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Measurement Mic Shootout (EMM-6, WM-61A, RS 33-2055, Audyssey)

122K views 389 replies 38 participants last post by  Mazza 
#1 ·
I just received my EMM-6 calibrated from Cross Spectrum Labs. This should be used as the reference in this comparison to see how the other microphones measure up.


The following meters and microphones were measured.

Dayton Audio EMM-6 calibrated by Cross-Spectrum Labs from 5hz-25khz

RadioShack Digital-Display Sound-Level Meter 33-2055


RadioShack Analogue Sound-Level Meter 33-2050 (added later)

Linkwitz Modified WM-61A Capsule with amplifier

Audyssey MultEQ Microphone







Dayton EMM-6, calibrated 5-25hz is $75.



RadioShack 33-2055 Digital SPL Meter, $50 new.



RadioShack 33-2050 Analog SPL Meter, no longer sold.



WM-61A Linkwitz modified Microphone Capsules, costs about $10 and an hour to build.





Audyssey MultEQ Microphone, can be found on ebay for under $10.




All measurements were taken as close to the same location as I could manage. The radio shack meter was set to use C weighted compensation. A valid sound card calibration was performed for two configurations. The receiver was also in the loop for this calibration since the PC is hooked up via HDMI. For the EMM-6, I put the mic amplifier (M-Audio Audio Buddy) into the loop as well to make sure the results were accurate. REW was calibrated to the correct level with each microphone so they would overlay nicely. All measurements were taken with the mics facing straight up. Unfortunately, I did not have all of my treatments up and I had furniture all over place since I'm in the middle of repairing water damage from a plumbing leak, so these measurements aren't as smooth as they normally wood be.




This will be the baseline. This measurement was taken with the calibrated EMM-6. The mic and loopback calibrations are displayed in this graph as well. You can view this mic's calibration info
.





This is the EMM-6 vs the first WM-61A capsule microphone. This capsule was mounted in the end of a pen attached to the project box. A 10uF Capacitor was used. This mic is very accurate from 7hz-1200hz






This is the EMM-6 vs the second WM-61A capsule microphone. This capsule was mounted to the side of the project box the microphone was installed in. A 4.7uF capacitor was used. These capsules will do excellent for measuring bass response, but the upper frequency ranges are inconsistent.






This is the EMM-6 vs the Audyssey MultEQ microphone. Many people have this mic and it should do fine for taking measurements without any calibration files. This seems to be the best performer without calibration data, however it is also the most expensive out of the pack if purchased individually. Be careful of the ones on ebay, apparently, there are a lot of fakes. More information on that here , but generally if it has a stereo jack, its a fake.






This is the EMM-6 vs the RS meter. No calibration data was used for this, only C weighting. It gives excellent readings from 7hz-200hz and should provide accurate measurement data for measuring subwoofers. Above that range, it is not very consistent.





This is all four microphones plotted together. There is quite the variation in the upper frequency ranges.





Any of these will make an excellent mic for measuring subwoofer response. This is all of the mics from 5-100hz without smoothing.






I have included the measurements and calibration files here if anyone wishes to look at the data closer.



UPDATE: I have performed some close mic sweeps showing 5-90hz with these mics.





This is the calibrated EMM-6. You can see the loopback calibration for the soundcard and the mic amp, as well as the mic's cal here.





Here is one for the Audyssey mic. No calibration is used other than the loopback calibration for the soundcard.





Here is the RadioShack 33-2055 Digital SPL meter. C Weighted correction was applied, as well as the loopback soundcard calibration.





This is an RS33-2050(old analog RS meter) compared to the EMM-6. I graphed the RS meter without correction, with C weighting, and with the calibration from the HTS page. C calibration wasn't enough as expected with the older meter, and the HTS calibration was too much. The reading was affected by the noise floor right after 9hz, so it wasn't included in the graph.




Here is the WM-61A, (2) RS 33-2055, RS 33-2050, calibrated EMM-6, and Audyssey mic overlaid.




