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[ratite]

I recently got a z29 pad which I am guessing locks between the capsule and body of a km54.It has a switchable ring and 3 marks which can be aligned(no detents though),a line,one dot and 2 dots.Does anyone know the meaning of these symbols?

Unfortunately I'm not in a position to power up my 54's to check the pad and ascetain for myself.

I have read that km54/56's have nickel capsules.Does this mean Nickel evaporated/sputtered on mylar/polyester or actual metal diaphragms?

How does nickel construction affect longevity of the diaphragm?

What are the subjective qualities/deficiencies of nickel vs gold in capsule construction and why might one be chosen over the other?


Futhermore I read somewhere on rep about gefell making new nickel caps (I'm assuming for 54's,56's,256's etc).This isn't mentioned on their website,can anyone confirm this and has anyone tried them?Cost,similarity to well kept originals?

Thanks in advance for answers to my flurry of questions.

[Klaus Heyne]

ratite wrote on Wed, 08 February 2006 20:49

I recently got a z29 pad which I am guessing locks between the capsule and body of a km54.It has a switchable ring and 3 marks which can be aligned(no detents though),a line,one dot and 2 dots.Does anyone know the meaning of these symbols?

No idea. Never heard of this pad before

Quote:

I have read that km54/56's have nickel capsules.Does this mean Nickel evaporated/sputtered on mylar/polyester or actual metal diaphragms?

Actual metal diaphragms, around 0,9

[Barry Hufker]

Here's a photo of a Z29 pad, taken from sonicworld.de

Barry

[ratite]

Barry Hufker wrote on Thu, 09 February 2006 15:28

Here's a photo of a Z29 pad, taken from sonicworld.de Barry

Yes,that's how Idetermined what I had.Though I could only find this one reference on the net so we can't cross-check sonic world's claim.Though I have emailed them,I wonder if they know what the markings mean?

Thanks for the detailed reply Klaus.
Having asked at the Neumann forum I know the dates of manufacture for my 2 KM54's but I note one has an "a" after the serial number and the other an"aC".Does this mean only differing batches or perhaps component differences?

Also from checking pics on the web I see 2 head grille designs for the 54,one with 3 paralell vents and another with vertical vents.Any veiws on performance differences and interchangeability?

[Barry Hufker]

"A" stands for the "A" version of the electronics.  "C" stands for the "C" version of the electronics, which are an improved design over "A".  The "A" can be converted to a "C."

Barry

[Klaus Heyne]

Neumann's "a" versions of mics (always spelled in lower case and printed after the model number or sometimes embossed after the serial number) can be converted to "c" versions (same nomenclature system as above.)

As a matter of fact, if there is no "c" mentioned on any Neumann AC 701-equipped tube mic, it did not come with the "c" circuit.

What is the "c" circuit?
It's simply biasing the AC 701 tube in a "self-biasing" mode. That means that the cathode of the tube is connected directly to ground via a cathode resistor and bipass capacitor.

This scheme yields about 2-4 dB better noise specs, and alters the sound of the mic slightly, compared to the "fixed biasing" scheme used with the AC 701 and other tubes prior to 1961.

The change over is fairly simple for an experienced technician.