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 1 
 on: September 15, 2020, 11:21:29 am 
Started by afterlifestudios - Last post by Jim Williams
Most diode noise is ultrasonic.

 2 
 on: September 14, 2020, 12:31:28 pm 
Started by afterlifestudios - Last post by RuudNL
True, when they are 'zenering'...
But under the zener voltage a zener diode is virtually non existent.
(A .1 uF capacitor won't help very much to reduce zener noise in the audio frequency band.)

 3 
 on: September 14, 2020, 12:15:51 pm 
Started by afterlifestudios - Last post by Jim Williams
Zener diodes create a lot of rf hash and noise. Place a fast .1 uf film cap across it to filter it.

 4 
 on: September 13, 2020, 02:42:39 pm 
Started by afterlifestudios - Last post by RuudNL
I am going to install a 10 Watt/120 Volts zener across the output.
This will reduce the output voltage to a safe value, even with no load.
When loaded with the microphone, the voltage will be lower than 120 Volts anyway.
(So the zener doesn't 'exist' with the microphone connected.)
And even when the microphone gets connected with capacitors charged to 120 Volts, this won't hurt the microphone.

 5 
 on: September 13, 2020, 12:20:38 pm 
Started by afterlifestudios - Last post by Jim Williams
Place a 1 meg 1/2 watt resistor on the output of the psu caps to ground to drain them when shut off. It also provides a load if the mic is not connected.

 6 
 on: September 12, 2020, 09:38:01 pm 
Started by afterlifestudios - Last post by afterlifestudios
Yes indeed.  No “hot swapping” here.  If one my NG PSU’s gets turned on unloaded, I drain the caps with a big resistor and measure for any stored voltage before connecting the mic. (Either that or wait 20 mins, as those caps can hold a charge for quite a while.)

 7 
 on: September 12, 2020, 04:00:33 pm 
Started by afterlifestudios - Last post by RuudNL
I am interested in your findings!
I don't suppose + or - 10% will make an audible difference, but I never tried...

By the way: I measured the unloaded voltage of the original Neumann U47 power supply.
The unloaded DC voltage of my power supply is 378 Volts!
So it is very important to connect the cable and microphone first before switching on the power supply!
The capacitors in the power supply will hold the voltage for a long time.
And I am sure the VF14 wouldn't like a burst of 378 Volts! (Which means theoretically a filament voltage of ~126 Volts...)

 8 
 on: September 10, 2020, 12:55:00 am 
Started by klaus - Last post by Timtape

3. Speaking of distances: here is the most overlooked and biggest flaw of shootouts - a flaw so big, it will render any comparison between two or more mics pointless and inconclusive: to position several mics at the same exact distance from the sound source.

We see pictures of several totally different microphones with totally different sensitivities and timbres being meticulously lined up so that their capsules were aligned within millimeters - all in service to the illusion of scientific objectivity. As if we didn't know that every mic has its own sweet spot- a factor recording professionals pay close attention to: who would place an SM58 and a U47 at the same distance from the singer?

I agree Klaus. The SM58 is equalised for close vocals. The U47 isnt. At the same distance of course they will sound very different. Used as per their respective user manuals, not nearly so different.

 9 
 on: September 10, 2020, 12:37:20 am 
Started by klaus - Last post by Timtape
Studio work is mic shootout all the time.

Perhaps so but the mere fact that it occurs  doesnt validate it.

The motive is important, may be honourable or not, and the practice may or may not be be based on solid evidence.
 
It's  easy  to "impress" a client vocalist who knows nothing about microphones and production, that testing ten different microphones on his or her voice  - all this wonderful personal attention - which extra time the performer may well be paying for - is  justified in the cause of producing a  superior product. That the "expert" is searching for the mic that allegedly best "matches" this one voice seems superficially impressive especially if the vocalist doesnt know any better.

What is the evidence that it works or is the best method? And best method for achieving  what exactly?

Tim


 10 
 on: September 09, 2020, 12:28:02 am 
Started by afterlifestudios - Last post by afterlifestudios
Thank you, gentlemen.  Yes, that correct.  100VDC B+ on my NG (loaded) with mains at 115 VAC. 
I’m more curious about the sonic effect of the resulting change in capsule polarization voltage, than the VF14.
I’ll give it a try, keeping the Variac so that the measured B+ is within 10% of 105VDC.
Thanks again for your thoughts.

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