UPDATE 2:


I received LTD02's RS 33-2055 in the mail today. I just finished running sweeps and the results are interesting.


I found that with close-mic measurements, it measures closer to the rest of the mics, but in room, it reads a couple of db lower at the same frequency.


It's also way off in the upper frequency ranges. MKtheater's RS meter measured very close to mine, however LTD02's seems to measure differently. I even used a fresh battery in it to rule that out.


Here is from 200-20000hz, LTD02's RS meter is colored red here, and you can see how far off it is from the rest of the mics.




This is 7-100hz from the same sweeps. His meter says pretty close until about 15hz where it drops off by 2db. At 10hz it is sitll only 2db off, but at 7hz it is 5db low.




I measured the same range close mic, and then things got slightly interesting. His mic was still reading low, but not as far off.


This is 0-200hz close mic with 3 RS 33-2055 meters and an EMM-6. LTD02's is in gold.





I took some fresh close mics as well to verify the results, here is 0-100hz with my RS 33-2055, EMM-6, and LTD02's RS 33-2055. You can still see it start to go off 1-2db at 15hz, but it doesn't seem to deviate further below 10hz.




I applied the correction file from the HTS to this mic, and it seemed to bring it in line to 9hz, but then overcompensated below that. Here is a graph showing the differences.





I disassembled the meter, and the only thing I noticed different was the markings on the chip. The mic capsule was also labeled WD.


Mine was LM324 / TG 0701, LTD02's was YD325 JC.1.Z


UPADTE3:


The WM-61A has been calibrated, and it has been confirmed flat to 5hz.


WM-61A without calibration:




WM-61A with calibration:

 
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#5 ·
Thanks for the effort...Were you defeating the calibration file for the EMM6 when measuring with the other mics? You should expand the scale even more to something like 65-110db. It looks very close for the most part but there are a few differences of what looks like almost 7db but the 10db scale makes it hard to judge.
 
#7 ·
One thing to try is to measure with one mic, remove it, put it back in the same spot and measure again. This will show some idea of how much error is involved regarding placement.
 
#9 ·
Much better - they are a lot easier to read now.
 
#10 ·
Couple Qs re: the Audyssey Mic, I assume this is just the standard mic that comes with Audyssey Multi XT equipped AVRs? Also, do you simply hook it up to a phantom power device with some sort of 3.5mm to RCA or 1/4" jack adaptor?
 
#11 ·
The differences between the 2 wm61 mice could easily be accounted for by the housing around them. The one flush mounted into a box will likely have a lot of reflected energy finding its way into the mic. I would prefer the one constructed more like a normal mic with a thin pen or pipe containing the capsule. Either would be fine for low bass really. Small changes in orientation and placement could account for some of it along with production variance.


What I find most interesting is how the rs meter performed with just c weighting. General belief being that it will be much further off. I wonder if these calibration files suggesting 20 or 30db of correction is needed in the low bass were based off of running the meter A weighted? Others still show a huge difference with the rs meter. I think more investigation is in order preferably by someone else with a calibrated mic and also a ratshack. Maybe the rs used here is the magic rs.
 
#12 ·

Quote:
Originally Posted by Ricci /forum/post/20292547



What I find most interesting is how the rs meter performed with just c weighting. General belief being that it will be much further off. I wonder if these calibration files suggesting 20 or 30db of correction is needed in the low bass were based off of running the meter A weighted? Others still show a huge difference with the rs meter. I think more investigation is in order preferably by someone else with a calibrated mic and also a ratshack. Maybe the rs used here is the magic rs.

From Ilkka's "TrueRTA for dummies" thread from 2005:

Quote:
I have now measured it against my analog RS meter. As I have said, the RCA output jack is weighted (C or A). But as Ethan showed, it appears that the output of the RCA jack of the digital RS meter is unweighted when set to C-weighting, when set to A, it's A-weighted. When set to C, it has a flat FR atleast down to 20 Hz.
Quote:
Digital:

Do not use any correction files when measuring with TrueRTA or similar. The output of the RCA jack is unweighted when set to C-weighting. When measuring manually, add corrections shown above to the readings.

