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Author Topic: Gefell M296 Question  (Read 27152 times)

mr.gefell

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Re: Battery powering the TLM50
« Reply #45 on: April 07, 2007, 03:01:55 pm »


the m102.1 is newer version of the old mk102. the original mk102 was manfactured from the late 50's early 60's to the 1990's. When the wall went down manufacturing was improved. I had  a pair of mk102's that i wanted to buy from german ebayer ,both from the 60's and they went in for a check at the factory, and the optical engineer concluded they needed new diaphrams. So beware of "vintage" mk102'


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Mujtaba Hussain,Oslo Norway

Schallfeldnebel

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Re: Gefell M296 Question
« Reply #46 on: April 07, 2007, 05:07:03 pm »

Do not compare a 296 with a 221. The 221 is far more omni up on to high frequencies, and gives an improved stereo-image. The 296 will pull the stereo-image much more aside because of it's higher directivity and little peak.

In the above mentioned "amen" soundsample, in my personal opinion the recording is too much in favour to the choire, even when only recorded with two microphones this can happen. I cannot follow everything in the orchestra that clear.  

Erik Sikkema
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d_fuchs

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Re: Gefell M296 Question
« Reply #47 on: April 07, 2007, 05:19:21 pm »

Schallfeldwebel wrote on Sat, 17 March 2007 23:44


There can be a negative side when using measuring microphones. The resonance point of this microphone is around 11Khz, there is a 90 degrees phaseshift already around that frequency, which gives some unpredictable behaviour above 20Khz.

Erik,
could you tell me more about this phase shift issue or point me to more information?

The 296 was on my wishlist for a long time, but it's not really any more now... There is something I dislike about most MTGs I've tried, and some of it is reflected in commenst/postings in this thread.
I have a pair of Jim-Williams-modified C460s with CK62DF diffuse field omnis and a pair of Neumann K 131 for all my omni needs...  Smile
Daniel
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kostavox

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Re: Gefell M296 Question
« Reply #48 on: April 07, 2007, 08:14:26 pm »

Just use 2 X 6.8K metal film resistors from the battery 48V to pins 2 & 3 and the GND of the battery to pin 1
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kostavox

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Re: Battery powering the TLM50
« Reply #49 on: April 07, 2007, 08:18:53 pm »

Markus Sauschlager wrote on Sat, 07 April 2007 09:23

Hello Kostas,

kostavox wrote on Fri, 06 April 2007 14:36


The sound improvement is HUGE. Same works wonders for other mics.




Could you please describe that a bit?
What is the difference in sound and in which way is it improved by battery powering?

Best regards,

Markus



The sound has much more width/depth and inner detailing. I think this is because most 48V phantom powering circuits use a simple oscillator/Inductor circuit to generate the 48V so it really isn't stable. Using a pure DC source gives the mics an absolutely stable supply as well as not "conflicting" with the "Audio Frequency" requirements - remember that pins 2 & 3 are also handling the low-level microphone signal. rgds Kostas
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davebl

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Re: Gefell M296 Question
« Reply #50 on: April 08, 2007, 04:14:57 am »

I found the samples here, origional directed to them by another person.

http://www.mil-media.com/LargeEnsembleListeningTest.html

There are some more for comparison that may be of interest.

Erik, I like your sample, thanks for posting it. To my ear it has some depth to it, how big was the hall ?

Dave Blackham
UK
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Schallfeldnebel

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Re: Gefell M296 Question
« Reply #51 on: April 08, 2007, 08:27:28 am »

The capsule type Mk 221 on the Josephson 617 uses, is a 50mV 1/2 inch capsule, normally the output of 1/2 inch types is not more than a 14mV/Pa, giving a quite bad S/N ratio. To enhance the dynamic range, the capsule is made with a lower mechanical tension but unfortunately loses bandwidth. Also some strange bumpy behaviour around 26Khz occurs. A 90 degrees phase shift already occurs within the audio range, something you rather try to avoid with music microphones.

What can happen is that you hear sometimes  a rather umpleasant pressure on the ears, and esp. with organ recordings the far high end, the so called mixtures and sharps get a very unnatural sort of scattering sound. (high frequency vibrato)

In the amen sample from the Millennia page done with Josephson's I do not hear a problem occur, but the violins are very soft in the total balance, and that is just the group where I would expect it the most audible.

