Internal attenuation-pads on condenser microphones (question)

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

clintrubber

Well-known member
Joined
Jun 3, 2004
Messages
5,982
Location
The Netherlands
Hi,

The short question:
How likely would it be that one needs to handle more than 145 dB SPL ?
I don't need to record gunshots & rocket-launches, but does for instance a snare on a bad day go beyond this figure ?
Are people often using mic-pads up to 20dB ? (will depend on situation & mic-specs, but...)  



Was wondering what most of the pads on LDCs & SDCs are actually addressing,
the overload of their own internal buffer or the subsequent mic-preamp.

It'll of course depend on the specific mic & situation, but who knows there are some common
things among the various mics.

Of the condenser-mic schematics I saw so far, the most common thing is to add a capacitor
'to the capsule' to form a cap-divider & prevent overload of the own buffer.
This is for '-10dB pads'. Mics that go further for a -20dB setting leave it at that & attenuate
further down the internal electronics, so that's more targeted at preventing overload of
the mic-preamp at the other end of the cable. The AKG C451B is an example of this.

But this could easily be added as a pad between mic & preamp as well (XLR-barrel).


So how likely would it be that one needs to handle more than 145 dB SPL ?
I don't need to record gunshots & rocket-launches, but does for instance a snare on a bad day go beyond this figure ?
People using pads up to 20dB (again, it'll depend on situation & mic-specs, but...)  


The background to my question is actually this: I have a SDC that can handle
up to 145dB-SPL with the 10dB-pad engaged. Might buy another of the type, but there's also
a model that goes to 155 dB (20dB pad).

Thanks,

 Peter
 
The three mics I use on snare are:
Microtech Gefell M300 max SPL 147dB (has no pad)
AT PRO37r max SPL 141dB (has no pad)
ATM450 max SPL 142dB without pad, 152dB with -10dB pad, which I have never felt obliged to engage.
AFAIC, I could do without pads.
 
Hi & thanks for adding.


BTW, the trigger here was that I bought one of those AKG budget SDCs (Perception 150)
which has a 10dB pad and that mic was replaced by essentially an identical mic (Perception 170)
but now with a 20dB pad (raising the max SPL to 155dB).
So the thought came up whether it was a necessary move or just an update to have an update.

Regards,

  Peter
 
The hardest hit I can measure--I'm not a drummer, mind you--peaks at about 150dBSPL with a mic 1" from the head.  Either top or bottom side can get that peak that loud, but the bottom side tends to be a little louder on average when near the wires.  After 20msec, it's less than 140dBSPL.

These are really hard, ape-like hits, but then drummers are a bit simian . . . a normal hit for me peaks at 140dBSPL, and is around 134dBSPL after 20msec, again 1" from the head.

Inside kick can get louder, although I don't have a measurement.
 
Hi,

Thanks for adding. Figures close to or a bit above what that mic here can handle (145dB with 10dB pad engaged).

A few distorted hits not too big a problem (change mic & redo), but mic-damage would be a pity.

But IIRC this specific mic (SDC: AKG Perception 150) has a 'single-sided-sputtered-diaphragm' to avoide cap-plate clashes, which seems to indicate that plate-clashes are not an insurmountable problem, not leading to permanent damage. But that's just an assumption.


But apart from that, say if it had been a 20 dB pad (making it the AKG Perc 170), that loud hit would have meant the same to the capsule I assume.
Assuming that the mechanical dynamic properties _don't_ change from engaging attenuating caps (to be verified),
using a pad just attenuates the signal for the electronics; I'd say that any capsule damage would happen the same way, pad or not.

Bye,

 Peter  

 
Back
Top