A source for used NTI M2010 Class 1 measurement microphones.

[Speaker_tweaker]

Toronto Surplus & Scientific has a large inventory (245pcs) of used NTI M2010 microphones for sale, with the current exchange rate they are $255 USD + shipping on eBay. This microphone is currently $1395 direct from NTI. I have no affiliation with Toronto Surplus, I just thought other speaker hobbyists might want to know about this.

In my mind this mic has two desirable features:

1. It has an ACO Pacific 7052 cartridge with metal diaphragm, flat response and excellent stability.
2. It's 48V phantom powered with an XLR input jack, so it can be connected to a standard USB audio interface (I confirmed this with NTI)

See data sheet here: https://www.nti-audio.com/Portals/0/data/en/M2010-M2015-Measurement-Microphone-Product-Data.pdf

For calibration I see a few options:

1. NTI has the original FR compensation on file and will supposedly send it via email ([email protected]) on request. I talked to an NTI rep and he said the compensation is likely good even after many years as long as the mic hasn't been "knocked around."
2. Get a fancy calibration from Scantek for $175. This sounds like a lot, but the total cost of the mic + calibration would still be less than a new Earthworks M23.
3. Get a cheap $60 calibration from Cross Spectrum. Ironically, their reference mic is also an ACO Pacific 7052, which they have calibrated at Scantek.

The NTI rep suggested getting photos of the microphone diaphragm from the seller to make sure there are no punctures or distortions in the film. He said dust can be removed with care and only affects sensitivity, not response.

I've decided to take the plunge and ordered two of these. I requested pictures of the diaphragms and Toronto Scientific obliged, see below. I ordered over the phone, they matched their slightly lower ebay price and unlike ebay there was no sales tax. I've also requested the original calibration data from NTI, we'll see if they actually deliver.

If I'm able to get the calibration data from NTI I will compare the mics to each other, see how well they match, and report back later. If I am unable to get the data from NTI or the mics don't match, I will get one calibrated at Scantek.

The eBay listing is here: https://www.ebay.com/itm/233473735821
The product page on the seller's website is here: https://www.torontosurplus.com/nti-audio-m2010-1-2-professional-measurement-microphone.html

This seems like a good deal to me. Let me know if you agree, have other thoughts, etc. (or if you disagree and I'm an idiot that's cool too)

 

[Speaker_tweaker]

Ok, so no one seems to care about this, but that's ok. I'll just keep posting, maybe it will help someone, someday?

NTI emailed me the frequency response correction files for both microphones this morning, free of charge. After I ordered the mics I learned their policy is to charge $100 for each file, but no one asked for money. YMMV.

I plotted the data for both mics, see below. Mic #1928 is +/- 0.5 dB from 20Hz to 17.2kHz, and Mic #3341 is +/- 0.5 dB from 20Hz to 15.4kHz. #1928 is obviously quite nice, so I'm happy about that. Again, when I actually get the mics I will check them against each other and see if they match after compensation. Regardless of the results, I may still send #1928 to Scantek for recalibration.

The calibration files also contain the dates of calibration, which are 2008 and 2010. These dates are probably the same as the manufacturing date.

 

[jhenderson0107]

Speaker Tweaker -

Thanks for this information. I've ordered some mics based on your experiences.

 

[Speaker_tweaker]

Speaker Tweaker -

Thanks for this information. I've ordered some mics based on your experiences.

You're welcome. I hope it works out!

 

[jhenderson0107]

Mics arrived and seem to work well. Here's the calibration data from NTI:

 

[Speaker_tweaker]

Mics arrived and seem to work well. Here's the calibration data from NTI:

Nice. I have received mine but have yet to do any testing.

 

[rynberg]

Wow, thanks for this, but the only listing on ebay I can find says they have sold 8 and only have 6 available. Is there another source (I don't see your quantity of 245, although I realize it's been 3 weeks)?

