How to test large diaphragm capsules?

[Wouterplop]

Hi All,

I was wondering how capsules are being tested.

For instance u47 original capsule vs copies.
Would that be done with an original u47 and swap capsules?
Would it then be measurement in an Anechoic chamber for instance or just a studio?
How can capsule manufactures keep there consistency when making them.

I see many many u47 copies for instance that there model sound the same as the original but you can choose alot of diferent capsules as options.

What kind of equipment is need to perform such tests.

Googling this question didnt got me anywhere.

hope any experts here could chime in

 

[Bo Deadly]

It takes a pretty fancy rig I'd guess. They also need to check the polar pattern and anything that depends on the capsule like a pad. Presumably they have some kind of reference mic fully enclosed with basket, some sound source and then probably rotate the whole thing while taking measurements.

The biggest problem for DIY measurements is that you can't take the measurements in a room that has any reflections whatsoever. Every room has resonances that will create bumps and dips in the frequency response. But you can still try. You can see the difference between capsules in a regular room as long as it's not too small or too echoey. Just place your mic ~1m from a studio monitor, run through test tones or bursts of noise or impulse chirps or whatever and then do FFT. You might be able to adjust the plots afterward a little such as by using a measurement mic to capture the response of the whole rig and then use that as a control to "subtract" from your equivalent plot with just the mic being different.

But generally trying to measure microphones (and speakers) is quite tricky as you can never really be sure if something is the mic or the room or the speaker or something else. Testing something in the physical world is a lot different than testing an electrical component in the electronic or digital domain.

 

[Khron]

https://groupdiy.com/threads/rode-nt1-kit-the-black-one-mods.77086/

 

[abbey road d enfer]

Hi All,

I was wondering how capsules are being tested.

It really depends on what you want to assess.
The most difficult task is producing specs, like those you see from known mfgrs (Schoeps, Sennheiser; Neumann...). Measurements above about 200Hz can be done with the help of a windowing software, that manages to isolate reflections from direct response. At lower frequencies, the use of an anechoic room or a large open space is mandatory.
Some of the characteristics, particularly directivity, often need post-processing of several measurements. It's highly technical.
If you just want to assess the differences between two capsules, it's doable, but still needs some background to understand the results.
The source (the loudspeaker used for measurement) must obey certain principles. One often has to use two different speakers wit overlapping frequency response (not a multi-way system, and not a bass-reflex).

How can capsule manufactures keep there consistency when making them.

Mfgrs use dedicated systems with specific jigs and measurements test sets. Check NTI, for example.

I see many many u47 copies for instance that there model sound the same as the original but you can choose alot of diferent capsules as options.

U47 has become some kind of generic term for a style of center-terminated capsule, like C12 for edge-terminated.

What kind of equipment is need to perform such tests.

You can use a soundcard with the REW software. They even have a cost-effective reference mic, and the user support is rather good.

Googling this question didnt got me anywhere.

Googling "microphone measurement" gives about a dozen worthy links in the first page.

 

[ZHAOMENG]

In the case of batch production, all the conditions are fixed, such as the design of the back plate, the thickness of the gasket, the only variable is the tension of the diaphragm, so only need to determine the tension of the diaphragm at the time of assembly, can be maximum consistent with the test subject