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Dayton OmniMic Precision Measurement System - Page 51

post #1501 of 2086
Quote:
Originally Posted by bwaslo View Post

Uh, no, that's not what accuracy is. That's resolution. You can have a very high resolution inaccurate measurement.

What is the point of a high resolution measurement ?
post #1502 of 2086
Resolution (in this case, stated desire for frequency resolution of 0.33Hz) means that the data can show a meaningful difference between measurement at two frequencies 0.33Hz apart. like between 1Hz and 1.33Hz, or between 10000.0Hz and 10000.33Hz. It isn't possible to resolve that kind of difference unless you listen to or analyze data that is more than 1/0.33Hz (3 seconds) long.
post #1503 of 2086
Okay, thanks. Not sure I understand but you're the guru here so if the resolution isn't too important then so be it. I just need to know that this software and mic combo is accurate enough to see all that's there to see for the room response (when unsmoothed).

Stupid question time. Can you set speaker/subwoofer levels with the Omnimic sofware ?
post #1504 of 2086
Sure, put the mic where you sit at ear level, play the chirp test sweep and measure the response. Adjust sub levels/phase/eq for best flatness.
post #1505 of 2086
Quote:
Originally Posted by bwaslo View Post

It isn't possible to resolve that kind of difference unless you listen to or analyze data that is more than 1/0.33Hz (3 seconds) long.

I thought it was the freq being measured that determines the required duration, i.e. to measure .33 Hz requires at least 3 s...
post #1506 of 2086
It's the same thing to tell between frequencies also.
post #1507 of 2086
A few other differences:

1) Heavy-duty carry case
2) Tripod included
post #1508 of 2086
Quote:
Originally Posted by bwaslo View Post

Sure, put the mic where you sit at ear level, play the chirp test sweep and measure the response. Adjust sub levels/phase/eq for best flatness.

So you don't use the receivers internal test tones at all ?
post #1509 of 2086
Quote:
Originally Posted by goneten View Post

So you don't use the receivers internal test tones at all ?

Goneten,

When I am setting each individual speaker (and subs) to 75db I use the SPL/Spectrum tab, no weighting and slowest damping and my Onkyo internal test tone.

A little screen shot of that tab is below.

James
LL
post #1510 of 2086
Quote:
Originally Posted by DaytonAudio View Post

A few other differences:

1) Heavy-duty carry case
2) Tripod included

That sounds good since a lot of folks ask about what type of tripod to use with this mic.

James
post #1511 of 2086
Quote:
Originally Posted by exojam View Post

Goneten,

When I am setting each individual speaker (and subs) to 75db I use the SPL/Spectrum tab, no weighting and slowest damping and my Onkyo internal test tone.

A little screen shot of that tab is below.

James

gotta stress that you have the spl calibrated correctly though right? Or is that just on the FR graph that it is adjustable.
post #1512 of 2086
Quote:
Originally Posted by exojam View Post

That sounds good since a lot of folks ask about what type of tripod to use with this mic.

James

Hasnt it been shown that it should be on the end of a pole, because otherwise you get tons of reflections off the tripod at higher freq.
post #1513 of 2086
BA,

I am not sure what you are referencing on this part gotta stress that you have the spl calibrated correctly though right?.

What I was stating was that I setup up the Omni software, play a test tone from my Onkyo which plays an odb tone through each individual speaker and adjust the speakers or subs to 75db using the trim.

I usually shrink the window to center around 60HZ for the subs and 1KHZ for the speakers since that is what they appear to center on and the Onkyo is probably setup to play at those frequencies. I have a little e screen shot attached so you can see what I mean.

I hope that explains it a bit better.

Omegaslast,

I will be very honest a say I have not researched if the mic stand would cause my reading to be incorrect do to the reflections.

My last few runs I have set the measurement to be all which the manual states as this:
this setting shows a frequency response that includes all room echoes and reflections. In other words, the entire impulse response. In this view, impulse response itself is not shown.

My reason for trying is that I feel that is actually what I am hearing (per say) so why not see what it looks like.