I still place a question mark, where many other microphone manufacturers try to manage as flat as possible phase-characteristics for their microphones, with this 50mV / 1/2 inch type of microphones a phase shift of 90 degrees is already introduced at 14K. B&K especially designed the 4006 to overcome this problem. (24kHz-90)

It is very depending on the sort of music you record.

Erik Sikkema
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Schallfeldnebel

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Re: Gefell M296 Question
« Reply #52 on: April 10, 2007, 10:10:18 am »

davebl wrote on Sun, 08 April 2007 16:14

I found the samples here, origional directed to them by another person.

http://www.mil-media.com/LargeEnsembleListeningTest.html

There are some more for comparison that may be of interest.

Erik, I like your sample, thanks for posting it. To my ear it has some depth to it, how big was the hall ?

Dave Blackham
UK


The recording was made in Haarlem, Doopsgezindekerk, The Netherlands. This is the same venue where in the 1960s Harnoncourt and Leonhardt recorded their famous J.S.Bach Kantate Cyclus.

To make another remark about microphones and nonlinear phase characteristics, the following: (and maybe some more technical forum reader could reply on it.)

Personally I do not like rulerflat microphones which have no flat phase characteristic in the audioband, as examples many measuring microphones and several music microphones. I have less problems with microphones having not a ruler flat phase characteristic and at the same time little peaks or dips in the audioband related to the phase-shift.

E.g. The Neumann TLM 170 has a minor phaseshift in the audioband around 3-4k, but at the same time it dips at 3-4k about a 2 dB. I like that microphone very much. Maybe the ear is very sensitive to phaseshift while the frequency response stays linear. When phase response and frequency response go together it may all be nicer for the ear. It also depends very much on the music material.

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."

davebl

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Re: Gefell M296 Question
« Reply #53 on: April 12, 2007, 01:39:12 pm »

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davebl

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Re: Gefell M296 Question
« Reply #54 on: April 12, 2007, 01:40:23 pm »

What is the B&K (DPA) 1/2 capsule equivilent of the 4145, ie a B&K mk221 that would be suitable for music recording. If mated to a Josephson would it be prefered over a 4006.

thanks,

Dave Blackham
UK
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Marik

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Re: Gefell M296 Question
« Reply #55 on: April 12, 2007, 05:23:53 pm »

davebl wrote on Thu, 12 April 2007 18:40

What is the B&K (DPA) 1/2 capsule equivilent of the 4145, ie a B&K mk221 that would be suitable for music recording. If mated to a Josephson would it be prefered over a 4006.

thanks,

Dave Blackham
UK


The 1/2" equivalent is 4165. For reasons Erik has described above (wider bandwidth, so the 90* phase shift is above audio range), the 4133/MK202is more suitable for music, but have higher noise. Because of thinner Nickel diaphragm vs. stainless B&K, the MK202 is a little hotter. I am getting a pair of these Gefells next week and will be able to compare with my 4133s.

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

davebl

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Re: Gefell M296 Question
« Reply #56 on: April 13, 2007, 05:48:37 am »

Thanks for the advice. My only concern about this approach is the reported phase issues that may be present with 1/2 capsules. So Im trying to determin the most suitable capsule whether it be mk221, mk202, or the 1" mk102 or the B&K equivilents. Obviously it isnt a cheap option, but then neither are the DPA, Schoeps, Sennheiser alternatives.

So far as I can tell the C617 preamp is no issue at all apart from having a high output which again is fine if the preamp will cope with it.

I have a client who wishes to use the mics if there is confidence the reported phase issues are not problematic as there seems to be so much going for the approach allround with the lack of coloration and high detail resolved etc.

Please let us know your thoughts following your comparison trials.

Dave Blackham
UK
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Schallfeldnebel

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Re: Gefell M296 Question
« Reply #57 on: April 13, 2007, 10:44:23 am »

Mark's comments are all correct. The modern equivalent of the 4145 in the half inch version can be obtained in two versions, the prepolarized 4189 and 4190 for 200V outside polarization.
The 4165 is not produced any longer. The modern version of the 4133 is the 4191.

