Members badhabit Posted December 20, 2007 Members Share Posted December 20, 2007 OK, I'm trying to wrap my brain around these power ratings. I have some JBL 18" drivers rated @ 600 watts continuous program. The amp I'm using is rated at 650 watts per channel @ 8 ohms. The amp doesn't mention RMS, continuous or program. Just says the various power levels at various ohms and bridged. Is the power rating for the JBL 18" drivers 600 RMS watts? Is that basically the same as continuous program watts? Is the amp I'm using @ 650 watts @ 8 ohms the proper power for these speakers? They are 8 ohms as well. I know I could run both of them on one side @ 4 ohms @ 1100 watts but then that would be a little less power to them. What would be the optimal way to power these subs? They are mounted in bass reflex ported cabinets of proper dimensions and quality construction. Should I continue to run each of them off their own channel @ 650 watts? Link to comment Share on other sites More sharing options...
Members dboomer Posted December 20, 2007 Members Share Posted December 20, 2007 Wow, I haven't posted these for a couple of months now Here ... check these http://www.peavey.com/support/technotes/concepts/THE_LOUDSPEAKER_SPEC_SHEET_GAME_2005.pdf http://www.peavey.com/support/technotes/poweramps/HOW_MUCH_POWER.pdf Link to comment Share on other sites More sharing options...
Members badhabit Posted December 20, 2007 Author Members Share Posted December 20, 2007 Thank you! Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 20, 2007 Members Share Posted December 20, 2007 500-600 watts is great for those speakers. Exactly which speaker... some are 4 ohms so you need to be aware of this due to the amp delivering more poer into a 4 ohm load than an 8 ohm load. Link to comment Share on other sites More sharing options...
Members badhabit Posted December 20, 2007 Author Members Share Posted December 20, 2007 the speakers are JBL 2240H, which are supposed to be 8 ohms each Link to comment Share on other sites More sharing options...
Members killersoundz Posted December 20, 2007 Members Share Posted December 20, 2007 650 into those speakers is fine. I always try to shoot a couple hundred watts over on my amp power compared to speaker handling power just for the extra headroom. Doesn't mean you have to use it all, it's just nice to have it there and let your amps take a nap. Unexperienced person with too much headroom available though could easily toast their drivers. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 20, 2007 Members Share Posted December 20, 2007 Wait a minute, the 2240 is a significantly different speaker than the 2241. I revise my power recommendation to a 400 watt RMS limit. The difference between the two drivers is pretty big... the VC wire and gap dimensons is way larger and the former is glass-epoxy on the 2241 & 2242 these days, compared with the 2240 (and 2245). I do a LOT of recone work on all these drivers. Headroom is fine, but you must be sure the signal is high-passed appropriate to the box tuning and that you really use headroom as just that. Recones are not cheap. The "H" suffex denotes 8 ohm. Link to comment Share on other sites More sharing options...
Members badhabit Posted December 20, 2007 Author Members Share Posted December 20, 2007 Thank you Aged. I use the JBL 2240's as subs only and the crossover point is at 100 Hz. Everything above that goes to my 15" + Hi freq. horn cab. For some strange reason, the 40 Hz low cut filters on my new DBX 223 crossover does not seem to be working. I press the buttons in but they don't stay engaged. I am running the 223 in stereo mode. Does this effect the operation of the low cut filters? So far, the 2440's have not "protested" the program material I've used them for. I also find it odd that JBL rates them @ 600 watts continuous program but you recommend an amp @ 400 watts RMS. I guess this points to the Peavey articles re: manufacturers ratings and how dubious they are. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 20, 2007 Members Share Posted December 20, 2007 Thank you Aged. I use the JBL 2240's as subs only and the crossover point is at 100 Hz. Everything above that goes to my 15" + Hi freq. horn cab. For some strange reason, the 40 Hz low cut filters on my new DBX 223 crossover does not seem to be working. I press the buttons in but they don't stay engaged. I am running the 223 in stereo mode. Does this effect the operation of the low cut filters? So far, the 2440's have not "protested" the program material I've used them for. I also find it odd that JBL rates them @ 600 watts continuous program but you recommend an amp @ 400 watts RMS. I guess this points to the Peavey articles re: manufacturers ratings and how dubious they are. No, the problem is that the specs are misleading. The 2240 is rated at 300 watts RMS, 600 watts program power. The info is there in the data sheet but not clearly represented. Marketing may have asomething to do with this. You guys have to trust me with this kind of stuff, and use my commentys as the jumping off point for additional learning. Read footnote #1 in the specs for clarification!!! http://www.jblpro.com/pub/obsolete/2240.pdf Link to comment Share on other sites More sharing options...
Members badhabit Posted December 20, 2007 Author Members Share Posted December 20, 2007 Thanks again. I did read that spec sheet and I refer back to my orig. post, the question of continuous program rating vs. RMS ratings. So, IF I understand correctly, continuous program equals roughly double (2x) an RMS rating. So the 2240 rated at 600 watts continuous program means a 300 watt RMS power rating? I did see on the spec sheet where it noted the Pe (MAX) was 300 watts continuous sine wave. Does this refer to a RMS rating? If that is the case, and assuming my Crown amp is rated using RMS rating, then the 650 RMS watts per side @ 8ohms is WAY more power than I should be using? Would it be safer/better to run these subs/speakers @ 4 ohms off just one side of the amp and reduce the power to the speakers to 550 watts each? This is the footnote you are referring to. "Continuous program power is defined as 3 dB greater than continuous sine wave power and is a conservative expression of the transducer Link to comment Share on other sites More sharing options...
Members Not Serial Posted December 20, 2007 Members Share Posted December 20, 2007 is this amp the XS1200? i think a lot of this depends on how you run the system rather than raw numbers. i tend to play it very safe and match the rms numbers to each other (except in the C-rig which all bets are off number-wise ) on my srx rig its pretty well matched; one side of a plxII3602 goes to each speaker or sub pair, but the system never see's anywhere near max spl. i bet this rig has never broken 94db at FOH (but thats a guess). however on a buddy's rig he has a bridged 3402 on each mtl-1x (!!) this is approx triple the rms rating (3400 into 1200). i drive the snot out of this rig (no clips) and while i have been vocal about the situation nothing has needed a recone (yet). i cant see how this will last in the long run. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 21, 2007 Members Share Posted December 21, 2007 Marketing has something to do with this but as long as you are careful and recognize the limitations you should be ok with 600 watts. Don't let others run it without your oversight though. The program rating came about because generally undistorted program, 3dB additional for peak headroom was no problem and there weren't all these "stupid-big" amps being used by those without common sense and restraint. Also, JBL's big market is/was the cinema market and with playback you don't see some of the abusive behavour that the music industry gives speakers... especially subs. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 21, 2007 Members Share Posted December 21, 2007 however on a buddy's rig he has a bridged 3402 on each mtl-1x (!!) this is approx triple the rms rating (3400 into 1200). i drive the snot out of this rig (no clips) and while i have been vocal about the situation nothing has needed a recone (yet). i cant see how this will last in the long run. Here's what will happen IME... the limitation on the EVX drivers isn't so much thermal as it is mechanical. Initially there will be visible stress on the surround, it will begin to fatigue and crack either right at the cone edge or right at the basket flange. There will also be a corresponding softening of the spider (note how stif a new one is compared to an abused one, the difference is remarkable) and as the TS parameters shift the driver will no longer load correctly and it will tear itself apart. The EVX driver is a great unit, just needs to be used with a little care. Recones are not cheap either. Link to comment Share on other sites More sharing options...
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