Dayton OmniMic Precision Measurement System - Page 72 - AVS Forum | Home Theater Discussions And Reviews
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post #2131 of 2261 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?
Quote:
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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Display: JVC RS400
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post #2132 of 2261 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?
End result when overlaid should look like this.

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post #2133 of 2261 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 2261 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 2261 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 2261 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 2261 Old 08-04-2015, 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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Speakers: 3 JTR 212HTR (LCR), 2 Jtr Single 8LP (S), 2 JTR Triple 12LF (SB)) , 4 Volt 10LX (Atmos)
Subwoofers: 10 Sealed UXL-18, 5 Crowson Shadow 8 transducers, 3 Buttkicker LFE
Display: JVC RS400
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post #2138 of 2261 Old 08-04-2015, 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).

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post #2139 of 2261 Old 08-04-2015, 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...

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post #2140 of 2261 Old 08-05-2015, 05:12 PM
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I installed Windows 10 and the Omnimic is reading high. I have to turn the gain down and am still having trouble. Computer settings changed from XP compatibility to windows 8 and the readings are not as high but, still off. I will contact Parts Express in the AM looking for a fix.
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post #2141 of 2261 Old 08-05-2015, 07:11 PM
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Don't forget to set it for 2channel mode. Later Windows default to single channel.

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post #2142 of 2261 Old 08-06-2015, 07:47 AM
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Thanks. That was an easy fix.
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post #2143 of 2261 Old 08-14-2015, 01:46 PM
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I could use a few "OmniMic Waterfalls for Dummies" tips...



My FR charts look fine (track 2 on the OmniMic CD), but if I select the Waterfall button I get the worthless chart shown above. There's no data in the low frequencies that I'm mostly interested in. What settings do I need to change to get a useful waterfall chart?
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post #2144 of 2261 Old 11-05-2015, 07:26 PM
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Anyone tried this with Windows running under Parallels on a Mac? For some reason, the computer doesn't see the USB mic? I have other Windows apps that have USB inputs that work but not this one.

I was one of the first OmniMic users and love it but my Mac running as a PC is a lot faster (and lighter) than any of my Laptop Pc's.

[Edit]: Problem solved. Macs don't like the long 'powered" USB cable extension so I will need to find a better way to extend the length of the USB cable.

Last edited by audioguy; 11-06-2015 at 07:33 AM.
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post #2145 of 2261 Old 11-26-2015, 10:38 PM
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Hi,

Just got Omnimic yesterday and it was very easy to setup. I think I am having a problem with the mic though. I downloaded and applied the calibration file but it seems to read very high, like 20-25db too high.

I checked it against my RadioShack meter and the app on my phone. I know they are not the best, but it shouldn't be that far off.

Just measuring SPL in my living room it is measuring 72-74db. I took some sweeps last night and at -23 on my pre-pro it measured 107 on the graph in places. I do have a house curve on my subs of about 8-10db.

I am using Windows 8.1 and am running in XP compatibility mode.

The sweeps were louder than my REW sweeps I did last as -10db on the volume.

I noticed if I right click on my speaker icon in my toolbar there is an option for recording devices. If I select th Omnimic and then properties and levels it was set at 89. What should this be set at? If it is supposed to be 100 then it reads 10 even higher.

Thanks
Ray


EDIT: I hooked the omnimic mic up to REW and it appears the SPL reading in REW with this mic is correct or very close to my Radio Shack meter. Starting the Omnimic software and running the SPL tab it is way too high. I moved the slider at the top right all the way to the right and now it appears to give me the correct SPL reading. If having the slider all the way to the right gives me the correct reading, why would I ever move it to the left?? Wouldn't that skew the SPL readings to be incorrect? I am having a hard time understanding what the slider does, someone please enlighten me!!



I am mentioning the following people as this thread seems dead and you all had many posts as I read this thread over the last day, hoping one of you can help me understand the slider!!
@bwaslo @beastaudio @carp @Phillips751 @exojam @cr136124 @FOH @Scott Simonian @Archaea

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post #2146 of 2261 Old 11-27-2015, 01:18 PM
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Hmm. That's a pretty large amount of dB offset from your other SPL meters. Definitely not normal.

I use Win7 64bit but I'd have to assume that it runs fine on Win8 by now. Have another computer to try it on? Just to check.

I'd remove any software or drivers associated with the Omnimic system and just start fresh on that install. Give that a go first and see if that helps.
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post #2147 of 2261 Old 11-27-2015, 01:52 PM
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Quote:
Originally Posted by Scott Simonian View Post
Hmm. That's a pretty large amount of dB offset from your other SPL meters. Definitely not normal.

