# Observation of differences when calibrating in morning vs. lunchtime



## hearingspecialist (Mar 15, 2010)

I have noticed some major differences when calibrating with YPAO in the morning vs. around lunchtime. All possible variables minimized, same mic placement (left in place), I'm the last to leave in the morning, nobody home during day, noise levels the same (super quiet), and so on. I'm religous with my YPAO use and really get into the calibration programs that are out there. Wish someone did a evaluation comparing all of them using a "Flat" protocol with same setup and see which one is most accurate.:clap:

It doesn't matter which scheme within YPAO, flat, front, or natural. I just get my best audible differences and it sounds best when done in the morning. Don't know if I can say the air is more dense and cooler in the morning when experimenting with this, there is only a difference of 2 or 3 hours (done around 8:30am or around 11 or 11:30am).

Anyone else share the experience or have thoughts???:nerd:


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## mechman (Feb 8, 2007)

Hmmmm... that's actually pretty interesting. And I'd bet the differences would vary depending upon the extremity of the environment - temp, humidity, etc. onder:


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## gorb (Sep 5, 2010)

Hopefully my new receiver will be there when I get home today. I'll see if I can replicate your experience since this will be my first time using YPAO


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## nholmes1 (Oct 7, 2010)

I would say it would have to do with environmental factors such as heat and humidity as this would effect the density of the air. It would be interesting to grab one of those small handheld weather stations and take measurements of temp, humidity and barometric pressure and see how much those change and the effect it has on the YPAO.


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## hearingspecialist (Mar 15, 2010)

Thanks for the responses. The way our home sits and the back of our home faces directly South, the temp is consistent. What's interesting is that its the low freqs I seem to loose thru the towers verified with the higher crossover point YPAO chooses. Normally it sets the crossover to 40hz (lowest YPAO setting) for my mains and they are tuned to 32hz /low C but in the mid day it sometimes sets it to 110 or 80hz and the sound is super thin and obviously out of phase with the lows. It has even set the phase differently for the subs which typically isn't affected by YPAO other than whatever crossover freq it chooses for them and level.

So, this does affect the high freqs as well and is not as sharp and defined but the biggest audible difference is in the lower ranges of my towers. The highs become more obvious that something was off there when its done again in the morning and you go holy smokes there was a huge difference!

My thinking is like all of yours, it has to be humidity/temp related even though it seems consistent. I just love calibrating and experiencing the affects of it. I'm so intrigued by Audyssey XT32 and the Pro version, can't wait to get my ears on that program!


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## Drudge (Sep 1, 2008)

It could be that the mic positions are also 'ever so slightly' off from the previous positions.I know with Audyssey Pro no matter how much I try to get the positions matched perfectly to the previous ones(even using measurements)I still get slightly different results.

Those systems also have some calculating variance involved with them as well.


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## Stroh (Sep 14, 2010)

Just my 2 cents but I have read about how music will sound better around the midnight hours, most of this is due to the body, mind, etc... But one thing they also brought up was the "dirtiness" of power during the day. Such as factories and AC units being more demanding during the daytime hours not sure if this would have any impact on your testing but just another angle to consider.


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