It may depend on the meter, but this seems to be the only logical answer in this case.


Bosso
 
#13 ·

Quote:
Originally Posted by pbc /forum/post/20292267


Couple Qs re: the Audyssey Mic, I assume this is just the standard mic that comes with Audyssey Multi XT equipped AVRs? Also, do you simply hook it up to a phantom power device with some sort of 3.5mm to RCA or 1/4" jack adaptor?

No phantom power, just straight to mic in on my htpc.

Quote:
Originally Posted by bossobass /forum/post/20292750


\\It may depend on the meter, but this seems to be the only logical answer in this case.


Bosso

J Palmer Cass measured just the electronics output of the RS Meter and it definitely requires correction for a C weighted output curve. This matches up with my results as well.

http://www.avsforum.com/avs-vb/showt...0#post20226160
 
#14 ·

Quote:
Originally Posted by notnyt /forum/post/20292831


J Palmer Cass measured just the electronics output of the RS Meter and it definitely requires correction for a C weighted output curve. This matches up with my results as well.

http://www.avsforum.com/avs-vb/showt...0#post20226160

I'm always confused by these comparisons and discussions of RS meter-as-mic.


So, you applied a standard C-Weight correction file for the measurement, but Ethan and Ilk say not to when using the digital meter?


Were Ethan and Ilk on crack when they wrote those help guides, or is there a weighted/unweighted craps shoot when using the out jack of a digital meter from meter to meter?


And, then I assume that what Josh brought up is that there are correction files that add considerably to the C-Weight correction?


I wish someone would update a guide for those who use the RS Meters to measure because the recent close mic and maybe most of the LP graphs are probably grossly distorted, which just muddies the waters of getting a clearer picture of what subs do in rooms vs their respective models.


Bosso
 
#15 ·

Quote:
Originally Posted by Ricci /forum/post/20292547


What I find most interesting is how the rs meter performed with just c weighting. General belief being that it will be much further off. I wonder if these calibration files suggesting 20 or 30db of correction is needed in the low bass were based off of running the meter A weighted? Others still show a huge difference with the rs meter. I think more investigation is in order preferably by someone else with a calibrated mic and also a ratshack. Maybe the rs used here is the magic rs.

You may have missed it but I did a very similar exercise and posted the results in notnyt's other thread a couple weeks ago:
http://www.avsforum.com/avs-vb/showt...0#post20221950


The .cal file was spot-on for my Rat. Shack meter as compared to my calibrated ECM8000 on the low end. Also my Audyssey mic was right on as well which I was quite surprised by - just running it to the 1/8" mic jack on my PC. There were much wider variances on the high end though - as expected...
 
#16 ·

Quote:
Originally Posted by lennon_68 /forum/post/20293057


You may have missed it but I did a very similar exercise and posted the results in notnyt's other thread a couple weeks ago:
http://www.avsforum.com/avs-vb/showt...0#post20221950


The .cal file was spot-on for my Rat. Shack meter as compared to my calibrated ECM8000 on the low end. Also my Audyssey mic was right on as well which I was quite surprised by - just running it to the 1/8" mic jack on my PC. There were much wider variances on the high end though - as expected...

There must be different mic capsules being used in the RS meters of the same version. Can you confirm you have a 33-2055, the newer digital meter?

Quote:
Originally Posted by bossobass /forum/post/20292979


I'm always confused by these comparisons and discussions of RS meter-as-mic.


So, you applied a standard C-Weight correction file for the measurement, but Ethan and Ilk say not to when using the digital meter?

Yes, the RS meter was measured with standard c-weighting correction applied.

Quote:
Originally Posted by bossobass /forum/post/20292979


Were Ethan and Ilk on crack when they wrote those help guides, or is there a weighted/unweighted craps shoot when using the out jack of a digital meter from meter to meter?