I use Win7 64bit but I'd have to assume that it runs fine on Win8 by now. Have another computer to try it on? Just to check.

I'd remove any software or drivers associated with the Omnimic system and just start fresh on that install. Give that a go first and see if that helps.
Thanks.

It seems that slider is my problem. The program opened and it is a bit more than halfway to the left by default. Putting it back towards the left fixes it, or use leaving it on auto. Why does it say not to use auto all of the time?
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post #2148 of 2261 Old 11-27-2015, 05:14 PM
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If I remember correctly the mic has to be set to XP mode in Windows 8. Different usb inputs on the computer can also measure different. I have the opposite problem after migrating to Windows 10. The mic consistently measures low, lol. It's OK since I don't really need max sweep number and just use the mic to shape the curve.
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post #2149 of 2261 Old 11-27-2015, 07:12 PM
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Quote:
Originally Posted by derrickdj1 View Post
If I remember correctly the mic has to be set to XP mode in Windows 8. Different usb inputs on the computer can also measure different. I have the opposite problem after migrating to Windows 10. The mic consistently measures low, lol. It's OK since I don't really need max sweep number and just use the mic to shape the curve.
Thanks.

I did set it to run in XP service pack 3 mode.

I guess I would need to do this for REW too.
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post #2150 of 2261 Old 11-27-2015, 07:20 PM
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Quote:
Originally Posted by stef2 View Post
Hello to everyone.

I just received my omnimic kit and I am thrilled to find out what results I will get in my dedicated home theater (I built it myself and it took me more than 8 years to complete...now only the projector is missing!). I have read through this whole thread and I have learned more than a lot! BTW I am using the software on Windows 8 and it works perfectly!

Since I dont know much about room analysis software and it is the first time I ever get to do this, I was wondering if I did everything right? Please, comment, correct me, ask me questions...I want to learn from this!

First of all, using the omnimic SPL, c-slow, I measured a background noise level of 38.6 dB. Does that make any sense? the room is well soundproofed. Here is the graph I got:



How come the highest bar I see is at 25 dB?

Then, turning all Audyssey stuff off on the AVR, I ran a short sweep from the omnimic DVD test tone, playing only the LFE track. Here is the frequency response I got (no smoothing) and the corresponding waterfall, recorded with the mic facing down, main listening position:





I will experiment further tonight, but so far, do my readings make any sense?

Thanks a lot! Again, please correct me if I am wrong, and dont hesitate to ask for clarifications, sometimes my english is not perfect...
Sorry to quote such an old post, I have been reading this thread for the last 2 days.

How did you get the waterfall plot down to 20hz? I don't think I am able to get one below 200hz.

I have been saving my impulse as a wav and importing into REW to view it. Would much rather do this in Omnimic.

Also seems there hasn't been a new release in a year. Is development still being done on this product?

@dwaslo
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post #2151 of 2261 Old 11-27-2015, 10:42 PM
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Quote:
Originally Posted by henrich3 View Post
I could use a few "OmniMic Waterfalls for Dummies" tips...



My FR charts look fine (track 2 on the OmniMic CD), but if I select the Waterfall button I get the worthless chart shown above. There's no data in the low frequencies that I'm mostly interested in. What settings do I need to change to get a useful waterfall chart?
Look at my quote on post 2150 - this person was able to get a waterfall that went down to 20hz.

I would like to be able to do this as well

@dwaslo
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post #2152 of 2261 Old 11-29-2015, 04:44 PM
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Hello. I just set up my subs using my OmniMic. I ran a continuous track No. 2, and found a spot for all four subs. I used my MiniDSP to flatten the response.


Since this is where I usually end the setup, what can I test next. I'd like to get as much out of my subs as I can, and learn all I can about OmniMic......Apparently I have software ver. 3.06


here's what I got so far.....



As of Feb 20th still looking for a Marantz SR7010
**HT Build https://www.avsforum.com/forum/19-ded...-door-0-a.html **


DIY HT builds, are 90%planning, 10%construction

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post #2153 of 2261 Old 12-01-2015, 04:38 PM
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Hi did you do the test for location, one at a time or summed?


Are they summed up when playing or e.g. run 2 x front to 2x back?


Waterfall another step which is very important. I have setup my two subs with focusing on flat response + focusing on waterfall the waterfall sounds miles better, with a still a good response. There is a compromise. Better positioning + setup with multiple subs can cancel modes.


