U47 Noise Cardioid Mode (Solved)

[ln76d]

Vintage microphone, you mean Mic and mid shop?

Yes, it is virtual brand for 55$ chinese capsules.
He is even lying customers.
We know that he's thief and liar, but please - not another thread...

It's actually a "Vintage Microphones France" Capsule. I'm not sure if they really make it themselves. There is no homepage available. Maybe it's just a renamed Chinese K47 (looks equal).
It really feels as if the gap between the membrane and the backplate is very very thin and the membrane does not really have the right tension. When hit by a medium loud sung "p", even through a pop shield, the "wind" appears. After some time it feels as if the tension is "ok" again and it goes away.
But let's forget that faulty thing and see what Mr. Thiersch has to offer
The Voltages seem to be fine. 56V on the capsule and 105 for B+.

I'm already looking forward to another build. Still have to decide on a mic...

Thank you!

56V?
Did you measured before or after R1 100M resistor?
If after, you should try before
Beside polarisation voltage, most important is to check after R5 100K on the tube plate.
For M7 definately you should go for Neumannn specified 63V.

 

[JRJR]

I'm totally out of this discussion.

That's good to know!
I forgot it, let me check again. I just read somewhere that for the PVC capsules 10V more are better but for the Mylar version the normal "around 60V" are correct. I ordered the Mylar version. I'm actually not familiar with what +/-5V polarization voltage do with the sound.

 

[ln76d]

I'm totally out of this discussion.

That's good to know!
I forgot it, let me check again. I just read somewhere that for the PVC capsules 10V more are better but for the Mylar version the normal "around 60V" are correct. I ordered the Mylar version. I'm actually not familiar with what +/-5V polarization voltage do with the sound.

Use U47 schematic, there are marked voltages, exactly five.
105V at the input, 34V at the plate, 36V filament, 1.1V cathode, 63V capsule backplate.
In my opinion, the best what you can make is close as possible to original circuit.
If your multimeter have lower input impedance than 1Gohm, you need to measure backplate polarisation  before R1.
If your measurement is correct, you have right now 7V of difference on the backplate.
It's the value where you should hear difference in sensistivity for higher frequencies.
Did you use whole kit from micandmod or build your own or any other kit?
If first - i didn't found any BOM for it.
Anyway what are the values of R7 and R8?

 

[JRJR]

Did you study mic building? Exceptional knowledge!
I measured all the voltages again (after letting the unit warm up) and got everything right. Tolerances are okay I guess (+/- 2V).
Indeed I checked it on the wrong points and wrong direction. Thank you!
R7 and R8 are 2 and 3 M.
Everything seems to work now. Still waiting for the M7 and very excited for the results!

I got a whole kit from Mic and Mod. Can't complain (except capsule...)

Thank you all!

 

[ln76d]

Did you study mic building? Exceptional knowledge!
I measured all the voltages again (after letting the unit warm up) and got everything right. Tolerances are okay I guess (+/- 2V).
Indeed I checked it on the wrong points and wrong direction. Thank you!
R7 and R8 are 2 and 3 M.
Everything seems to work now. Still waiting for the M7 and very excited for the results!

I got a whole kit from Mic and Mod. Can't complain (except capsule...)

Thank you all!

Nope, am learning here a lot

Great that everything works fine and you are happy

For micandmod kit.

Of course you already have the kit, but maybe someone other will choose something different

For 838,80euro kit include - chinese body, chinese capsule and transformer probably is also chinese.

There's few much better options for making U47 "clone"

 

[JRJR]

Hi guys!

so, I just installed the new Thiersch capsule and boooom what a sound! Also I got new Philips tubes from the early 60s.
Very pleasing, smooth and expensive sound.

BUT sometimes (when the mic is warm) I still get a "sirrr", very high, not that loud but too loud to record. What could it be?
Especially since it's caused by heat obviously I don't have any idea.

Thank you all very much!

 

[JRJR]

So, I'm finally there!
It works!
Obviously it was some kind of moisture inside the mic that evaporated the moment the mic really warmed up but came back a little once it cooled down. Its gone now after some days. The noise floor is incredibly low, the sound is amazing.
The highs are so damn smooth! Perfect for sibilant male vocals.
The overall tone is very warm, there are no peaky mids and it takes very little processing to have an astonishing vocal sound that sounds like a record.

Thank you all very much!

 

[Glacier]

JRJR, I just went through the same troubles you did with this kit.

Please see my post about the fix.  It'll make your mic nice and quiet.