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Optimizing, Room-Calibrating Microphone

Wolfwood

Wolfwood

In the Valley of the Sun
For the last few weeks , I have been experimenting with the " Auto - Setup " function ( on my Yamaha RX - v2500 ) via the Opitimizing Microphone that came with the receiver. I have owned this receiver for almost a year now, and before this , I had its little brother ( the Yamaha RX - v2400 ). Until now, I havent spent much time taking advantage of the RX - v2500's real potential !

To start off , I love this receiver. I could spend hours explaining why, but Ill just take a few moments to explain some of the features that are first's and favorites for me.

1. - On Screen Menu
2. - (dare i say it) 7 Channel Stereo :)
3. - Pure Direct* 2 Channel Stereo
4. - Automatic Room Calibration via Optimizer Microphone


The journey began when I plugged an video cable from the " Monitor " out to my T.V. Upon pressing the Menu button on the remote, a lovely background screen pops up on the T.V. as well as a menu screen. Avoiding all the other options at the moment, I select " Auto Setup " . You have a menu that lets you choose what exactly you want the optimizer to configure. The list goes as follows

- Wiring , Distance, Size , Equalizing and Level

I select all of the above and press " Start " which wouldve activated the optimizer process, but we forgot one vital thing, the mic ! After plugging the mic in I was trying to figure out what to set the mic on, and stumbled upon the perfect solution. A standard camera tripod , which happens to screw into the bottom of the microphone !! Setting the tripod on my usual listening position, I level out the Micrphone to where my head sits and declared the whole house silent as I press the " Start " option !

During the Distance , Size and Level portions of the setup , you hear some scary sounds , but you press on ! Given everything went ok during the setup, a screen pops up displaying which speakers are in normal phase or reverse phase. Oddly enough, the manual states that the process might say that your speakers are in Reverse Phase , when they actually might not be ( which is usally the case ). The next screen is really cool ... It actually shows you a graph of each speakers response( at least thats what I believe it is ) It doesnt really explain on the menu screen. Moving on to the next screen reveals the distance of your speakers from the microphone, Immediately followed by a screen that reveals each speakers level tweaking. Example : Front Left + 0.5 db / Surround Right - 1.0

With the setup complete, you test out the new configuration with one of your favorite songs... and WOW! What a difference it makes in sound. I was enveloped in a totally new world. A much more open and round soundstage. It revealed that my previous ( manual ) tweaking made my setup sound very condensed and boxed up, like my listening space was a box ( which it is ). As if I could close my eyes and pick out where each speaker was located. I close my eyes now and its all vanished ! Where did you go speakers !? I also can describe it as , the point of origin of the sound extends out beyond where my speakers physically are. Imaging isnt like a laser anymore. My room is meager at best- 12' x 15' but I can still move around quite a bit without losing the sweet spot :)

I would rabble on but this post is growing rather long ! So my point is , what are your opinions and experiences with using room calibrating microphones !? Have I been missing out on a well known gem or what !?

- Wolfwood
 
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I used to use the calibration mic on my RXV665 and it worked well for a while. Suddenly though, one day the internal decoders started messing up. Movies are supposed to have dynamic explosion scenes. That's the way it used to be until this one particular day, and ever since, the voices were in your face and the explosions sounded like distant whispers. That's a major decoder failure. So that receiver has since been decommissioned from HT use and replaced with a Dolby CP45, which sounds much better and much more dynamic.
That receiver is barely used anymore, and when it is, its for 2ch in direct or pure direct. It is no longer used for movies.


I find that using my pro audio measuring mic and my analyzer software on my laptop along with the CP45's internal EQ sounds much better anyways. (Though I would rather use an external EQ if I had another one left over).
 
I use a mini boom stand for guitar mikes.

dayton-mike-002.jpg


That sits on a shelf behind the comfy chair, and I adjust and angle the mike as needed so it's placed right in the sweet spot. I use a Dayton mike, and find that I can get more accurate results by swinging the mike towards the speaker as I graph each channel, then straight forward for the final tweaks.

Oh. And I've since replaced the duck tape with a genuine threaded connector. <G>

Oh Oh. I'm old school, so no built in RTA goodness for me. I use a laptop and TrueRTA to get the job done.
 
