Measurement Mic Shootout (EMM-6, WM-61A, RS 33-2055, Audyssey) - Page 4 - AVS Forum
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post #91 of 375 Old 04-14-2011, 05:31 AM
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Found these tidbits of info on the web and Audyssey site:

* The Audyssey mic (pyramid shaped), is calibrated within +/-2 dB from 10 Hz to 24 Khz.

* The Audyssey Pro mic is calibrated within +/-0.5 dB from 10 Hz to 24 Khz; or perhaps even more extended in the lower and higher frequencies of the audio range.


"The Audyssey Pro mic is individually calibrated by serial number and this makes it more accurate, but that improvement is really only apparent in the high frequency range. The consumer and Pro mics have equivalent performance in the low frequency range."

Chris Kyriakakis Audyssey

http://ask.audyssey.com/entries/7637...ter-resolution


AudioXpress tested the Panasonic Capsule and the results are amazing...
http://www.audioxpress.com/magsdirx/...avaras2861.pdf

"Conclusion:
a) You can use the standard microphones
without any calibration for frequencies up to about 2 to 3kHz. Above this limit, if you require accuracy, the microphones should be calibrated.
b) The distortion of the standard microphones
is acceptable, providing that the peak sound pressure level is always below 115-120 dBSPL.
c) You can use the microphones modified according to Linkwitz without any calibration for frequencies up to about 4 to 5kHz. Above this limit, if accuracy is required, the microphones should be calibrated.
d) The Linkwitz modification offers
a dramatic improvement on the distortion, making the microphone
suitable for near-field measurements."

Charlie
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post #92 of 375 Old 04-14-2011, 07:04 AM
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Quote:
Originally Posted by chaywood View Post

Found these tidbits of info on the web and Audyssey site:

* The Audyssey mic (pyramid shaped), is calibrated within +/-2 dB from 10 Hz to 24 Khz.

* The Audyssey Pro mic is calibrated within +/-0.5 dB from 10 Hz to 24 Khz; or perhaps even more extended in the lower and higher frequencies of the audio range.

Charlie

This would appear to answer the question. My Aud mic is down -4dB at 10 Hz (which most BS specs writers would call +/- 2dB), and not's would qualify in the higher res spec category.

not, do you have the Aud Pro mic?

Charlie, can you link to this info?

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post #93 of 375 Old 04-14-2011, 08:08 AM - Thread Starter
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I don't know if I have the pro mic. I know the Denon 5308 can be upgraded to Audyssey pro via software, so it's a possibility. I thought they were referencing the calibration in the receiver though, since each mic is matched to the receiver.


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post #94 of 375 Old 04-14-2011, 08:17 AM
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Quote:
Originally Posted by notnyt View Post

The first thing to try is make sure you're plugged into the right mic port. Then make sure the level is high enough that in the 'recording devices' screen you can see the bars light up green if you blow onto the mic. You can choose this as the default recording device to make things easier in REW, or just make sure to choose this as the input device in REW under preferences. Drop me a PM or aim me at nyttt if you have any questions.

hey notnyt, this might be a stupid question but here goes...

the mic has a phono connection right?

do i need to get a 3.5mm mono to stereo adapter?

right now, i connect the mic directly to the "line in" on the soundcard. i suppose this is incorrect?
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post #95 of 375 Old 04-14-2011, 08:19 AM - Thread Starter
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Quote:
Originally Posted by smokarz View Post

hey notnyt, this might be a stupid question but here goes...

the mic has a phono connection right?

do i need to get a 3.5mm mono to stereo adapter?

right now, i connect the mic directly to the "line in" on the soundcard. i suppose this is incorrect?

You should connect to "mic in" if you have it. I don't think any adapters are necessary.


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post #96 of 375 Old 04-14-2011, 08:28 AM
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ok, i'll try the mic in tonight.

it's stated over at the HTS that "mic in" is not ideal due to noises?
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post #97 of 375 Old 04-14-2011, 08:36 AM
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Quote:
Originally Posted by notnyt View Post

I don't know if I have the pro mic. I know the Denon 5308 can be upgraded to Audyssey pro via software, so it's a possibility. I thought they were referencing the calibration in the receiver though, since each mic is matched to the receiver.

Yes, this is the only thing that makes sense. But, that puts us back to square one.

Again, this: * The Audyssey mic (pyramid shaped), is calibrated within +/-2 dB from 10 Hz to 24 Khz. works well with my results using the ACO as a reference.

Later today I'll run the test again, paying closer attention to a flatter starting FR and exact mic position.

