YPAO mic

[Nuglets]

I currently have a Radio Shack digital meter and a YPAO mic that came with my Yamaha reciever. Does anyone know how accurate this mic is? Also I can't seem to figure out how to calibrate it to the correct level. I get a reading in the mic's dB SPL but the bar labeled dB F does not move on the mic side. I get a graph that focuses around 75dB but before it shows me the graph a warning message pops up telling me that the input measurement is far too low. I am going to mess with the input volume manually to see if that helps. Will I want to compensate for c-weighting with the YPAO mic? Thanks.

[Manic Miner]

You're touching upon something very important here. Lots of people have an YPAO, MCACC, etc. mic laying about. What we need is correction files for the mics that come bundled with different receiver brands.

I understand that this will not give us the absolute numbers, but for calibration purposes relative numbers are enough.

[brucek]

Will I want to compensate for c-weighting with the YPAO mic? Thanks

Yes, you need c-weighting turned on.

Using a mic that hasn't been calibrated won't provided meaningful results. You would need to have it calibrated.

Since you have one, you should use the RS meter with its calibration file.

brucek

[Nuglets]

Thank you. I did end up using the RS meter with the calibration file because the YPAO mic has an extremely low sensitivity. It required me to go buy a few cables that I didn't have lying around but I do think it is more accurate. At least I hope so, because the results are quite different between the two mics. I am going to change the batteries in my RS meter because it has been used a lot on the same batteries. In fact I've picked it up at times and noticed that it had been on since the last time I used it, which could have been days so I think that a battery change will give me the most accurate results.

About the mic being calibrated. Wouldn't Yamaha have calibrated the mic prior to packaging it? If not then it would be completely useless when trying to automatically set up the PEQ, right? I personally think that it sounds like garbage when I let YPAO set my EQ settings so I bypass that anyways, but for people that do use it, is it inaccurate?

[brucek]

Wouldn't Yamaha have calibrated the mic prior to packaging it? If not then it would be completely useless when trying to automatically set up the PEQ, right?

It would make more sense for them to purchase an inexpensive microphone and determine its calibration specifications - that are then compensated for in their DSP software.

When you use this microphone elsewhere, it isn't calibrated........

brucek

[Nuglets]

Yeah that makes perfect sense. Thank you.

[Wayne A. Pflughaupt]

It would make more sense for them to purchase an inexpensive microphone and determine its calibration specifications - that are then compensated for in their DSP software.

Yup- that’s the way it’s done. Obviously they can’t afford to include $5000 mics with the receivers! Bottom line, any calibration mic is only for the unit it’s intended for. And that includes expensive stand-alone professional RTA’s as well.

Regards,
Wayne

[aceinc]

Could REW be used to approximate the calibration of a mic?

Consider running a sweep of your speakers with a baseline mic like a RS or ECM8000 with the appropriate cal file loaded. Next run the same sweep with the target mic with no cal file loaded, such as a ypao.

Shouldn't you be able to build a cal file from the delta's between the two graphs?

It may be tedious to do manually, but programmatically it seems straight forward. What would be great is if you could hookup both mics (with two cal files) simultaneously and get two separate graphs.

Paul

[brucek]

Shouldn't you be able to build a cal file from the delta's between the two graphs?

This is the method we used to create the three calibration files on this site..

[aceinc]

Great minds think alike...

How much work is it?

Perhaps someone would loan their ypao, or mccac mic if it isn't too much effort...

BTW, where can I find the ecm8000 cal file?

[brucek]

How much work is it?

It's not that difficult. It just takes time. You require a professionally calilbrated ECM8000. It would be adding extra variables if you used a generic ECM calibration file.

The method is to position the calibrated microphone and the unit under test quite close together to eliminate errors caused by positional differences. Then, using a subwoofer, you sweep from 10Hz to 200Hz and record the readings. It's important to use a system with as flat a response as possible to obtain the smoothest graphs so as to avoid rapid changes in response that produce anomolies.

The resulting mdat files are converted to text and comparisons made as to the differences. The calibration file is derived from those differences. Once the file is created it is then tested to ensure both the ECM and unit under test match sweep to sweep...

Be cautioned that using measured data (as we have done) is a dubious method to derive a calibration file for a meter. We simply decided that it would be a heck of a lot more accurate than what was available at the time. Aside from the questionable method of deriving the files, the discrepancies between like units is completely ignored. You would really need a better sample size to derive any real confidence in the results.

The easiest thing to do of course is to simply purchase an ECM8000 and preamp. They are quite accurate and ridiculously cheap....

brucek

look in this thread for the generic ecm8000 file