Wow , you guys and your pro mic setups ! lol This really never came to mind at all ! What exactly are you guys doing ? Dusty42701 mentioned he uses analyzers on his laptop and such. What exactly are you guys doing ? Do you setup the mic and run your programs and tweak your system accordingly ? Or simply does the act of running your program , directly interact with your receivers / preamps ? Whats goin on ! lol
 
The program has a pink noise generator which outputs to your receiver and out through your speakers. The mic picks up what your speakers are outputting and sends the sound back to the computer. The computer program analyzes the dB level at each frequency and displays it on a live graph. We use that live graph to manually adjust an equalizer to change the sound to get a flat response from the input of the receiver to the speaker output.
 
Everyday I am reminded how much of a greenhorn I still am hehe ;) Thanks for the lesson Dusty !
 
Here's so you can get a bit of a better idea:
(BTW this is for demonstration, this is not proper mic placement :D )
Using a mic like this:
IMG_0270.jpg

Connected to a phantom power preamp like this:
IMG_0269.jpg

This is what you get, the graph, or analyzation of the speaker output using the mic:
(NOTE: I have mine set to a 1/3 octave step visualization so that every block on the graph perfectly represents each fader on a 31-band EQ, this can be changes to 1/1 octave, 1/3, 1/6, etc. including a full range graph that shows everything in exact representation, not in summed blocks.)
VA1.jpg

And just to point out the sound generators, white noise, pink, sine, square, saw-tooth, it has them all.
VA2.jpg
 
Awesome ! Thanks for the pics ! So is this all something everyone does but nobody talks about ?! lol I know of the concept of this all but really didnt think people use this kind of tech outside of labratories , realizing its practical for personal / private use is embarrasingly new to me ! :P Again sir , Thank You ! :)
 
Well, I always used that cheapo mic that came with the yammy, I never started using the more expensive analyzer systems until I got started into pro-audio. When I got three graphic equalizers, I wanted to be able to use them correctly with more than just my ear and a cheap mic if ya know what I mean. I wanted to use them like they're meant to be used. That's the reason I bought a calibration mic and portable phantom preamp.

I was going to get a Samson D-1500, but someone pointed me to a free computer software. Much cheaper than buying a $200 dedicated analyzer. After all, I already had an external Hi-hi sound card for my laptop, why not use it? (analyzing can't be done with factory on-board audio).
 
I was wondering if those analyzer programs you mentioned were out of my budget , glad to know they are free !! would you mind letting me know how / where to download them ? :)
 
On my current computer I wouldnt even know or want to tell you lol Thank you for the link though, I'll definately save it for when I get a proper PC rig :) My buddy has quite the pc and is into audio, it will definately be mulled over on my next visit !
 
This is the kind of stuff that would have once had an army of nerds in white coats descending upon your listening room with all sorts of magical instruments. I know - that's how my room was first done. Let's hear it for the wonders of today's technology.

So, why "voice" a room? The human ear is incredibly sensitive to the slightest changes in the audio spectrum, but the brain has a hard time dealing with all the possibilities, especially when you get into things like 1/3rd octave eq and such. We can get used to most anything with time, and the brain will train to what it's hearing, for bad or worse. Don't get me wrong - you CAN listen and appreciate your equipment right out of the box - usually - but if you want to hear it as it was intended to be heard, you have to match your room acoustically. The RTA (real time analysis) process can do all that automatically. Even those who thought their systems were doing a bang up job will usually see a major improvement once everything is fine tuned. Kinda like a "where did that come from?" moment when the music that had been hiding pops out ...

PS ... the original goal when voicing is a flat trace across the spectrum. Response is a bit low in a certain band, tweak it up using that eq section - repeat as needed. However - totally flat room response suffers severe suckage more times than not. Once you get it flat, then apply a "room curve" based on your musical preferences. Here again, software saves the day. Most of the programs will allow you to assign a curve internally and map the results taking that into account. From there, it's a simple transfer from the graph to the sliders on the eq. Then one more go to make sure your eq is calibrated accurately is all.

I go an extra step on the home system. Besides the 31 band graphic eq, I have a four band parametric that handles the big lumps. That by itself gets me real close, and the 31 bander fine tunes and feathers that. All in all, works quite well.

There's also outboard units that will do the same automagically for classic systems, but they tend to be ... not cheap.

And yes ... it is anal retentive to the extreme ... but hey, that's what makes us aw dee ohhhh files ... :D
 
Just remember that most of the avr's specify to use the mic that came with the unit. There are supposed to be matched for that specific system, thats how it is for my denon.
 
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