are perfectly suited for this set-up, if you can afford them. That's what they told me and I had the PX-2181's. Not bridged into 2.6 ohms they aren't. No way. In stereo, they are fine, but so is every other pro amp. Link to comment Share on other sites More sharing options...
Members Dogoth Posted April 29, 2012 Members Share Posted April 29, 2012 dan, most amps are designed to run, if not totally happily, at two ohms stereo. however, bridging the amp, and here i may be a bit off but i dont think so, halves that impeedence as it combines channels, meaning that most amps can only safely bridge to four ohms or higher, and some cant do that without risk of damage. You are correct. I'll add to this in that most amps are not as stable running the same total wattage (across twice the lowest rated "per channel" impedence) as they would be running seperate channels (it has to do with floating the center away from that stable ground reference). At least that's been my experiance. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 29, 2012 Members Share Posted April 29, 2012 Ah, I missed the part about it being bridged. Thanks. -Dan. Link to comment Share on other sites More sharing options...
Members dboomer Posted April 29, 2012 Members Share Posted April 29, 2012 Not that I expect this is the answer you want, but here's one ... Crest 10001:thu: http://www.crestaudio.com/media/pdf/10001_10-15-97.pdf Of course it weight 150 lbs and costs $$$$. The other thing is that in practice your minimum load is probably lower than 2.67, which is the nominal value. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 29, 2012 Members Share Posted April 29, 2012 My back hurts looking at that. -Dan. Link to comment Share on other sites More sharing options...
Members Rezrover Posted April 29, 2012 Members Share Posted April 29, 2012 Not bridged into 2.6 ohms they aren't. No way.In stereo, they are fine, but so is every other pro amp. Missed that part. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 29, 2012 Members Share Posted April 29, 2012 Not that I expect this is the answer you want, but here's one ... Crest 10001:thu:http://www.crestaudio.com/media/pdf/10001_10-15-97.pdfOf course it weight 150 lbs and costs $$$$. The other thing is that in practice your minimum load is probably lower than 2.67, which is the nominal value. I just realized that the second paragraph touts the amp's power-to-weight ratio. lol, awesome. -Dan. Link to comment Share on other sites More sharing options...
Members Unalaska Posted April 29, 2012 Members Share Posted April 29, 2012 5k @ 1 ohms per channel. 1250w per dual 18 or 625w per driver times 16. 1/3 power AC draw of 25amps PER LINE. wow. Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 29, 2012 Members Share Posted April 29, 2012 5k @ 1 ohms per channel. 1250w per dual 18 or 625w per driver times 16. 1/3 power AC draw of 25amps PER LINE. wow. and about 5x their budget, and bigger than the rack will accept I suspect. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted April 30, 2012 Members Share Posted April 30, 2012 Not that I expect this is the answer you want, but here's one ... Crest 10001:thu:http://www.crestaudio.com/media/pdf/10001_10-15-97.pdfOf course it weight 150 lbs and costs $$$$. I believe the same could be said for a Crown MA-10K (rated to 1/2 ohm operation). Link to comment Share on other sites More sharing options...
Members agedhorse Posted April 30, 2012 Members Share Posted April 30, 2012 I believe the same could be said for a Crown MA-10K (rated to 1/2 ohm operation). Yes, as well. Link to comment Share on other sites More sharing options...
Members spottyaudio Posted April 30, 2012 Author Members Share Posted April 30, 2012 definitely out of budget but damn cool to look at either way! Link to comment Share on other sites More sharing options...
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