# Passive subwoofer amp recommendation(s)



## vanderschel (Dec 27, 2012)

I'm using a pair of SVS passive 16-46 subwoofers powered by a QSC RMX 850 (rated at 280 wpc @ 4 ohms). The subs are placed in opposite corners of the same wall. I don't think the QSC is up to the task, because I'm only getting 45 +/- decibels on the SLM utlizing the test signal from the AVR. 

I was considering this unit: Crown XTi2002 Power Amplifier 

If anyone knowledgeable could advise, I'd appreciate it.


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## Ed Mullen (Jul 28, 2006)

vanderschel said:


> I'm using a pair of SVS passive 16-46 subwoofers powered by a QSC RMX 850 (rated at 280 wpc @ 4 ohms). The subs are placed in opposite corners of the same wall. I don't think the QSC is up to the task, because I'm only getting 45 +/- decibels on the SLM utlizing the test signal from the AVR.
> 
> I was considering this unit: Crown XTi2002 Power Amplifier
> 
> If anyone knowledgeable could advise, I'd appreciate it.


First make sure the subs are the same absolute polarity. Place them side-by-side and individually calibrate to the same SPL. Then turn on both subs and the SPL should increase 6 dB. 

Then make sure the SPL meter is set to C-weighted Slow and you aren't using A scale or (worse yet) a smart phone SPL meter (which are virtually useless in the bass ranges). 

Finally, it's possible the sub-out signal strength from the AVR is not compatible with the QSC, but that has not been my experience with these amps. Check the sub channel level in the AVR and crank it up fairly high (bit not maxed out) and this will help. If you still can't get decent SPL, then consider a line-level gain booster.


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