If the phase issue is not problematic, why did B&K in the early eighties design the 4006 from scratch? Was it not simple to take the 4165 and sell it as a quiet and versatile music microphone, or take the equivalent capsule from other microphone manufacturers like Sonodore and Josephson do?

When the Sonodore came on the market, the story was that the 4006 was too directional in higher audioband, causing the effect of the "hole in the middle of the stereo image" and that Sonodore had found the solution, a smaller diameter capsule, and even better noise values than the 4006. Fifteen years earlier B&K had rejected the use of the 4165 because of the phase issue, and designed a complete new microphone. Make up your own mind I would say, and use your ears.

The problem with this type of 1/2 inch 50mV measuring microphone is, in one situation it sounds very good, as in the examples of Millennia earlier in this post, but I know several recordings where I get a headache from the sound, but again it is very personal.

Personally I do not like the Sennheiser MKH20 omni, and I suspect the phase characteristic in the high end of that microphone, so the issue is not only with measuring microphones.

Erik Sikkema
Schallfeldwebel






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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."

d_fuchs

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Re: Gefell M296 Question
« Reply #58 on: April 14, 2007, 08:54:29 am »

Could you please tell us more about that phase issue?

Daniel
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davebl

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Re: Gefell M296 Question
« Reply #59 on: April 15, 2007, 03:12:44 am »

I have asked Josephson to comment on the issue and have recieved this reply and josephson kindly agreed to allow me to post the response here. I will also ask Gefell to comment. Both companies have been extreemly helpful with customer support so am gratful for their help and support.

My Question :- Thanks again for the info so far. I wanted to try to find out more about the various phase comments about the mk221 capsuel, I've read, in so far as I can, the comments via the various web sites. is there any technical data about phase response available ? Im not that concerned about it but would like some more info if possible.

Kelly Kay from Josephson :-

The rate at which these phase changes "wrap", that is how gradual the changes are relative to frequency change, is directly related to the damping inherent to the resonance. In order to make any sort of reasonable, useful, directional or omni dc-biased condenser mic internal mechanical and acoustic damping must be *very* high so these phase wraps will be inherently very uniform and very gradual. If the damping were not very high you would instead have very high, audible, resonance related response (presence) peaks as well and an audible objectionable ringing.

Given the above, if you consider the phase wraps one sees when comparing the phase of a "source" of a signal to the signal after it has propagated over a distance...phase relative to the source wraps at increasing rates with increases in distance from the source. It is no surprise that much of the psycho-acoustic research done on the human ability to detect phase variations in recording playback shows that the human ears ability to perceive and differentiate real from artificial is dependant not on absolute flat phase response but instead on smooth and uniform variation in phase response (which absolute flat phase response is a sub set of.) (Note: in the extreme case of comparing compression to rarefaction, in-phase vs. full 180 degree out of phase, it has been shown that a limited number of very good listeners can tell the difference can tell the difference but even then only on something like a strong isolated kick drum sound.)

Sorry, I don't have any references on hand, but a large amount of the foundational psycho-acoustic research into the impact of phase response was published in the AES journal about 20 years ago. The motivation was typically interest in gaining an understanding of criteria required for "accurate" loudspeaker playback however there has been no question as to the fact this should apply to all of the playback chain. So, you may in actually have several of these phase wrap frequencies in your loudspeaker playback (3 if you have 3-way monitors)? the wraps just need to be very gradual over a wider range of frequency (like a slope) and not narrow range (like a step ? which would inherently be tied to a strong resonant ringing.)

Given that, some low-end microphone manufacturers do use questionable resonator structures in their capsule design (intentionally and not), which may in fact cause audible phase related artifacts however, I assure you that is not the case with the well designed MK221.

Also, directional microphones inherently have much more ?trouble? with resonance in the audible range. So, if having a 14Khz diaphragm resonance is considered a problem solely based on its statistic, then directional microphones... particularly the more directional ones (Hyper Cardioid and Bi-directional) should by comparison be quite unusable.

The diaphragm resonance and what the designer both allows it to do and trys to prevent it from doing by making a well though out decision regarding *all* the trade offs is only a single contributor amongst vary many that make up the sound of any capsule?. Then there is the matter of the electronics after that!

Ill ask gefell to comment also and if they will be agreeable to posting a response here.

Dave Blackham
UK
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