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[brett]

Always heard these spoke of as in the same vein as they were both used in U47's. But looking at the published freq responses, the M7 looks like it has more top end than the chinese k67's.

Trying to figure out what capsule to put on a bottle mic. I currently use a 414eb with a ck12 brass and find I am boosting at 2k and cutting with a notch at 10-12k to make them usable. seems the k47 already has that kind of response. Trouble is, there are no k47's mounted in bayonet's like the M7 for me to demo aside from the blue B7 knock off. Their curve doesn't seem to match the original.    

sorry for the poor images. they are all I could find.

[brett]

M7

[brett]

I remember listening to a U47 by Blue compared to a Tele USA U47 and didn't like the Blue much. It was a few years ago though. Did the reconditioned Blue U47's come with the B7 capsule?  I am considering a M7 type bayonet with either a working M7...rare... or a thiersch or a Blue B7. The Blue is the only one I know I can go to a  music store and demo. The others options could be more costly and may not yield what I am after.

Can you rent just an M7 bayonet or a Blue for that matter?

Also how hard would it be to mount a k47 in a Neumann bayonet? where can I even find an empty bayonet?

And what K47, manufacturer, or restorer should I be looking to talk to?

I know I have a lot of questions. Any help would be appreciated.

Thanks,
Brett

[Klaus Heyne]

Brett,
A K47 will not fit inside a Neumann bajonet or 'P' head.

As to comparing frequency plots: That's like comparing verbal descriptions of colors; due to the impossible nature of capturing the timbre of a capsule with a frequency graph, let alone the imprint of the processor behind the capsule (at what volume, what distance from the sound source, what source were these graphs created, and then how were they averaged or correlated to the mic pres?) these graphs are unreliable and unsuitable for comparing sounds or responses; and certainly of just the capsules.

Example: you show an B.L.U.E. frequency graph of supposedly just their "B7" capsule. Do we know what processor was used to arrive at that (obviously smoothed and averaged) graph? Was it a stock U47 that capsule was mounted in?  Or maybe one of the B.L.U.E. "modified" U47 with 6072 tube, third party transformer, or FET processor?

Any time you want to look at what just one component in a famous mic contributes to the whole, you will not get very far, because you cannot strip out the contribution of the others.  In the case of a condenser mic capsule, it is impossible to weigh the contribution of it by itself. Compare the sound of a genuine M7 in a U47 and an M49. There is quite a difference.

Ask the eminent AES standards and protocols authority on such matters, David Josephson, and he can sing you a song about the various, parallel, often incongruent, testing protocols and (non-) standards in our industry that to this day render most of the condenser microphone measurements and comparisons you can research a farce.



P.S.: only Neumann capsules should be termed M7 and K47. Every other manufacturer's copies would need to be acoustically evaluated by you on their own terms, regardless of their appropriation of another company's names.

[brett]

Thank you Klaus. The graphs are more confusing than they are helpful. But I do hear audio professionals talking about the frequency response of mics when comparing the capsules. You stated "An M7 will not fit inside a Neumann bajonet or 'P' head. "

Also I am just looking for suggestions on makers of clone capsules, or reconditioned originals that fit that format of bottle mic bayonets, lolipops, p-heads or any other name they can go by.

So what variances are to be expected in an original U47 with a K47 vs a U47 with an M7. Lets pretend they are new and not aged and not out of tolerance. All other variables being equal. Just differences in the capsule.  How do they differ sonically and frequency response wise?

I am thinking of mounting the capsules on a bottle mic that features an EF86 and cinemag tranny. Anyone used a Flea Capsule on your bottle mic? Heck, I may just demo the flea U47 clone. Nice looking clone.  

[compasspnt]

A good microphone is a complete system, wherein the capsule, electronics, transformer, and even internal acoustic spaces and grille are carefully designed to work together.

Just interchanging capsules may not give you what you want, and it certainly explains why published specifications of one single part of the system may be misleading.

[brett]

that is why I am planning to try multiple capsules. the mic is designed to work with these types. Considering how many capsules are available in that format I am sure I will find a few that will give me what I need.

(Re: K47 not fitting inside Neumann bajonet head):
Flea for instance uses an "M7" type of capsule in their mic and their bayonet. They also put a k47 in a bayonet. I was planning to demo both of these on the lewilson bottle.  Those and the Blue seem to be my best options. If the results don't work the bottle has a return policy.

[Nick Sevilla]

Hi Brett,

I own one U47 with a K47 capsule, and am getting a second, older U47 repaired, which has a M7 capsule with it.

When I get it back from repair, I will be conducting some tests, swapping out different components in each, to compare them more accurately.

One of the tests will be pink noise, then white noise, and some sine waves at various frequencies, all at the same level and coming from the same sound source speaker, distance, etc.

Another test will be a few instruments I have, into the various combinations of the two mics, again at the same distance from the mics, and recorded at the same time each pass, to minimize chances of the instrument being at a different position. I might build a holder for the instrument, so I cannot change the position of it from the mics.

I plan to swap :

a.- The capsules between the two bodies as they are with all other components as I bought them originally.

b.- The tubes, with all other parts in their original bodies (since I have an Andreas Grossman replacement "tube" to test on the older mic,thus necessitating the tube swap).

c.- The mic to power supply cables, with all other components in their original mics.

d.- The power supplies, with all other components in their original mics.

This will give a few answers as to how the M7 capsule works, as well as the Andreas Grosse "tube" replacement, which is actually a solid state solution, which uses exactly the same voltages as the VF14m tube. If this replacement proves to suck, I will then save some money for a genuine working and tested VF14m tube, and buy it from whomever is a reputable seller (Klaus Heyne, or anyone else respected in the mic community). FYI: I don't sell tubes. K.H.

I should have this mic in my hands in a few weeks... and after the tests are done, I hope it will be useful for the general community here, to dispel a few myths, and also to create some new questions regarding mics in general, and specifically to allow for people to listen to these tests, and then do their own tests in their studios, following my methodology, especially when comparing the multitude of U47 clones now being made.

This test will live on my website indefinitely, and at 24/96Khz sample rate Broadcast Wave audio files. I'll probably include the Pro Tools session with a zipped archive for download, along with a PDF detailing the process, and a few pictures for good measure

Cheers

[brett]

sounds interesting.

[David Satz]

Brett, attached is a clearer scan of the second flyer that you posted, with both sides combined into one image since this forum allows only one image file per message slot.

Based on the Schoeps model that's featured opposite the Neumann, I figure the flyer must be from 1954-55. "American Elite" (the publisher of this flyer) was Telefunken's U.S. representative at that time.

The blue Gotham Sales Co. catalog page that you posted in your first message appears to be from 1957-59; I think it's unlikely to be 1957, though, because the M 49 and M 50 are already shown with "b" designations.

--best regards