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Essential tools for proper/accurate audio calibration? - Page 2

post #31 of 48
Quote:
Originally Posted by arnyk View Post


Equal loudness a little out in left field?

Wow!

So you're dubious about Fletcher and Munson?

 

 

 

Nope, not at all.

 

You and Ethan IMO are stating what might not be obvious to some, and I'm sure they appreciate your extensive explanation.  I understand equal loudness in the context of this discussion, but disagree.

 

Your assertion If I understand correctly is:  You can't hear the magnitude of inaccuracy inherent in the mic so it doesn't matter.

 

My assertion is:  I measure for accuracy, not close enough, or good enough, or within audible tolerances, so 3db matters to me even if it is not audible.

 

Call it OCD, if you like, won't be the first time I've heard that..... 

 

Furthermore, IMO knowing about 3db differences can be beneficial in setup and/or tweaking even if you can't hear it in an A/B comparison.

post #32 of 48
why not let the OP decide what his tolerances and definition of "accurate" is - see thread title.
post #33 of 48
I was going to start a similar thread, I'd like to ask a few questions.
Is the omnimic v2 kit a viable alternative to the Behringer (or Dayton) mic and the ART stereo USB interface route? I don't see a USB interface sold with the kit, am I correct in assuming that is not needed since the microphone in the omnimic is USB? Is this setup of comparable quality to the one suggested above, and would I be able to use it with REW also, besides the bundled software? So far I've been using REW with a Galaxy 140 SPL metre to help integrate my subs. Is there any point in taking full range measurements with the Galaxy? I am thinking no... rolleyes.gifbiggrin.gif
post #34 of 48
Quote:
Originally Posted by BarracudaDelGato View Post

I was going to start a similar thread, I'd like to ask a few questions.
Is the omnimic v2 kit a viable alternative to the Behringer (or Dayton) mic and the ART stereo USB interface route?

So it seems.
Quote:
I don't see a USB interface sold with the kit, am I correct in assuming that is not needed since the microphone in the omnimic is USB?

Yes. There is a USB "B" connector on the Omnimic where you would expect to find a XLR connector on most mics.
Quote:
Is this setup of comparable quality to the one suggested above, and would I be able to use it with REW also, besides the bundled software?

So it seems.

http://techtalk.parts-express.com/showthread.php?229380-Is-it-possible-to-use-the-OmniMic-hardware
Quote:
So far I've been using REW with a Galaxy 140 SPL metre to help integrate my subs. Is there any point in taking full range measurements with the Galaxy?

The Galaxy 140 appears to have somewhat non-flat frequency response, but any software that handles mic calibration curves such as REW can address the situation.

http://audioinvestigations.blogspot.com/2011/02/room-eq-wizard-running.html
post #35 of 48
Quote:
Originally Posted by localhost127 View Post

why not let the OP decide what his tolerances and definition of "accurate" is - see thread title.

I agree with that whole-heartedly. The relevant issues are laid out here in the thread. People should do what makes them comfortable and productive.
post #36 of 48
it makes me comfortable and productive to hear about how the room itself doesnt always show large dB fluctuations.

the lines of an real time analyzer will show you just how much a person cares .. because all of the peaks should meet on the same line (not always possible when looking at the largest biggest impact of an average)

but the room is like a gelatin.. if the frequencies are allowed to swing 6dB on one end and another 6dB on the other end ... when it comes time to making that gelatin solid, your results might use extra power than necessary to re-create sounds that are far from what was recorded.


...and dont forget...
a ruler flat dB line for far distances isnt always the same corrections as the ruler flat dB line for near up close distances.


you are supposed to be solidifying the gel in the room, as if it is a radar signal coming from the speakers.
just so happens that the signal is louder and large enough to hear it or feel it.. not the same when it is down in the 'dog whistle' sizes.


the calibration file is supposed to be taken from a solid gel that doesnt care if the space is 1 inch x 1 inch or 100ft x 100ft

they will stop using ears and look at electrical accuracy in it's most perfect view .. existance.
then there are people that will judge what is on the screen.
once that existance has been calibrated itself .. then and only then could the microphone be moved in there to get calibrated.

