Behringer ECM8000 / SMS-1 mic

[Spridle]

I have a Velodyne SMS-1 parametric EQ that comes with a microphone that looks just like the Behringer ECM8000. Is it the same microphone and can I accuratly use the Velodyne microphone with the calibration file for the ECM8000?

For a mic preamp, I ordered the AudioBuddy.

[brucek]

Is it the same microphone and can I accuratly use the Velodyne microphone with the calibration file for the ECM8000?

Yeah, I believe its an ECM8000..........

brucek

[Spridle]

I ran a comparison of 3 microphone setups. It appears that the microphone that comes with the Velodyne SMS-1 is designed to significantly roll off after 1000Hz, so it must be a modified ECM8000. However, since I have yet to have a microphone calibrated, I don’t know which curve is closest to being accurate.

microphone comparison.jpg

RED
Radioshack Digital meter
REW C Weight checked
RADIOSHACK-33-2055_4050.cal (HTS posted correction file)
Laptop 48 Soundcard.cal (specific to my soundcard)

GREEN
Velodyne SMS-1 Microphone
REW C Weight UNchecked
newecm.cal (HTS posted correction file for Behringer ECM8000)
Laptop Soundcard w Audiobuddy.cal (specific to my soundcard with Audiobuddy mic preamp/phantom supply)


BLUE
AudioControl RTA 3050 Microphone
REW C Weight UNchecked
No Microphone Calibration File
Laptop Soundcard w Audiobuddy.cal (specific to my soundcard with Audiobuddy mic preamp/phantom supply)

My guess is that the Blue line for the AudioControl microphone is closest to being accurate. I have created a correction file for the AudioControl microphone that closely matches the SMS-1 response with the newecm.cal file, so the low ends now match.

[brucek]

(specific to my soundcard with Audiobuddy mic preamp/phantom supply

When you use an external microphone preamp, it is wise to include its response weaknesses, (just as you do the soundcard). To accomplish this, create a soundcard calibration file that includes the preamp device within the loopback cable during the calibration process. Then the soundcard cal file will compensate for both the soundcard and the mic preamp to ensure a more accurate measurement.

brucek

[Spridle]

Notice above that the calibration file I used in the green and blue graphs includes the soundcard and the Audiobuddy preamp, whereas the calibration file for the measurement with the RS meter only includes the soundcard.

[brucek]

Ah, Ok, good stuff.

So, why do you feel the AudioControl RTA 3050 Microphone is the accurate one?

I see you're using no calibration for it. Is it a particularily high quality mic that is actually flat from 15Hz to 20Khz?

brucek

[Spridle]

I found the below in an AudioControl Owner's manual for a product that used the same CM-10microphone. I created a calibration file that resembles this plot and I think I'll be +/- 1dB from 20-20K -- good enough for Shack work!

CM-10 FR data.JPG

[brucek]

Great.

I guess you realize the REW mic cal files are negative values when the response of the mic is negative, so the file you should use would look like this.

20 -1.5
100 -0.5
8000 +1.5
20000 -2.0

brucek

[Spridle]

Attached is my .cal file in case anyone wants to give it a try. I just EQed my subs with it and it sounds awesome!

AudioControl CM-10 Microphone.cal

[avaserfi]

For anyone who is still interested I contacted Velodyne a while ago asking them this specific question and was told that the SMS-1 Mic is a rebadged version of the ECM8000. So if I was told the truth they are the same mic.

[Spridle]

avaserfi, I think the operative word is "version" of the ECM8000. It appears that starting at 800Hz, the SMS-1 mic rolls off steadily to about -20db by 20kHz. They must have put a capacitor in there to limit the high end sensitivity since it used only for low freq. measurements. However, below 800Hz, it does appear to measure like the the ECM8000.

I am having my CM-10 mic calibrated and I'll compare it to my SMS-1 mic and post results (may be several weeks from now).