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Post by Boomzilla on Jun 2, 2017 6:09:18 GMT -5
OK - I've been dragged (kicking and screaming) into the briar-patch of the "measurers." I need REW software for Mac.
But to use it, I'll also need:
A calibrated microphone
An interface box with a USB output (?) & microphone power
A flexible and sturdy microphone stand
The majority of recommendations I find on Google have to do with Windows-based PC cards as an interface, and don't much discuss stand-alone interfaces.
A variety of microphones are available with calibration curves for "direct" and "90-degree" use. Do I need both?
I already have an exceptionally good microphone stand (thanks, Lyngdorf!)
So for those of you who do REW, your recommendations would be appreciated. I'd also mention that I'm not opposed to buying this equipment used, so if you've some you're not using...
Thanks - Boomzilla
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Post by LuisV on Jun 2, 2017 6:56:44 GMT -5
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Post by Boomzilla on Jun 2, 2017 7:00:23 GMT -5
Your link references multi-channel. I need but one measurement channel at a time. But thanks for the pointer.
Boom
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Post by LuisV on Jun 2, 2017 7:30:33 GMT -5
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Post by copperpipe on Jun 2, 2017 7:37:04 GMT -5
www.minidsp.com/products/acoustic-measurement/umik-1The umik-1 is fully supported in REW; it recoginizes the mike when it launches, prompts you to provide your unique calibration file (which you can download from the minidsp site), it's probably the easiest way. It has both normal calibration and 90 degree, and each calibration file is specific to your serial number on your umik.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Jun 2, 2017 8:52:54 GMT -5
If you want a really well calibrated mic, contact Cross Spectrum Labs and get a calibrated UMIK-1 or Dayton UMM-6 with the CSL calibration. The original calibration on these mics is an assembly-line calibration and is subject to a little more variation, and Cross Spectrum Labs does a bit more careful job of it (though some of their marketing strikes me as hyperbole regarding the accuracy of the factory calibration; I believe he is referencing the uncalibrated mic in his comparisons rather than the resultant of the uncalibrated mic and the calibration transfer function). You can also get an XLR phantom-powered RTA microphone from a variety of makers and then use a Blue Microphones "Icicle" single channel USB interface for a very simple setup, although not as simple as a USB measurement mic.
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Post by Boomzilla on Jun 2, 2017 15:36:27 GMT -5
Rory - I'll be looking into the UMIK-1 / Dayton UMM-6 mics, but what is "CSL calibration?" - DOH - I JUST FIGURED OUT THE ANSWER TO THIS ONE MYSELF - CSL = CROSS-SPECTRUM LABS... (slaps forehead)
Also, just to be clear, with the USB-interface calibrated-mic, I won't need a microphone interface box at all? Just mic to computer's USB port & take it away from there with REW software? Having read the description, I figured out this one too - the answer is "yes."
And with this setup, I should be able to measure a 1-watt / 1-meter measurement for a loudspeaker?
How will the software send the 20-20K sweep to the system for reproduction through the speakers?
Will I need a separate signal generator?
While I'm on the topic of measurements, is there an inexpensive device that can create an impedance trace for a speaker (20-20KHz) and display that graph electronically?
Is there an inexpensive device that can accurately measure amplifier output in watts and identify the point at which the (manufacturer's) distortion specification is exceeded?
Is there an inexpensive device that can measure speaker phase angle over the audible range?
How about an inexpensive device to measure jitter in a digital signal stream?
Thanks all - Boom
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klinemj
Emo VIPs 
Official Emofest Scribe
Posts: 15,095
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Post by klinemj on Jun 2, 2017 16:03:13 GMT -5
CSL Calibration is "Cross Spectrum Labs" Calibration...done 1 at a time. And with the USB mic, you will not need a mic pre-amp...just mic to USB port and go!
I don't know if you are able to do the 1 watt/1 meter measure...never did that myself. I just set levels to a level the mic could "hear" well, and played the tones.
REW sent the full spectrum to the system to be read by the Cross Spectrum...LOL...couldn't resist...
On the other questions..."I dunno!!!" I'll defer to other more advanced nerds than me (as I sit here wearing my "Eat My Moondust" Purdue T-shirt...typing on a bluetooth keyboard that is speaking to a Surface tablet and wirelessly communicating to you...as I prepare to leave the house and go camp outside without a tent for the weekend.)
Mark
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Post by novisnick on Jun 2, 2017 16:06:19 GMT -5
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Post by Boomzilla on Jun 2, 2017 16:20:01 GMT -5
I had the following questions but 3 minutes of research provided all the answers:
What is the tolerance of an uncalibrated mic? (+/- dB range) - doesn't matter - all come calibrated (0-degrees - mic pointed at source)
What is the tolerance of a calibrated one? (+/- dB range) - FOUND THIS ANSWER (UMIK-1 specs page) 20 Hz - 20kHz +/-1dB with calibration loaded
Are the microphones calibrated to any weighted curve (A, C, etc.)? - No - unweighted measurement
What is the frequency range of the microphones? - FOUND THIS ANSWER (UMIK-1 specs page) 20 Hz - 20kHz +/-1dB with calibration loaded
Assuming one had a ANSI-calibrated SPL meter, could one calibrate one's own microphone against the SPL meter? - no need - all come calibrated.
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Post by musicfan on Jun 2, 2017 19:26:27 GMT -5
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Post by foggy1956 on Jun 2, 2017 20:23:18 GMT -5
Only if you are using the 90deg cal file |
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Post by musicfan on Jun 2, 2017 20:39:31 GMT -5
Only if you are using the 90deg cal file No I meant for in room measurements. They should be take with the mic pointing straight up (and of course using the 90 degree file) Measuring with the mic pointed at the speakers (and the 0 degree file) is incorrect for in room |
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Post by Boomzilla on Jun 3, 2017 10:39:46 GMT -5
Actually, since I want this rig for near-field speaker measurements (rather than room measurements), I think that the 0-degree calibration is the appropriate one. |
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Post by musicfan on Jun 3, 2017 11:01:52 GMT -5
Actually, since I want this rig for near-field speaker measurements (rather than room measurements), I think that the 0-degree calibration is the appropriate one. Yes you are correct Can I ask why you want it for nearfield? |
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Post by Boomzilla on Jun 3, 2017 13:48:04 GMT -5
I write reviews for the Secrets of Home Theater and High Fidelity website. It helps to be able to see the frequency response when reviewing speakers.
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Post by musicfan on Jun 3, 2017 16:38:58 GMT -5
I write reviews for the Secrets of Home Theater and High Fidelity website. It helps to be able to see the frequency response when reviewing speakers. oh cool!! |
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Post by Boomzilla on Jun 3, 2017 17:26:50 GMT -5
UMIK-1 ordered - REW installed.
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Post by thrillcat on Jun 3, 2017 21:16:33 GMT -5
For the record, I've never been able to get the HDMI output working on my MBP for output, so I've used a UMIK-1 for input and a USB output device that sends audio out over RCAs and connected that to my UMC-200.
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