Members Bandeng Posted July 2, 2014 Members Share Posted July 2, 2014 I've got a rig I use mostly for outdoor gigs. It consists of 2 Grundorf 3600GT's double 18" subs (2000 w/RMS) & JBL SR4731 tops. I currently have it stereo tri-amped using a DCX2496 and the following amps - (2) QSC DCA3022's (mids & highs) & (1) Peavey IPR2 7500 on the subs. I've been thinking of going just stereo bi-amp using the IPR2 7500 for the tops (running passive) and bridging the two DCA3022's (3000w/4oms) and running one on each sub. My reason for doing this is the way it is now, the jbl's are not as efficient as the subs and I need more gas outdoors. The tops are rated for 1200w continuous. What's your opinions? Also power is not a consideration at the outdoor gigs (have more than enough circuits available. Link to comment Share on other sites More sharing options...
Members Pro Sound Guy Posted July 3, 2014 Members Share Posted July 3, 2014 Honestly more gas translates to more boxes.More loudspeakers translates to moving more air and that it the physics of it.More boxes = More subs and more tops. Link to comment Share on other sites More sharing options...
Members agedhorse Posted July 3, 2014 Members Share Posted July 3, 2014 More power will translate to bigger bang and more magic smoke. I wouldn't power those subs at more than 2000 watts. Not if I cared about them lasting. Have you priced recones? Link to comment Share on other sites More sharing options...
Members Bandeng Posted July 3, 2014 Author Members Share Posted July 3, 2014 Just re-coned an 18 last month, not overpowered, just an open coil. My cost was $140.00The tops are under-powered, not the subs. JBL recommends 1.5 to 2 times the 1200w continuous rating for the SR 4731 power. I'm not running the system into clipping, I'm looking for it's max potential without blowing it up. I've not blown a driver in over 25 years, had failure, but not by abuse. Link to comment Share on other sites More sharing options...
Members agedhorse Posted July 3, 2014 Members Share Posted July 3, 2014 How do you think voice coils generally become open? If you already know it all, why are you asking these questions? Link to comment Share on other sites More sharing options...
Members Bandeng Posted July 3, 2014 Author Members Share Posted July 3, 2014 I've re-coned enough speakers to know when they were abused vs fatigued, the 18 was 7 years old and the cab was then powered by a single channel of a DCA 3022 (950w/4ohms) at the time it quit, not clipped. I never said I knew it all, just looking for the max output and headroom I can get with what I have currently. Link to comment Share on other sites More sharing options...
Members Dookietwo Posted July 3, 2014 Members Share Posted July 3, 2014 I'd stay with the Triamp system you have just add an amp. IPR7500 still on the subs. An IPR7500 on the midrange. One channel of the 3022 per horn. Going from 2000 to 3000 watts on your subs is only going to give you a db or so. Plus it will add to the heat and power compression in them so they may even drop in output when things heat up. Having the potential of 2000 watts going through the passive crossover on the tops is asking a lot of voltage for the crossover to swing. Regardless of the passive crossover design all passive crossovers dissipate some voltage into heat so you will again loose some of this power. Right now you have about 900 watts to each mid range? I believe the qsc amps are cinema series amps. Going from 900 + horn wattage to 2000 with the ipr amp on the tops full range is just a little more than a 3db gain. Add to that the loss in the passive crossover plus the debatable sound quality loss by dropping down from triamp to biamp I don't see this as a gain. Even with adding a 7500 on the mid range and staying bi amp on your tops they will only be 3dbs louder. Is that really worth a grand or so investment? Doug Link to comment Share on other sites More sharing options...
Members agedhorse Posted July 3, 2014 Members Share Posted July 3, 2014 With power compression, the increase is likely to be less than 2dB with greatly increased risk to driver reliability. The drivers are already operating at the point of diminishing returns. You usually can't look at a bad driver and state with authority that a driver was not overpowered without proper forensic analysis. There are mechanical faults that are not visible to the eye. I operated a factory level recone facility for over 20 years, I might know just a little bit about this topic... Link to comment Share on other sites More sharing options...
Members Bandeng Posted July 3, 2014 Author Members Share Posted July 3, 2014 I'd stay with the Triamp system you have just add an amp. IPR7500 still on the subs. An IPR7500 on the midrange. One channel of the 3022 per horn. Going from 2000 to 3000 watts on your subs is only going to give you a db or so. Plus it will add to the heat and power compression in them so they may even drop in output when things heat up. Having the potential of 2000 watts going through the passive crossover on the tops is asking a lot of voltage for the crossover to swing. Regardless of the passive crossover design all passive crossovers dissipate some voltage into heat so you will again loose some of this power. Right now you have about 900 watts to each mid range? I believe the qsc amps are cinema series amps. Going from 900 + horn wattage to 2000 with the ipr amp on the tops full range is just a little more than a 3db gain. Add to that the loss in the passive crossover plus the debatable sound quality loss by dropping down from triamp to biamp I don't see this as a gain. Even with adding a 7500 on the mid range and staying bi amp on your tops they will only be 3dbs louder. Is that really worth a grand or so investment? Doug I somewhat agree, I like having lots of headoom. I will have a QSC GX7 available when my other monitor amp is repaired...Or I can get another IPR2 for $650. Adding more top boxes is not an option because the extra horizantal coverage would be bouncing off two 40' high brick walls, 25' on each side of the stage/venue. Link to comment Share on other sites More sharing options...
Members Bandeng Posted July 3, 2014 Author Members Share Posted July 3, 2014 With power compression, the increase is likely to be less than 2dB with greatly increased risk to driver reliability. The drivers are already operating at the point of diminishing returns. You usually can't look at a bad driver and state with authority that a driver was not overpowered without proper forensic analysis. There are mechanical faults that are not visible to the eye. I operated a factory level recone facility for over 20 years, I might know just a little bit about this topic... I'm sure you do, I learned from a authorized JBL re-coner. You sound like you've been at this as long or longer than I have. Link to comment Share on other sites More sharing options...
Members Shaster Posted July 3, 2014 Members Share Posted July 3, 2014 I've got a rig I use mostly for outdoor gigs. It consists of 2 Grundorf 3600GT's double 18" subs (2000 w/RMS) & JBL SR4731 tops. I currently have it stereo tri-amped using a DCX2496 and the following amps - (2) QSC DCA3022's (mids & highs) & (1) Peavey IPR2 7500 on the subs. I've been thinking of going just stereo bi-amp using the IPR2 7500 for the tops (running passive) and bridging the two DCA3022's (3000w/4oms) and running one on each sub. My reason for doing this is the way it is now, the jbl's are not as efficient as the subs and I need more gas outdoors. The tops are rated for 1200w continuous. What's your opinions? Also power is not a consideration at the outdoor gigs (have more than enough circuits available. Are you borderline or do you need substantially more SPL from you top boxes? If it's the former, you might consider just living with it. If it's the latter, it sounds like you need more boxes, or or in other words, abiigger top box rig. Also, is this a case where a repeater stack or center fills might solve the problem better than pushing your JBL's to the max? IMO going from a nice tri-amped system to a passively crossed over system could be construed as a step in the wrong direction. But that's my opinion. I'll concede that you're the one running the PA and therefore know your own specific needs. Link to comment Share on other sites More sharing options...
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