MV691, MV692 and N691 signal drop

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Murdock

Well-known member
Joined
Jan 28, 2015
Messages
844
Location
Germany
Hey folks,

I recently purchased a MV691, MV 692 (both with M70 capsules) and a N691 PSU unit.
The problem is, the signal drops to almost nothing after a few seconds... I checked the PSU, and get about 12V to the mic.
Does anybody know, what the problem could be?
 
hmm now it works... I left the PSU and a mic on for a few minutes and now they both work. Seems that they need quite some "burn in" time. Is that normal?
Also the MV692 is quite noisy... it sounds like there is a constant "wind".  Any hints on what could cause that?

EDIT: It's one of the capsules... I switched capsules and only one needs quite some "burn in" time. It slowly rises the level, but if it is at normal level it is quite noisy/windy.
Also when I shake the capsule head (not mounted on the body), I can hear that there is something loose inside.
Does anybody know, how I can open up these "headbaskets" to get access to the capsule?
 
No, not really. They´re operational after about a second or two. Might be dirty connectors...

The "wind" noise you hear would be from a defective caspule, typical for the M70 and M94 (nickel) capsules is that the mambrane detoriate over time.  A reskin is necessary, MTG or Thiersch can do that.
 
Most of the old capsules get noisy along the years.
Send them to re-membraning to Thiersch.
Costs 75€ and the capsule will be OK for 30 years again.

Also change the old capacitors of the output stage. 
 
Sredna said:
The "wind" noise you hear would be from a defective caspule, typical for the M70 and M94 (nickel) capsules is that the mambrane detoriate over time.  A reskin is necessary, MTG or Thiersch can do that.
MTG and Thiersch can reskin Nickel diaphragm capsules??  :eek:
 
Could actually be Thiersch does it for Gefell, too.
I believe at one point he did.
Not sure about the current situation.
I once was wiser than I am now.  :(
Not that it matters much, BTW.
 
thanks for the replies guys. I contacted thiersch about sending him my capsules but got no reply... will wait some more
 

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