microphone too hot - can I just insert a resistor?

[BobG]

I'm surprised that switching in the mixer pad didnt fix it. Tried
that? Maybe theres a bunch of DC from the phantom power biasing your
preamp up near clipping. Any caps in the signal from the mic to the
mixer preamp? If you have a nice hot mic signal, you can unbalance it.
Might work into the line in then.

 

[Sjouke Burry]

tempus fugit wrote:

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:6h2lgjFia5s1U1@mid.individual.net...
"tempus fugit"

The mic is made by Karma Audio - I chose it for it's small size:
http://karmaaudio.com/kmp.html

** That ( electret ) mic has extremely high output - over 40 mV at 94dB
P - when most condenser mics have only 5 or 10 mV.

But that 145dB SPL figure is complete bollocks - cos the mic would need
to
deliver 15 volts rms.

Allowing for the bass boost from proximity effect ( all cardioids have
that), a peak output of 1 volt rms is not too unlikely for one sitting
inside a guitar.




..... Phil


Thanks for that expanation Phil. I wasn't sure what a normal condenser would
have for an output. That expains the overdrive problem then. The pad seems
to have helped, but I still have a huge amount of distortion from the low
G-C notes (in the 200Hz area). No doubt this is the proximity effect,
combined with the fact that it's already exceedingly bassy inside the
guitar. I may just have to scrap the idea of using this mic and just go back
to my old capsule.

Thanks again


Are you really sure that at low frequencies the mic does

not bounce around in its mounting?
Cause that would produce "ditorsion" alright.

 

[Eeyore]

tempus fugit wrote:

Hey all;

I've got a condenser microphone (balanced output, 48v phantom power) mounted
inside my guitar. The output however, is WAY to high, and it's distorting
the input on my mixer.

What mixer ?

Graham

 

[BobG]

Look like that button next to the channel volume knob is a gain
button.... or a pad if you like to use industry jargon..... I usually
use a pad to kneel on when weeding the garden, or to crash in when
visiting my hippy friends in the city.

 

[Eeyore]

tempus fugit wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
tempus fugit wrote:

Hey all;

I've got a condenser microphone (balanced output, 48v phantom power)
mounted inside my guitar. The output however, is WAY to high, and it's

distorting the input on my mixer.

What mixer ?

Graham

The mixer is here:

https://www.carvinguitars.com/products/single.php?product=PA620

Inadequate data. A pro mixer (even a Behringer) probably wouldn't grumble at
the mic output level since they have variable gain input stages.

This Carvin is MI grade garbage. Sorry.

Graham

 

[Eeyore]

tempus fugit wrote:

I've just tried putting about 15K worth of resistance in series with the
output, and using a true 48v phantom power, and the sound is really quite
good. I suppose I could hardwire the resistors and lug around the extra 48v
supply to gigs, but I think I'm going to try going back to my original mic
element and using the 15v phantom power from the mixeramp to power it. I'm
pretty sure the mic is only rated for a 10v supply V+ though. Do you think
that it would handle the extra 5v without going up in smoke, or should I
build a voltage divider?

I'd suggest paying more attention to specs and buying compatible equipment in
the first instance.

Graham

 

[Tim Wescott]

tempus fugit wrote:

"tempus fugit" <toccata@quitspammingme.ciaccess.com> wrote in message
news:217d6$48aad759$d1d89b63$9097@PRIMUS.CA...
Hey all;

I've got a condenser microphone (balanced output, 48v phantom power)
mounted
inside my guitar. The output however, is WAY to high, and it's distorting
the input on my mixer. Can I lower the output by simpy inserting a
resistor
in series with then output, or do I need something more complex?

Thanks

I just thought of another thing - since the inputs are balanced, could I
just insert the resistor between in the path to ground (thus using only 1
resistor, rather than 1 for each of the + and - in the balanced path)

Thanks again



You should use a pad -- a series resistor from the mic, followed by a

parallel resistor to keep the resistance "seen" by the amplifier low.

Or use a pot, so you can experiment to find the right setting.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html