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Class 1 Measurement Microphone 1/2", 1/4" vs class 2 calibrated

SIY

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Any opinions on 1/4" microphones from G.R.A.S, PCB and Aco Pacific? I want B&K but that price is brutal, or should I just take a risk and buy used from ebay?
Have you looked at Earthworks? I have a couple of theirs which are excellent. My reference 1/4" mike is from PCB, quite comparable to B&K, but the price (while not cheap) is significantly less brutal.
 

Graph Feppar

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Have you looked at Earthworks? I have a couple of theirs which are excellent. My reference 1/4" mike is from PCB, quite comparable to B&K, but the price (while not cheap) is significantly less brutal.
I have, its just that Earthworks doesnt even list the size of their microphones and they appear to me to be not as professional brand like B&K, PCB or G.R.A.S.

They seem to me to be a middle grade company aimed at studio and live sound measurements while the above brands are general purpose science oriented R&D microphones, which is what I want. I am not even decided if I want 1/4" or 1/8" and I think I will need pressure type microphone so that will reduce my choice to either B&K or G.R.A.S.
 

SIY

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I have, its just that Earthworks doesnt even list the size of their microphones and they appear to me to be not as professional brand like B&K, PCB or G.R.A.S.

They seem to me to be a middle grade company aimed at studio and live sound measurements while the above brands are general purpose science oriented R&D microphones, which is what I want. I am not even decided if I want 1/4" or 1/8" and I think I will need pressure type microphone so that will reduce my choice to either B&K or G.R.A.S.
The M23R and M50 have both been in my lab and both use 1/4" capsules. The big feature of the M23R is the flatness of response, and it lives up to the claims. The M50 will give you more bandwidth.

PCB's 1/4" phantom condenser runs, I believe, about half the cost of B&K and gives up nothing in performance.
 

Graph Feppar

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The M23R and M50 have both been in my lab and both use 1/4" capsules. The big feature of the M23R is the flatness of response, and it lives up to the claims. The M50 will give you more bandwidth.

PCB's 1/4" phantom condenser runs, I believe, about half the cost of B&K and gives up nothing in performance.
Sounds good! What is the difference between 23 and 23R? Is the 30 worth it over 23/R?
 

SIY

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Sounds good! What is the difference between 23 and 23R? Is the 30 worth it over 23/R?
The R version is gain-matched so that you can buy more at a later date and they'll match the original. Frequency response is also trimmed to be flat, so much less need for a calibration file.
 

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BoredErica

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The M23R and M50 have both been in my lab and both use 1/4" capsules. The big feature of the M23R is the flatness of response, and it lives up to the claims. The M50 will give you more bandwidth.

PCB's 1/4" phantom condenser runs, I believe, about half the cost of B&K and gives up nothing in performance.
I have a kindda crazy idea. I'd like a flat microphone with low noise and the m23r fits the bill for voice chats. (Yes, I want to try a flat microphone for voice chat instead of one that make me sound "better".) I also need a measurement mic in a bit for room/speaker calibration. I know UMIK-1 is enough for calibration, but its self noise is significantly higher. So I was thinking about splurging for a m23r and dealing with background noise with Nvidia broadcast. In the future when I get my own house, I want to sound proof the computer room and move the computer outside of the room and use optic fiber cables to transmit data. M23r is not too long and not bulky looking. It has non-objectionable aesthetics imo though the mic stand is a little eh-looking. m23r should be stable for a very, very long time.

However, such a microphone would not be screw in with my standard microphone arm, or have an option for shock mount most likely.

What do you think? Crazy stupid or just might work? Maybe there are flat enough microphones that also are silver/white with options for shock mounts and fits on mic arms which cost the difference between UMIK-1 and m23r. Not sure.
 