the only thing changing in the room is the air, and if the gel doesnt measure up to holding it's calibration .. then the calibration of the microphone isnt justified , all because one person wasnt prepared enough to change through the seasons of a year to compensate for different times of the year.
hell..
people can build boxes with a hole for the microphone tip and use the same temperature | humidity | pressure readings from inside that box as they would their room.

coloring from a box of 12 crayons isnt the same as a box of 128
..i cant believe i heard somebody say something about the calibration file being not important.
you cant stack up the harmonics to build the pressure without an accurate calibration file and know if your results are from you being playful or if the results are accurate for the room.
flat is the important part.. otherwise you might get a harmonic stack with peaks and dips, but you dont care because it went to the solid noise for you and somebody left you there to think it was laboratory grade accuracy.


density and flat is what it boils down to.
density can be changed, flat cant.
there is reference density.. see you get the room itself and use the opposite to get a flat neutral, and that should be all the reference you need.
but zooming in..
the microphone itself might require a specific density to be added or removed from the density in the room..
or
maybe the density needs an equation principle performed first, like quantam compression or expansion or something.
as if life is not lining up.. people get a table to catch things, and then the things on that table are organized .. and finally the table itself gets an axis of tip to lean one way or the other.


for the audio software to work.. it must be able to do more than one density, that is why it is scrolling through until it locks on the room size you are in.
and that is why it could ever change while doing an adjustment.
things like finding two extremes, then working a middle average could take place.
post #37 of 48
Quote:
Originally Posted by NicksHitachi View Post

My assertion is:  I measure for accuracy, not close enough, or good enough, or within audible tolerances, so 3db matters to me even if it is not audible.

Call it OCD, if you like, won't be the first time I've heard that..... 

For most people in the real world though, dealing with + or - 20dB peaks and dips in the frequency response is the first hurdle to cross. Worrying about how much a mic may or may not roll off at the extreme ends is largely irrelevant.

I myself just use the calibration mic that came with my AVR plugged into the soundcard of my PC with TrueRTA as my software of choice. The improvements I have been able to make to my system and room by doing so at virtually no extra cost to myself has to be the best value ever I have had in this hobby. Bass is no longer just a large 50hz peak with a monstrous 80hz null... now it is reasonably flat from 25hz and up.

I do recommend others to start measuring the frequency response of their rooms as well... but unfortunately many get put off from doing so because others make it out to be far more complicated than it needs to be.
post #38 of 48
Quote:
Originally Posted by BarracudaDelGato View Post

I was going to start a similar thread, I'd like to ask a few questions.
Is the omnimic v2 kit a viable alternative to the Behringer (or Dayton) mic and the ART stereo USB interface route?

not if you're looking to do accurate time-domain analysis (eg, ETC). the hardware loopback is used with the USB ART DUAL PRE to account for hardware propagation delay.
post #39 of 48
Isn't the bigger question "what do you do with your measurements?" I mean, If I find that my speaker has a resonant hump of 5dB at 1200Hz, both on and off axis, with a narrow Q (any cheap uncalibrated mic can measure that) - my common receiver is going to be totally inadequate to deal with that. Where's the rest of the toolbox? (Clearly in this case, better speakers would be the best move, but I think the point stands, doesn't it?)

Said another way - you haven't calibrated anything by measuring it.
post #40 of 48
Quote:
Originally Posted by localhost127 View Post

not if you're looking to do accurate time-domain analysis (eg, ETC). the hardware loopback is used with the USB ART DUAL PRE to account for hardware propagation delay.

Thanks arnyk and localhost. I think I'll go the traditional (XLR) mic route then, and try to learn to use REW, in time. smile.gif
post #41 of 48
Quote:
Originally Posted by kiwi2 View Post

For most people in the real world though, dealing with + or - 20dB peaks and dips in the frequency response is the first hurdle to cross. Worrying about how much a mic may or may not roll off at the extreme ends is largely irrelevant.

add some waterbed conditioner and see if your senses can detect flat with a roll up or down.
post #42 of 48
Quote:
Originally Posted by anwaypasible View Post

add some waterbed conditioner and see if your senses can detect flat with a roll up or down.

Our hearing sensitivity isn't linear through the 20hz to 20k range.
post #43 of 48
Quote:
Originally Posted by kiwi2 View Post

Our hearing sensitivity isn't linear through the 20hz to 20k range.

while yours might not be, another person could be.
and while one person might not be, another has memorized the reference level from the microphone.


either way is possible.
post #44 of 48
Thread Starter 
Did I just open pandora's box asking about calibrated mics lol? Lots of great info was shared though so thanks a lot for that guys.

