Audio range on electret condenser elements?

[mechanic]

Having wound up with a dead dynamic element on my HR2510 mic, (no replacement) I decided to try a small electret element salvaged from an old cordless phone (good for parts!)... The response was not too good on AM but SSB was not too bad :mellow:

I was wondering if there is a way to in crease the sensitivity overall on this element? I also tried a Heil type element from an old Motorola HT and it was about the same as the electret element.

Drop in replacements to fit the original mic for the 2510 are hard to find...

Mechanic

 

[bob85]

electrets tend to have a pretty flat and wide frequency response compared to the dynamics found in cb/ham mics, 30hz-15khz is not unusual for a typical small phone type, thats not ideal unless you want wideband audio and have a mic equaliser,

the case of any mic also effects the sound, more so if you dont seal around the cartridge with high density foam or something similar to minimise reflections from within the mic case coloring the audio,

you could try two electrets in parallel for more ooomph, go smaller on the capacitor to remove bass,
heres my buddy motors wideband dual electret mod for the d104.

Dual Electret Mic circuit (AKA Motormouth Mic)

 

[SR385]

There are many types out there so you have to look at the specs.

I was looking at communications elements the other day at mouser.com and the common spec for mic elements was 100-10kHz, so they vary. A 100 roll off isn't bad, particulary for mobile use as all that energy below 100 is useless when it's a noisy environment.

 

[Robb]

The size/diameter will change the quality drastically. A lot of these small-capsule mics offer little performance. THe stock Cobra mics come with small capsule condensers and sound lousey. Whereas the stock Magnum OmegaForce power condenser mic works outstanding - using the same size element! It is a question of the electronics WITH that condenser element that is going to make ALL of the difference...

After all, if you are going to use a condenser mic, you might as well make it sound as good as you can - right? A half-inch diameter condenser capsule is a pretty good place to start, An inch diameter is better - but they are harder to find and are outrageous in price. But properly adjusting the tone curve will yield a superior product.

A cheaper/easier way to go is a large-element dynamic mic(non-condenser) - like the old Road Talker mics had. Building a preamp for this type of element is pretty easy to do. The larger the mic transducer, the better freq response and db it can handle before overloading the element...

 

[RickC.]

I've built quite a few mics with electret condenser elements, some for amateur use, some for contact mics for instruments for live use.

The small Sony electrets from Digikey, etc., have a flatter response and can work very well on instruments in some situations. The Radio Shack elements do have a midrange rise and do not sound as natural in that application-- BUT that same property makes them better for communication use, I think. My D-104 in which I replaced the dead ceramic element with a Rat Shack electret sounds better to me on my IC-718 than the Heil ICM, which sounds flat and dull in comparison.

Depending on you application, you may not need a preamp for an electret. Most of them will work up to 10V, and on the ones I built for instruments were SCREAMING with a 9V supply through a 1K resistor, and I quickly learned to use a simple voltage divider pot on the output, as well as lowering the supply voltage to 5-6 volts. They are considerably hotter than dynamic mics, even with the supply voltage down around 4V, with the little Sony elements (which can be a challenge to solder) being hotter than the RS ones.