Bosso
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post #98 of 375 Old 04-14-2011, 08:43 AM - Thread Starter
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Quote:
Originally Posted by smokarz View Post

ok, i'll try the mic in tonight.

it's stated over at the HTS that "mic in" is not ideal due to noises?

Depends on the soundcard, but that sounds a little nonsensical to me. The mic input on my motherboard (realtek) sound is flat to at least 5hz and there is no noise.


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post #99 of 375 Old 04-14-2011, 09:06 AM
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thanks, i read the REW guides/threads over at HTS. and though they're helpful, they seem a bit outdated.

no mention of "mic in", or even HDMI?

most people run HDMI connections these days on an htpc.
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post #100 of 375 Old 04-14-2011, 09:23 AM - Thread Starter
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I'm running HDMI between my HTPC and my receiver. Most people aren't using REW on an HTPC, but on a laptop that they just plug in temporarily.


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post #101 of 375 Old 04-14-2011, 09:29 AM - Thread Starter
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Quote:
Originally Posted by J_Palmer_Cass View Post

Well, that is not what I see when I measure. All my sweeps measure different in the low end. RS Digital SPL meter is used as the microphone, with the SPL C scale adjustment factors activated (MIC CAL button is ON).

These sweep measurements were made with TrueRTA. Under normal conditions, I would delete the obvious "bad looking" sweeps, and then average them. REW sweeps are a bit different, and REW goes off track at 8Hz when I measure with REW.


Top set of curves are 15 consecutive TrueRTA QuickSweeps overlaid no smoothing. 110 dB SPL sweeps measured at the close mic SPL meter position.

Second curve from top is the average of all 15 sweeps no smoothing applied.

Third set of curves is the soundcard calibration on and off. Minimal soundcard compensation is required.

Fourth curve down from top is the noise floor of room measured with microphone on and no noise except for the PC fan. No smoothing is applied.

Bottom is noise floor of electronics and cables with SPL meter turned off but still connected. No smoothing is applied.


One note, if you clip the RS SPL meter you can smooth out the curves (AKA SPL meter reads over range). Same thing applies to all electronics in the chain!


I cannot reproduce the issues you are seeing. Perhaps TrueRTA sweeps too quickly with not enough data points down low or there is an issue with your meter.

I took 5 sweeps with each mic at exactly the same location using a mic stand with the mic about 1-2" away from the woofer.

The EMM-6 is obviously the best and most consistent of this group. Please note these close mics are with EQ enabled and without the correct calibration files for each mic. I just did this quickly to show how multiple graphs overlay.


EMM-6, consistent to 2hz:


Modified WM-61A, consistent to 3hz


Audyssey MultEQ mic, consistent to 3hz


RadioShack 33-2055, consistent to 6hz


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post #102 of 375 Old 04-14-2011, 10:43 AM
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Quote:
Originally Posted by notnyt View Post

I cannot reproduce the issues you are seeing. Perhaps TrueRTA sweeps too quickly with not enough data points down low or there is an issue with your meter.

I took 5 sweeps with each mic at exactly the same location using a mic stand with the mic about 1-2" away from the woofer.

The EMM-6 is obviously the best and most consistent of this group. Please note these close mics are with EQ enabled and without the correct calibration files for each mic. I just did this quickly to show how multiple graphs overlay.


RadioShack 33-2055, consistent to 6hz





RS 33-2055 for close mic, measured with REW. Length used was 1M! Sweep from 1 to 100 Hz.

Perhaps speaker location has something to do with it. Not going to move my speaker to a different location.

Perhaps it could be that your lowest room mode peak is at 7 Hz and mine is at 10 Hz, or your room mode low is at 9 Hz and mine is at 12 Hz.



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post #103 of 375 Old 04-14-2011, 10:45 AM - Thread Starter
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Try it with 512K and sweep from 0-200, see if it looks any better.


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post #104 of 375 Old 04-14-2011, 11:23 AM
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J - you might find that the sweeps are more consistent lower if you raise the level... Looks like you are both being limited by the noise floor of the room on the mics with a larger compensation factor. For example if the compensation factor for the mic is 20dB at 2hz and the noise floor of the room is 40dB the source of the measurement must be able to produce more than 60dB at 2hz or all you'll see is the noise floor. Actually J didn't you say you're measuring a woofer on one of your speakers? That could be why the discrepancy as it likely can't overcome the noise floor + compensation factor at those lower frequencies?


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post #105 of 375 Old 04-14-2011, 11:23 AM
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Quote:
Originally Posted by notnyt View Post

Try it with 512K and sweep from 0-200, see if it looks any better.


I tried them all and used different frequency ranges. This 1M value looks the best and has the slowest sweep!

