Electrets can be very cheap and of poor quality yet they are now available at modest cost for the home music producer, and will result in stronger audio tracks. Learn about their design, their special benefits and disadvantages, and their application for Youtubes in particular.

1. Electret Microphones:
The Musician’s Friend
 Created by Clarice Stasz for assignment in
Music Production taught by Loudon Stearns,
Berklee School of Music, www.coursera.org,
2013

2. Electrets are based on Condenser
Microphones, which are known to be
 Less sturdy than dynamic mics
 Preferred studio mic
 Offer larger frequency response for collecting
partials than dynamic mics
 Require phantom power

3. Invented 1962
 Gerhard Sessler and James West at Bell Labs
Developed to improved telephone communications.

4. DEFINITION
 “An electret microphone is a type of
condenser microphone, which eliminates the
need for a polarizing power supply by using a
permanently charged material.”
 http://en.wikipedia.org/wiki/Electret_microphone

5. Or,
 A microphone consisting of an electret
transducer in which the foil electret
diaphragm is placed next to a perforated,
ridged, metal or metal-coated backplate, and
output voltage, taken between diaphragm
and backplate, is proportional to the
displacement of the diaphragm.
 McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright ©
2003 by The McGraw-Hill Companies, Inc.

6. Engineering
Preamp
Vibrating membrane
Itc.nyu.edu

7. Small size advantage
Openmusiclabs.com

8. You use them all the time.

9. Do you make Youtubes?
 Electrets are in your laptop and portable
phone.
 They consist of about 9o% of microphones in
use today.
 Their quality is surprisingly good for many
purposes.

10. Time for a new recording mic?
 Your computer mic is fine for everyday uses,
like Skype, taking audio notes.
 Music on the same mic may sound tinny
because of distortion and limited response.
You sound better than what you hear.

11. Benefits of electret
 Very inexpensive, under $1 for lowest quality,
hence popular with gearheads
 Suits voice recording well
 Extremely wide frequency response (from
10Hz to 30kHz ) in best cases.
Sample inexpensive electret

12. Technically superior
 This is according to the technical sound
engineer papers . The electret design is
supposed to be the most accurate transducer.
 Of course, this will be affected by the quality
of the production. Nonetheless,
theoretically, electrets should be the best.

13. A look inside one type
 Being condensors, they need power so some
include an amp.
http://sound.westhost.com/project93.htm

14. Others include a battery and
then connect to the amp.
www.caitches.com

15. Electrets have a bad reputation with some
 Vibrating membrane can wear out in a couple
of years
 More fragile overall than a dynamic mic
 Cheap models mean poor quality
 Some users find the bass range
unsatisfactory

16. Disadvantages of lower
quality (cheap) models
 Output impedance is relatively high
 Relatively low sensitivity
 Noise is relatively high
 Sound level handling ability is low,
typically < 90 dBSPL

17. Home recording
Today you can find
good quality electrets
for under $50, with the
specs you need in
terms of pickup
pattern, frequency
Stereo ominidirectional
with direct plugin to response, and more.
minimize vibration

18. Performing mics as well.
This looks like a
dynamic mic.
It’s an electret
specifically for
vocalists to reduce
pops, optimize lower
frequency response,
and minimize
distortion. It is also a
cardioid design.

19. One pro’s experience
 “The cheap electret mics polarize the
diaphragm. This is cheap to make but results in a
diaphragm that's quite thick (maybe 20 microns
or so).
 A back-electret puts that charge on a sheet
that's between the backplate and the
diaphragm. With this arrangement, you can use
a normal diaphragm thickness… so it may be
difficult to tell the difference between an electret
and an externally polarized condensor mic in
performance - that gap is narrowing.”
 From “Dale” on Gearslutz.com.

20. Recommendations
 For spoken word or singing with a single
instrument, your computer mic could be just
fine
 For higher quality, and ability to make finer
mixes before uploading, explore quality
electrets now widely available at moderate
prices.
 For performing, because electrets are
technically the purest transducer, you may
want to try one out.

21. In other words…
 Where ten years ago people said the electrets
were lousy for serious sound work, this is no
longer true.
 Major microphone firms make professional
level electrets, up into hundreds of dollars.
 Given the same price and specs, the back-
electret design is your better choice.

22. Connecting to computer
 This is a topic in itself. Try these for help:
 http://manual.audacityteam.org/man/Tutoria
l_-_Connecting_a_Microphone
 http://www.ehow.com/how_6362940_connec
t-electric-condenser-microphone-pc.html
 http://support.apple.com/kb/HT2508

23. Self-evaluation
 As a result of this project, I learned:
 Three of my music-based mics are electrets:
flute, ukulele, and Sony mini-stereo
recording.
 It is worth using an external electret for my
laptop for quality recording.
 A lot of sound reference materials require
some engineering background to
comprehend. I definitely missed some
understanding in putting this together.

24. If I had more time,
 I’d have sound samples with various mics to
demonstrate differences
 I’d use Camtasia to make a video from this
PowerPoint with an audio track added
 In that last case, I’d reduce all the written
slides and have more visuals. For example, I’d
open up a mic to show the parts.

25. If you evaluate this….
Don’t hesitate to note
errors,
Or to suggest additions.
ukestasz@gmail.com