Can anything other than capsule overload cause crapping out?

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jackinthebox

Member
Joined
Jul 2, 2011
Messages
24
I've had couple of my mics crap out recently in high SPL situations and I've been wondering what can be done to improve the headroom or max SPL. I am guessing it is the capsule diaphragm hitting the backplate but if anyone out there has any ideas on what else might be the cause I would love to hear your views. I would have thought that excessive SPL would have caused distortion in the other components but wouldn't cause actual crap outs. Like the signal cuts out rather than it distorting.
I will post examples of the audio if anyone is interested.
Thanks in advance for any advice.
J
 
Tube condenser microphones. One with a beezneez k7 and another with a tim Campbell Ct12.  The  mics use a russian submini tube. I am using a 60v polarisation voltage. I can't imagine anything other than the capsule crapping out but perhaps I'm missing something. I've though about fitting a pad between the capsule and the grid but if it's the capsule that wouldn't solve the problem.
 
Tim's capsule should not have more than 60v, as I am sure you know.  If, you are certain that the capsule is bottoming out, it may be a question of the signal itself: is there a lot of very low frequency content?  Is it actually a blast of wind that is hitting the capsule?

Personally, I would do some measurements to ascertain the amplifier overload point before assuming that the capsule is causing this problem.

David
 
Do you think the amplifier overloading would cause the signal to cut out? I would assume that the tube would saturate and the transformer and other components would go in to distortion rather than cutting/crapping out. Would the other components, for instance the capacitor between the capsule and grid have a cutting out overload characteristic?
 
jackinthebox said:
Do you think the amplifier overloading would cause the signal to cut out? I would assume that the tube would saturate and the transformer and other components would go in to distortion rather than cutting/crapping out. Would the other components, for instance the capacitor between the capsule and grid have a cutting out overload characteristic?

Have you checked for a cold/unattached solder joint that could be wiggling loose from the vibrations caused by high SPL?

-James-
 
Possibly the power supply voltage dropping very quickly because the large amount of fairly instant voltage swing from the large SPL? Put another way the power supply doesn't have enough current?
 
Hmm. Definitely a possibility. Do you think bigger caps in the PSU would solve that to some degree? More charge available for short bursts of large current draw?
I'll give it a try and report back. Any other thoughts on increasing the available current would be interesting. J
 
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