Rew with cond mic? - AVS | Home Theater Discussions And Reviews
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post #1 of 25 Old 08-08-2014, 12:37 PM - Thread Starter
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Rew with cond mic?

What would happen if i broke out the old phantom powered condenser mic and downloaded rew? I'm guessing it's not "calibrated" so it would just be inaccurate? How bad could it be? Especially since it's free.
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post #2 of 25 Old 08-08-2014, 01:32 PM
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Good enough to get started and (possibly) be surprised by what you measure.

I used the microphones in a Tascam hand-held recorder at first.

I'll be back later...


links::: 1.5RQ > digits > 1177a > OpenDRC-DI > DEQ2496 > DAC2 > KCT > FPB 350mcx > reQuest > Sweetspot
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post #3 of 25 Old 08-08-2014, 03:22 PM
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With an uncalibrated mic I wouldn't trust the <20hz or >7khz measurements, or whatever it's rating is (if it even has one).
Still better than using your ears for finding peaks and dips.

Even a sweep captured by a smartphone or camera dumped into Audacity's spectrum analyzer would be better than "guessing".
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post #4 of 25 Old 08-08-2014, 03:44 PM
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Your results are only as accurate as the mic is. Some condensers are very accurate, but not all by any means. You could do your own calibration file if you could find the manufacturer data sheet with frequency response chart.

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post #5 of 25 Old 08-08-2014, 03:46 PM
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Quote:
Originally Posted by Tstan7777 View Post
What would happen if i broke out the old phantom powered condenser mic and downloaded rew? I'm guessing it's not "calibrated" so it would just be inaccurate? How bad could it be? Especially since it's free.
What mic? Shouldn't be hard to find the manufacturer's basic frequency response for the mic, but many have a largish peak, say six dB plus or minus 3, somewhere in the presence range, say somewhere between 2khz and 8 KHz. And many roll off steeply above 10 kHz. Especially large diaphragm condensers. After you correct for the mic inaccuracies your system may sound oddly dull but airy.
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post #6 of 25 Old 08-08-2014, 03:58 PM
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Quote:
Originally Posted by JHAz View Post
What mic? Shouldn't be hard to find the manufacturer's basic frequency response for the mic, but many have a largish peak, say six dB plus or minus 3, somewhere in the presence range, say somewhere between 2khz and 8 KHz. And many roll off steeply above 10 kHz. Especially large diaphragm condensers. After you correct for the mic inaccuracies your system may sound oddly dull but airy.
I'm assuming the OP only wants to use it for bass, as higher frequencies really should be room eq'ed, just from about 200hz and down.
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post #7 of 25 Old 08-08-2014, 04:16 PM - Thread Starter
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I'd love to see what's going on in my room. I have no way to eq right now, but i have 3 spots for the sub I'd like to measure. The mic is a basic single pattern from samson. That just got me thinking...would it have to be an omni? Cause i don't think it is. I know for sure it's not a selectable pattern. I'd like to measure my mains too because they're rated to 38hz and ypao always xover at 120hz? The sub is an old hsu vtf-2. The 10 incher.
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post #8 of 25 Old 08-09-2014, 02:57 AM
 
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Quote:
Originally Posted by RayDunzl View Post
Good enough to get started and (possibly) be surprised by what you measure.

I used the microphones in a Tascam hand-held recorder at first.
Even vocal mics are pretty flat from 200 to 2 KHz, and if you just got that right in a system it might be an improvement.
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post #9 of 25 Old 08-09-2014, 03:02 AM
 
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Quote:
Originally Posted by Tstan7777 View Post
I'd love to see what's going on in my room. I have no way to eq right now, but i have 3 spots for the sub I'd like to measure. The mic is a basic single pattern from samson. That just got me thinking...would it have to be an omni? Cause i don't think it is. I know for sure it's not a selectable pattern. I'd like to measure my mains too because they're rated to 38hz and ypao always xover at 120hz? The sub is an old hsu vtf-2. The 10 incher.
Every Samson mic I've seen has a model number on it someplace.

Given that you can pick up fairly decent measurement mics for $20 and up, why are you punishing yourself this way? ;-)


http://www.ebay.com/itm/Audyssey-mic...-/251608682554

For example if you plug a Audyssey/YPAO/MCACC calibration mic into the mic input on most computers, its good enough to started with REW.
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post #10 of 25 Old 08-09-2014, 12:54 PM - Thread Starter
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Ok, been looking into true measurement mics more. Since i do have available phantom power, is there any advantage with one of those or should i just go with the usb umik? The article i was reading was from 2010 so not sure if the pricing or availability of the mics mentioned are still relevant.
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post #11 of 25 Old 08-09-2014, 02:19 PM
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This is what you want:
http://www.parts-express.com/dayton-...phone--390-808

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post #12 of 25 Old 08-09-2014, 03:35 PM
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I actually use the Umik-1, don't know if there are any advantages over any others. I was ordering a Minidsp anyway, so I went ahead and order the mic from them as well.

From what I understand the UMM-6 needs a SPL meter too, and the Umik-1 doesn't, not sure of the details on this.
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post #13 of 25 Old 08-09-2014, 04:49 PM
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The UMIK-1 with calibration file works well with REW.

REW considers it not to need calibration and disables the calibration function, when the calibration file is used.

I think you need to be sure the windows recording level for the UMIK-1 is set to 25, though.

