A Reel Person
It's Too Funky in Here!!!
Aha!
Aha! Great info!Harvey Gerst said:
S
Shadowdog
New member
Sweet guys, thanks for the info. I have had these mics forever, my Dad gave them to me (think his band used them back in the day.) SO good to know they are usefull, espeicall if they were free to me.
M
metalj
New member
bgavin said:These are great SDC electrets.
Ive seen the word "electrets" typed on more than one post on this thread, so it must not be a typo.
what the heck is "electrets" ????
just wondering.
sorry for the dumb question, but i cant sleep at night not knowing
yep
M
MadTiger3000
New member
dgatwood said:Know any good mods for their stereo mic to take out the white noise generator?
Why go'n do that fer? Das' the BEST part!!!!
PhilGood
Juice box hero
metalj said:bgavin said:These are great SDC electrets.
Ive seen the word "electrets" typed on more than one post on this thread, so it must not be a typo.
what the heck is "electrets" ????
just wondering.
sorry for the dumb question, but i cant sleep at night not knowing
yep
An electret mic is based on the same idea as an LDC/SDC but is usually extremelly small. It's a low mass condenser that has an FET buffer or amp built into the capsule. The current can be applied differently to the diaphram/FET to be a 'source follower' which can handle higher SPLs. The capsules are extremely cheap, but can yeild high sound quality.
The capsule kind of looks like a small coin or plug with one or more holes in one side to allow sound to the diaphram.
TeyshaBlue
It's the smell..
I've got one of these too....I use it as a hat/snare mic...it's performed great in that role. 
PhilGood
Juice box hero
http://www.epanorama.net/circuits/microphone_powering.html#electretintro
Harvey, I've searched the web looking for any info on that mic and can't even find one page that even proves it exists, but since you want me to explain electrets (double post) HERE. I'll get you a link on the "Linkwitz mod" for electrets to change them to a source follower if you like!!!
Introduction to electret microphones
An electret MIC is the best value for money omnidirectional microphone you can buy. Electret microphone can be very sensitive, very durable, extremely compact in size and has low power requirements. Electret microhones are used in very many applications where small and inexpesive microphones with good performance characteristics are used. Electret microphone occupies (at a rough guess) the lower 90% of applications, quality wise. Most lavalier (tie-clip) microphones, consumer video camera microphones and microphones used with computer soundcards are electret microphones.
The electret is a modified version of the classic capacitor (or condensor) microphone, which exploits changes in capacitance due to mechanical vibrations to produce voltage variations proportional to sound waves. Whereas the condensor MIC needs an applied (phantom) voltage, the electret has a built in charge, and the few volts needed are to power the built-in FET buffer, not to create an electric field.
Typical electret condenser microphone capsule is a 2 terminal device (there are also 3 pin capsules) which approximates to a current source when biassed with around 1-9 volt and routinely consumes less than half a milliamp. This power is consumed by a very small preamplifier built into the microphone capsule which makes the conversion of very high impedance source of the electret element itself and the cable which needs to be driven. Be aware that this impedance is swamped at signal frequencies by cable capacitance so that at 1kHz the assembly will exhibit an impedance of a few 10's of K.
The load resistor defines the impedance and can be matched to the low noise amplifier intended. This is usually 1-10kOhm. The lower limit is defined by amplifier voltage noise and the upper limit by interference pickup (and amplifier current noise). Suitable resistsnce values are typically in the range of 1-10 kohm. In many cases the microphone is powered from 1.5V-5V power source through a resistor which has reistance of few kilo-ohms.
Because the electret itself contains a small buffer amplifier which adds noise, it is common to specify a signal to noise ratio (usually at 94dB SPL) or self noise figure, which is the equivalent acoustic noise level, commonly around 20-30dB SPL.
Electrets need biassing because of the built-in FET amplifier inside the microphone capsule. Bias voltages should be kept clean, because the noise in thiss will get to the microphone output.
Basic electret microphone powering circuits
Basic circuit
+---------------------------- battery +ve (3 to 12 Volts)
|
2k2 R1
|
o---------- 10uF ------o----- output
|+ |
CAPSULE 10k R2
|- |
+----------------------o----- GND, and battery -ve
This is the basic electret microphone powering circuit which you can use as generic reference when receivign circuits which use electret microphones. The putput impedance is determined by R1 and R2. If you leave out R2 the output impedance is roughly the resistance of R2.
Here is another drawing of the same circuit:
vcc
O
|
/
\
/
\ EQUAL TO REQUIRED IMPEANCE
/ EX.= 1000 Ohm
\
|
| CAPACITOR MOST ANY VALUE 10uF 16v
|---| | + | /
| |---0----| |------- AUDIO OUT
| | | \
| |----O--------------
|---| |
|
-----
---
-
Battery powered electret microphone
This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones. When you build this circuit inside the microphone case (or to small external box) you can make yourself an universal microphone out of an electret capsule.
10 uF
+ | |
+---------------------+--------| |--------------> to amplifier
| | | |
| (positive lead) |
| +----------/\/\/\---------+
MIC 2.2 kohm |
| | +
| (ground lead) (-) -------
| (battery 9v or so) ---
| |
| |
+-----------------------------------------------+----> ground
If you are building this circuit it would be a good idea to add a switch to switch off the battery when you do not use the microphone. You should note that the output signal level of this microphone is noticable higher than the signal available form typical dynamic microphones so you have to turn down the gain in your microphone input (if there are no suitable adjustments then this higher level can cause distortion in microphone preamplifier more easily). The output impednace of this circuit is aroun 2 kohm so I don't recommend very long microphone cables to be used or you will loose some high frequency definition (few meters are o problem).
Super-simple powering circuit
In many cases it is possible to use one or two 1.5 V batteries (depends on microphone type) as a power supply for the mic. Battery is directly in series with the microphone.