Funny thing is I almost never use sweeps. It is much easier to put in a CD and play the correct wide band tones for SpectrumLab, TrueRTA, and REW if I am just going to look at FR. I don't pay that much attention to how things measure below 20 Hz except where the rolloff starts and to identify speaker to speaker interference.
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post #106 of 375 Old 04-14-2011, 11:25 AM
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Quote:
Originally Posted by desertdome View Post

That is really good. My Cross Spectrum calibrated ECM8000 needs 17 dB at 5 Hz, 13 dB at 10 Hz, and 4.84 dB at 20 Hz.

I've read that the EMM-6's require quite a bit less compensation than the ECM8000's...


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post #107 of 375 Old 04-14-2011, 11:31 AM
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Quote:
Originally Posted by lennon_68 View Post

J - you might find that the sweeps are more consistent lower if you raise the level... Looks like you are both being limited by the noise floor of the room on the mics with a larger compensation factor. For example if the compensation factor for the mic is 20dB at 2hz and the noise floor of the room is 40dB the source of the measurement must be able to produce more than 60dB at 2hz or all you'll see is the noise floor. Actually J didn't you say you're measuring a woofer on one of your speakers? That could be why the discrepancy as it likely can't overcome the noise floor + compensation factor at those lower frequencies?



I posted noise floors in my TrueRTA chart. Electrical, room background, and sweep levels are to a calibrated SPL scale. The sweeps measured 110 dB SPL C scale at the RS SPL meter (110 dB scale was used). The average and calibration files are not to scale. They are placed where they would fir on the chart.

REW also stops C scale compensation at 5 Hz.
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post #108 of 375 Old 04-14-2011, 11:37 AM - Thread Starter
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Quote:
Originally Posted by lennon_68 View Post

J - you might find that the sweeps are more consistent lower if you raise the level... Looks like you are both being limited by the noise floor of the room on the mics with a larger compensation factor. For example if the compensation factor for the mic is 20dB at 2hz and the noise floor of the room is 40dB the source of the measurement must be able to produce more than 60dB at 2hz or all you'll see is the noise floor. Actually J didn't you say you're measuring a woofer on one of your speakers? That could be why the discrepancy as it likely can't overcome the noise floor + compensation factor at those lower frequencies?

All of our sweeps were above the noise floor even at the lowest levels.


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post #109 of 375 Old 04-14-2011, 11:54 AM
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Quote:
Originally Posted by notnyt View Post

All of our sweeps were above the noise floor even at the lowest levels.


There may be some additive bass effect between the room and the speakers.

I noticed that the peaks in the room background noise clearly line up with peaks in the speakers FR on my TrueRTA charts at low bass frequencies. There is some type of room / speaker interaction going on even though I sweep at levels well above the room noise floor.

No need to go any further with this. I am not going to run sweeps any louder than I run right now.
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post #110 of 375 Old 04-14-2011, 11:55 AM
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Lennon68 is right. It is very common to have 50-70 db of noise down below 10hz. Your compensation will boost this also. You have to get enough signal to noise ratio to get a clean measurement down there. This is what.is happening below 10hz on some of the measurements. It is better to not need compensation. This has nothing to do with the rest of the measurements themselves which are fine we are talking strictly below 10hz here or whever you start to see that sort of random measurement artifact that isn't repeatable. Another give away is if the response goes from smooth into a jagged region. You can also start your rta with nothing but the ambient room noise and lower the window to start at 10db or so and look at the distribution of the noise. It will be piled up at the low end. If you add calibration or compensation in and out of the equation you can see how it will boost the noise floor. Another thing you can do is start with a very low volume sweep and try a few at much higher levels and take a look at the sub bass freqs and how they change and get more accurate at higher volume levels. Sub 20hz frequencies have a lower snr in most real world measurement instances.


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post #111 of 375 Old 04-14-2011, 12:02 PM
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Lennon is correct. As you drop below about 90dBSPL in single digit territory what you see is noise, not subwoofer.

I just finished repeating the ACO/AUD comparison. I placed the mics at exactly the same position and ran sweeps with Audyssey on and off. The result is the same every time. The AUD mic starts to roll off at approximately 20 Hz and is down approximately -4dB at 10 Hz and -8dB at 5 Hz.

Bosso
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post #112 of 375 Old 04-14-2011, 12:09 PM - Thread Starter
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Quote:
Originally Posted by bossobass View Post

Lennon is correct. As you drop below about 90dBSPL in single digit territory what you see is noise, not subwoofer.

I just finished repeating the ACO/AUD comparison. I placed the mics at exactly the same position and ran sweeps with Audyssey on and off. The result is the same every time. The AUD mic starts to roll off at approximately 20 Hz and is down approximately -4dB at 10 Hz and -8dB at 5 Hz.

