2x18 subs

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    I purchased 4xB&C 18PS46  built 2x18 bass reflex  cabs 450 litres tuned to 36hz .I bought these brand new they are xmaxing at low power .I ran 500w -1000w and bridged 2100w and they xmax.I put the  old jbl 2240's in the same cab and there fine no problem with xmax
18 ps 46 specs qts.31/vas.386/fs.28/re.5.3/le.2.40/xmax.6mm/qms.7.60/qes.o. 33/pe.700w/spl.96.5/bl.20.8/sd.1130cm 

any help would be  appreciated        & amp; nbsp;    thanx Ron

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ronmaio Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 24 May 2005 Status: Offline Points: 14	Post Options Post Reply Quote ronmaio Report Post Thanks(0) Quote Reply Topic: 2x18 subs Posted: 04 April 2006 at 9:00pm
	I purchased 4xB&C 18PS46 built 2x18 bass reflex cabs 450 litres tuned to 36hz .I bought these brand new they are xmaxing at low power .I ran 500w -1000w and bridged 2100w and they xmax.I put the old jbl 2240's in the same cab and there fine no problem with xmax 18 ps 46 specs qts.31/vas.386/fs.28/re.5.3/le.2.40/xmax.6mm/qms.7.60/qes.o. 33/pe.700w/spl.96.5/bl.20.8/sd.1130cm any help would be appreciated & amp; nbsp; thanx Ron

minaximal Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 26 September 2004 Location: United Kingdom Status: Offline Points: 1780	Post Options Post Reply Quote minaximal Report Post Thanks(0) Quote Reply Posted: 05 April 2006 at 11:35am
	do you hpf them? 34hz or above.
	Subs + Barges = :) www.metaacoustics.com

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Posted: 05 April 2006 at 2:29pm
	Odd, the excursion of the driver at a particular frequency and volume should depend almost entirely on the cabinet itself (or so it seems from simulation and makes sense). 450L is actually quite large for a twin 18" box, personally I'd prefer 350-400L and a tuning closer to 40Hz. Can you sweep them with a signal generator to find out at what frequencies the excursion is causing a problem? If it's below the tuning, this is to be expected and can be cured with a HPF as minaximal says. If it's around 60-70Hz then it indicates that the box might be tuned too low. Have you done simulations with the two drivers?

ronmaio Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 24 May 2005 Status: Offline Points: 14	Post Options Post Reply Quote ronmaio Report Post Thanks(0) Quote Reply Posted: 06 April 2006 at 3:58am
	Thanks for the sign wave tip. The input on the DBX drive rack sat at 0db but the output was swinging from -10 to +15 mainly at the begining of each frequency.Its the processer that has the problem.we hooked up an analogue jbl xover and its fine . Couldnt tell just with a kik drum but the steady sign wave made it easy cheers; Ron