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SIY

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I have a kindda crazy idea. I'd like a flat microphone with low noise and the m23r fits the bill for voice chats. (Yes, I want to try a flat microphone for voice chat instead of one that make me sound "better".) I also need a measurement mic in a bit for room/speaker calibration. I know UMIK-1 is enough for calibration, but its self noise is significantly higher. So I was thinking about splurging for a m23r and dealing with background noise with Nvidia broadcast. In the future when I get my own house, I want to sound proof the computer room and move the computer outside of the room and use optic fiber cables to transmit data. M23r is not too long and not bulky looking. It has non-objectionable aesthetics imo though the mic stand is a little eh-looking. m23r should be stable for a very, very long time.

However, such a microphone would not be screw in with my standard microphone arm, or have an option for shock mount most likely.

What do you think? Crazy stupid or just might work? Maybe there are flat enough microphones that also are silver/white with options for shock mounts and fits on mic arms which cost the difference between UMIK-1 and m23r. Not sure.
It does come with a standard mike stand clip… I’ve done some test recordings and it works great for that purpose.
 

Blumlein 88

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I have a kindda crazy idea. I'd like a flat microphone with low noise and the m23r fits the bill for voice chats. (Yes, I want to try a flat microphone for voice chat instead of one that make me sound "better".) I also need a measurement mic in a bit for room/speaker calibration. I know UMIK-1 is enough for calibration, but its self noise is significantly higher. So I was thinking about splurging for a m23r and dealing with background noise with Nvidia broadcast. In the future when I get my own house, I want to sound proof the computer room and move the computer outside of the room and use optic fiber cables to transmit data. M23r is not too long and not bulky looking. It has non-objectionable aesthetics imo though the mic stand is a little eh-looking. m23r should be stable for a very, very long time.

However, such a microphone would not be screw in with my standard microphone arm, or have an option for shock mount most likely.

What do you think? Crazy stupid or just might work? Maybe there are flat enough microphones that also are silver/white with options for shock mounts and fits on mic arms which cost the difference between UMIK-1 and m23r. Not sure.
The Line Audio omni might fit that description. Around $150 or so with shock mount. Comes with a clip for less. Omni's don't need shock mounts as much as cardioids anyway. Pretty darn flat though not so flat as the M23R.

Omni's tend to pick up everything though. It certainly possible to use them this way.

Another option is maybe a 2nd hand Shure KSM32 combined with the Umik 1 or even Line audio omni. These look like side address LDC's, but are actually MDC's. Cardioid pattern. They are heavy so you need a good mic arm. Come with a good shock mount and clip. Pretty flat, but like all cardioids roll off a bit below 100 hz. Have just a tiny treble peak. Often it is complained about that they have no character they just sound like what is put in front of them. Available for in and around $350 used. Advantage here is more suitable for your voice chats, and sometime later you can resale for about $350 making cost of ownership near nothing. They do have a proximity effect which you might want sometimes to move in close and deepen your voice. They have a response just about as shown below.

f_8b98e3d9-f773-435c-9ac0-09ea3b37b291-ENG.png


If SIY has done recordings with the M23R and they are fine, then I'd probably look at that or the Line Audio option.
 

Trell

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I have a kindda crazy idea. I'd like a flat microphone with low noise and the m23r fits the bill for voice chats. (Yes, I want to try a flat microphone for voice chat instead of one that make me sound "better".) I also need a measurement mic in a bit for room/speaker calibration. I know UMIK-1 is enough for calibration, but its self noise is significantly higher. So I was thinking about splurging for a m23r and dealing with background noise with Nvidia broadcast. In the future when I get my own house, I want to sound proof the computer room and move the computer outside of the room and use optic fiber cables to transmit data. M23r is not too long and not bulky looking. It has non-objectionable aesthetics imo though the mic stand is a little eh-looking. m23r should be stable for a very, very long time.

However, such a microphone would not be screw in with my standard microphone arm, or have an option for shock mount most likely.

What do you think? Crazy stupid or just might work? Maybe there are flat enough microphones that also are silver/white with options for shock mounts and fits on mic arms which cost the difference between UMIK-1 and m23r. Not sure.

The SM4-R suspension shock mount from RØDE fits the M23R nicely.

