The most common microphones I use on corporate events are Shure wireless SM58, WL185 Lavalier, and wired MX418. I created three EQ snapshots using a mic compare measurement in Smaart for a more transparent starting point.
What is a mic compare measurement?
In the same way that we use the transfer function measurement in Smaart to observe changes to our mix as it passes through speakers and the air, we can also observe changes to the source as it passes through microphones.
To do this, first position the mics so that their capsules are as close as possible to each other. It’s often easiest to place them on-axis with each other with the source at 90º.
Connect the monitor output of your mix console to an input of your audio interface. Create a new transfer function measurement pair using the console’s monitor output as the measurement signal and your measurement mic as the reference signal.
Start the measurement and signal generator in Smaart.
On the mix console, hit solo on the mic channel that you want to measure (sending it to the monitor buss), flatten the EQ, and turn up the monitor output until the measurement trace in Smaart centers around 0dB. For better data on global trends, create an average from several mics like I did.
Creating the snapshot
Adjust the channel EQ to your satisfaction.
Keep in mind that many (most?) microphones include purpose built non-linearities like helpful EQ enhancements. Think every kick mic you’ve ever used.
Here’s an RE320 I measured. I chose to make no EQ changes because I listened to it in headphones and the room and it sounded great.
Shure SM58
Here’s the pre and post EQ measurement for the SM58.
Here’s the manufacturer’s specification.
Here’s the EQ I came up for a more transparent response.
And here’s the EQ I settled on after listening on a show. You can download all of the snapshots here.
Shure 185
Here’s the pre and post EQ measurement for the 185 capsule.
I couldn’t find the manufacturer’s specification. If you have it, let me know.
Here’s the EQ I came up for a more transparent response.
And here’s the EQ I settled on after listing on a show. You can download all of the snapshots for X/M32 here.
Shure MX412
Here’s the pre and post EQ measurement for the MX412.
I couldn’t find the manufacturer’s specification. If you have it, let me know.
Here’s the EQ I came up for a more transparent response.
And here’s the EQ I settled on after listing on a show. You can download all of the snapshots here.
Have you tried a mic compare measurement? What were your results?
Smaart® and the Smaart logo are registered trademarks of Rational Acoustics LLC and are not affiliated with Nathan Lively or Sound Design Live.
I always find SM58 too boomy at 168 – 170 Hz… strange, since it doesn’t show here.
Also why would You shelf off all the high freq? For me it’s still muddy even left flat.
And what if someone speaks low or off axis which is quite common.
cheers 😉
The boomy-ness may be a combination of precedence effect, body resonance, speaker to speaker summation, speaker to room summation, or any number of acoustic phenomenon that are not related to the actual frequency response of the mic. That’s why this is a starting point that simply attempts to remove any manufacturer non-linearities.
Hi Nathan. Re the measurement of mics at 90 Deg to the sound source.
Aren’t you measuring the off axis response of a cardiod mic against an omni directional mic? Is that really relevent?
I can see it being useful if both mics are omni. Or if you are measuring the off axis or feedback rejection of the cardiod mic. But not an frequency comparison
Not that I’m an expert. I just cant see it working.
J
You are totally right Jim. Arthur Skudra schooled me on this in the FB comments for the post:
“I do this very often with my systems with great success. A few pointers:
1. Measure both mics on axis or their normal position, not the 90 degrees off axis as shown. Yes, there will be a slight time difference, and more opportunity for reflections to affect the TF, but watch your phase curve and get it as “flat” as possible to get your delay time between the two perfectly matched, and watch your coherence curve. The reason for this becomes glaringly obvious with cheaper mics….their off axis frequency response is different than on axis. So unless you’re measuring a $$$$ schoeps or neumann that is consistent in frequency response on or off axis, do your mic compare on its intended pickup axis. Even omni measurement mics have a bit of directionality that you cannot avoid! Cheap measurement mics even more so!!
2. Measure the mic in situ. If it is a podium mic, have it positioned exactly where it will be in relation to the podium surface, and move your measurement (reference) mic right beside it. If the person speaking at the mic will be wearing a hat, then wear the hat! If it’s a lavalier, then wear the lavalier where it will be positioned on the person. This will catch any reflections/cancellations that you need to be wary of when you apply whatever corrective EQ you’re applying.
3. Use maybe 2-3 filters to correct the response of the mic, then leave well enough alone. Don’t go crazy at the extreme ends of the response curve. If the mic rolls off at the high or low frequencies, don’t try to correct for that. Also the HF bump on most vocal mics can be a help to you for clarity and intelligibility, so be conservative on the cut, no point boosting those frequencies further down the signal chain because you cut too much! Less is more.
4. Use a broadband sound source with pink noise. I usually use my NTi Talkbox, which has a mirror smooth flat response 100-10,000 Hz, but really any decent speaker/studio monitor will do the job just fine.
EDIT:
5. Then I get the spectrograph happening with the mic being adjusted (post EQ), and do any final tweaks or adjustments to the mic for a smooth and consistent response with the person’s voice. This is especially helpful when eq’ing lavalier microphones, you can easily pick up the resonances of the person’s voice/chest. On podium mics, you can watch what happens when you change the position of the mic in relation to the podium surface itself…very educational on how reflections affect the tonal nature of podium mics.”