James
LL
post #1514 of 2086
Guys,

Quick question that I think was mentioned earlier, if my Omni is reading a higher SPL than my external Galaxy meter, should I calibrate the software so it matches my meter? I have confirmed with both the galaxy and radio shack that the Omnimic software is reading a higher SPL.
post #1515 of 2086
Quote:
Originally Posted by jmalto View Post

...if my Omni is reading a higher SPL than my external Galaxy meter...

My OM was reading high (+6dB) as well and ended up being defective. I had my Galaxy meter calibrated and I found that it was reading low by 4dB...

I have received a new OM and now the readings are within .5dB of each other.
post #1516 of 2086
[quote=bwaslo;21596920]Guys, I just discovered a bug in the Impulse Response WAV export function. Seems it is exporting with the points upsampled -- in other words, there are 7 extra samples for each sample point. The displayed impulse response on the "frequency response" page is upsampled for better detail in the IR, but that results in the exported IR appearing as if time is stretched out (and frequency content is compressed by 8 - an 8kHz peak would appear as if it were at 1kHz.....).

Edit: Looks like it's a false alarm. Appears to be from changes in unreleased code, so shouldn't affect anyone using currently released versions. Next ver will have some enhanced wav export features.[

Bill please can you give more info on the enhanced wav export features in the next version.
post #1517 of 2086
Just a way to choose the bit resolution of the file and to specify gain or hold it constant so IRs files' level doesn't always get normalized.
post #1518 of 2086
Quote:
Originally Posted by bwaslo View Post

Just a way to choose the bit resolution of the file and to specify gain or hold it constant so IRs files' level doesn't always get normalized.



Will this enable to export the impulse more effectively in to another software, this would be the ultimate
When do you hope to release the next version?
post #1519 of 2086
Quote:
Originally Posted by laugsbach View Post

My OM was reading high (+6dB) as well and ended up being defective. I had my Galaxy meter calibrated and I found that it was reading low by 4dB...

I have received a new OM and now the readings are within .5dB of each other.

Hmm, disappointing. Did you have a hard time getting a replacement? I guess I will email parts express and see how they handle it. My galaxy and RS meter are within 1db of each other so I have to assume they are reading right and the OM is not.
post #1520 of 2086
Quote:
Originally Posted by jmalto View Post

Did you have a hard time getting a replacement?

No problem at all...PE is very good to work with. How much higher is the OM reading?
post #1521 of 2086
There were a number of mics that were originally miscalibrated by the factory. Most were ok, but unfortunately there's no way to know without recalibrating.
post #1522 of 2086
I use a Squeezebox touch so I was ripping the test CD to Flac using DBpoweramp. DBpoweramp thinks the test CD in a David Bowie CD, very strange. The tracks seem to work fine.

Bob
post #1523 of 2086
Well, yes, we had David sing those sweep tones for us.
post #1524 of 2086
Quote:
Originally Posted by bwaslo View Post

Well, yes, we had David sing those sweep tones for us.

It is funny, I will have to ask over in the dbpoweramp forum why this is the case.
post #1525 of 2086
Quote:
Originally Posted by laugsbach View Post


No problem at all...PE is very good to work with. How much higher is the OM reading?

6DB or so. I sent them an email late last night yo see if I can get it recalibrated or replaced since it is still within the warranty period I believe.
post #1526 of 2086
Hi All,

I just set up my new Omnimic and the SPL's seem too high. Does the attached file look normal for a quiet room with nothing playing? I was suprised how high the low frequencies are showing. Thanks Bob
LL
post #1527 of 2086
Quote:
Originally Posted by bob_m10 View Post

Hi All,

Does the attached file look normal for a quiet room with nothing playing?

No, there is a problem there. Did you double check that you entered the proper mic calibration code?
post #1528 of 2086
I finally found the time to to get the file & found the link off of the PE web page is bad. (That page that also states that my model has been discontinued & says that the calib file is a .txt file) After a little searching, I found the correct .omm file.
Where the link failed: http://www.parts-express.com/pe/show...number=390-790
post #1529 of 2086
The cal file look up can be found towards the bottom of the page on the link below.

http://www.daytonaudio.com/index.php...nt-system.html

James
post #1530 of 2086
Quote:
Originally Posted by Gooddoc View Post

No, there is a problem there. Did you double check that you entered the proper mic calibration code?

I did and I re-downloaded the file with the same results. If I remove the file the SPL's get cut about 50%.

-Bob
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