 

ScottG

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..realize this is an older thread, but

My solution: Trying to keep it cheap but high quality.

the *Line Audio OM1 but I'll use the Cross Spectrum "calibrated" UMIK-1 for checking/"calibrating" the OM1 once I get my new test baffle complete.

*(..though I just received the OM1)

WHY the OM1 (instead of just using the UMIK-1)?
1. Dual Channel measurements (or semi-dual channel measurements) - because it is NOT a USB microphone. (and used in conjunction with the UMC204HD which allows a return signal.) This allows for more precise timing/phase measurements AND the ability to effectively remove the amplifier and 204HD noise from the measurement (for non-linear distortion testing).
2. ..also for non-linear distortion testing, the OM1 is much lower in noise and particularly lower in noise at higher spls. This makes a difference for **extreme nearfield distortion testing (where the closer you get to the driver under test, the LOUDER the signal). PLUS if you want to do extreme nearfield non-linear distortion testing at different sp-levels to see how distortion increases it just makes it that much louder for the microphone (adding to distortion).

**you test with the microphone up very close to the driver for lower freq.s to lower the overall influence of the room.


note: I doubt the OM1 really needs a shock mount (at least indoors on a boom), and it will almost certainly interfere a bit with measurements.

The UMIK-1 also does "double duty" as an SPL reference (basically a sound-meter) with its standard calibration at 1 kHz with REW. Only pulling it out of its case for this (and then putting it back in immediately after use), with the rare exception of checking the OM1's calibration over time.

Both will need custom "booms" from carbon tube along with a custom XLR for the OM1 integrated into the "boom" for it, and I've yet to do that either.

That along with my UMC204HD should make for a cheap but hopefully very useful result.

If I needed ***very low noise I'd probably pull-apart a Rode NT1-A, create a rear absorber panel for it along with a more appropriate "case", and then "calibrate" it with the UMIK-1.

***much lower than the OM1, but it's a caridoid and not a small omni - as a result it's not suitable for extreme nearfield testing. What I might use it for though is with a DIY Anechoic room (plus cepstral editing for correcting the low-freq. behavior of the room) and 1 meter non-linear testing at lower freq.s (..but I'm not anywhere near that project yet.)

The Rode mic. would also be good for very low-noise vocal capture.
 
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ScottG

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On the relative frequency response accuracy of the Cross Spectrum calibration file with the UMIK-1 (see bottom of page):


This does of course assume that the M23 as reference is more accurate (..which it probably is).


..and a lot of poor performance with regard to non-linear distortion (..and those thinking the UMIK-2 would be better are going to be disappointed):

 
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Blumlein 88

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On the relative frequency response accuracy of the Cross Spectrum calibration file with the UMIK-1 (see bottom of page):


This does of course assume that the M23 as reference is more accurate (..which it probably is).


..and a lot of poor performance with regard to non-linear distortion (..and those thinking the UMIK-2 would be better are going to be disappointed):

I wonder about these tests. Using them so close in a waveguide I don't know about. I've measured speakers with lower distortion than shown here for a couple of them. Measuring so close to the driver/waveguide makes positioning very, very critical. I'm thinking I wouldn't make any decisions based upon this data.
 

DonH56

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I compared the response of my CSL-calibrated UMIK-1 to my reference Earthworks M30 (which comes with a cal curve) when I measured my system. Mics on same boom stand, same position, capsule as close to the same point as I could manage (guessing ~0.25", and yes it was a PITA). The curves essentially overlaid except for some very HF wiggles and a slight (<1 dB) difference around 5 Hz or so (the UMIK-1 was cal'd to 5 Hz; the Earthworks to 3 Hz, also the lower limit of the spectrum analyzer (*), and REW gave essentially the same result as the spectrum analyzer). And of course over about 24 kHz or so (don't recall when the UMIK-1 rolled off, this was over ten years ago). This was an in-room measurement of my speakers so I was not checking absolute response, just comparing the UMIK-1 to the Earthworks M30.

