Distortion in Measurement Microphones - actual measurements

[b_force]

To be honest, the problem with standards is that everyone has their own standards.
AFAIK, Brüel & Kjær spec their capsules at 3% THD, and peak SPL at 10% THD.

Here's what I've gathered so far study on microphone capsules / phantom powered microphones:
In no particular order...

�

Brand​	Model​	Noise Floor​	Maximum SPL based on THD (%)​
​	​	dB​	Not listed​	10%​	3%​	2%​	1%​	0.5%​	0.3%​	0.1%​	0.03%​
Sonarworks​	SoundID Reference(2024)*​	​	124​	​	​	​	​	​	​	​	​
Merry Electronics​	MMA209-003*​	​	​	133​	​	130​	128​	​	120​	110​	94​
Sonarworks​	Xref20/SoundID​	24​	128​	​	​	​	​	​	​	​	​
miniDSP​	Umik-1​	​	​	​	​	​	133​	​	​	​	​
miniDSP​	Umik-2​	20​	125​	​	​	​	​	​	​	​	​
Line Audio​	Omni1​	18​	​	​	​	​	​	133​	​	​	​
iSEMcon​	EMX-7150​	30​	​	​	144​	​	136​	130​	​	​	​
​	CPX-1212​	​	​	​	155​	​	​	​	​	​	​
micW​	M215​	18​	​	​	​	​	135​	​	​	​	​
Earthworks(2022)​	M23​	20​	​	​	​	​	​	​	​	​	​
Earthworks​	M23R​	​	140​	​	​	​	​	​	​	​	​
Earthworks​	M30​	20​	140​	​	​	​	​	​	​	​	​
Earthworks​	M50​	20​	140​	​	​	​	​	​	​	​	​
Audix​	TM1/Plus​	28​	140​	​	​	​	130​	​	​	​	​
ACO Pacific​	7502PH​	18​	​	​	​	​	150​	​	​	​	​
PCB Piezotronics​	376A31​	40​	​	​	165​	​	156​	​	​	​	​
​	376A33​	22​	​	​	​	​	150​	​	​	​	​
​	376A32​	15​	​	​	​	​	137​	​	​	​	​
Dayton Audio​	EMM-6	24​	​	​	​	​	127​	​	​	​
Behringer​	ECM8000​	​	NL​	​	​	​	​	​	​	​	​
NTI Audio​	M2010​	24​	​	​	142​	​	​	​	​	​	​
​	M2215​	25​	​	​	153​	​	​	​	​	​	​

I have some more information for you;

https://www.pcb.com/contentstore/MktgContent/LinkedDocuments/Reports/3P03218condensedreport.pdf

 

[tktran303]

@b_force

Fantastic.

 

[1audio]

I found this interesting item wrt HIGH SPL calibraton of microphones: https://bswa.oss-cn-shanghai.aliyuncs.com/202309/20230912143350179.pdf It does not look too difficult to make if somneone can work through the math. Use a compression driver to drive it.

 

[b_force]

Well here is something interesting.

Since I have some work coming up this week and most of my stuff is STILL in moving boxes, I though you know what, let's just do a fun comparison since I have everything out anyway.

This is all measured at 95±3 mm distance, with a sampling rate or 44.1kHz and a sequence length of 64k (important! )

Mics in this test:

• Dayton EMM6
• Beyerdynamic MM1
• Line Audio Omni 1

Audio Interface: EMU Tracker Pre
Amplifier: LM3886

SPL was later checked and calibrated with the Dayton EMM6 with a B&K 4230 (just because of no particular reason) at a 115dB peak @ 95mm.
Although I will do another proper check again to make sure.
It doesn't really matter, it's about the relative differences! (but nice to have the right numbers there )
Speaker: no idea, some kind of Kenwood cheapo whatever, the rest is still in moving boxes

Don't pay attention to the exact differences at the higher frequencies, except for the distance, the mics were NOT 100% exactly lined up (so above a certain frequency you will see differences)

But hello H2/D2/K2, didn't see you coming.

The effect is much worse at even higher SPL's, will show you after dinner or so

btw; pixel peeping will be punished! ☝️

 

[markbakk]

I guess you refer to the low figures of the Line Audio eh? @ScottG has pointed that out a while ago. Here’s my quick and dirty comparison of the Omni1 and an ECM8000 from a while ago.
Oh I didn’t calibrate SPL here.

 

[1audio]

I wonder how much of the LF distortion is Phantom power circuitry compromises. Phantom power has always struck me as a compromise for convienence. One very difficult to maintain down to very low frequencies.

 

[b_force]

I wonder how much of the LF distortion is Phantom power circuitry compromises. Phantom power has always struck me as a compromise for convienence. One very difficult to maintain down to very low frequencies.

If the circuitry inside the mic itself has proper regulation, this is not a problem at all.

That being said, I also don't understand why we are still working with an ancient old standard that makes very little sense. Al major mic brands have their own power supply solution for this reason.

For phantom power stuff; just get rid of those silly 6k8 resistors, and give a proper regulated power supply and everyone is happy

 

[b_force]

I guess you refer to the low figures of the Line Audio eh?

Well not really, the Beyerdynamic and Line Audio are similar.
Only the H2 of the cheap Dayton mic shoots up like crazy, while H3 stays basically the same between all of them.

I will try STEPS as well, especially with the higher harmonics.
Speaking of which, is swear that ARTA also used to do higher harmonics? 🤔🤔

 

[markbakk]

Nah ARTA only does up to D4. 13 years ago too, just checked.
I’d say the Omni1 is cheap too and it betters the MM1.