R/E/P Community

R/E/P => R/E/P Archives => Klaus Heyne's Mic Lab => Topic started by: davebl on March 17, 2007, 05:09:32 pm

Title: Gefell M296 Question
Post by: davebl on March 17, 2007, 05:09:32 pm
Please could some one describe the sound of a Microtech Gefell M296 for me comparing it to say a Schoeps Omni or Sennheiser MKH20 if thats possible to do.

How would a pair perform as a main spaced pair for orchestral work. Perhaps point me to a known recording using them ?

I know I need to borrow some to listen for my self but there are none around localy to where I am.

thanks,

Dave Blackham
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 17, 2007, 06:44:28 pm
This 296 model is directly derived from the 1 inch measuring capsule MK102.1 you can find on the website of Microtech-Gefell.

There is only made a compromise, instead of polarizing it with the standard 200V, it gets only 80V. This probably gives a bit more of presence peak than when 200V is used. The 296 has a max peak of 2 dB, the MK102.1 has about 0.5 to 1 dB max.

I use myself the B&K 4145 which is to the ANSI specs the equivalent of the MK102.1. The sound is very much comparable with the Schoeps MK2 or the Sennheiser MKH20 with the HF switch in the flat position, but it less omni directional in the higher regions. I assume the Microtech 296 will sound a little bit more bright with it's +2dB of rise.

There can be a negative side when using measuring microphones, especially the one inch has some unpredictable behaviour above 20Khz. I enclosed a file with a recording I made in 1994 using the 4145 as a test. As soon as the voice goes up to the higher octaves and gets loud, I hear a pressure on my eardrums, I do not know if MP3 is good enough to show you that. This recording was made with a small A-B of two 4145's.

http://webzoom.freewebs.com/eriksikkema/Soprano.mp3


Erik Sikkema



Title: Re: Gefell M296 Question
Post by: davebl on March 18, 2007, 05:10:54 am
Erik,

Thank you for your advice and the sample which was very useful and also very pleasant to hear.

I am interested in the Gefell since may people seem to rate the Nickel capsuels, I do hear that some others regard them as 'metalic' sounding whcih may be a function of the high detail they seem to resolve. I guess only listening will answer the question properly.

Best regards,

Dave
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 18, 2007, 11:34:37 am
"I am interested in the Gefell since may people seem to rate the Nickel capsuels, I do hear that some others regard them as 'metalic' sounding whcih may be a function of the high detail they seem to resolve."


I do not think one can generalize and say that metal diaphragms sound more metallic, and users who have that opinion may have heard the bad designs.

Think about the famous aluminum Neumann M50, and the Sanken CU44X cardioids, .
.
Here's a soundfile of piano-solo (N.B. the Yamaha, S. Richter used in Holland to play his concerts on) recorded with ONLY two Sanken CU44X double membrane(titanium), two way microphones.

http://webzoom.freewebs.com/eriksikkema/Bach%2DYamaha.mp3

Erik Sikkema
Schallfeldwebel


Title: Re: Gefell M296 Question
Post by: Arf! Mastering on March 18, 2007, 09:16:06 pm
The metallic character of the MTG 295/296 is something I can personally confirm.  It's not due to the use of nickel, however, my Neumann nickel capsuled KM254s and KM56s are not at all metallic sounding yet they have great presence.  The problem with the 295/296 is that there are some nasty resonances in the upper mids.  They are still very useful mics though, just not as glorious as the Neumann nickel KMs.
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 19, 2007, 04:57:16 am
This confirms there are good designs and bad designs, and both might find their use in recording.

Do not forget the Neumann KM254s and KM56s are small diameter membranes, and the Gefell 294-295 are large membrane designs. I do not think Neumann could fix the problem with resonances either when they would come up with a nickel U87.

Also cardioids tend more to a metal sound than omni's. So the 296 omni is quite another beast than his brothers the 294-5.