FWIWFM - Don

(*) Keysight N9030A, with low noise and phase noise/noise figure options, 3 Hz to 67 GHz. I did not measure the mics quite that high.
 
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ScottG

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I can't seem to reply w/ a quote; (probably my old browser)

..but about the measurement condition from MTG.

I found the absolute results of the non-linear distortion to be questionable, but the *comparative results were not.

As for the freq. response measurements:

I typically don't like near(er)-field but 20cm (8") isn't bad, and he has done testing out to almost 3 feet for his other comparison so he should have a good "handle" on if the 20cm was providing reasonably accurate results above 1kHz. So on an absolute basis it looks good to me.


Of course the *comparative results are excellent.

*this assumes that the test setup was exceedingly close to identical for each test, and I'm willing to accept that it was.
 
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1audio

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I just found this discussion. I have been collecting measurement microphones for 40 years, not intentionally at first. I currently have 4 1" ,7 1/2", 2 1/4", and a probe microphone all 200V metal diaphragm types. Most old enough to vote. Some are ready for social security. I have also put together the necessary stuff to properly calibrate them. What i have learned is that they do hold up very well over time.

However chasing high frequency response is basically fraught. There are too many uncontrollable variables to presume the response at 10 KHz or 30 KHz or 70 KHz is accurate to better than +/-1 dB or even +/-2 dB. There are atmospheric effects, diffraction effects etc. that are really hard to control. Changing the mike stand can affect the response. The best solution is a long rod directly behind the mike with no changes in the diameter at the junction.

The primary reference calibration is a free field reciprocity calibration using three microphones and really tedious. Its not used for normal calibration. That uses a pistonphone for sensitivity and an electrostatic actuator for frequency response. Then a number of corrections are applied depending on the application of the microphone.

Early on I discovered that the mike preamps are not necessarily low distortion. In some setups (B&K Measuring amp + preamp) the preamp distortion limits the system. Its challenging to handle the necessary dynamic range from a few millivolts to 10V with an infinite input impedance and enough drive to pass 200 KHz at full level. The B&K setup has a number of separate level controls to make it all more complicated. Keep in mind they were designed primarily for measuring level. Distortion is a secondary feature.

I have a selection of ECM mikes as well. For most applications they are quite adequate. Way cheaper as well. I put this presentation together for Burning Amp some years ago. https://www.linearsystems.com/lsdata/files/Demian Martin Burning Amp Slides 2019.pdf It illustrates some of the challenges in measuring speakers and measurement microphones.
 

Savi

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Hi.
I am in a beginning of a long diy speaker project. I am in no rush and want to learn step by step.
At the moment I have a pair of bliesma t25b and a friend gives me its motu m4 he is no using anymore.
My first plan is to buy a xlr mic and built a measurement turntable and play with rew following vituixcad tutorial.

I am debating between Line Om1 (135€) and beyerdynamic mm1 (165€). Which one will you chose ? Other suggestion ?

Thx
 

ScottG

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The OM1. (..see my posts above.)


The mm1 has higher distortion a fair bit lower in spl - which means it's not a good mic. for nearfield non-linear distortion testing.

122dB (1%THD)

vs. the OM1

133db (.5%THD)

Also, the mm1 (like the behringer and a lot of other small capsule mic.s) is a diffuse-field microphone with a bit of "lift" above 2 khz (and mostly above 6 kHz) that needs to be used on an angle of 60 degrees to get a fairly flat response to 12 kHz or so unless corrected with a calibration file that accounts for that.
 

1audio

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I could not get details on the Line audio mike but the Beyerdynamic may not be what you want. Its calibrated for diffuse field, which is different from free field. Free field means flat response to a source in axis where diffuse field means response to a broad angle, usually with an HF peak to correct for the off axis response.
Something like this may be a better value: https://www.parts-express.com/Dayto...912Hb8_6hCh081pJ4SH23cQRm_BnOmbcaApncEALw_wcB
 
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