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Author Topic: Neumann U48  (Read 27393 times)

Oliver Archut

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Re: Neumann U48
« Reply #45 on: February 10, 2010, 06:45:54 pm »

Depending how you hook up your meter something around 16 to 26 Ohm.

Best regards,
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Oliver Archut
www.tab-funkenwerk.com

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J.J. Blair

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Re: Neumann U48
« Reply #46 on: February 10, 2010, 07:14:00 pm »

Greg Norman wrote on Wed, 10 February 2010 15:20

This was bought from Bill Bradley like  J.J suggested.


Not to bag on him, but ... I find it hard to believe that he's the one well known tech who insists on using solid core wire in very high impedance positions.  Coincidentally, he's the same tech that did not pad the resistors in a M49 he serviced, leaving it unusably microphonic.  It seems odd that somebody with that much experience is so unaware of this issue.

Maybe if he participated in this forum, he would learn these things!
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studio info

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piedpiper

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Re: Neumann U48
« Reply #47 on: February 11, 2010, 01:07:14 am »

Sorry if this has been covered, but what exactly is the issue with "using solid core wire in very high impedance positions"?  
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Tim Britton

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johnR

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Re: Neumann U48
« Reply #48 on: February 11, 2010, 01:43:36 pm »

piedpiper wrote on Thu, 11 February 2010 06:07

Sorry if this has been covered, but what exactly is the issue with "using solid core wire in very high impedance positions"?  

It can be microphonic, ie. sensitive to mechanical vibration. In a lower impedance circuit any signal generated by this is more likely to be shunted out by the circuit impedance, but in very high impedance circuits it can be a problem.
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Greg Norman

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Re: Neumann U48
« Reply #49 on: February 11, 2010, 02:19:48 pm »

Oliver Archut wrote on Wed, 10 February 2010 17:45

Depending how you hook up your meter something around 16 to 26 Ohm.

Thanks!
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piedpiper

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Re: Neumann U48
« Reply #50 on: February 11, 2010, 08:15:19 pm »

johnR wrote on Thu, 11 February 2010 12:43

piedpiper wrote on Thu, 11 February 2010 06:07

Sorry if this has been covered, but what exactly is the issue with "using solid core wire in very high impedance positions"?  

It can be microphonic, ie. sensitive to mechanical vibration. In a lower impedance circuit any signal generated by this is more likely to be shunted out by the circuit impedance, but in very high impedance circuits it can be a problem.


Thanks John.
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Tim Britton

row, row, row your boat...

Oliver Archut

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Re: Neumann U48
« Reply #51 on: February 11, 2010, 08:36:59 pm »

To put it in better perspective, a microphonic tube is in the end a condenser mic. The movement of the electrodes polarized by any operating voltage creates a capacitive difference that produces an electric signal.
Something similar happens when a solid core wire is used; if you use a stranded wire you mechanical short out that possibility.

If you use a solid core wire with a high dielectric property (capacitive amplification) like Teflon, you have a bunch of microphonics.

There are several ways to counter act this problem...

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Oliver Archut
www.tab-funkenwerk.com

We are so advanced, that we can develop technology that can determine how much damage the earth has taken from the development of that technology.

Klaus Heyne

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Re: Neumann U48
« Reply #52 on: February 12, 2010, 02:39:06 am »

...like either avoiding solid core wires altogether, or if you absolutely must use one, dampen and arrest its movements with a (high impedance) adhesive.
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Klaus Heyne
German Masterworks
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MDM,

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Re: Neumann U48
« Reply #53 on: February 12, 2010, 04:33:14 pm »

I wonder if using very thin solid-core wire might improve things.
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monoman

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Re: Neumann U48
« Reply #54 on: February 13, 2010, 06:27:13 am »

How about Litz?

Brian.
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Brian Clark.

KaiS

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Re: Neumann U48
« Reply #55 on: February 13, 2010, 06:54:46 am »

MDM, wrote on Fri, 12 February 2010 15:33

I wonder if using very thin solid-core wire might improve things.

No, it's even worse: the thin wire resonates at higher, more audible frequencies if there is no dampening isolation around.

With plastic isolation it can be an improvement.
The capacity depends on the size of the surface.
Therefore the side effects are reduced with thin wires.

Reliability can become a problem - thin wires tend to break, specially at the soldering joints, where smooth copper turns to hard bronze alloy.
You could use silver wire, best with foam isolation, like in high Q HF cables.

Regards
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Klaus Heyne

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Re: Neumann U48
« Reply #56 on: February 13, 2010, 02:18:41 pm »

Assuming no clear sonic advantage of using solid-core wire in the high-impedance section of mics (except when purposely boosting high end, by using certain types of Sterling wire) and nothing but trouble with its reliability, microphonics and solder adhesion, I see absolutely no reason for ever using it in the first place, other than cost.

But even there: how much do a few inches of multi-strand wire, like 96-strand Gotham GAC 3 material, cost? Pennies!
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Klaus Heyne
German Masterworks
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Eric H.

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Re: Neumann U48
« Reply #57 on: February 19, 2010, 06:15:48 pm »

This thread  got me thinking:

How much is vintage a vintage mic that has most of its passive components renewed?
And would it be possible for a 40+ years old microphone to still work nicely with the same components it had since it first left the factory?
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eric harizanos

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