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Calibrating speakers with AUDYSSEY MIC but without AUDYSSEY ;)

post #1 of 8
Thread Starter 
Hello everybody,


I want to recalibrate my speakers, since I'm not very happy with what audyssey automatic setup did tongue.gif. So I need to set all my speakers @ 75 decibels. The big problem is, that I don't have a decibel meter tongue.gif. I don't want to buy an expensive decibel meter, just to use once. So I was thinking if I could use the audyssey microphone that came with my onkyo to measure 75decibels. I've searched a bit on the internet and I found this: http://www.avsforum.com/t/1328136/measurement-mic-shootout-emm-6-wm-61a-rs-33-2055-audyssey
And there they say the audyssey microphone does a good job redface.gif. So I want to plug the microphone in my laptop microphone input and start to measure smile.gif. I've downloaded this software: http://www.orban.com/meter/
The Meters-screen looks like this:https://dl.dropbox.com/u/64092960/meters.jpg
and the Settings screen looks like this: https://dl.dropbox.com/u/64092960/settings.jpg

But don't know where I can how much decibels there are at the moment tongue.gif. Can anyone help me with this?
I can set the
Meter scale: relative-absolute
Meter range: EBU+9 or EBU+18
ITU BS.1770 type to : BS.1770-1 or BS.1770-2
and the attack time: 5ms or 10ms

Can somebody tell me where I can read the current decibels ? And if this is good software to use, Is there better I should use?
Is this a good idea to calibrate my speakers like this? Or is it worth to spend extra cash to an expansive decibel meter I will only use once...?
Can I use c weight with this microphone and laptop? I see it all over the internet to use c weight :@


Thanks in advance
Edited by bosiwow - 1/16/13 at 6:04am
post #2 of 8
Thread Starter 
Hmmm, just discovered REW v5 redface.gif. Can I just plug in my audyssey audyssey multeq in my computer, launch rew, click SPL, turn on C weight and put it on slow?
https://dl.dropbox.com/u/64092960/db%28c%29.jpg

Are there any calibration files on the internet I should use? Or is it accurate enough?

Can I also run other tests with REW to fine tune my sound installation? Bass test orsoething else ? tongue.gif
Just want to get the best from my audio system wink.gif

I'm using an onkyo tx-nr807
In combination with this: http://homeavdirect.co.uk/media/shop/var/variation_image/1889.jpg?v=1278425131
post #3 of 8
well, as you nmight imagine, Audyssey diesn't ship $450 Earthworks M23 measruement mics with their products. In fact their mics are, by necessicity, pretty inexpensive. That means they're imperfect (but that's true of most mics). What we real worlders need is a mic correction file that allows REW to reverse the inaccuracies of our particular mics, so that the results aren't skewed by the mic's irregularities. Audyssey includes such compensation in their software, but it's for sort-of a median audyssey mic, and there may be at least some deviations from the imaginary median mic and any mic that you have in hand Iid only because the actual mic capsules, to be cost effective, cannot be subjected to massive QC).

I THINK there may be Audyssey mic correction tables out there somewhere, but i haven't looked. Heck maybe REW even has one as part of the package. In the meantime, sure, you can use the Audyssey mic, but you may be getting data that's skewed by, I'd guess, 1-3 dB at particular unknown frequencies because of the mic's particular frequency response.
post #4 of 8
Quote:
Originally Posted by bosiwow View Post

I need to set all my speakers @ 75 decibels. The big problem is, that I don't have a decibel meter tongue.gif. I don't want to buy an expensive decibel meter, just to use once. So I was thinking if I could use the audyssey microphone that came with my onkyo to measure 75decibels
Without knowing the sensitivity of the Audyssey mic, how will you know that the sound it is picking up is at 75 decibels?
post #5 of 8
Thread Starter 
Okay thank you, In fact all the speakers need to be at the same volume, so if there is a misreading by the audyssey mic, it will be the same for every speaker, right?

So if the audyssey mic says 75 db (but in fact it is 77db), this isn't going to be a problem I guess? tongue.gif

Somebody has suggestions how to calibrate a subwoofer?


edit: when I've got time I will search for calibration file wink.gif, can I calibrate sub with the audyssey mic? Or are there better ways?
post #6 of 8
you can calibrate everything to be equal with the AUdyssey mic. like every mic in the world, the Audyssey generates a voltage based on movement of the diaphram. Entirely analog, nowhere to encode how many millivolts equal 70 dB or whatever. Every different mic design is different (even, in Ethan WIner's testing, 2 relatively inexpensive mics that appeared to use the same capsule) so you can't just plug it in and know what output level from the mic equals 75 dB.

SO the mic never says "75 dB" It outputs a voltage. If the device into which it is plugged has been calibrated to respond to the voltage from the particular mic, then you can know absolute SPL (within the error range of the particula mic design). If not, all you know is you have a voltage . . . .
post #7 of 8
Quote:
Originally Posted by bosiwow View Post

So if the audyssey mic says 75 db (but in fact it is 77db), this isn't going to be a problem I guess? tongue.gif
Depends on what you're trying to do.

If you are simply trying to get all your speakers to the same level, then it's not a problem (just pick some arbitrary number to level-match all your speakers).

However, if your goal is to do what you stated earlier ("I need to set all my speakers @ 75 decibels."), then you've got a problem (you won't know what the real level is).
post #8 of 8
Thread Starter 
Yea, in fact I need to set all my speakers at the same level. I searched a bit on the internet and they say I had to sale them to 75 80 or 85 decibels. So it isn't that important if they are all 70 decibels or 80 decibels, they just need to be equal wink.gif. Thank you guys.
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