 

[Speaker_tweaker]

Wow, thanks for this, but the only listing on ebay I can find says they have sold 8 and only have 6 available. Is there another source (I don't see your quantity of 245, although I realize it's been 3 weeks)?

Here:

NTI Audio M2010 1/2" Professional Measurement Microphone

<p><strong>Manufacturers Specifications:</strong><br /> <br /> M2010 Measurement Microphone<br /> <br /> The M2010 are compact and accurate measurement microphones for acoustics, R&D and production. They are particularly suited for applications with

www.torontosurplus.com

Again, if you are in the US and you order over the phone they will match the ebay price and there is no sales tax.

 

[rynberg]

Thank you!

 

[jhenderson0107]

These inexpensive microphone clips hold the NTI M2010 well.

 

[robwpdx]

I looked but could not find information on using these for music. Have people tried these for that?

One would guess you could get a thinner nickel diaphragm, maybe .7 microns rather than 3-4 for mylar, better long term moisture & temperature stability, no electret deterioration, and greater diaphragm tension.

You do see a few high end and high voltage nickel diaphragm recording microphones. And presumably they are more expensive to manufacture and made in lower volume.

 

[robwpdx]

Has anyone used these for music or field sound?

Who is the original manufacturer? My understandimg is that metal diaphragm condenser makers are scarce.

 

[Blumlein 88]

Has anyone used these for music or field sound?

Who is the original manufacturer? My understandimg is that metal diaphragm condenser makers are scarce.

Somebody probably has. These type microphones often have high self noise that can make them problematic for field sound or music recording. They don't list that spec further making me think they have high self noise. Neumann and Earthworks among some others make similar microphones. They too have higher self noise, but they've managed to keep it okay for music recording and have very flat response.

 

[mikessi]

You nabbed a fantastic deal! I used a 1" ACO Pacific mic capsule + preamp (which the capsule screws into) + dedicated 200V power supply for extremely low noise measurements for 10+ years. The self noise was literally inaudible under almost any conditions (something like 5 dBA) -- even at max gain with super accurate headphones -- and the FR was ruler flat from 2 to 20kHz. I sold it last year because it seemed like overkill to use a $2000 mic system for a hobby, but I kind of regret it.

I expect the 1/2" capsule + 48V PSU isn't nearly as quiet, so you'll be somewhat limited to the level of distortion you can measure, but I'd be interested to know your experience with them. I'm tempted to nab one myself, as there appear to 199 units available still at Toronto Surplus & Scientific. USD275 now. Hmmmm.... Speaker_tweaker, pls lmk how they're working for you!

PS -- there's nothing in any of the docs at either NTI or Toronto Surplus & Scientific about the origin of the capsule. How did you find out it's an ACO 1/2"?

 

[No. 5]

PS -- there's nothing in any of the docs at either NTI or Toronto Surplus & Scientific about the origin of the capsule. How did you find out it's an ACO 1/2"?

It's printed on the underside of the capsule, if you unscrew it from the body, the ACO model number is there with a serial number.

 

[mikessi]

So is anyone using one of these NTI mics from Toronto Surplus for measuring Speakers or...? Can you please report how it's working out for you?

 

[jhenderson0107]

I use them concurrently via an RME AVB Tool to accelerate automated speaker testing. They work well are small, light and reliable.

 

[AwesomeSauce2015]

Anyone else here using these mics from this source who can comment on it?
Thinking about grabbing one to finally have a properly calibrated measurement setup, but it's still a fair bit of money so...

 

[mikessi]

One would guess you could get a thinner nickel diaphragm, maybe .7 microns rather than 3-4 for mylar, better long term moisture & temperature stability, no electret deterioration, and greater diaphragm tension.... Has anyone used these for music or field sound?

The ACO 7052 capsules in these NTI mics have a titanium diaphragm. Extremely thin & light. The 1" version I had could pick up incredible detail across the entire spectrum. I used them as low noise measurement tools but also made some music instruments. With a wind/pop filter, it was top notch.