tips for room analysis

[jcparks]

Would like to experiment with doing some analysis in my living room theater, but I dont want to spend any money. I downloaded the free REW measurement program to my surface pro, plugged in a blue snowball mic which i placed in my primary listening position, and plugged the surface into the an hdmi in on my receiver. I used to program to run sweeps and the response I got was actually really flat with just a few peaks and dips which I found to be a bit suspect being that I was running without any room correction software.
I have a lot of learning to do about how to properly calibrate the equipment and the software, but my main question is...
Will my Mic
http://www.amazon.com/Blue-Microphones-Snowball-Condenser-Microphone/dp/B006DIA77E/ref=sr_1_2?ie=UTF8&qid=1453754465&sr=8-2&keywords=blue+microphones+snowball
Do correction of its own on the incoming audio signal? Should I use a less forgiving mic?
Just started on all this experimenting and I know I have a lot to learn.

 

[WaynePflughaupt]

Will my Mic
http://www.amazon.com/Blue-Microphones-Snowball-Condenser-Microphone/dp/B006DIA77E/ref=sr_1_2?ie=UTF8&qid=1453754465&sr=8-2&keywords=blue+microphones+snowball
Do correction of its own on the incoming audio signal?

Mics are transducers. They don’t “correct” anything. Perhaps you meant something on the order of a calibration file?

Should I use a less forgiving mic?

There’s not much chance a $45 mic is all that “unforgiving,” and the frequency response graph below from Snowball’s web site is all the evidence we need.

Most likely the reason your response looked so good is that you had the graph’s vertical axis was set really wide, like maybe a top-to-bottom span of more than 100 dB. The vertical axis should be a more reasonable 60 dB span. If that’s the case, you’ll see that things probably don’t look as good as they did before.

Bottom line, there’s no free lunch. If you want accurate measurement you’ll need to buy a mic with its own specific calibration file. Cross Spectrum Labs offers them in the $100 range. When you consider that it wasn’t too many years ago that hardware to do this kind of thing (which is all that was available) cost well over $1000, it’s a heckuva deal.

If you’re happy just getting “general idea” measurements, you can get a used Behringer ECM8000 and use the generic calibration file that the Home Theater Shack offers.

Regards,
Wayne A. Pflughaupt

 

[highfigh]

Would like to experiment with doing some analysis in my living room theater, but I dont want to spend any money. I downloaded the free REW measurement program to my surface pro, plugged in a blue snowball mic which i placed in my primary listening position, and plugged the surface into the an hdmi in on my receiver. I used to program to run sweeps and the response I got was actually really flat with just a few peaks and dips which I found to be a bit suspect being that I was running without any room correction software.
I have a lot of learning to do about how to properly calibrate the equipment and the software, but my main question is...
Will my Mic
http://www.amazon.com/Blue-Microphones-Snowball-Condenser-Microphone/dp/B006DIA77E/ref=sr_1_2?ie=UTF8&qid=1453754465&sr=8-2&keywords=blue+microphones+snowball
Do correction of its own on the incoming audio signal? Should I use a less forgiving mic?
Just started on all this experimenting and I know I have a lot to learn.

How did you orient the mic? Usually, it's supposed to be aimed up, not at the speakers.

It's possible that your room is good for frequency response, but I would recommend checking for reverberation. This can be done in REW or, if you have an iPhone, you could download an app called ClapIR. It's written specifically for measuring for RT60. I would recommend using balloons over hand clapping- it's not very easy to clap and produce the same sound every time, but it's easy enough to erase the test and do another.

If you clap your hands and can hear reverberation for an easily measurable time or hear repeats that come at short intervals, the room needs something- how you treat it is up to you but a single reflecting area can cause sounds that seem to come from places that don't have speakers and it's not because of the mix.

I used ClapIR at a customer's house where I'll be installing a home theater and the initial tests from the main listening position show reverberation time for some frequencies of more than 5 seconds. This one is gonna be interesting, but they do want it treated, so it won't be a disaster.

 

[WaynePflughaupt]

How did you orient the mic? Usually, it's supposed to be aimed up, not at the speakers.

Only if you have a 90° calibration file. If not, upright orientation will get a graph that starts to droop above 1-2 kHz, as the mic becomes less omnidirectional above that point. (At least a proper measurement mic does – can’t speak for the mic the OP is using.)

Regards,
Wayne A. Pflughaupt