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Author Topic: Gefell M296 Question  (Read 25134 times)

Schallfeldnebel

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Re: Gefell M296 Question
« Reply #60 on: April 16, 2007, 05:21:04 am »

I agree with Kelly Kay, if phase-shift is going very gradually it is less problematic for the human ear. The phase shift at 14K is very gradually with the MK221, and it has no effect on the frequency curve, but what bothers me, and what is never published, at the outer end from all of these 50mV type half inch measuring microphones, around 26K, the frequency response is very turbulent and bumpy. And here the phase shift is not gradual anymore. Even when outside the audioband, this behaviour causes audible effects, depending on the sort of music. Organ mixtures are a disaster!

Erik Sikkema
Schallfeldwebel
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Marik

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Re: Gefell M296 Question
« Reply #61 on: April 19, 2007, 10:37:58 pm »

Yesterday I received a pair of Gefell MK202 and today had a chance to compare them to my B&K 4133 on my piano at home.

Although some claim those two are very similar capsule, there is not a little difference in their sound. For now I won't speculate whether it is different voicing, protective grill influence, or difference in diaphragm material, but the 4133 had a "harder" sound and not nearly as rich. The Gefell was much more rounded and sweet.
Both have roughly equal output.

Although I did not try it yet for a serious studio job, my preliminary feeling is that Gefells will get more use than 4133. I am still concerned with their S/N for some applications. For that reason, most likely I will also need to order a pair of MK221 and see for myself what's up with those.
For my applications (classical music, mostly piano) whenever I can use omni, anything bigger than 1/2" is no good.

Best, Mark
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Mark Fouxman
Samar Audio & Microphone Design
www.samaraudiodesign.com

davebl

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Re: Gefell M296 Question
« Reply #62 on: April 20, 2007, 03:34:34 am »

Quote <I am still concerned with their S/N for some applications >

Do you think it is the preamp or the capsule that is noisy ?

Dave Blackham
UK
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Marik

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Re: Gefell M296 Question
« Reply #63 on: April 20, 2007, 02:46:27 pm »

davebl wrote on Fri, 20 April 2007 08:34

Quote <I am still concerned with their S/N for some applications >

Do you think it is the preamp or the capsule that is noisy ?

Dave Blackham
UK


Definitely capsule. I know it for sure.

Best, M
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Mark Fouxman
Samar Audio & Microphone Design
www.samaraudiodesign.com

Schallfeldnebel

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Re: Gefell M296 Question
« Reply #64 on: April 20, 2007, 05:53:51 pm »

Mark is right, the noise comes from the capsules. You can look up the specs here:  http://www.bksv.com

Erik Sikkema

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Marik

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Re: Gefell M296 Question
« Reply #65 on: April 20, 2007, 06:26:35 pm »

In fact, the lower S/N is not the only problem, as the noise of the capsule itself (i.e. the noise of the air trapped at the backchamber, aka Johnson noise) is pretty high, as well.

I have a special transformerless custom made microphones, which with special adapters accept a wide range of capsule types--M70/M94 etc., CK61/62 ULS, and B&K/Gefell 1/2" capsules, and others.
There is a special dedicated PSU to switch capsule bias from 30V up to 200V to match voltage with specific capsule.

Whenever I switch from MK202/4133 to say CK62 the "idle" noise drastically drops.

I "discovered" the output without protective grill is about 2db higher. I'd think, this together with use of EQ balls can bring the noise to a very usable figure.

In a few weeks I have a few serious piano sessions and will be able to be more specific.

Best, Mark
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Mark Fouxman
Samar Audio & Microphone Design
www.samaraudiodesign.com

Schallfeldnebel

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Re: Gefell M296 Question
« Reply #66 on: April 20, 2007, 07:07:58 pm »

Mark,

that is correct, the AKG CK62 has about a 10 dB lower noise level referred to 1 Pa than the B&K 4133 and Gefell MK202.

But, the B&K and Gefell have a much lower (not specified) lower mechanical harmonic distortion. Measuring capsules often run on a much higher polarization voltage allowing for larger distances between backplate and membrane, and also much less smaller backplates than the actual width of the membrane, all to lower harmonic distortion from the capsule itself.

B&K could easily get values like the CK62, or even better with the 4133, by making the backplate and membrane closer together, but then the distortion esp. in the low end will be much higher. One microphone where the backplate and membrane are extremely close, is the Neumann TL(M)50 omni, and as an effect of that it produces a warm ( = louder) lowend, and often problems in humid envirements (nickel capsule).

Erik Sikkema
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Bill Mueller:"Only very recently, has the availability of cheap consumer based gear popularized the concept of a rank amateur as an audio engineer. Unfortunately, this has also degraded the reputation of the audio engineer to the lowest level in its history. A sad thing indeed for those of us professionals."

Marik

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Re: Gefell M296 Question
« Reply #67 on: April 21, 2007, 01:27:37 pm »

Schallfeldwebel wrote on Sat, 21 April 2007 00:07


But, the B&K and Gefell have a much lower (not specified) lower mechanical harmonic distortion.


Absolutely!

The interesting thing, it especially noticable with distant miking (classical recording) where with CK62 for example, all the picture sounds like a mess. You practically cannot distinguish direct sound from room reverberation content.
On the other hand, Gefell/B&K keep things tight, clear, with high degree of intelligibility.

Best, Mark
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Mark Fouxman
Samar Audio & Microphone Design
www.samaraudiodesign.com
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