Erik Sikkema


Title: Re: Gefell M296 Question
Post by: davebl on March 19, 2007, 06:40:57 am
This is very usefull and informative, I think the only way is to have a listen to them. I wonder if the 1" 296  is any better (or worse) than the 1/2" version used ont he josepheson 617 pre amp.

Dave
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 19, 2007, 08:47:01 am
The Josephson 617 uses standard the Microtech-Gefell MK221 1/2 inch capsule, which is the equivalent of the discontinued B&K 4165. In fact those capsules are successors of the 1 inch version 4145. B&K has discontinued the production of 1 inch measuring microphones, although they might have some on stock.

Problem with the 50mV 1/2 capsules is, the lower noisefloor can only be achieved by using some mechanical acoustical tricks, what one has to accept is a rather low bandwidth for a 1/2 inch capsule (only 20kHz max), and you pay it with unpredictable behaviour above 20 Khz, there are some very strange bumps and dips before the final roll off.

In a way the 1 inch and 1/2 inch 50mV types are quite alike, and using them for music recording is a bit questionable. The main difference between them is that the 1/2 inch version stays omni directional for much higher frequencies.

Both Sonodore and Josephson use the limited bandwith 1/2 inch versions, Josephson uses Gefell MK221 and Sonodore is a bit mystical where they get the capsules from, but I think they use ACO Pacific titanium diaphragms.

Both designers probably know the phase characteristic is not that smooth as with the low output 4133 12.5 mV type of 1/2 inch capsule, but probably there is a demand from the market to produce these models.

It is no coincidence B&K (DPA) did (re)design one of their measuring microphone concepts to the 4006(3) model in the early eighties. If the phase issue was not serious, they would have never done that. Designing new models costs a lot of research money.

I use my 4145 1 inch capsules for very specific situations, and if I could decide today again, I would not buy them. I use them only very few, and it is not worth the investment.

Even when you try-out a microphone of this type, you may have other opinions some day in future. To sell off these odd 1 inch models may take a while.

Erik Sikkema




Title: Re: Gefell M296 Question
Post by: Robert Castiglione on March 19, 2007, 09:00:56 am
I use two Gefell 296s regularly.

My experience is that they are rather "specialty" omnis if that makes any sense. I wish I had bought the Schoeps MK2s first.

Having said that and having worked hard getting used to their particular characteristics, I have used them successfully in many applications from close micing (turned off axis) on vocals and acoustic guitar,  to diffuse field omnis for a choir,  and even the mid element in an M/S array to record nature recordings.

They are extremely articulate and just have a staggering ability to capture great detail.

Yes, I enjoy using these mics.

Rob
Title: Re: Gefell M296 Question
Post by: davebl on March 19, 2007, 10:36:36 am
Hmmm, From what I hear I think that I would prefer the Schoeps MK2s or the Sennheiser MKH20 by first choice.

I am in a slight dilema betwen the two as I use CCM 4's and like these mics a great deal. But I also have alot of MKH mics and two 'spare' MKH30's  so could create an Omni/8 pair if needed. The MKH mics are absolutly quiet and have a good deal of detail.

I once put up a 30/40 MS pair agains a 414 EB AB pair and it was so much more defined that I was very pleasantly supprised.

I have always thought that the Schoeps have a sort of more 'musical' quality to them which I find hard to describe but equaly like the MKH mics.

Do you have used the MKH 20 v the CK2s  in a spaced tree configuration ?
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 19, 2007, 10:53:53 am
Hmmm, From what I hear I think that I would prefer the Schoeps MK2s or the Sennheiser MKH20 by first choice.

There is quite a difference between the Schoeps MK2s and the Sennheiser MKH20. The last one is in the neutral switch position rather dark, while the Mk2s has quite a presence boost. (+3dB?)

What makes the difference here is the 296 has because of it's larger membrane, a much less omni characteristic in the HF range, which makes it very suiteable for creating detail even on a larger distance, without getting a sharper sound.

Erik Sikkema
Title: Re: Gefell M296 Question
Post by: ioaudio on March 19, 2007, 01:20:36 pm
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 19, 2007, 01:53:20 pm
The model MK102 is the one running on a full polarization voltage of 200V, and has a flatter frequency curve than the "music" type 296. The MK102 is equivalent to the B&K 4145.

No experience with tube versions of these models.

Erik Sikkema

Title: Re: Gefell M296 Question
Post by: Robert Castiglione on March 19, 2007, 06:58:18 pm
To choose the MKH series omnis or the Schoeps.

Sorry I have been trying to refer to the Schoeps MK2 (and have added the s inadvertently). I am referring to the Schoeps omni suitable for close applications. there are many sound samples of the MK2 on the 3D Bulletin Board (look for threads by IVO who has several). The good thing is that he has used them on many instruments and the sound clips are WAV and not compressed formates.

I have had MK30 and still have MKH40. This is totally subjective I know but there was something about the electronically extended nature of the MKH series which got on my nerves. I used to use the MKH30/40 in midside then decided to sell the MKH30 and get go for a Schoeps M/S instead generally using the cardiod as a centre. Much prefer the Schoeps which is capable of really good stereo imaging when the two capsules are aligned.

The MK2 is a very beautiful sounding omni!

Sorry, all these subjective descriptions are of course of little use to you. Just my journey with MKH series and Schoeps.

Rob
Title: Re: Gefell M296 Question
Post by: ioaudio on March 19, 2007, 10:28:02 pm
Title: Re: Gefell M296 Question
Post by: Plush on March 19, 2007, 10:49:26 pm
The 296 was asked for by Gotham Audio in NYC.
It was to be an M50 imitator because it too had increased
directivity at higher frequencies.

The above was told to me by Jerry Graham at Gotham.
Title: Re: Gefell M296 Question
Post by: davebl on March 20, 2007, 04:58:26 am
Plush wrote on Tue, 20 March 2007 02:49

The 296 was asked for by Gotham Audio in NYC.
It was to be an M50 imitator because it too had increased
directivity at higher frequencies.

The above was told to me by Jerry Graham at Gotham.


This is very interesting to me, if anything I had wanted a M50 acousticly styled mic and thought of using a ball arangment behind the capsule. The M50 is an SDC really rather than a larger capsuel may be the 296 can be regarded as Mic DC in this respect.

Teddy, tells me the best example is the Josehson/Gefell 211 combination which is SDC and Id hope very low noise.

I note the comments about the metalic coloration, or not depending on your view, from the Gefell Nickle capsuel and this does still concern me a little.

Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 20, 2007, 04:08:49 pm
The M50 is an SDC really rather than a larger capsuel may be the 296 can be regarded as Mic DC in this respect.

I see the M50 as a mix between a large membrane and small membrane microphone, but the capsule itself is off course a small diaphragm.

You cannot compare the Josepson with the M50 or Gefell 296, the Josephson is very omni directional, the M50 because of the sphere is very directional for higher frequencies, and the 296 will be somewhat in between the other two.

hello erik,
do you have experience with the mk102/4145 capsule with non-tube mic bodies? - i´d like to learn more about the sound of these capsules.


Yes, I have, I would call the sound present in the midrange for an omni, and silky for the HF part. I have made a link to my website with a music sample of soprano and lute.

http://webzoom.freewebs.com/eriksikkema/Soprano.mp3

Sorry I have been trying to refer to the Schoeps MK2 (and have added the s inadvertently). I am referring to the Schoeps omni suitable for close applications.

The B&K 4145 and Gefell mk102 are very alike the Schoeps MK2, ONLY the Schoeps is more omni directional for higher frequencies, and I think the Schoeps has a better phase characteristic. The 4145 sounds like it has lower distortion altogether, but that could also be caused by the limitations of phantom powered systems like the Schoeps. The Gefell 296 where this thread is about may come more close to the Schoeps MK2H than to the MK2.

Schallfeldwebel
Title: Re: Gefell M296 Question
Post by: davebl on March 20, 2007, 04:52:10 pm
http://webzoom.freewebs.com/eriksikkema/Soprano.mp3

Hi Erik,

This is very pleasant, and interesting to listen to, what was the mics configuration, Im assuming it ia a 4145 pair ?

Dave
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 20, 2007, 05:46:40 pm
Small A-B approx. 65-75 cm, 2x B&K 4145.

Schallfeldwebel
Title: Re: Gefell M296 Question
Post by: ioaudio on March 21, 2007, 01:18:38 pm
Title: Re: Gefell M296 Question
Post by: davebl on March 27, 2007, 01:42:56 pm
Erik, You expertees and advise again please.

Does the Gefell MK102 and the B&K 4145 measurement capsuels sound near identical. and are there any reasons to select one manufacturer over the other ? Also is there a prefered preamp for these measurement capsuels ? It seem that 1/2 to 1" convertors can be found and 1/2 caps could be used as an alternative for some work.

Also how comparible to the Gefell M296 is the Mk102 or 4145. I know theres an HF lift on the M296.

From what I hear the M296 has a very silky top end and Id welcome your view as to its use in preference to the 102/4145's discussed.

thanks again,

Dave
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 27, 2007, 06:18:03 pm
The sound samples I made a link to are made with B&K 4145 not the Microtech 296. I do not think the 296 will have that "silky" sound in the top end.

To choose between 296 or 102/4145 depends on if you look for the round sound as heard in my example, and if you like the sound of microphones like the SCHOEPS mk2.

The decision between Gefell 102 or  B&K 4145 depends very much on what you want to spend on them. The 4145 are discontinued, but probably still on stock, but cost about the double of the Gefells.

About the quality, my friend Kostas Metaxos used many equivalent capsules from B&K and Gefell, and always preferred the B&K's in terms of sound quality, but this is very personal.

To go back to the 296, this microphone is a modified 102, works with a lower polarization voltage, not to accomodate a special sound, but just for the easiness of the fact this preamplifier is used for more existing Gefell microphones and runs on 48V.
The effect of the lower polarization voltage is the presence peak, and indeed it gets a bit the characteristic of a microphone placed in a sphere like the Neumann M50, but the fact the shape of the 296 is not spherical, it will never sound like a M50.

I use the standard Falcon preamps from B&K to match it with my Lake-People V25 preamps, using a mechanical adaptor.

Hope this helps,

Der Schallfeldwebel
Nur f
Title: Re: Gefell M296 Question
Post by: Gunnar Hellquist on March 29, 2007, 03:07:27 pm
This Sunday I did a recording using two M296 as the L and R mics in a (homebrew) Decca tree. I will try to post some samples up, towards the weekend is my guess.

Gunnar
Title: Re: Gefell M296 Question
Post by: RichS on March 29, 2007, 03:13:12 pm
To clear up any possible confusion...

Although listed as "M296 large diaphragm 1" omnidirectional condenser" on the Microtech Gefell website, the M296 capsule size is approx. 19.5mm (3/4 inch). The outside diameter of the head (which is listed in the specs) is 24mm, a little less than 1 inch.

There is a M296S model, which is intended for measurement and instrumentation applications.

I have a matched pair of M296 and use them mainly for organ/orchestra.

Title: Re: Gefell M296 Question
Post by: RichS on March 29, 2007, 03:31:12 pm
Schallfeldwebel wrote on Sat, 17 March 2007 18:44

I enclosed a file with a recording I made in 1994 using the 4045 as a test. As soon as the soprano goes up to the higher octaves and gets loud, I hear a pressure on my eardrums, I do not know if MP3 is good enough to show you that. This recording was made with a small A-B of two 4045's.

http://webzoom.freewebs.com/eriksikkema/Soprano.mp3



The "pressure effect" you've described is not a problem with the mic's... after more than 30 years experience singing with "straight-tone" (no vibrato) cathedral choirboys and early music sopranos, I can attest to the "pressure effect" being easily heard in performance. Those sounds are almost pure sine wave in quality, and will drill through you head... even at the back of a cathedral!

Shocked
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on March 29, 2007, 04:56:40 pm
Rich,

I know what you refer to, but that is not the effect I mean. I hear it also with stringquartett and plucked instruments like guitars and lutes, when recorded with measuring microphones having phase anomalies. (e.g.B&K 4065)

Most measuring microphones are optimized for certain aspects in the measuring field. Either for noise, then often the phase characteristic is poor, or for bandwidth, then the noise floor is too high. For music we want a flat frequency response, extended bandwidth, smooth phase response and low noise.

The 296 and e.g. the much more peaky DPA4041 belong to a group of special purpose omni's. I have also made very succesful recordings with the 4041, even organ, but it would not be my first choice. What just stays a fact with these "larger" diameter measuring capsules, the mechanical distortion compared to their half inch brothers and sisters is higher.

Erik Sikkema
Schallfeldwebel

Title: Re: Gefell M296 Question
Post by: kostavox on March 30, 2007, 07:45:56 pm
I tried a pair of the "8 micron" 296 briefly and compaed them to my Neumann TLM50s [pair of titanium and pair of nickel-which I prefer] and they weren't in the same league. They sounded more like an instrumentation mike - and I've have a lot of experience with all the B&K and Gefell instrument mics [which I own].

My favourite instrumentation mikes are B&K 4135 [1/4"] or for an even "sweeter" sound, the equivalent GEFELL MK301s. The only problem is the noise floor. Although with large scale loud orchestral or Jazz, you wouldn't know.

These mics are my "reference point" for recording what is really happening in space [and I use them with heavily modified Stellavox Tape machines].

The 4133s 4145s MMK202s are not in the same class.

But my musical preference is for the Neumann TLM50s and M150s. The TLM50s are VERY fussy with 48V powering. I use 5 X 9V DURACELLS in  series per channel to get their best sound.

You can hear samples of these recordings at www.metaxas.com or on this BBS
http://recforums.prosoundweb.com/index.php/m/230249/16812/?s rch=metaxas#msg_230249

rgds

Kostas Metaxas  
Title: Re: Gefell M296 Question
Post by: kostavox on March 30, 2007, 07:49:12 pm
I forgot to mention I just purchased a pair of the 4micron 296 versions which I want to experiment with their "electronics" to modify them in a similar way that the folks at Polyhymnia modify the guts of their Neumanns.

I looked inside my M294 [very easy to get into] and saw that the circuit is a pretty basic one - capacitor coupled FET input etc...
Title: Re: Gefell M296 Question
Post by: davebl on March 31, 2007, 05:20:01 am
Hi Kostas,

Is the 4 micron 296 the 296S or is the other way round ?

I had thought the TLM 50-S had to be phantom powered and there was no other means of powering the mic. I am assuming that this is a custom modification that you have made ?

Thanks for your samples, Im going to ahve a listen now.

Dave Blackham
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on April 01, 2007, 03:46:56 am
Kostas,

where did you get the information about 4 micron and 8 micron thick membranes in the Gefell 296?

The B&K 4145 is about 2 micron thick, and an 8 micropn thick nickel diaphragm to me seems to be rather heavy. Is this information correct?

Schallfeldwebel
Title: Re: Gefell M296 Question
Post by: ioaudio on April 01, 2007, 05:08:09 am
Title: Re: Gefell M296 Question
Post by: mr.gefell on April 01, 2007, 09:40:31 am

the capsules used in the sms200 series by gefell ( m70,m94 etc) are all 0.8 micron nickel.Which equals to 3 micron mylar diagphram. the nickel type has more more desity.

all measurement capsules ny gefell are 0.4 micron nickel, even the modidied one used in m296.

for more info contact gefell

* A sharing of actual, real world experiences with specific microphone brands and models"


yes the mk102 and m296 sound different. I prefer the mk102.
Title: Re: Gefell M296 Question
Post by: davebl on April 01, 2007, 02:02:30 pm
Thanks, as the 296 is a much newer mic in design, Im informed it is strongly prefered over the older Omni M93/M58 capsues with the MV692 series preamp, I beleive the old omni caps don't have have nickel capsuels.

This next question should really be in another thread I started ealier, So appologies for asking the question here.

I am told, but do not have first hand expirience, that the MV692/70 sounds reasnobly similar to the 295 and like wise the MV692/M94 cardioid mics. Would any one have first hand expirence to coment on the models ?

Again sorry for the question but these are a family of mics which are of interest.

Dave
UK
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on April 01, 2007, 02:27:50 pm
Mr. Gefell,

where did you get this information? On the site there is only mentioned for the cardioid 294 and 295: Die Wandlerelemente besitzen eine Nickelmembran mit einer Dicke von weniger als 1 Micrometer.

The info over the 296 omni does not say anything about membrane thickness.

I am not so surprised the 294 and 295 have such thin nickel membrane, in a cardioid microphone the membrane tension is much lower than in a omni. What I find hard to believe is that according to you the omni 296 even has half the thickness of the 294/5, and to my opinion the membrane would be near to collapse when the higher tension is applied an omni needs to have to function.

The DPA 4041 has a membrane thickness just under 2 micron, and so about the 4145 from B&K. I simply cannot believe your info is correct, unless Gefell uses much lower tension than B&K does.

Maybe someone from the Gefell factory should jump in here.

Der Schallfeldwebel
Title: Re: Gefell M296 Question
Post by: mr.gefell on April 01, 2007, 02:34:12 pm

Greetings Erik,

I got the info from the supreme being.Acronym 786.

Shocked

now let's not get spooky. Razz


contact Frank M
Title: Re: Gefell M296 Question
Post by: Gunnar Hellquist on April 01, 2007, 04:17:19 pm
As promised, a recording where the m296 is used as L and R in a Decca tree. C is a MKH20, various mics used other places. Preamps are Millenium HV3D, AD is Lavry Blue. This is no way mixed yet, no time alignment done on tracks, no reverb added, no EQ.

http://trombonisten.se/m/mix.wav
here is only the 296 mics (volume as in mics)
http://trombonisten.se/m/m296.wav

Both files are 15megabytes, uncompressed 16 bit/44.1kHz

A rather bad picture of the setup is here:
http://trombonisten.se/b/IMG_4051.JPG
Also rather large at 4 MegaBytes.

Gunnar
Title: Re: Gefell M296 Question
Post by: kostavox on April 06, 2007, 08:36:14 am
I'm not sure yet as I receive them next week...I'll let you know how it goes.

As for the TLM50s, they are normally 48V phantom powered. But since they are quite a complicated circuit, the quality of phantom powering is critical for them to reveal their true potential. They also tend to draw more current.

I have constructed a very simply diecast box with XLR ins/outs and inside I parallel 5 X Duracell 9V batteries which actually give me 48.5V, and llast for at least 5-8 concerts before needing replacement or the addition of another battery.

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

I explained to a Recording friend that many consoles which use transformer ins, actual defeat the purpose of outstanding CMRR because the earths on both sides of the transformer are shorted to be able to offer a 48V phantom powering.
Title: Re: Gefell M296 Question
Post by: bushwick on April 06, 2007, 01:00:18 pm
It seems to me that Gefell is in a very good place to offer a gift the recording community and make some money at the same time were they to make an Omni head utilizing a perspex sphere ala the M50. They already have the technology down pat for making the diaphragms.

josh
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel on April 06, 2007, 06:41:48 pm
Hej Gunnar,

With the example where only the 296's were used, it is obvious the L-R separtion is very strong in the discant. This is off course because you had the microphones directed very much outside, but it is also a characteristic of all large membrane omni directional microphones. It is also the reason I am preferring small diameter capsules as main pair with this kind of orchestra set-ups. The over directionality of LD omni's force you to compensate with a M(iddle) microphone and a lot of spots to correct the stereo image.

