Members twostone Posted March 5, 2007 Members Share Posted March 5, 2007 Need help with the ohm's law had a disaster at our gig because drummer doesn't understand ohm's law. Please tell him you can't mix match 4ohms and 8 ohms together he ran 4-4ohm into one side of amp and 5-8ohms to the other side and wondered why his amp fried I need to print this info. out from you experts that know that way I have more proof he's stubborn and claims he did this set up at 100's of gigs in California. Link to comment Share on other sites More sharing options...
Members prosigna Posted March 5, 2007 Members Share Posted March 5, 2007 That would be a 1-ohms and 1.6 ohms load on each side. That is real similar to sticking a screwdriver between the output poles on the back of the amp. Link to comment Share on other sites More sharing options...
Members GCDEF Posted March 5, 2007 Members Share Posted March 5, 2007 Ohm's law isn't really applicable directly here. He needs to learn how to calculate impedances without going below the amp's limit. You can run 4 and 8 ohms together if you want, although keep in mind the lower impedance will get more power. This is probably the most useful formula for him. 1/(total resistance) = (1/R1) + (1/R2) + (1/R3)... Link to comment Share on other sites More sharing options...
Members prosigna Posted March 5, 2007 Members Share Posted March 5, 2007 Ohm's law isn't really applicable directly here. He needs to learn how to calculate impedances without going below the amp's limit. You can run 4 and 8 ohms together if you want, although keep in mind the lower impedance will get more power.This is probably the most useful formula for him.1/(total resistance) = (1/R1) + (1/R2) + (1/R3)... You are correct, you can run different ratings on either side. I read the OP to say he ran five 8-ohms on one side and four 4-ohms on the other. 1/((1/8)+(1/8)+(1/8)+(1/8)+(1/8) = 1.6-ohms 1/((1/4)+(1/4)+(1/4)+(1/4)) = 1-ohms at least thats waht I read it to say. Link to comment Share on other sites More sharing options...
Members GCDEF Posted March 5, 2007 Members Share Posted March 5, 2007 You are correct, you can run different ratings on either side. I read the OP to say he ran five 8-ohms on one side and four 4-ohms on the other.1/((1/8)+(1/8)+(1/8)+(1/8)+(1/8) = 1-ohms1/((1/4)+(1/4)+(1/4)+(1/4)) = 1-ohmsat least thats waht I read it to say. I did too. The problem as you pointed out was the total load went too low, not that he had 8 ohm cabs on one side and 4 on the other. Link to comment Share on other sites More sharing options...
Members Square Posted March 5, 2007 Members Share Posted March 5, 2007 While it is possible to chain together an 8 ohm enclosure and a 4 ohm enclosure to one side of an amplifier that can handle 2 ohms loads (the load would be 2.66 ohms), the bigger issue is that you would would be operating 2 different types of boxes on the same frequency band (bad idea), AND you would be sending wattage to each box (with the 4 ohm box getting most of the power). It would be pretty much impossible to balance these boxes, and EQ them properly. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 5, 2007 Members Share Posted March 5, 2007 Need help with the ohm's law had a disaster at our gig because drummer doesn't understand ohm's law. Please tell him you can't mix match 4ohms and 8 ohms together he ran 4-4ohm into one side of amp and 5-8ohms to the other side and wondered why his amp fried I need to print this info. out from you experts that know that way I have more proof he's stubborn and claims he did this set up at 100's of gigs in California. 5 ea. parallel 8 ohm loads would be nominally 1.6 ohms 4 ea. parallel 4 ohm loads would be nominally 1.0 ohms The reason I say: "nominally" is because an 8 ohm rated speaker could have a minimum impedance as low as somewhere around 5 1/2 ohms. A 4 ohm rated speaker could have a minimum impedance as low as somewhat less than 3 ohms. Therefore, the 4 ea. parallel "4 ohm" speakers could have a minimum impedance well below 1 ohm. But, since it appears it's his amp he snuffed, and he knows he's got his act together on this sort of stuff... why bother trying to explain something to somebody who knows better? Link to comment Share on other sites More sharing options...
Members prosigna Posted March 5, 2007 Members Share Posted March 5, 2007 My calculator did not understand me, I fixed it now (1.6 not 1) Link to comment Share on other sites More sharing options...
Members nobrainer440 Posted March 5, 2007 Members Share Posted March 5, 2007 Even if your amp had a low enough impedance rating to handle it, the lower impedance box would be working a lot harder than the higher impedance box, so why even bother? Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 5, 2007 Members Share Posted March 5, 2007 He needs to learn a more proper protocol. I'm in CA, and the rules apply here as well as everywhere else on this planet. Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted March 6, 2007 Members Share Posted March 6, 2007 Ohms law: Pi R square. Cake R round. LOL :: Link to comment Share on other sites More sharing options...
