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#198709 - 03/02/08 03:42 PM SPL meter calibration?
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
Just curious if any of you have noticed this when using a meter to calibrate your speakers using the receivers test tones.

First of all, I've always used 75dB's as my target SPL when running the pink noise. In addition, we all know to use C-weighting and "Slow" response.

What I've noticed is that there is a lot of difference between using 70 or 80dB on the rotary dial. If I use the 80dB selection and calibrate to 75dB's, when I switch it back to 70dB, it shows 73 on the meter.

I guess my main question is what is more accurate, using 80dB and measuring 4-5 dB's below 80, or using the 70dB selection and using 5dB above 70, it seems there is a difference according to the meter.
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#198710 - 03/02/08 04:01 PM Re: SPL meter calibration? [Re: SirQuack]
Kruncher Offline
devotee

Registered: 10/05/06
Posts: 484
Loc: Maple Ridge, BC
On a related note (directly? I'm not certain), have a look at the SVS RS SPL meter correction table.

Also, I quickly found a pretty lengthy discussion on the topic of corrections that might be useful on the AVS forum.

Thought these were worth pointing out. Personally, I use a test tones CD downloaded from RealTraps, with the 70 + 5 setting.

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#198711 - 03/02/08 04:14 PM Re: SPL meter calibration? [Re: Kruncher]
Wid Offline
axiomite

Registered: 06/22/03
Posts: 6789
Loc: The Peoples Republic of Il.

What difference would it make as long as you use the same the same target numbers.
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"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud


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#198712 - 03/02/08 04:22 PM Re: SPL meter calibration? [Re: Wid]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
That is what I was thinking Rick. The problem I'm having is trying to calibrate all my subs (3 now). I'm doing them one at a time. I moved the 600 near the back wall, and have the twin 350v3's on the front wall.

I've tried calibrating them all seperately, then turning them all on, which jumps the SPL like 9dB higher then where I calibrated them. Am I supposed to calibrate them low, so the sum equals the end goal? I know Ian in the video says the increase is not what is seems as the RS meter does not read below 50hz well. However when I sweep using the SMS-1 mic, in NON EQ mode, the low freq's are way to high.

Another weird problem is that I have to turn my ep600 volume knob all the way to the MIN selection, and still have to put my Denon on like -5 to -6dB's to achieve 75dB's on the meter. Then when I add the other subs up front the meter spikes above 80dB's and I have to crank the volume on the 350's to about 60% since the receiver is so low.

Another thing that is weird is that Ian says the front subs should be at 0 phase, but when I switch them and the 600 to 180 phase the graph with the SMS is very flat, not like when they are on 0 phase.

This is so much fun. arggggggggg

ps: one thing is sure, these 350v3's put out some serious LFE for the price.
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#198733 - 03/02/08 07:08 PM Re: SPL meter calibration? [Re: SirQuack]
terzaghi Offline
connoisseur

Registered: 04/04/07
Posts: 4870
Loc: Tulsa, Oklahoma
I think they say to put the front subs at 0 and the back at 180. This does not work for you?

Just out of curiosity- are you daisy chaining all of the subs together?
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#198738 - 03/02/08 07:15 PM Re: SPL meter calibration? [Re: terzaghi]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13565
Loc: Iowa
I tried both on 0 first, then tried switching the rear 600 to 180, that really created a huge hump in the 40-60hz range. That flattest response came with all at 180, which confuses me because I figured that since the 350's are lined up with the front of the 80's it would be 0, maybe since I two up front spread out 1/3 from each side wall that messes with phase.

Yes, I currently have them daisy chained togethor receiver-350-350-600. I have not noticed any problem. Before I ran a seperate line for the 600 and I didn't notice any difference.
_________________________
M80s-VP180-4xM22ow-4xM3ic-EP600-2xEP350
Anthem AVM60 Outlaw 7700 Emotiva A500 Epson 5040UB



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