Measuring microphone differences (somewhat scientifically?)

[cyrano]

Knowles SPU0410LR5H-1 looks promising and available in smaller quantities:

https://www.mouser.com/datasheet/2/218/-748366.pdf
sensitivity -38 dBV/Pa
noise 94 dB (A weighted)

EDIT: unfortunately, the few others I encountered already are obsoleted.

 

[k brown]

Not sure what you guys are after that a Primo EM273 won't do for you.
Very flat, very quiet.

 

[lightningbefore]

Please ignore the method by the seasonal podcast shared. I have no idea how they came up with that.

Place reference mic on axis at 20-40cm away from speaker between tweeter and woofer. Do a sweep sine measurement in REW. Now do the same at exact same position with the mic you are interested in(dut). Sub milimeter accuracy required when it comes to positioning!

Once you get both curves simply in trace arithmetic section divide the dut curve by the reference mic curve. This will get rid of speaker and room anomalities to an extent. Use smooting up to 1/12 for reliable but prettier curves. There is much more to it, but enough for somewhat scientific requirements of your op.

EDIT.
Dont put up both mics at the same time, one will affect the others FR in close proximity. Measure one at a time.

Thanks! Does volume louder/quieter matter that much here? Like quieter possibly to reduce reflections in my sub-optimal bedroom pop setup?

And thank you everyone for all your replies. This is super interesting and not at all what I was expecting.

 

[kingkorg]

MEMS mics?

I've seen some ruler-flat curves on data sheets. Not always easy to get in small quantities tho...

As far as i could tell these DPA mics use MEMS.
https://groupdiy.com/threads/dpa-4099-guts.72483/

 

[kingkorg]

Thanks! Does volume louder/quieter matter that much here? Like quieter possibly to reduce reflections in my sub-optimal bedroom pop setup?

And thank you everyone for all your replies. This is super interesting and not at all what I was expecting.

Nope, loudness doesn't affect the measurement.

 

[Chrisfromthepast]

@kingkorg Have you seen this video?

As far as i could tell these DPA mics use MEMS.
https://groupdiy.com/threads/dpa-4099-guts.72483/

I love 4099’s for spot micing strings, and double bass, but noise, output level and the shape are meant for spot micing. Speaking into them is fine, and there are a ton of mounts, but all are for getting the mic very close to the source.

 

[kingkorg]

@kingkorg Have you seen this video?



I love 4099’s for spot micing strings, and double bass, but noise, output level and the shape are meant for spot micing. Speaking into them is fine, and there are a ton of mounts, but all are for getting the mic very close to the source.

Not that exact one. Definitely mems. But wow, i thought the production was more automated. What fascinated me the most with the one i disassembled is the kind of interference tube that creates the pattern. Of course it's incredible engineering achievement, great for close miking, but low end and noise were quite bad.

 

[ccaudle]

Not sure what you guys are after that a Primo EM273 won't do for you.
Very flat, very quiet.

Agree, that Knowles datasheet shows a very flat response, but suspiciously so, looks to have been heavily smoothed.
And the SNR is 15dB worse than the Primo. Does not seem to have any advantages if you do not need to pick-and-place compatible package and have extreme height restrictions (e.g. inside a phone).

 

[Chrisfromthepast]

Not that exact one. Definitely mems. But wow, i thought the production was more automated. What fascinated me the most with the one i disassembled is the kind of interference tube that creates the pattern.

I got interested in these when a missing windscreen scared one of the engineers into thinking the capsule was missing!.! and it ended up on the service desk.
The video is the production process for the dvote capsule which are at the core of the 4099. Those are back electrets with the preamp circuitry mounted to the backplate, and given directivity by the interference tube.

 

[Bo Deadly]

Knowles SPU0410LR5H-1 looks promising and available in smaller quantities:

If the bandwidth is only 100-10k, the SNR number is going to be higher because noise is over a certain BW. So this is not that great of a part.

 

[Chrisfromthepast]

4099 is an awesome little rider friendly mic system, well regarded and worth the money for a rental house, solo string player, or quartet playing live events.
That, and mems aside, the OP wants to know about measurements.
He could build one. Thats the DIY spirit.
As @kingkorg points out, pretty much any measurement mic will do the trick, given the power of the REW software. Choose one, from earthworks to dbx
The arithmetic function is revealed by clicking the little controls button, top rightish in REW.
- purely helpful intentions, not tryin to fight the folks that have pointed me towards so much helpful information
Chris

 

[lightningbefore]

Not sure what you guys are after that a Primo EM273 won't do for you.
Very flat, very quiet.

Does the prebuilt EM272 get close enough to the 273? Primo Omini module, Mono with 3.5mm plug, 1 m - micbooster.com

I've had a hard time figuring out how to make the 273 work with the components the site is offering.

Or should the Sonarworks measurement mic I already have do a good-enough job?

 

[k brown]

272 has the FET's source pin grounded inside the capsule. 273 brings the source leg out to it's own pad ('2-wire' capsule vs '3-wire').

You can use a 273 same as 272 just by grounding pad #2 (as shown on the spec sheet), then just use the circuit shown for 272.

I would imagine the 272 is sufficient for measurement purposes.

 

[MicUlli]

https://groupdiy.com/threads/primo-em273-with-p48-phantom-power-supply.80309/
is an example for getting the the very best out of EM273 capsules. You have a measurement mic AND a very quiet omni recording mic..

 

[cyrano]

If the bandwidth is only 100-10k, the SNR number is going to be higher because noise is over a certain BW. So this is not that great of a part.

It was suggested for bat mics, since the bandwidth is at least 75 kHz.

 

[lightningbefore]

Thanks y'all, I reached out to Micbooster and will likely start with the 272 for my sake of sanity. They said:

"The EM272 and EM273 are identical in performance and unless you particularly require the high SPL performance of the EM273 then I would suggest you stick with the EM272."

 

[Chrisfromthepast]

Build a reference mic because mics are fun to build. Performance will likely be on par with the sonarworks mic you have.
If you want to start measuring other mics you’ve built, you don’t need to wait.
Start getting familiar with REW and your test setup. Start working with the sweep function to find a reliable position in relationship with the monitor’s woofer, tweeter, and port(s), where the sonarworks mic gets a nice flat reading.
Then, measure all your mics in that exact spot.

 

[Speedskater]

an old Earthworks paper:

How Earthworks Measures Microphones
By Alex Khenkin, Director of Engineering, Earthworks
How to measure microphones and the implications relating to measuring loudspeakers.
http://recordinghacks.com/pdf/earthworks/how-earthworks-measures-mics.pdf
the paper was rescued by 'recordinghacks'. Some of it can be used for DIY measurements.