Microphone Distortion Comparison

[Joseph Crowe]

I would like to share my latest blog where I test microphone distortion between four different mics.

Microphone Distortion Comparison

In this blog post I compare distortion performance between four different microphones. From left to right I have the following microphones. Dayton UMM-6 I've used the UMM-6 for about a decade now and it has served me well. It is the only USB microphone in this test. The microphone retails for...

josephcrowe.com

Below are the test results between the four mics.

 

[Blumlein 88]

Could you elaborate about what the test signal is? Many tones by the look of it. It is likely just lack of screen resolution, but maybe a linear scale would spread it out where it is more legible. In some panels it looks like there are some high difference tones well above the grassy noise floor or maybe just poor resolution of the graph. Also were SPL levels the same for each microphone with gain turned up so the DUTs all output the same signal level to the ADC?

 

[sq225917]

Quote from the link.

"I am convinced that loudspeaker distortion is on par with that of upstream components (Amplifiers, DACS, Streamers) since it is very common to hear differences in these devices through loudspeakers."

That's at least two orders of magnitude from being correct as it relates to SOTA amps and dacs. For some individual speaker drivers in test fixtures, particularly HF units, maybe one order of magnitude.

It assumes that distortions rather than other mechanisms account for audible differences in amps and dacs and it apparently does so without discounting the accuracy of heard/ perceived vs blind AB tested and proven audible differences.

 

[DonH56]

You measured ~130% THD+N for all the mics? How was that number calculated? Seems rather high...

 

[Joseph Crowe]

Could you elaborate about what the test signal is? Many tones by the look of it. It is likely just lack of screen resolution, but maybe a linear scale would spread it out where it is more legible. In some panels it looks like there are some high difference tones well above the grassy noise floor or maybe just poor resolution of the graph. Also were SPL levels the same for each microphone with gain turned up so the DUTs all output the same signal level to the ADC?

I did a video explaining this about a year ago.

Quote from the link.

"I am convinced that loudspeaker distortion is on par with that of upstream components (Amplifiers, DACS, Streamers) since it is very common to hear differences in these devices through loudspeakers."

That's at least two orders of magnitude from being correct as it relates to SOTA amps and dacs. For some individual speaker drivers in test fixtures, particularly HF units, maybe one order of magnitude.

It assumes that distortions rather than other mechanisms account for audible differences in amps and dacs and it apparently does so without discounting the accuracy of heard/ perceived vs blind AB tested and proven audible differences.

I mention two ASR amplifier reviews (which are the first two I randomly selected) which are linked in the blog post where IMD is on par with my driver distortion results. "Distortion performance across the frequency spectrum is consistently -80dB. This converts to only 0.01% which is the distortion performance for many amplifiers. An example of this can be found here and here. "
Below are the two randomly selected amplifier IMD results that highlight my point in the blog post. Of course there are better performing products orders of magnitude better. But my point is that ASR has highlighted many products that perform in the range of -80dB on an IMD test.

You measured ~130% THD+N for all the mics? How was that number calculated? Seems rather high...

Please ignore that. It's a software display setting and I'm not sure how to remove it.

 

[Blumlein 88]

Does not answer my questions, but whatever.....

 

[Joseph Crowe]

Does not answer my questions, but whatever.....

I've created hyperlinks on the images to view them in higher resolution. I hope that helps.

 

[sq225917]

So you're measuring a tweeter with a microphone, but including imd products down to 20hz in the distortion calculation? I think that the distribution of signal power might be giving you better numbers than the mic's deserve.

Well done for choosing two shit amplifiers to use against your SOTA microphone. Perhaps benchmark, neurochrome or ncore amps might be more realistic choices.

 

[Joseph Crowe]

So you're measuring a tweeter with a microphone, but including imd products down to 20hz in the distortion calculation? I think that the distribution of signal power might be giving you better numbers than the mic's deserve.

Well done for choosing two shit amplifiers to use against your SOTA microphone. Perhaps benchmark, neurochrome or ncore amps might be more realistic choices.

I describe the area of the graph that is of interest here. I'm not sure about your other comments. I am using N-Core for the amplification. What do you mean "SOTA microphone"?

 

[sq225917]

State of the art

 

[Dave Zan]

...I test microphone distortion between four different mics.

Thanks Joseph, despite some quibbles this does look quite informative.
It would be very helpful to compare an Earthworks measurement microphone, since they are almost a default standard for quality at less expense than a real Bruel & Kjaer or one of the wannabes like the ACO Pacific.

Best wishes
David

 

[AnalogSteph]

My 2 cents:
Dayton UMM-6 and EMM-6 look more alike than different, except that the UMM-6 is, for lack of a better description, one noisy sucker. What was its input gain set at? They must already be using a FET in source follower configuration (think Linkwitz mod) in order to meet the published top level of 135 dB SPL at 1%.
The SM58 has essentially no inherent distortion (what's there might actually be from the mic preamp - what was it?), but obviously its response really tanks up top.
The 7052PH obviously delivers the best results, but at the price it better do!

(BTW, I think I have a mic that's arguably worse than all of them, a Monacor ECM-40. Self-noise in the 40s dB SPL, plenty of second harmonic, and that as an analog mic for XLR. I think it's a really old construction, it's got this 1980s feel to it. My current Sonarworks mic didn't come with as much cal data, but is so much less noisy it's not even funny.)

I might have tossed in a random (cardioid) LDC for fun. From what I can tell, even inexpensive ones tend to have good IMD performance (using a clone of what is apparently a classic Schoeps circuit), while SDCs with their more restricted internal space tend to fail a "key jangling" test more easily - I suppose they are more often than not using a single-ended 2-transistor affair, à la Oktava MK-012. I imagine the Rode NT5 would already be more refined.

It is interesting how you basically can't see any IMD from the tweeter itself. I wouldn't have expected the microphones to give up first. Mind you, there's always the option of increasing the distance, self-noise permitting, but...