Timing would be the next step with the mains and centre


Omnimic is good for setting up with the waterfall due to seeing it live like RTA.
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post #2154 of 2261 Old 12-01-2015, 05:52 PM
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Quote:
Originally Posted by Phillips751 View Post
Hi did you do the test for location, one at a time or summed?


Are they summed up when playing or e.g. run 2 x front to 2x back?


Waterfall another step which is very important. I have setup my two subs with focusing on flat response + focusing on waterfall the waterfall sounds miles better, with a still a good response. There is a compromise. Better positioning + setup with multiple subs can cancel modes.


Timing would be the next step with the mains and centre


Omnimic is good for setting up with the waterfall due to seeing it live like RTA.
Are you able to get a waterfall plot below 200hz?

There is a screenshot a few posts above showing it down to 20hz but I can't seem to get one to go below 200hz.

Hoping @dwaslo will pop in and clarify.
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post #2155 of 2261 Old 12-02-2015, 04:13 PM
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Sorry meant the Bass Decay tab, I don't use the Waterfall graph, .
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post #2156 of 2261 Old 12-02-2015, 07:59 PM
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On getting waterfall data at low frequencies:

Look at your impulse response graph, and notice the part that is marked in red. That is the only data that is used for calculating CSD waterfall (or for non-blended windowed frequency response, for that matter). The idea is that you can window out reflections in the measurement (like in your data, the big reflections at around 2 and 2.8msec) that are due to other stuff in your measurement arrangement, and process only the uncorrupted part that occurs before echoes come in. But, a little math: if you only have T milliseconds of data used, you can't process and get ANY information for frequencies below 1000/T Hz -- you have to have at LEAST a cycle or two of the associated frequency's sinewave (which is longer in time for lower frequencies!) to know anything AT ALL about response at that frequency - otherwise how could it mean anything? Really, several cycles at least is needed to have any confidence at all in that measurement, Omnimic cuts out stuff below several cycles worth at a given frequency (or blends in some echo corrupted stuff, for the frequency response display, if so arranged).

So if you want to get CSD waterfall curves to lower frequency:

1) SET THE WINDOW LENGTH LONG ENOUGH! You set the length by clicking your mouse on the impulse response graph where you want it to end (i.e., go red in color). Tip: look in the rather extensive HELP in Omnimic, search under "Cumulative", "Windowing", "echoes", "impulse", etc. Or check for similar terms in the HELP index.

2) If you are looking for a CSD of a speaker only, you will likely have to have the microphone pretty close to the speaker so you get enough time in the impulse response before a reflection (i.e., echo) arrives (you will set the red windowed section of the impulse response to end before the reflection starts). Or be outdoors facing upwards, or somewhere else that can be arranged to get an impulse response without other surfaces for sound to bounce off of.

3) If you are looking for a CSD of a speaker in (and) a room, all reflections are included. Set the window to as far as you can go in the impulse response (you have to use the arrows to make it stretch out further to the right, 250msec or more). And set the CSD graphs to go to much longer time lengths (the part that moves out toward you), you aren't going to have stuff in the room decay in just a few miliseconds, sound takes about 1 millisecond to go just one foot of distance. In room decay stuff (if that's what you want to use a CSD for) it won't mean much unless you have a lot of impulse response time included and let things drop a significant number of dBs (after quite a few sound wave bounces, which take quite a while). You'll also need to include proper smoothing to not see just grassy hash or flat waves.... adjust to taste (i.e., for something that is meaningful).

4) For room decay stuff, a CSD waterfall isn't usually the thing to use. Time Energy Curve (a.k.a. "Energy Time Curve", or ETC) are usually used for that, with selected frequency range and time smoothing values (in the ETC graph tool). Or for something maybe less tricky to adjust, the Bass Decay tool (doesn't require you to do frequency bands separately and tries to focus on just the bass where room reflections are not separable and are necessarily a fact of life).