Members twostone Posted March 6, 2007 Author Members Share Posted March 6, 2007 Thanks guys very well appreciated now I have other people's input as well. I think this drummer crazy I think he's thinking that 2000 watts was enough to run 9 speakers who knows WTF he was thinking. Link to comment Share on other sites More sharing options...
Members GCDEF Posted March 6, 2007 Members Share Posted March 6, 2007 Thanks guys very well appreciated now I have other people's input as well. I think this drummer crazy I think he's thinking that 2000 watts was enough to run 9 speakers who knows WTF he was thinking. With all due respect, the drummer doesn't seem like the only one that's confused. 2000 watts is plenty of power to run 9 speakers. Lack of power wasn't the problem. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 6, 2007 CMS Author Share Posted March 6, 2007 Hmmm, so he did this in California 100's of times. Well, it must be the amp's fault. So why butt heads? Let him do the 'buy and fry a few more times. Here in the forums I'm persistent because I assume someone asking for help really wants it, but in 'real life', if you don't want to take my advice, I don't push it. Your drummer doesn't understand impedance matching, and obviously doesn't care to, even though it's in his best interest. I can't think of a better reason to leave him to his own devices. It makes the "I told you so" look you give him all the more satisfying. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 6, 2007 Members Share Posted March 6, 2007 With all due respect, the drummer doesn't seem like the only one that's confused. 2000 watts is plenty of power to run 9 speakers. Lack of power wasn't the problem. Well... if indeed the amp was capable of delivering 2000 watts to basically stereo 1 ohm loads (in Calif)... that would mean the amp would possibly be rated somewhere around a 125w @ 8 ohms... Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted March 6, 2007 Members Share Posted March 6, 2007 Well... if indeed the amp was capable of delivering 2000 watts to basically stereo 1 ohm loads (in Calif)... ....That would mean that it would put out maybe 125W in a conservative state. Link to comment Share on other sites More sharing options...
Members prosigna Posted March 6, 2007 Members Share Posted March 6, 2007 If that is 2000-watts peak then it is like 31.25@8-ohms RMS!!!!! Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 6, 2007 CMS Author Share Posted March 6, 2007 If that is 2000-watts peak then it is like 31.25@8-ohms RMS!!!!! And it's seriously 'underpowered':rolleyes: . Maybe the drummer should get a much bigger amp. Surely more power will solve this one:rolleyes: Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 6, 2007 Members Share Posted March 6, 2007 And it's seriously 'underpowered':rolleyes: . Maybe the drummer should get a much bigger amp. Surely more power will solve this one:rolleyes: Or he could always bridge it... that way he can blow it up with even less effort. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 6, 2007 CMS Author Share Posted March 6, 2007 Or he could always bridge it... that way he can blow it up with even less effort. I thought it was just a 'given' that the amp had to be bridged. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 6, 2007 Members Share Posted March 6, 2007 I thought it was just a 'given' that the amp had to be bridged. I forgot to read that audio fantasy magazine article... thanks for reminding me Craig;) Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 6, 2007 CMS Author Share Posted March 6, 2007 I forgot to read that audio fantasy magazine article... thanks for reminding me Craig;) Dude, it's on Page 53 of BOOM. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 6, 2007 Members Share Posted March 6, 2007 And it's seriously 'underpowered':rolleyes: . Maybe the drummer should get a much bigger amp. Surely more power will solve this one:rolleyes: Well... a Crown MA-10K would solve the problem. Admittedly at 8 ohms they're only rated somewhere around 800 watts, and admittedly they're a mono amp, but they're stable down to 1/2 ohm... so 16 ea. 8 ohm speakers could be parallel chained... and are rated at 10KW driving a 1/2 ohm load. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 6, 2007 CMS Author Share Posted March 6, 2007 Well... a Crown MA-10K would solve the problem. Admittedly at 8 ohms they're only rated somewhere around 800 watts, and admittedly they're a mono amp, but they're stable down to 1/2 ohm... so 16 ea. 8 ohm speakers could be parallel chained... and are rated at 10KW driving a 1/2 ohm load. Yup, for sure it is. Just don't worry about that 240v mains power; I've got some good jumper cables out in the truck..... Link to comment Share on other sites More sharing options...
Members tlbonehead Posted March 7, 2007 Members Share Posted March 7, 2007 Thanks guys very well appreciated now I have other people's input as well. I think this drummer crazy I think he's thinking that 2000 watts was enough to run 9 speakers who knows WTF he was thinking. As G meantioned, 2000 watts is certainly enough power to split between 9 monitors. That's over 200 watts each, if it could be correctly divied up between them. The power thing wasn't the issue. Link to comment Share on other sites More sharing options...
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