I'll be back later...


links::: 1.5RQ > digits > 1177a > OpenDRC-DI > DEQ2496 > DAC2 > KCT > FPB 350mcx > reQuest > Sweetspot
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post #14 of 25 Old 08-09-2014, 05:21 PM - Thread Starter
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So it sounds like there is no advantage to using a mic with phantom power. You mention windows and recording level. I use an AISO driver through my audio interface for audio. Is that going to make a difference? You can always switch the driver back to a default driver but when it comes to audio, I'd much rather use an AISO driver.
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post #15 of 25 Old 08-09-2014, 05:36 PM
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ASIO is for output. I don't think it plays a part on input. I could be wrong. I see that I am, Audio Stream Input Output.

USB mic does the ADC and sends digits to the PC.

I dunno. Play with it.

I'll be back later...


links::: 1.5RQ > digits > 1177a > OpenDRC-DI > DEQ2496 > DAC2 > KCT > FPB 350mcx > reQuest > Sweetspot
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post #16 of 25 Old 08-09-2014, 09:27 PM - Thread Starter
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Aaah yes, i forgot i would be using the usb for the mic input. Not the audio interface. Normally the aiso would handle all audio, but I'm sure using the usb for the mic input has it's own implementation. Really the main point of aiso drivers is the ability to play and record audio at the same time.
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post #17 of 25 Old 08-10-2014, 06:02 AM
 
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Quote:
Originally Posted by Tstan7777 View Post
Ok, been looking into true measurement mics more. Since i do have available phantom power, is there any advantage with one of those or should i just go with the usb umik? The article i was reading was from 2010 so not sure if the pricing or availability of the mics mentioned are still relevant.
Here's a summary of many alternatives from Bob Smith. This came from an Pacific NW group AES presentation that JJ recently posted a link to:



You can find the whole presentation at numerous sites if you Google it with the string: "Acoustic Measurement Systems 101"

It includes FR graphs for most if not all of the alternatives listed above.

If you follow this link: http://www.aes.org/sections/pnw/pnwrecaps/2012/jj_jan/ You can also find it, in a clearly labelled zip file. IMO the real treasure on that page is a file called SWISHA.WAV which might be the next MLS.
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post #18 of 25 Old 08-10-2014, 11:01 AM - Thread Starter
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What is the swisha wav file for? Does that replace a sweep? I think I'm just going to with the umik.
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post #19 of 25 Old 08-10-2014, 01:34 PM
 
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Quote:
Originally Posted by Tstan7777 View Post
What is the swisha wav file for? Does that replace a sweep? I think I'm just going to with the umik.

The swisha file indeed replaces the customary sweep, but usually develops higher resolution measurements in significantly less time.
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post #20 of 25 Old 08-10-2014, 05:45 PM
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Quote:
Originally Posted by Tstan7777 View Post
So it sounds like there is no advantage to using a mic with phantom power. You mention windows and recording level. I use an AISO driver through my audio interface for audio. Is that going to make a difference? You can always switch the driver back to a default driver but when it comes to audio, I'd much rather use an AISO driver.
Dynamic mics are typically a lot less extended than a small diaphragm consenser can be. Knee jerk reaction, I would much prefer to be applying a few dB of correction to a reasonably flat condenser vs 10 dB or more at the high and low end of a normal (like an sm57 or -58) dynamic. If you have an re20 or maybe an sm7 the required corrections might be less extreme but you can get a calibrated condenser for a quarter of the price or less.
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post #21 of 25 Old 08-10-2014, 06:43 PM - Thread Starter
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Went and looked...this is the one I have

http://www.samsontech.com/samson/pro...crophones/c01/
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post #22 of 25 Old 08-12-2014, 10:07 AM
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cardiod pattern mic not good for measuring. It "hears" differently from the sides and back than from the front, and that will skew measurements. Also lots of roll off in the bass (minus about 6 dB by 50 Hz, the manual does not show frequency response any lower, but safely assume the roll off continues at least as strongly as what is shown. Full range, it's reasonably flat from 100 Hz to about 15KHz, but then rolls off sharply (from the front). FR is all over the place from the back, and there's not going to be a location in your room where sound doesn't bounce off walls, floors and/or ceilings and reach the mic from the back (or sides . . .)

In short, not an ideal measurement mic by a long shot . . .
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post #23 of 25 Old 08-12-2014, 10:53 AM
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Quote:
Originally Posted by arnyk View Post
The swisha file indeed replaces the customary sweep, but usually develops higher resolution measurements in significantly less time.
Which free software analyzes the result of a swisha?

---

edit:

Oh, now I see, it's there but it didn't register before.

I'll be back later...


links::: 1.5RQ > digits > 1177a > OpenDRC-DI > DEQ2496 > DAC2 > KCT > FPB 350mcx > reQuest > Sweetspot

Last edited by RayDunzl; 08-12-2014 at 08:10 PM.
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post #24 of 25 Old 08-12-2014, 02:14 PM
 
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Quote:
Originally Posted by Tstan7777 View Post
Went and looked...this is the one I have

http://www.samsontech.com/samson/pro...crophones/c01/
At my old place we had a pair of those, so I am familiar with them. Used them a lot. For hypercardioids (which they are Samson specs notwithstanding, check their directional patter) they are pretty flat except at the bottom end.



The question I ask is whether a mic, if used to measure a system and followed, would make or break the system being measured.

I'd say, not ideal, but if used as a measurement mic on a speaker system, it will probably help it out or make it.
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post #25 of 25 Old 08-13-2014, 02:19 PM - Thread Starter
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Well folks, instead of buying a umik/minidsp i bought some speakers. Dang it! Crutchfield had some psb b5's open box for $212 and i couldn't resist. I've always wanted to hear some and this was my chance. I may measure with that mic just to learn rew...no expectations in mind. With that pick up pattern, the mic would need to be vertical right? Like a singer would hold a mic?
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