Did I mention the Omnimic HELP ??
(It has a search function that works pretty well)

___________________________________________
DIY Synergy horn spreadsheet Synergy horn spreadsheet and pdf
XSim -free crossover designer and simulator XSim install file
Easy and cheap sound diffusers (the "Depot Diffusers") making easy DIY depot sound diffuser-panels-step by step.html
SmallSyns - point source controlled directivity in a manageable size SmallSyns

Last edited by bwaslo; 12-02-2015 at 08:22 PM. Reason: added links for the online copy of Help at Dayton Audio (HELP is also built into the Omnimic program).
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post #2157 of 2261 Old 12-02-2015, 08:25 PM
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Quote:
Originally Posted by bwaslo View Post
On getting waterfall data at low frequencies:

Look at your impulse response graph, and notice the part that is marked in red. That is the only data that is used for calculating CSD waterfall (or for non-blended windowed frequency response, for that matter). The idea is that you can window out reflections in the measurement (like in your data, the big reflections at around 2 and 2.8msec) that are due to other stuff in your measurement arrangement, and process only the uncorrupted part that occurs before echoes come in. But, a little math: if you only have T milliseconds of data used, you can't process and get ANY information for frequencies below 1000/T Hz -- you have to have at LEAST a cycle or two of the associated frequency's sinewave (which is longer in time for lower frequencies!) to know anything AT ALL about response at that frequency - otherwise how could it mean anything? Really, several cycles at least is needed to have any confidence at all in that measurement, Omnimic cuts out stuff below several cycles worth at a given frequency (or blends in some echo corrupted stuff, for the frequency response display, if so arranged).

So if you want to get CSD waterfall curves to lower frequency:

1) SET THE WINDOW LENGTH LONG ENOUGH! You set the length by clicking your mouse on the impulse response graph where you want it to end (i.e., go red in color). Tip: look in the rather extensive HELP in Omnimic, search under "Cumulative", "Windowing", "echoes", "impulse", etc. Or check for similar terms in the HELP index.

2) If you are looking for a CSD of a speaker only, you will likely have to have the microphone pretty close to the speaker so you get enough time in the impulse response before a reflection (i.e., echo) arrives (you will set the red windowed section of the impulse response to end before the reflection starts). Or be outdoors facing upwards, or somewhere else that can be arranged to get an impulse response without other surfaces for sound to bounce off of.

3) If you are looking for a CSD of a speaker in (and) a room, all reflections are included. Set the window to as far as you can go in the impulse response (you have to use the arrows to make it stretch out further to the right, 250msec or more). And set the CSD graphs to go to much longer time lengths (the part that moves out toward you), you aren't going to have stuff in the room decay in just a few miliseconds, sound takes about 1 millisecond to go just one foot of distance. In room decay stuff (if that's what you want to use a CSD for) it won't mean much unless you have a lot of impulse response time included and let things drop a significant number of dBs (after quite a few sound wave bounces, which take quite a while). You'll also need to include proper smoothing to not see just grassy hash or flat waves.... adjust to taste (i.e., for something that is meaningful).

4) For room decay stuff, a CSD waterfall isn't usually the thing to use. Time Energy Curve (a.k.a. "Energy Time Curve", or ETC) are usually used for that, with selected frequency range and time smoothing values (in the ETC graph tool). Or for something maybe less tricky to adjust, the Bass Decay tool (doesn't require you to do frequency bands separately and tries to focus on just the bass where room reflections are not separable and are necessarily a fact of life).

Did I mention the Omnimic HELP ??
(It has a search function that works pretty well)
Excellent!!

Thanks so much for the post!

I did read the help files but didn't see anything in there about using more than one cycle for the waterfalls. I will give this a try tomorrow.

Thanks again!!
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post #2158 of 2261 Old 12-04-2015, 01:04 PM
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Quote:
Originally Posted by raynist View Post
Sorry to quote such an old post, I have been reading this thread for the last 2 days.

How did you get the waterfall plot down to 20hz? I don't think I am able to get one below 200hz.

I have been saving my impulse as a wav and importing into REW to view it. Would much rather do this in Omnimic.

Also seems there hasn't been a new release in a year. Is development still being done on this product?

@dwaslo
I was wondering how long it would take, considering you were paging the wrong guy three times with "dwaslo." Dyslexic much?

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post #2159 of 2261 Old 12-04-2015, 01:13 PM
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Originally Posted by beastaudio View Post
I was wondering how long it would take, considering you were paging the wrong guy three times with "dwaslo." Dyslexic much?
LOL!!

Oops!
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post #2160 of 2261 Old 12-30-2015, 07:30 PM
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I am really liking Omnimic over REW.

One thing that I keep needing to do each time I use it is lower the mic level in Windows. I run sweeps at -20 on my AVR and it shows 100+ db's and I know for sure it is not that loud. I go in to the microphone settings in win 8 and the mic is set at +15 or so. Does anyone know why this happens? It is easy enough to go in at set it back to 0 gain but would be nice if I could fix it permanately.

Thanks
Ray
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