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 1 
 on: Today at 02:59:39 pm 
Started by radardoug - Last post by Nob Turner
It's obvious - this mic will give you a more golden sound... leading to more gold records.

 2 
 on: Today at 11:07:35 am 
Started by Recording Engineer - Last post by klaus
(...) It's the only transformer I've ever held in my hand that rattles... And apparently it's the way Neumann did it and should go away once mounted? Magnetostriction...

As I understand it, magnetostriction is only present in ferromagnets- those that remain magnetized at all times (i.e. permanent magnets).
Transformer magnets, as used in condenser mics, are not ferromagnetic, so that phenomenon would not be encountered there.
I would therefore question your use of the word "apparently".

Besides, I have never run into rattling magnets in microphones, new ones or old ones, aside those with badly constructed or sloppily assembled transformers. Which would indicate that, whatever rattles in yours will not go away with time.

I would suggest you inspect the transformer closely for manufacturing slop.

 3 
 on: Yesterday at 06:52:32 pm 
Started by Recording Engineer - Last post by Recording Engineer
A friend is building me a U47-type mic with a Neumann capsule. I'm currently gathering transformers from IOAudio, AMI, and Andreas Grosser as options and the IOAudio has come in first. It's the only transformer I've ever held in my hand that rattles... And apparently it's the way Neumann did it and should go away once mounted? Magnetostriction... Someone care to explain in laymen-terms and confirm this is indeed the way Neumann did it?

By the way, if anyone cares, I'm also gathering the currently-manufactured "tube substitutes/alternatives" by Telefunken, Phaedrus, IOAudio (should be available at some point this year), and my friend's wishful-thinking but completely expected to come in dead-last ("arrangement"?) with a widely-available and used cheap tube.

And we could careless that it won't sound like an original vintage U47; as we already know it won't! Just trying to make the best-sounding mic (to us) with a U47 circuit and parts-types as we can with the best readily-available parts... Andreas Grosser and some others are already do that, but this is the next-best alternative concerning price.

 4 
 on: March 23, 2017, 12:00:37 pm 
Started by MikeCheck - Last post by Jim Williams
Use an el cap to bypass the reference/adjust pin to ground on a LM317/337/LT1085, etc. It lowers the noise. I use 47 uf here, a Panasonic FR series tantalum replacement. Those have lower impedance specs than a tantalum cap.

 5 
 on: March 23, 2017, 08:35:14 am 
Started by radardoug - Last post by boz6906
http://www.neumann.com/forums/view.php?bn=neumann_mictec&key=1236063072&v=f

 6 
 on: March 22, 2017, 10:33:16 pm 
Started by radardoug - Last post by gtoledo3
Yeah, that is something that in fact did exist. It was for an anniversary year.

 7 
 on: March 22, 2017, 08:00:24 pm 
Started by radardoug - Last post by radardoug
Klaus, theres this guy listing a gold U87 on Ebay. Wants lots for it! He says 300 of these gold ones were made.
Can you or anyone else confirm this?

 8 
 on: March 22, 2017, 06:25:08 pm 
Started by MikeCheck - Last post by uwe ret
As the filament current for a single AC701(k) is only 100 mA you will probably be fine with your present arangement. If it is working satisfactorily without getting too hot to touch comfortably, there is no need to replace the regulator IC.

 9 
 on: March 22, 2017, 04:08:05 pm 
Started by MikeCheck - Last post by MikeCheck
Thanks Uwe for all your help and information!

I will change to the 220 package.

 10 
 on: March 22, 2017, 11:45:35 am 
Started by MikeCheck - Last post by uwe ret
Congratulations!
As I never considered this forum to be a DIY tutorial, I forgot to mention a recommendation to use a LM317-T in the TO220 package and mounting it to the metal chassis for proper heat dissipation.

As to the concerns about noise raised in previous posts to this thread:
a) the LM317 is an analog regulator with the reference far removed from the output path;
b) the filament is too sluggish to let its temperature follow mV noise variations in its supply;
c) to ameliorate any doubts, some data sheets suggest an additional capacitor of 1F or larger
    placed between the 'Adjust' terminal and ground (I never found it to make any difference);
d) anyone undertaking any equipment modifications should be qualified enough to possess a
    basic understanding about proper circuit layout and grounding principles.

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