Bosso

I disagree, but it depends on your noise floor.

I can take measurements down to 2hz and get readings of 65db. If I add 10db to the sweep level, my measurements will read 75db at 2hz.


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post #113 of 375 Old 04-14-2011, 12:12 PM
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Originally Posted by notnyt View Post

I disagree, but it depends on your noise floor.

I can take measurements down to 2hz and get readings of 65db. If I add 10db to the sweep level, my measurements will read 75db at 2hz.

That's not apparent in your graphs.

Bosso
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post #114 of 375 Old 04-14-2011, 12:14 PM
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Quote:
Originally Posted by bossobass View Post

Lennon is correct. As you drop below about 90dBSPL in single digit territory what you see is noise, not subwoofer.

Bosso


It would be mix of room background noise and speaker. Regardless, my TrueRTA charts start to show noise peaks from the room being added to the the speaker starting around the 95 dB SPL area. Taking an average of the sweeps seems to minimize the "noise effect", but it is still there.

Anyhow, cause and effect is good to know!
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post #115 of 375 Old 04-14-2011, 01:46 PM - Thread Starter
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Quote:
Originally Posted by bossobass View Post

That's not apparent in your graphs.

Bosso

WM61A, 10db increments up from the noise floor.




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post #116 of 375 Old 04-14-2011, 02:02 PM
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Quote:
Originally Posted by notnyt View Post

WM61A, 10db increments up from the noise floor.

Extend it down to 2hz though as in your previous example


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post #117 of 375 Old 04-14-2011, 02:05 PM - Thread Starter
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Quote:
Originally Posted by lennon_68 View Post

Extend it down to 2hz though as in your previous example

I used the WM-61 since it's less stuff to setup, it's only stable to 3hz. The EMM-6 as you can see from my other graphs is consistent to 2hz, but I'm getting tired of putting away and taking back out the mic amps and all the extra cables it takes to set it up

Quote:
Originally Posted by bossobass View Post

As you drop below about 90dBSPL in single digit territory what you see is noise, not subwoofer.

I think this refutes that well enough without going to 2hz


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post #118 of 375 Old 04-14-2011, 02:11 PM
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Quote:
Originally Posted by lennon_68 View Post

Extend it down to 2hz though as in your previous example

Agreed. Although the signal to noise in the measurement system looks exceptional, it's already off 6-7dB at 3 Hz before you hit 90dB.

Still, something is just not right here. The Aud mic rolls off, but not is showing no roll off. There should also be an apparent signal chain roll off around 5 Hz, especially in a room as large as not's. I know there is at least a HP roll off in the MA 5050 at 5 Hz.

Bosso
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post #119 of 375 Old 04-14-2011, 02:13 PM
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Originally Posted by notnyt View Post




I think this refutes that well enough without going to 2hz

Consult any well known acoustician who is familiar with such measurements and tell him that you've refuted the facts of the matter. I'd be interested to hear the reply.

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post #120 of 375 Old 04-14-2011, 02:35 PM - Thread Starter
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Quote:
Originally Posted by bossobass View Post

Consult any well known acoustician who is familiar with such measurements and tell him that you've refuted the facts of the matter. I'd be interested to hear the reply.

Bosso

You said any measurements in single digits below 90db would be all noise. Clearly this is not the case. The lowest sweep which goes down to under 50db is not accurate at 3hz. This could be due to the mic as well as noise floor, since it wasn't completely consistent even at 3hz during my previous measurements, but close. However, compare the levels at 4hz. It ranges from ~64-94db with very minimal deviation.

Quote:
Originally Posted by bossobass View Post

Still, something is just not right here. The Aud mic rolls off, but not is showing no roll off. There should also be an apparent signal chain roll off around 5 Hz, especially in a room as large as not's. I know there is at least a HP roll off in the MA 5050 at 5 Hz.

The graphs I just posted were with EQ. Furthermore, we have different MA-5050s. Apparently the new batch instead of blowing fuses, goes into a protect mode. I don't know what else is changed. I'd rather the old behavior as sometimes it seems to protect too easily, but I only run into this during high level sweep testing. Anyway, you say something isn't right here, but haven't been able to say what it is. I added 30, 20, and 10db to the sweeps to overlay them here. If something "wasn't right" would you expect to be able to do this? Keep in mind the only thing adjusted between runs was the output level in REW. I'm not Chase, there is no motive here to post doctored results or anything. I even bought a calibrated measurement mic to see how far off the other mics were, but all it did was match up with them in the bass ranges.




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