Re: MK-U47 - build thread
« Reply #700 on: October 23, 2020, 04:46:36 PM »
Before my NOS 408a tubes was noiseless, I put them in my Mic and burned them in for 3 Days nonstop.

Interesting. What sort of noise did you get?


EmRR

Re: MK-U47 - build thread
« Reply #701 on: October 23, 2020, 04:48:42 PM »
Thank you that's a good and cheap place to start. I'll try it first thing.
The noise is a scratchy static noise, not constant it never stops for longer than a second or two.

There should be plenty of comments about the 1K5 type in this thread. 

If it doesn't go away or change with different tubes, then it sounds next most likely to be a carbon resistor, there are a few in there. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Re: MK-U47 - build thread
« Reply #702 on: October 24, 2020, 01:35:24 PM »
There should be plenty of comments about the 1K5 type in this thread. 

If it doesn't go away or change with different tubes, then it sounds next most likely to be a carbon resistor, there are a few in there.
Thank you. the 1.5k resistor didn't make any difference but I've been with a tech today and we have ordered other resistors to replace.
One thing I was wondering and perhaps someone here can help me with; why are some resistors metal film other carbon etc? The tech guy wanted to replace the carbon ones with metal ones and he thought I was crazy for wanting to keep them the same type in case it changes the sound in some way.
Thanks again.

Gus

Re: MK-U47 - build thread New
« Reply #703 on: October 26, 2020, 05:19:01 AM »
The following has been posted about over the years

Sub in a 50pf to 100pf cap for the capsule. install the body and grill.
Let the microphone run and test for noise.

If no noise most likely the capsule or connection to the PCB board


If you still have noise

Can be the tubes I see GREEN paint in some pictures are they the 1980s run?

Something I would try but only do if you know what you are doing is to build a tube test burn in circuit to check the tubes for noise outside of the microphone




« Last Edit: October 26, 2020, 09:03:07 PM by Gus »


 

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