My G7 mic exaust my tubes..

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tamtamstudio

Well-known member
Joined
Jun 4, 2004
Messages
118
Location
Italy
:grin:
It's a funny question, but i can't explain by myself.
I don't believe much in coincidences, but during this month i feel a strange behaviour in a couple of my G7 mics.
I did a couple of G7 with Peluso CEK12 capsule and a couple with CEK369.
They sound different, of course,but very well and i love these mics.
I had used 4 equal old tubes (TESLA EF-86), i like their smooth sound.
But in the last days, i have substitute all the tubes on the CEK-369 mikes with 2 new, because a big noisefloor comes up (white noise, rumble..).
What do you think, why in the other 2 (CEK12) no perceptible noise was coming up.. These tubes are exaust? there is a way to test it?
:oops:
 
No, the tubes won't wear out anywhere near soon in the G7 - unless maybe if you have too high a heater voltage.

Could be "natural" early-fallout-rate of the tubes.

I have failure in maybe 10-20% of NOS tubes (that test right from start) after running for 48hours.

Jakob E.
 
these are the voltages on my mics ( i report you only one for example).
at
Pin 1 115V
P 57,6V
F 5,8V
A 53,5V
K 1 V

on the power supply (mic diconnected)
Pin 1 157,5V
F 6,1V

Seems a little bit low, what do you think?
can it compromise the sound?
 
Sorry again Jakob, in these mics i percieve a hum noise from alogen lights in the studio. This noise will disappear when i touch the grille with one hand and the body of the xlr with the other.
Inside the mic i connect the ground to the chassis mic, can be a ground loop? or is a better way to try with a thinest grid?
 
Is the grill soldered to the body? What is your mesh size holes pre inch or cm and what is the % open area. I have found 1 layer of 16 x16 per inch at 49% open about as open as I can go without noise.

Try bringing the fil to 6.3VDC maybe you have tube thats cathode oxides don't like to be underheated.
 
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