I've never heard of an RS meter not needing some type of correction until you just mentioned that.

Quote:
Originally Posted by bossobass /forum/post/20292979


And, then I assume that what Josh brought up is that there are correction files that add considerably to the C-Weight correction?

There are a LOT of different correction files for the RS meter. All are at least C weighting, and some are grossly exaggerated compared to what I measured. I don't think they are using different electronics, but it's possible they are using a different mic capsule.

Quote:
Originally Posted by bossobass /forum/post/20292979


I wish someone would update a guide for those who use the RS Meters to measure because the recent close mic and maybe most of the LP graphs are probably grossly distorted, which just muddies the waters of getting a clearer picture of what subs do in rooms vs their respective models.


Bosso

That's half the reason I started this thread and purchased an EMM-6. I noticed my Audyssey, WM-61A, and RS mics all lined up very close.


If anyone feels like sending me some RS meters that they feel need a compensation other than the standard C weighted curve, I'd be happy to measure them and/or disassembled to look for differences.


If you look at the SPL Meter correction table post, you can see how varied all of the calibration files are. It's crazy.

http://www.avsforum.com/avs-vb/showthread.php?t=505236


From the HTS/REW download page. This adds even more compensation than C weighting by a large amount.

http://www.hometheatershack.com/foru...oads-page.html

Quote:
10.0 -22.09

11.2 -19.25

12.5 -16.83

14.0 -14.69

16.0 -12.66

18.0 -10.61

20.0 -9.05

22.4 -7.64

25.0 -6.49

28.0 -5.33

31.5 -4.41

35.5 -3.61

40.0 -2.99

45.0 -2.41

50.0 -1.97

56.0 -1.64

63.0 -1.34

71.0 -1.14

80.0 -0.96
 
#20 ·

Quote:
If anyone feels like sending me some RS meters that they feel need a compensation other than the standard C weighted curve, I'd be happy to measure them and/or disassembled to look for differences.

PM me your info and I can send you my RS meter. I do not need it for about a month (I hope).
 
#21 ·
Notnyt, tell me what to use. I can use my RS meter or I can buy the Calibrated Dayton. Does the Dayton just plug into the computer like the RS meter? My digital meter is about 1 year old.
 
#23 ·

Quote:
Originally Posted by MKtheater /forum/post/20293266


Notnyt, tell me what to use. I can use my RS meter or I can buy the Calibrated Dayton. Does the Dayton just plug into the computer like the RS meter? My digital meter is about 1 year old.

I'd say try the RS meter with just C weighting. If you have an audyssey mic handy, they should line up fairly well below 200hz. If they do, then you know you have an accurate RS meter.


The EMM-6/ECM8000 mics do not just plug into a computer. You need to purchase a mic amp ($50), xlr male to female cable to hook up to the mic amp, and then whatever cable/adapters to hook the mic amp to the PC.


I used the M-Audio Audio Buddy. It has a TRS output, so I used a 3.5mm male to male cable and an adapter to connect it to the PC.
 
#25 ·

Quote:
Originally Posted by penngray /forum/post/20293263


PM me your info and I can send you my RS meter. I do not need it for about a month (I hope).

I'm going to disassemble mine first and post pictures. This way others can do the same to compare and we can see if there are any obvious differences first. If nothing stands out, I'll shoot my info over so I can measure them side by side.
 
#26 ·

Quote:
Originally Posted by penngray /forum/post/20293275


MK, the Dayton (EMM-6) requires phantom power so a USB sound card like the M-audio mobile Pre is required.

I would hate to spend $200 on something if the RS meter with or without cal file comes very close. I just don't know which to use. With cal files(digital meter) I am flat, with c-weighted only I am sloping like a sealed sub or down 12 db's at 10hz from 20hz. My room gain should take care of that so I am assuming mine works with the cal file. We all know what assume means though.
I could always send my meter to notnyt to find out which one it is. I will do that today if he wishes.
 
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