Dayton OmniMic Precision Measurement System - Page 72 - AVS Forum | Home Theater Discussions And Reviews
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post #2131 of 2139 Old 07-04-2015, 04:43 AM
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Thank you.
So to do compression sweeps to measure the limit of my subwoofers, I have to keep raising the volume while letting the sine sweep repeat to build the averages? That wouldn't be a good idea at higher volumes.. Is there a way to do it with one sweep?
Also can the omnimic be used with rew?
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Originally Posted by primetimeguy View Post
The sweep should keep repeating so you should see a constant plot, but more than likely shifting slightly. Hit the pause button in the top left to pause the measurement. then you can save, print or do whatever you'd like with it.
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post #2132 of 2139 Old 07-04-2015, 07:00 AM
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Quote:
Originally Posted by ahmedreda View Post
Thank you.
So to do compression sweeps to measure the limit of my subwoofers, I have to keep raising the volume while letting the sine sweep repeat to build the averages? That wouldn't be a good idea at higher volumes.. Is there a way to do it with one sweep?
Also can the omnimic be used with rew?
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post #2133 of 2139 Old 07-31-2015, 07:26 PM
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What's the minimum SPL that Omnimic V2 will measure? Does it go low enough <25 db to measure the noise floor in a hightly treated theater?
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post #2134 of 2139 Old 08-01-2015, 09:53 AM
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I have seen level of around 18 db's in my room.
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post #2135 of 2139 Old 08-01-2015, 08:14 PM
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Another question.

To check how flat a sub is and where the 3 db drop off is, how do you measure with Omnimic.

I'm assuming I use the requency response tab and play pseudo noise. Is this correct?

Also, what's the best way to ONLY test the sub, and not the rest of the speakers?
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post #2136 of 2139 Old 08-02-2015, 09:37 AM
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Yes, use the Frequency tab to look at the sub and room response. The stated 3 db point is not much use in the HT. To measure just the sub, a mic can be put around 6 in. in front of the sub/s. This will minimize the room influence. I don't worry about that and just measure the sub/s and mains at the MLP. This way I can see how well they are playing together and look at the XO point. Use 1/6 or 1/12 smoothing and scale the graph 20 Hz to 200 Hz.

I don't worry much about anything above the XO since autocalibration is taking care of that. For vented subs the 3 db point is Ok but for sealed I also look at the -10 db point. Additional DSP, PEQ, and a way to make adjustment is needed. The I Nuke DSP amps or MiniDSP are good for this.
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post #2137 of 2139 Old Today, 06:43 AM
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My omnimic seems to be around 9-10 dbs off on the spl meter tab. I selected C weighting and fast. Is there something that could be causing that ?

Also, how do I measure the individual speakers L , C , R using the provided test tones? I noticed they have left and right tracks only..
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post #2138 of 2139 Unread Today, 07:50 PM
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Yes

Yes, see the note about operation in Windows 8 in Help. Essentially, it comes down to: Run omnimic in WinXP SP3 compatibility mode. Win8 screws up input levels with USB mics (and throws away several bits of dynamic range in the process).

DIY Synergy horn spreadsheet http://libinst.com/SynergyCalc/
XSim -free crossover designer and simulator http://libinst.com/Xsim/XSimSetup.exe
Easy and cheap sound diffusers (the "Depot Diffusers") making-easy-diy-depot-sound-diffuser-panels-step-step.html
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post #2139 of 2139 Unread Today, 07:52 PM
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For C channel (or any except L and R), you need to use the DVD test disc. Or disconnect unwanted speakers. CDs can only do L or R...

DIY Synergy horn spreadsheet http://libinst.com/SynergyCalc/
XSim -free crossover designer and simulator http://libinst.com/Xsim/XSimSetup.exe
Easy and cheap sound diffusers (the "Depot Diffusers") making-easy-diy-depot-sound-diffuser-panels-step-step.html
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