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SPL Speaker Calibration: subwoofer on or subwoofer off?


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#1 of 6 OFFLINE   MuneebM

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Posted March 01 2004 - 10:17 AM

I've calibrated each of my speaker's to 75 dB using the test tones on DVE, but when I did it I turned off my subwoofer so as not to "throw off" my readings. When I got to calibrating the LFE level, I obviously turned on the subwoofer at that point. A friend of mine is SPLing his system and asked me if he should do it with the subwoofer on or off. I told him its better to calibrate all the speakers with the subwoofer off, but he tells me he gets very different measurements with the subwoofer on compared to when its off. He says the resulting SPL levels with the subwoofer on sound better than with it off. What's the proper way of doing this: (a) calibrate all the speakers with the subwoofer off because the bass from the sub will "throw off" the meter readings (and then you have to adjust the meter reading for lower frequency discrepancies) OR (b) calibrate all the speakers with the subwoofer on because that's how you listen to the system afterall

#2 of 6 OFFLINE   JohnSmith

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Posted March 01 2004 - 10:42 AM

The test tones should go to each speaker in turn- why is his outputting sub+other speakers too? If you output the sub tone it should only be outputted to the same- same for the other speakers. If it doesn't then something is seriously wrong with the av amp.

#3 of 6 OFFLINE   Stephen Weller

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Posted March 01 2004 - 11:16 AM

Turn the sub off where? If you're telling the AV amp "No Sub" then it sends full spectrum to the mains and sats. No? This will absolutely give you different measurements between sub-on and sub-off. If you're just switching of the sub - turning off the sub's power, that's a different matter and it shouldn't make a difference when you're "SPLing."

#4 of 6 OFFLINE   Joseph Hoetzl

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Posted March 01 2004 - 11:47 AM

Do you/he have a dedicated LFE channel on the AMP connected to the sub? (Usually an RCA jack<->RCA Jack) What you describe is having the sub being fed by the speaker level outputs, and then out from the sub to the l/r mains. In 5.1 test tones, each test tone is specifically targeted at one speaker. So even if you have the sub on, when the disc has the left speaker glowing (if I remember the screen correctly), just the left speaker should have ANY sound from it. The sub and all other channels should be completely silent.

#5 of 6 OFFLINE   MuneebM

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Posted March 01 2004 - 04:54 PM

never mind folks, I just spoke to my friend and discovered that he was using the full bandwidth test tones and not the band limited pink noise! I told him I never needed to turn my subwoofer off, so I found it weird that he was getting sound from his sub... anyways, this thread was pretty wastful, my bad, sorry!

#6 of 6 OFFLINE   Edward J M

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Posted March 01 2004 - 11:21 PM

Always leave both the sats and the sub on for all channel balancing with any calibration disc that uses Dolbly Digital or DTS. The bass management system will at times (on full bandwidth test tones and the subwoofer tone for each channel) split the signal between the sub and the sats. The only time the sub gets a discrete tone would be for the LFE (.1) channel test. S&V and Avia do not use the LFE channel for subwoofer calibration, they use the surround channel and redirected bass.
Ed Mullen
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SVS

www.svsound.com

"What we do in life, echoes in eternity."





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