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805's underpowered?

robbie130280

Standard Member
I recently bought a spl meter to test a svs pc13 that was sold to me from a member here (orchard6, amazing guy). There was just a small peak at 20hz that was easily fixed with the parametric eq and is now nice and flat from 80hz to 20. However, when i turned to spl meter to my B&W 805's, they were all over the place from the crossover at 80hz to around 150hz, with a 10db dip at 100hz too. I have always been a little dissapointed by the 805s, i think this could be why.

They're being powered by an onkyo sr-875 which has audyssey XT. Because audyssey has done such a wonderful job with my sub, I am being led to believe this could be the speakers being under powered. The amp puts out 140 watts at 8ohm, theyre rated 200 watt at 8 ohm, could i be right?

thanks. rob
 

Mark.Yudkin

Distinguished Member
They're being powered by an onkyo sr-875 which has audyssey XT. Because audyssey has done such a wonderful job with my sub, I am being led to believe this could be the speakers being under powered. The amp puts out 140 watts at 8ohm, theyre rated 200 watt at 8 ohm, could i be right?
No, unless you listen at silly ear-splitting volume levels or live in the Royal Albert Hall. For normal or even loud levels in a typical or large domestic enviornment, your 875 has more than enough power, and some to spare.

Your Onkyo TX-SR875 has Audyssey MultiEQ XT, which ought to have been able to compensate for most of the frequency differences if set up correctly. I would therefore suggest rerunning the Audyssey setup, paying careful attention to microphone placement and ambient noise. If that doesn't assist, I'd recommend calling in a professional installer with expertise in Audyssey Professional Calibration. Your dealer ought to have offered this service when he sold you the kit (was it too expensive for you?). He will use dedicated equipment to achieve results that are substantially better than those obtainable from the reeceiver's automatic setup.
 
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noiseboy72

Distinguished Member
Crossovers and filtering can play havoc with phase response and this could be giving you the odd results, as could room modes and indeed, the 2 speakers interacting with one another.

Try running just one speaker, located in the middle of the room and measure the response again. See if this is any better.

At least then, you know whether it is the speaker or the environment.
 
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