Film-Tech Forum ARCHIVE: Sound Calibration

This is topic Sound Calibration in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Annli Com (Member # 8266) on 01-23-2016, 12:11 AM:

Goodmorning Seniors
I Have Plan Purchase For a Full Sound Calibration Kit
Kindly Sugest Best Softwares and Omoni Mics Is Best.
And Any Aditional Equipment is Nedded ?
Iam Waiting For Your Valuable Advice
Thanks And Regards
ShibuPaul

Posted by Brad Miller (Member # 2) on 01-23-2016, 12:25 AM:

Annli - never post in multiple forums. You just posted this question 3 times and that makes searching the archives as well as keeping up with this one question a huge mess.

Your other threads have been deleted.

Posted by Annli Com (Member # 8266) on 01-23-2016, 12:34 AM:

Dear sir

Sorry For My Mistake, Not Repeat

Posted by Mark Gulbrandsen (Member # 72) on 01-23-2016, 09:52 AM:

The D-2 is the best current analyzer to buy.

Posted by Stephan Shelley (Member # 8587) on 01-23-2016, 01:00 PM:

Mark, does the D-2 include mics and mutiplexer? If not the Ultra Stereo kit does the job.

Posted by Dave Macaulay (Member # 813) on 01-23-2016, 01:58 PM:

The D2 is a complete analyzer with calibrated microphones - complete except you provide a laptop/PC to run the software.
The USL mic multiplexer can be used with a processor's internal analyzers (Dolby CP500-650-750-850 and many other brands' models) or with a hardware or PC based RTA. With any PC RTA, using a laptop's internal sound device input is best avoided. The D2 includes an outboard high quality A-D converter. If you use a PC RTA for analysis then you should get a high quality sound card, internal or external. Quality in these varies widely, of course.
To use a multiplexer you must have an RTA with time averaging. The basic hardware ones that can only display an instantaneous spectrum are not usable. Most PC based RTA programs will have time averaging.
Other tools like impulse measurement will show you problems that a simple RTA can't see, like room reflections and time smear. Useful in understanding why a room that looks properly equalized has poor sound quality... the problems are in the room's acoustic design and the speaker choices: room tuning can't do much (if anything) to alleviate them.

Posted by Mark Gulbrandsen (Member # 72) on 01-23-2016, 03:37 PM:

Try to stay away from cheap PC sound analyzers. The industry standard has long been the R-2 and it's now the D-2, both are four mic analyzers. Also consider that setting up a room with just a single mic is way more difficult to do correctly as a single mic and reading really doesn't reflect what the room ads to the response. The D-2 takes thousands of samples over a number of preset times you may choose from and averages out the signals from the four mics into a meaningful response curve that also reflects the room conditions.

Mark

Posted by Annli Com (Member # 8266) on 01-23-2016, 09:58 PM:

Thanks For The Great Info
And Kindly Share Your Experience In Smaart 7 , Behringer ECM 8000 And Roland Octacore Usb Pre.
Regards
ShibuPaul

Posted by Steve Guttag (Member # 268) on 01-24-2016, 09:13 AM:

A key thing that the R2 and now D2 bring to the table, that cannot be over emphasized is that each mic is calibrated AND that on the display they are normalized. That is, the mic nearest the screen will not be over emphasized since it will be receiving a louder signal.

When using other programs (built in CP analyzers or SMAART...etc.) is to consider your source. Lets say you use an awesome set of microphones and preamp...what normalizing those mics? That is, what is keeping each contribution to the spacial average the same?

People like to equate the USL MMP to the D2 because they are similar but they are WAY different. The straight USL mics are not calibrated. At best, USL can apply an RC type compensation to a mic response. With the D2, there is an actual offset file to each microphone that is applied in software so that microphone's response is perfect, not an approximation. When you are applying EQ with a +/- 3dB response and your microphone (each of four, hopefully) already has a few dB variance on the spectrum, that adds into the overall response you will see and compensate for...thus your compensation may be to your microphone(s) as much as your room response.

It is certainly possible to normalize the USL multiplexer on a room-by-room basis...but I seriously doubt that many do...it is too much work to tweak it for each room to get them right...there will be a lot of "good enough" rationalization.

The proof is in the results...take a room that was tuned up with either an R2 or D2 and have someone else put their R2 or D2 system in there after them, even months after and don't tell them where the mics were...the responses will be identical, within ISO 2969. At most, you'll see variations that can be attributed to humidity changes and decay of HF diaphragms.

The D2 is not the end-all in room analysis, it doesn't do impulse response and such but it does do cinema response VERY well and does allow one to measure RT-60 (Reverberation) and NC (noise floor) in addition to traditional RTA functions. One can even do STC measurements though that requires a bit of work on the user to utilize the data collected (plus I've found that one should bring their own external stimuli to ensure a meaningful result is captured).