tlm103 problem...

[FotisGR]

hi friends... i have a neumann tlm103 . sometimes the out is very low making strange noise and sometimes is ok...the last week i changed the capsule with a newone (original) and the problem comes again now...Low output and strange noise i check everything ... cables, mic pres... all ok...
any idea?

capsule's voltage = -265mV... with or without capsule connected
mic input voltage= 38.9V (50V from my mic pre but when mic xlr connected is going to 38.9V with all mic pres) this measurement is to inside mic xlr connector.

thank you

 

[reanimatorstudio]

first thing to do is replace the capsule with a small capacitor same value as the capsule (470 pF could work). And listen to the electronics.

 

[FotisGR]

i replaced the capsule with a 470pf cap and all electronics are ok... quiet like death... the problem is coming out only when i connect the capsule but... is new    i was wondering about capsules voltage... -265mV is ok? i tried also a peluso capsule and the problem is the same

 

[pasarski]

I don't know about the 103's capsule but isn't 470 pF  quite big for a dummy capsule? I thought most of the capsules fall in to 50-100 pF range. I don't know if it even matters in this case.

 

[reanimatorstudio]

How are you measuring the voltage? Impedance is very high and never negative. Have you got a schematic?
Yes 470 is to high

 

[12afael]

the noise is similar to this http://soundclick.com/share.cfm?id=6611446 ???

 

[FotisGR]

the noise isn't like this... is like more than a mass of air moving and is 30-80hz...is like the air moving around the mic capsule...
At schematic diagramm the x resistor is a white porcelain (smd) with a black line across it ... i know my english are very very poor
when i parallel this resistor with a 10Mohm resistor the mic out comes high and the noise dissapears but the sound is lacck of bass... if i parrallel witn a 100Kohm the sound is like a tellephone...

with or without capsule... from mic ground to capsule's center cable, the voltage across is -265mV

 

[bezen4uk]

Hi,
Try to change resistor x with new one 1GOhm (or add parallel to existing). 265mV measuring is OK - when you measure at that point you make resistive divider (resistor x and input resistance of multimeter).

 

[reanimatorstudio]

scope the voltage there where you measure 60 volts. If you don't have a scope put 47 n to ground and remove the one to ground, and listen again

 

[FotisGR]

i scoped the -60v and is ok... stable dc.. i will try to replace the x resistror...

 

[reanimatorstudio]

must be your capsule

 

[RuudNL]

Is the capsule absolutely dry? Neumann capsules can be very sensitive to moisture is my experience.
When the air humidity is high, they start to make funny noises!

 

[FotisGR]

...i was thinking that was a capsule's problem....i replaced the capsule with a new and original before 2-3 days but the problem is the same...

 

[ybmusic]

Hi, I'm having the same issue.  Did you ever find the solution?

 

[warpie]

Fotis,

I'm afraid I can't help ypu but have you shorten the pins with phantom power on at any point?
This can happen if you use TRS or bantam patchbay for the mics for example.

 

[gyraf]

isn't the mic's output short-circuit proof???

 

[pstamler]

Pack the mic in a well-sealed box with some silica gel and leave it for a week. Is the problem lessened or solved? If so, moisture was the problem - with both the old and new capsules.

Peace,
Paul