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:
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: