Topic: Gefell Nickel diaphragm mics (mv294, 295, capsules m70, m94)?

[illconditioned]

Anyone out there using Gefell's Nickel diaphragm mics?  These are supposed to be just killer. 0.8 micron nickel (pure metal) diaphragm!

Some of these are very old, and in very rough shape.  However, one Ebay vendor (hear2eternity) is selling off a bunch of m70 capsules that are supposedly reconditioned.  He told me they were reskinned by a former Gefell tech.  So, I took a chance and bought two m70 cardioid capsules.  Apparently the m94 are better for distance recording, but I think the m70 are still good.  I would consider buying the m94 if I could verify that the diaphragms were still good.  I noticed that the newer mics (mv295, mv295) are something like $1600 each.  Well, that is a lot of money, but I wonder if these would sound better than Scheops.  Also, the mv296 in that family is omni and has the genuine measurement capsule.  For $1600 you can get the real deal.

  Richard

[H₂O]

http://bt.etree.org/details.php?id=546322

[illconditioned]

Yeah, I've listened to a few of those recordings, tube mics with m94 capsules.  Nice sounding venue too.

I'm planning on just running the m70 capsules alone, with some wires, duct tape, and hot melt glue...

  Richard

[DSatz]

?? The material used for a condenser microphone's diaphragm isn't a major factor in the sound of the microphone. It isn't necessarily even audible on a direct comparison. Nickel as a diaphragm material has no "sound" of its own.

I used to own a pair of tube microphones with nickel diaphragms. One of the diaphragms needed replacing, and unbeknownst to me it was replaced (at the factory) with Mylar. When that capsule came back, I started using it again and never noticed any change in sound quality. The other microphone in the pair still had its original nickel diaphragm; they just didn't sound any more different from one another than any two other microphones of the same type generally do. It was months before it even occurred to me to ask the factory about the replacement diaphragm.

I'm no Gefell expert, but wasn't the M 70 originally made with PVC, and then in more recent decades with Mylar? I don't think I've ever heard of a metal diaphragm being used in an M 70 capsule.

--best regards

[illconditioned]

Dear David,

Thanks for you input.  Do you recall what mic you had?  Not the body, but the capsule?

As far as I can tell (by Google search and Google images, and the site "recordinghacks.com") there are just two metal capsules, the M70, and the M94.  There are a few earlier variants of the M94 (M56? or something) that were Neuman (before they split?).  There is also the Neuman M50.  I have not seen or heard these mics, though.  Well, I've listened to some M94 stuff on Archive.org.  I've also listened to an acoustic recording, drums: //http://soundcloud.com/lee-cardan/sets/eastern-bloc-studios-sdc-mic/.

I'm just beginning to explore this space.  Eventually I should compare M70 to some known quanitty like AKG 461.  I've only got 63 capsules, so I'm also looking for a set of ck61's.

  Richard

[F.O.Bean]

Well, that is a lot of money, but I wonder if these would sound better than Scheops.

NOTHING sounds better than Schoeps

[H₂O]

There is nickel diaphragm Schoeps as well the original m221 series caps (excluding the c versions) - mk22, mk23, mk24, mk240, mk241, mk26, mk28, m934, m934b- probably earlier Schoeps as well m201, cv51, etc

The Neumann KM53, KM54, and KM56 are all originally nickel diaphragm's as well.

I would think most condenser mics designed in the 1950's and before used some sort of metal diaphragm and most probably used nickel.  In the early to mid 1960's they transitioned to gold sputtered mylar.


 

[illconditioned]

Well, thanks for that information.  I want to just sit a pair of these mics side by side with a known quantity and hear for myself.

  Richard

[F.O.Bean]

Yes, thanks for the info. I learn something new everyday here

[H₂O]

It is important to point out that microphone manufacturers moved away from nickel to gold sputtered diaphragms was that nickel diaphragms where/are much more fragile versus gold sputtered diaphragms.

[illconditioned]

It is important to point out that microphone manufacturers moved away from nickel to gold sputtered diaphragms was that nickel diaphragms where/are much more fragile versus gold sputtered diaphragms.

It could also be cost.

Measurement microphones use metal (Titanium, Nickel and stainless steel).  Those are designed for harsh conditions.

By the way, other metal mics, stainless steel are Countryman B3, B6, and also Nevaton MCE400.  These are the best mics I've heard yet.

  Richard

[John Willett]

As far as I know the M70 series has a PVC diaphragm - certainly the current UM70s uses the original Georg Neumann M7 capsule which is only made by Gefell.

The current Gefell microphones that have nickel diaphragms are the new M221 and the M290 series.

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.  These are *not* designed for harsh environments as Neumann state they should not be used outdoors.

Any Gefell microphone repair really should be sent back to Gefell in Germany - they repair it to spec. and then put the mic. back into the anechoic chamber to check it all measures as originally.

[John Willett]

NOTHING sounds better than Schoeps

LOL    

There are quite a few mics that sound better than Schoeps - but it all depends on what you want to do.

I have often said that my top 5 are (alphabetically):- DPA, Gefell, Neumann, Sennheiser and Schoeps.

I rate these all pretty equal, but they all come from different directions when it comes to design.

It depends on whether you want colour or accuracy, what you are recording, the acoustic you are in, etc., etc.....

Most top studios will have a mixture of many of these in their collection and will choose the one best suited for what they are recording.

Schoeps the best - no ; but equal with the other four - yes.

[DSatz]

If I recall correctly the Neumann KM 53 used an aluminum diaphragm rather than nickel, and the M 50 went through four different capsule types one of which had a nickel membrane, but it was used only very briefly--Neumann changed over to Mylar in very short order as soon as it was available and had proven its worth.

The main reason for the change from nickel to Mylar was reliability. A nickel membrane can be ruined in an instant by exposure to wind, or if some bozo blows into the microphone to see if it's "on." When the diaphragm "bottoms out" against the backplate, the polarization voltage causes electrical arcing, and that tears little holes in the material. By contrast if that happens to a Mylar diaphragm, you just remove the polarization voltage, the membrane "unsticks," and normally no harm has been done apart from the interruption of service.

Where metal diaphragms arguably have a slight technical advantage is in the manufacture of pressure transducers (omnidirectional capsules), since those are more highly tensioned physically than pressure gradient transducers (the resonant frequency is at the upper end of the frequency range or a bit beyond it), and it is somewhat easier to bring a metal diaphragm up to a constant, consistent high tension than it is with polyester film. However, that hardly matters nowadays.

Mylar film is a patented product of DuPont. Gefell was "behind the Iron Curtain" as we used to say, and lacked both hard (Western) currency and any legal way (or government permission) to draw up sales agreements with Western sources of supply, so they were forced upon their own ingenuity and locally-sourced materials. The fact that they continued over the years to manufacture PVC and metal diaphragms reflects the mixture of choice and necessity in their very particular set of circumstances; it wasn't purism for purism's sake.

--best regards

[yug du nord]

He's not very active on board these days, but check with dactylus regarding this subject......  he's done a lot of research, and has a nice collection of vintage Gefell.

[page]

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.

off topic, but I'm curious if you know why that is. (the above phrase alludes to a restriction, not necessarily a choice of something else/better).

[illconditioned]

Dear David,

This is an interesting history to be sure.

I've read two things.  First is that Gefell put a (quartz or something else?) layer on the backplate to prevent the "bottom out" problems you refer to.  Second, there is a guy, former employee of Gefell maybe, who "reskins" the Gefell mics.  The story is that he does both PVC and Nickel capsules.  The vendor claims his m70 caps were reskinned, so we'll have to see.

You bring up an interesting point of tension in omni vs cardioid metal mics.  Well, I'll just have to listen and find out.  My eventual goal is to get a pair of Gefell MK2xx 1/2" omni capsules, but those are very costly.  I'll try the cardioids first.

  Richard

[Gutbucket]

I have 1970s DDR era m94 capsules and MV692 bodies modified for P48.  One capsule had problems so I sent the pair back to Gefell in Germany last fall and had them do work on both of them to bring them up to par. They came back with detailed response graphs showing a nice close match between them.  They're great mics and I'm quite happy with the match and their overall clarity and smoothness, especially through the midrange.  The response bump up top can be a nice attribute recording from a distance, and can be a bit much at times up close. I've used them mostly on stage and if that response ends up a bit bright there, it's easily managed with a bit of EQ, so I sort of think of it as 'pre-emphaisis' and compensate for it later.  I find their bass respose begins to taper down below about 400Hz, which is EQ-able too, but I usually mix them with omnis which takes care of the bottom.  I've used them mostly for acoustic stuff and would prefer a flatter response at the bottom, but on bass/subwoofer heavy material the tapered low end response could be helpful.  The combined response without EQ could be just the ticket for recording closer than the normal sweetspot at a large amplified event without front stage fills, compensating somewhat for the dull boom-zone up front.

I bought these not because the diaphrams are nickle, or because of the response bump particularly, but simply because their performance is very good, I was happy with what I heard on other recordings and the price was attractive for a pair of good quality German cardioids.  Even factoring in the cost of the return repair trip to Germany (pooled mics and shared shipping expense with several others here) I have a great pair of caridoids at significantly less cost than what I would have had paid for equivalent mics from John's other 'big 4'.

I hope that helps somewhat Richard.

I assumed the use of nickle for the diaphram was primarily due to a slower pace of technological change due to the cold-war isolation situation.  Interesting to hear more about the specifics. 

[Myco]

I have 1970s DDR era m94 capsules and MV692 bodies modified for P48.  One capsule had problems so I sent the pair back to Gefell in Germany last fall and had them do work on both of them to bring them up to par. They came back with detailed response graphs showing a nice close match between them.  They're great mics and I'm quite happy with the match and their overall clarity and smoothness, especially through the midrange.  The response bump up top can be a nice attribute recording from a distance, and can be a bit much at times up close. I've used them mostly on stage and if that response ends up a bit bright there, it's easily managed with a bit of EQ, so I sort of think of it as 'pre-emphaisis' and compensate for it later.  I find their bass respose begins to taper down below about 400Hz, which is EQ-able too, but I usually mix them with omnis which takes care of the bottom.  I've used them mostly for acoustic stuff and would prefer a flatter response at the bottom, but on bass/subwoofer heavy material the tapered low end response could be helpful.  The combined response without EQ could be just the ticket for recording closer than the normal sweetspot at a large amplified event without front stage fills, compensating somewhat for the dull boom-zone up front.

I bought these not because the diaphrams are nickle, or because of the response bump particularly, but simply because their performance is very good, I was happy with what I heard on other recordings and the price was attractive for a pair of good quality German cardioids.  Even factoring in the cost of the return repair trip to Germany (pooled mics and shared shipping expense with several others here) I have a great pair of caridoids at significantly less cost than what I would have had paid for equivalent mics from John's other 'big 4'.

I hope that helps somewhat Richard.

I assumed the use of nickle for the diaphram was primarily due to a slower pace of technological change due to the cold-war isolation situation.  Interesting to hear more about the specifics.

 
I agree with your observations whole heartedly. The reasons that you've mentioned were the main reasons that I chose Gefell's for the purpose of recording "rock" type shows. For taperssection recording, adding the omni's in gives the added bass boost that you'd like, and for closer in FOB type taping they give the necessary clarity to the bass, without getting too muddy or boomy from proximity.

[Gutbucket]

I posted the response charts which the MG factory returned with my M94s over in the team Gefell thread a while back if anyone is interested in seeing them.  It's an attachment on this post- http://taperssection.com/index.php?topic=144869.msg1974932#msg1974932. Reading that again, it seems we both pretty much repeated the same thoughts here, Myco. 

[John Willett]

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.

off topic, but I'm curious if you know why that is. (the above phrase alludes to a restriction, not necessarily a choice of something else/better).

This was in conversation with Stephan Peus several years back.

I don't know the reason, but they found they could not do it - so they used titanium instead.

Maybe it's the grade of nickel and it's something Gefell got right in communist days and have a source of the right grade of nickel for membranes.

All I know is that Neumann Berlin admitted they could not do it.

[dream]

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.

off topic, but I'm curious if you know why that is. (the above phrase alludes to a restriction, not necessarily a choice of something else/better).

This was in conversation with Stephan Peus several years back.

I don't know the reason, but they found they could not do it - so they used titanium instead.

Maybe it's the grade of nickel and it's something Gefell got right in communist days and have a source of the right grade of nickel for membranes.

All I know is that Neumann Berlin admitted they could not do it.

Maybe it's more like: Neumann don't want to make Nickel diaphragms anymore. As far as I remember Nickel membranes could cause problems with very small particles going between backplate and membrane causing crackles. I think they changed to Titanium for a reason.

[John Willett]

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.

off topic, but I'm curious if you know why that is. (the above phrase alludes to a restriction, not necessarily a choice of something else/better).

This was in conversation with Stephan Peus several years back.

I don't know the reason, but they found they could not do it - so they used titanium instead.

Maybe it's the grade of nickel and it's something Gefell got right in communist days and have a source of the right grade of nickel for membranes.

All I know is that Neumann Berlin admitted they could not do it.

Maybe it's more like: Neumann don't want to make Nickel diaphragms anymore. As far as I remember Nickel membranes could cause problems with very small particles going between backplate and membrane causing crackles. I think they changed to Titanium for a reason.

No - it *is* because they cannot do it.  They did try.

But the full reason, I do not know.

Any small particle between the diaphragm and back-plate will cause a problem - whatever material the diaphragm is made from.

That's why capsules are made in clean rooms.

[DSatz]

Gutbucket, it's difficult if you want truly flat low-frequency response for distant pickup with a pressure-gradient (velocity) condenser microphone. The force exerted on the diaphragm due to the pressure gradient effect reaches a maximum at the resonant frequency. That resonance is severely damped, of course--but it's still basically a bandpass filter, with an inevitable eventual rolloff at both low and high frequencies. Only a pressure transducer can have truly flat response down to the lowest audio frequencies and still have a usable overall level of sensitivity. If you equalize a directional microphone to be flat down to lower frequencies, you bring up the 1/f capsule noise and any solid-borne sound in the process.

Miking distance also needs to be considered in relation to proximity effect. I don't know of any cardioid condenser microphone that has truly flat low-frequency response (say, from 50 Hz on up) for semi-distant or distant pickup. The frequency response of a microphone is supposed to be measured under conditions equivalent to an infinite measuring distance--but no manufacturer that I know of has ever published response curves like that. Instead, they measure from whatever distance they measure for practical reasons--then they "correct" the result (i.e. they raise the low-frequency response that they publish) so that it corresponds to what would hypothetically occur at (most often) about a 1-meter pickup distance. That distance is typical for many studio applications, but with a pressure-gradient microphone at 1 meter, proximity effect is still boosting the low frequencies.

Thus even if a perfectly flat graph is published, your cardioid or other directional microphone will have a definite low-frequency rolloff when picking up more distant sound sources. And one well-known manufacturer "corrects" its published graphs to even less than 1/2 meter, so their flat-seeming low-frequency response curves really represent an even greater low-frequency rolloff in actual recording situations.

[Gutbucket]

Understood, thanks!

[dream]

Neumann Berlin can't make nickel diaphragm capsules, so their metal diaphragm mics use titanium - mainly the TLM50 / M150 / KM133-A/D.

off topic, but I'm curious if you know why that is. (the above phrase alludes to a restriction, not necessarily a choice of something else/better).

This was in conversation with Stephan Peus several years back.

I don't know the reason, but they found they could not do it - so they used titanium instead.

Maybe it's the grade of nickel and it's something Gefell got right in communist days and have a source of the right grade of nickel for membranes.

All I know is that Neumann Berlin admitted they could not do it.

Maybe it's more like: Neumann don't want to make Nickel diaphragms anymore. As far as I remember Nickel membranes could cause problems with very small particles going between backplate and membrane causing crackles. I think they changed to Titanium for a reason.

No - it *is* because they cannot do it.  They did try.

But the full reason, I do not know.

Any small particle between the diaphragm and back-plate will cause a problem - whatever material the diaphragm is made from.

That's why capsules are made in clean rooms.

I checked your assertion Neumann is not able to produce nickel diaphragms with the Neumann headquarter. Maybe it was a misunderstanding between you and Mr. Peus because I got the info directly from the source that Neumann around 2000 stopped producing Nickel diaphragms. That was because Titan is less prone to problems than Nickel. Nickel has less longevity than Titan. The 'trick' is to make the whole capsule from Titan, not just the membrane, something competitors are not to do similar easily, as it was a result of years of research. It was pointed out clearly to me that it was purely an engineers decision because of better quality and NOT because Neumann isn't able to make Nickel diaphragms anymore. They see Titanium as technical superior for manufacturing, durability and they have far less service cases for the corresponding capsules since then.
From the logical side it wouldn't make sense either ... Neumann had the knowledge to make Nickel membranes until around the year 2000 ... why should the knowledge suddenly be lost or the tools vaporize?

[SmokinJoe]

A few months ago I recorded a show in a small opera house.  I came in during sound check and could put mics wherever I wanted.  I put 3 pairs of mics in different locations, so I could pick the best one afterward.  I had:
- Schoeps MK4's actives head high in the sweet spot.
- Gefell M210 hypers hanging off the balcony rail (M21 caps with 200 series bodies)
- Gefell M295 cards at the corner of the sound board... basically 10' below the balcony rail Gefells.  I wanted these on stage, but the snake was full, so this was it.

This is not a controlled experiment at all... different mics, locations, preamps, etc.  But, it's human nature to compare the results, so I will. I've run my Schoeps and Gefells enough that I could predict the results, but I had no clue how the M295's would sound. The FOB Schoeps sounded fat, as I would expect.  The Gefell hypers on the balcony rail had a bit more presence/clarity, as I would expect. The M295's seemed to have significantly more presence than the M210's.  I would have needed to EQ some of that out.  Remember, this is only one data point in poorly controlled experiment.

If I still have the raw wave files, it's on the hard drive of a computer which is currently dead.  I plan to resurrect that computer soon, and if I find the files I'll try to post a sample.

[sdelsolray]

I currently have pairs of Gefell M295 and M296 and I used to have a pair of Gefell M294.  All I can say is the Gefell M29x Series mics are simply wonderful.  Accurate, detailed, quiet, predictable and honest.

[illconditioned]

I just received the Gefell M70 capsules and they look good.  They appear to have new "skins" on them, nice and shiny inside the dull metal of the capsules.

Well, I just put them on a pair of AKG 460 bodies, with a bit of brass mesh squeezed in "fill in" the outer shell/ground contacts.  They seem to sound good, but I'll need to get them in front of some music to really tell.

  Richard

[DSatz]

dream, I think you have been given incorrect or perhaps incomplete information. Neumann (Berlin) initially stopped manufacturing nickel-membrane capsules around 1970. It isn't a question of their not knowing (in the abstract) how to produce the membranes, but once Mylar had become well accepted, there was no reason to continue that troublesome process any more--or to produce further capsules which would only need replacing because they were so easily ruined.

The KM 54 was the nickel-diaphragm microphone that Neumann made in the largest quantities. Replacement capsules were often needed for this microphone, and once Neumann no longer made such capsules, they developed a way to fit the capsule head of the KM 64 (and later the 74 and 84) onto the KM 54's amplifier. You can often see such microphones for sale on eBay with no mention of the fact that the capsule isn't the original type. The difference there is far more than the diaphragm material, since the KM 64's capsule uses an entirely new (for its time) backplate design with considerably better off-axis linearity, but an unmodified KM 54 has a high-frequency elevation considerably greater than that of the KM 64/74/84 to begin with, so there really should be no pretense that it will sound at all the same.

When Neumann introduced the (solid-state) TLM 50 in about 1990, they again found themselves using nickel membranes for a while. But then they introduced the "M 150 Tube" with a titanium capsule. Soon they changed the TLM 50 to use this capsule instead, so that once again they are no longer producing any nickel-membrane capsules.

--best regards

[illconditioned]

It is interesting that Neumann is still making the titanium capsule.  There must be a reason, otherwise they would use mylar, right?  Apparantly ACO Pacific (Japan?) makes measurement capsules out of titanium as well (these are used by others, such as THE, for recording).  Other companies seem to be using Nickel (Gefell) and Stainless (G.R.A.S.).

  Richard

[dactylus]

*
bump for info

[Gutbucket]

Some measurement mics still commonly use stainless, nickel or titanium diaphragms.  I suspect one reason is to help ensure improved thermal stability by constraining capsule construction materials to those which have all have very similar thermal expansion properties, so that the entire capsule assembly to shrinks or expands in an isotropic way without varying diaphragm tension as much as might occur otherwise.  I suspect use in measurement mics may also have to do with retaining calibration over longer time frames, and/or application in environmental conditions which require such materials.

But don't overlook the influence of simple historical inertial.  Designs are tied to the materials and manufacturing techniques available at the time.  Once developed, sufficient economic incentive is necessary before it makes sense to redesign for new materials or manufacturing processes.  A new design uses currently available tech, whereas older designs retain the use of what was then contemporary but is now old tech, and economic factors determine whether those older designs remain in production as originally designed, are discontinued, or end up being redesigned.

Also keep in mind that stainless steels are alloys containing various amounts of chromium and nickel.  Metallurgically, there may not be as much difference between a "nickle" and a "stainless" diaphragm as one may imagine.

[mylesgm]

Well, I just put them on a pair of AKG 460 bodies, with a bit of brass mesh squeezed in "fill in" the outer shell/ground contacts.  They seem to sound good, but I'll need to get them in front of some music to really tell.

  Richard

How did you mount the m70s on a 460 bodies?!  They don't look even remotely the same diameter or have a similar mount...