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Notes on 4-ohm bridged / 2-ohm dual operation


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#1 Kevin Heber

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Posted 08 February 2011 - 10:52 AM

This is the scoop on 4-ohm bridged / 2-ohm dual operation.  All Crown pro audio amps built in the last 5 years are stable this way and will not shut down due to DC protect.  However, please note that this is an extreme load on any amp.  Think of a vehicle towing a huge trailer up a mountain pass -- it might be able to do it, but, it's wear & tear.  Also, DO NOT CLIP the amp with these loads because heat will build up extremely fast.

XLS-D (old): The 802 model technically needs a 20-amp power supply to run this way.  The old XLS series tends to overheat anyway with these loads, so we don't recommend doing it.

iTech/HD, MAi: These amps run on an extremely high voltage rail and will need to current-limit to run on these loads.  So power begins dropping off below 8-ohms bridged/4-ohms dual.

Update 6/28/13 by Avi:
XLi series amps don't support 2 ohm stereo or 4 ohm bridge!!

Note on combining 2 or more 8-ohm speakers in parallel:  There will be spots on the impedance curve, usually just above and below speaker resonance, where the impedance will be BELOW 8-ohms.  Therefore, the amp will actually see a load LESS THAN 4-ohm bridged / 2-ohm dual when combining these speakers in parallel, and may react badly to it.  Just something to be aware of.

#2 Tor

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Posted 27 February 2011 - 04:14 PM

I take this as a coincidental answer to my question (see my post)

How about running them in series/parallel to keep the impedance up.  And if so,  I never saw any body talk about reversing the wiring on your Speakon connectors so they would be + to - (series) instead of + to + (parallel)?

#3 Kevin Heber

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Posted 01 March 2011 - 02:26 PM

Nothing wrong with series/parallel in order to run multiple speakers, but you won't get any more power out of each speaker than you would if running in stereo.

#4 Tor

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Posted 04 March 2011 - 12:53 AM

The point is not to get more power, but to use whats available without letting the impedance drop too much.  From the literature, it seems like the amps dont like to be run at 2.67 ohms or 2 ohms for that matter.  I also think that the audience prefers to have the speakers closer in proximity and at less volume, rather than blasting them from stage speakers



#5 Kevin Heber

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Posted 04 March 2011 - 07:50 AM

Yep, if you want to push a larger number of speakers and spread out the power, then series-parallel works great.  The next logical step would be a 70V transmission-line-type system.

#6 sonar

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Posted 30 April 2011 - 09:25 AM

Hello.  I am about to buy the XLS1000.  I need 700 watts of power, so I will use it bridged.  The problem is my speaker is 2 ohms.  The XLS1000 can deliver 1100 watts in 4 ohms, but it is not recommended to load it with a 2 ohms speaker. Is it ok to use my amp in a 2 ohms load if I only drive it to 700 watts?

Thanks,

Sonar

#7 Kevin Heber

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Posted 03 May 2011 - 02:49 PM

Unfortunately the amp will almost surely short-protect itself if you try to connect a 2-ohm speaker in bridged mode, regardless of how hard you drive it.

#8 torres

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Posted 13 February 2012 - 10:52 PM

hello just out of curiosity and this is for future reference but i have the xls1500 i'm running a peavey sub 400watt its safe to say that i'm going to be able to run two of these in parallel whenever i get around to buying another sub or do i have to worry about something ? the sub is 8ohm and if im not mistaken will drop down to 4ohm?
im running the amp in bridged mono with the wires setup asper the specifications of the amp i rewired the speakon wires to match whatever the amp needed

#9 Adam Gale

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Posted 17 May 2012 - 11:20 AM

I am looking at  2 x SRX718 Subs and an Itech5000HD. Would it be preferable to run this amp in bridge mono with these 2 subs or would stereo work better? Stereo it would put out 1250watts per channel at 8ohms, is this too little for the SRX718's?

#10 sh_kol

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Posted 15 July 2012 - 03:50 AM

Hi Adam,

It's going to enough but , you won't get 100% of the juice out of the subs.

Shanir