And that is what you have done in your final mix, which sounds actually very nice. I must say I like the sound from the 296 as in your example, but I would not use them as main pair for large and complex set-ups, rather more for small and solo set-ups. I do not think either you can see this microphone as a competitor of the M50 or TLM50 from Neumann. The perspex sphere of the M50 creates a much more stable stereo image, without pulling the high midrange to the Left and Right outer sides of the stereo image.



Title: Re: Gefell M296 Question
Post by: davebl on April 07, 2007, 04:01:05 am
I can see Eriks view but still think the M296 is a usefull mic. I had heard these samples of the smaller MK221 capsuel on a Josephson body.

http://www.mil-media.com/media/Amen.wav
http://www.mil-media.com/media/Glory.wav
http://www.mil-media.com/media/Goodwill.wav

Credits are on the milennia site for the performance and recordist. One reviewer suggests the mics are too close and should have more room on the recording, I still think its a great recording and I like the closer perspective.

It seem the 296 can be 'steered' over the top or to the sides of the orchestra/choir or whatever due to its HF directionality where as the MK221 could not. How usefull is this charicteristic rather than adopting Josh's great idea of Gefell producing a sphere ? I would like to see a product of this type.

Do I detect from more expirienced users a preference for the smaller MK221 capsuel types over the larger 102 or 296 mics ? Also Is there any other option of preamplifier other than the Josephson C617 for these measurment capsuels ?

Dave Blackham
UK
Title: Re: Gefell M296 Question
Post by: liuto on April 07, 2007, 07:39:58 am
kostavox wrote on Fri, 06 April 2007 14:36


I have constructed a very simply diecast box with XLR ins/outs and inside I parallel 5 X Duracell 9V batteries which actually give me 48.5V, and llast for at least 5-8 concerts before needing replacement or the addition of another battery.



kostavox, how did you decouple 48VDC from the signal?
Thanks
Hermann Platzer
Title: Re: Gefell M296 Question
Post by: liuto on April 07, 2007, 07:41:11 am
sorry, double post, please delete.
Title: Battery powering the TLM50
Post by: Markus Sauschlager on April 07, 2007, 10:23:00 am
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

Title: Re: Gefell M296 Question
Post by: davebl on April 07, 2007, 01:35:10 pm
Would any one know the diference between a Microtech Gefell MK102 and MK102.1 capsule and if it is significant for our type of music work.

Thanks,

Dave
UK
Title: Re: Battery powering the TLM50
Post by: mr.gefell 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'


Shocked
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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
Title: Re: Gefell M296 Question
Post by: d_fuchs 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
Title: Re: Gefell M296 Question
Post by: kostavox 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
Title: Re: Battery powering the TLM50
Post by: kostavox 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
Title: Re: Gefell M296 Question
Post by: davebl 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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
Title: Re: Gefell M296 Question
Post by: davebl on April 12, 2007, 01:39:12 pm
Title: Re: Gefell M296 Question
Post by: davebl 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
Title: Re: Gefell M296 Question
Post by: Marik 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
Title: Re: Gefell M296 Question
Post by: davebl 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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






Title: Re: Gefell M296 Question
Post by: d_fuchs on April 14, 2007, 08:54:29 am
Could you please tell us more about that phase issue?

Daniel
Title: Re: Gefell M296 Question
Post by: davebl 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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
Title: Re: Gefell M296 Question
Post by: Marik 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
Title: Re: Gefell M296 Question
Post by: davebl 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
Title: Re: Gefell M296 Question
Post by: Marik 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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

Title: Re: Gefell M296 Question
Post by: Marik 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
Title: Re: Gefell M296 Question
Post by: Schallfeldnebel 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
Title: Re: Gefell M296 Question
Post by: Marik 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