Considering I can get a couple of mics for the price of 1 calibrated mic, I might go down that route by getting one now and another later then compare the results for fun :P, if they turned out to be very different I'll get a 3rd calibrated one lol.

If I didn't go for a calibrated one I can add some cash and get a USB pre-amp interface for the mic, what are the benefits of that above using the Behringer mixer I already have?
post #45 of 48
Quote:
Originally Posted by anwaypasible View Post

Quote:
Originally Posted by kiwi2 View Post

Our hearing sensitivity isn't linear through the 20hz to 20k range.

Right. Human hearing varies, but it varies within a range that is actually pretty rigidly defined, particularly in terms of sensitivity. Below certain well-known thresholds, nobody hears nothing.

A lot of ideas about the sensitivity of human hearing that we see in the popular press are artifacts of sighted evaluations and just don't stand careful examination.
Quote:
while yours might not be, another person could be.
and while one person might not be, another has memorized the reference level from the microphone.


either way is possible.

Not on this planet in this universe.
Edited by arnyk - 11/11/12 at 6:26am
post #46 of 48
Quote:
Originally Posted by kiwi2 View Post

Quote:
Originally Posted by NicksHitachi View Post

My assertion is:  I measure for accuracy, not close enough, or good enough, or within audible tolerances, so 3db matters to me even if it is not audible.

Call it OCD, if you like, won't be the first time I've heard that..... 

As the saying goes: "Denial isn't just a river in Egypt" ;-)
Quote:
For most people in the real world though, dealing with + or - 20dB peaks and dips in the frequency response is the first hurdle to cross. Worrying about how much a mic may or may not roll off at the extreme ends is largely irrelevant.

True as long as we are talking about mics designed for measurement. Vocal mics for example are so rough by design that many fail in even the sort of situations that you are talking about. Interestingly enough the art of system equalization based on measurements with microphones started out with using the vocal mics that were already in place.
Quote:
I myself just use the calibration mic that came with my AVR plugged into the soundcard of my PC with TrueRTA as my software of choice. The improvements I have been able to make to my system and room by doing so at virtually no extra cost to myself has to be the best value ever I have had in this hobby. Bass is no longer just a large 50hz peak with a monstrous 80hz null... now it is reasonably flat from 25hz and up.

This is the benefit that I hope gets delivered to more and more people.

Quote:
I do recommend others to start measuring the frequency response of their rooms as well... but unfortunately many get put off from doing so because others make it out to be far more complicated than it needs to be.

Agreed,

The word for the day should be KISS. Keep It Simple Stupid.

If you want to set up a NTIS-traceable measurement lab, it is your life and your money. I see no sense to burdening people with my own hang-ups if it can be avoided.
post #47 of 48
Quote:
Originally Posted by metallicaband View Post

Did I just open pandora's box asking about calibrated mics lol? Lots of great info was shared though so thanks a lot for that guys.

Considering I can get a couple of mics for the price of 1 calibrated mic, I might go down that route by getting one now and another later then compare the results for fun :P, if they turned out to be very different I'll get a 3rd calibrated one lol.

If I didn't go for a calibrated one I can add some cash and get a USB pre-amp interface for the mic, what are the benefits of that above using the Behringer mixer I already have?

What do you intend to do with the results?

  • Treatments?
  • Tweak Setup
  • Manual EQ

Which mic you thinkin?
post #48 of 48
Quote:
Originally Posted by arnyk View Post

Quote:
Originally Posted by kiwi2 View Post

Quote:
Originally Posted by NicksHitachi View Post

My assertion is:  I measure for accuracy, not close enough, or good enough, or within audible tolerances, so 3db matters to me even if it is not audible.

Call it OCD, if you like, won't be the first time I've heard that..... 

As the saying goes: "Denial isn't just a river in Egypt" ;-)

.

Haha, I'm not in denial, I don't have OCD, I dont have a problem, and I can stop anytime I want...... biggrin.gif

Never has $20-30 been so thoroughly debated, lol. While we disagree I appreciate your mostly respectful tone. Classy discussion among geltlemen is getting harder to come by on AVS.
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