----------- [ Battery ] ----------------------
I
----
Amplifier in Mic
----
I
----------------------------------------------
This circuit works if the microphone preamplifier passes though some small CD current and is not bothered by it. This quite often the case but not always. Normally direct current from the battery has no influence on the preamp, as the preamp is only amplifying alternating currents.
If you do not know the right polarity of the battery, try it in both ways. In most cases wrong polarity at those low voltage should not cause any damage to microphone element.
Harvey, I've searched the web looking for any info on that mic and can't even find one page that even proves it exists, but since you want me to explain electrets (double post) HERE. I'll get you a link on the "Linkwitz mod" for electrets to change them to a source follower if you like!!!
Introduction to electret microphones
An electret MIC is the best value for money omnidirectional microphone you can buy. Electret microphone can be very sensitive, very durable, extremely compact in size and has low power requirements. Electret microhones are used in very many applications where small and inexpesive microphones with good performance characteristics are used. Electret microphone occupies (at a rough guess) the lower 90% of applications, quality wise. Most lavalier (tie-clip) microphones, consumer video camera microphones and microphones used with computer soundcards are electret microphones.
The electret is a modified version of the classic capacitor (or condensor) microphone, which exploits changes in capacitance due to mechanical vibrations to produce voltage variations proportional to sound waves. Whereas the condensor MIC needs an applied (phantom) voltage, the electret has a built in charge, and the few volts needed are to power the built-in FET buffer, not to create an electric field.
Typical electret condenser microphone capsule is a 2 terminal device (there are also 3 pin capsules) which approximates to a current source when biassed with around 1-9 volt and routinely consumes less than half a milliamp. This power is consumed by a very small preamplifier built into the microphone capsule which makes the conversion of very high impedance source of the electret element itself and the cable which needs to be driven. Be aware that this impedance is swamped at signal frequencies by cable capacitance so that at 1kHz the assembly will exhibit an impedance of a few 10's of K.
The load resistor defines the impedance and can be matched to the low noise amplifier intended. This is usually 1-10kOhm. The lower limit is defined by amplifier voltage noise and the upper limit by interference pickup (and amplifier current noise). Suitable resistsnce values are typically in the range of 1-10 kohm. In many cases the microphone is powered from 1.5V-5V power source through a resistor which has reistance of few kilo-ohms.
Because the electret itself contains a small buffer amplifier which adds noise, it is common to specify a signal to noise ratio (usually at 94dB SPL) or self noise figure, which is the equivalent acoustic noise level, commonly around 20-30dB SPL.
Electrets need biassing because of the built-in FET amplifier inside the microphone capsule. Bias voltages should be kept clean, because the noise in thiss will get to the microphone output.
Basic electret microphone powering circuits
Basic circuit
+---------------------------- battery +ve (3 to 12 Volts)
|
2k2 R1
|
o---------- 10uF ------o----- output
|+ |
CAPSULE 10k R2
|- |
+----------------------o----- GND, and battery -ve
This is the basic electret microphone powering circuit which you can use as generic reference when receivign circuits which use electret microphones. The putput impedance is determined by R1 and R2. If you leave out R2 the output impedance is roughly the resistance of R2.
Here is another drawing of the same circuit:
vcc
O
|
/
\
/
\ EQUAL TO REQUIRED IMPEANCE
/ EX.= 1000 Ohm
\
|
| CAPACITOR MOST ANY VALUE 10uF 16v
|---| | + | /
| |---0----| |------- AUDIO OUT
| | | \
| |----O--------------
|---| |
|
-----
---
-
Battery powered electret microphone
This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones. When you build this circuit inside the microphone case (or to small external box) you can make yourself an universal microphone out of an electret capsule.
10 uF
+ | |
+---------------------+--------| |--------------> to amplifier
| | | |
| (positive lead) |
| +----------/\/\/\---------+
MIC 2.2 kohm |
| | +
| (ground lead) (-) -------
| (battery 9v or so) ---
| |
| |
+-----------------------------------------------+----> ground
If you are building this circuit it would be a good idea to add a switch to switch off the battery when you do not use the microphone. You should note that the output signal level of this microphone is noticable higher than the signal available form typical dynamic microphones so you have to turn down the gain in your microphone input (if there are no suitable adjustments then this higher level can cause distortion in microphone preamplifier more easily). The output impednace of this circuit is aroun 2 kohm so I don't recommend very long microphone cables to be used or you will loose some high frequency definition (few meters are o problem).
Super-simple powering circuit
In many cases it is possible to use one or two 1.5 V batteries (depends on microphone type) as a power supply for the mic. Battery is directly in series with the microphone.
----------- [ Battery ] ----------------------
I
----
Amplifier in Mic
----
I
----------------------------------------------
This circuit works if the microphone preamplifier passes though some small CD current and is not bothered by it. This quite often the case but not always. Normally direct current from the battery has no influence on the preamp, as the preamp is only amplifying alternating currents.
If you do not know the right polarity of the battery, try it in both ways. In most cases wrong polarity at those low voltage should not cause any damage to microphone element.
SouthSIDE Glen
independentrecording.net
A Reel Person said:to paste right over the R/S name!!
Heck, as long as you're going that far, tape ofver the R/S logo and replace it with the word "Neumann"
G.
PhilGood
Juice box hero
Harvey Gerst said:
A more direct answer: (from previous post)
"Whereas the condensor MIC needs an applied (phantom) voltage, the electret has a built in charge, and the few volts needed are to power the built-in FET buffer, not to create an electric field."
In most cases of electrets the diaphram is small. I guess Sony figured out how to make a 1" that has a built in charge. It still has the FET if it's an electret.
H
Harvey Gerst
New member
My Sony ECM370 is a cardioid, not an omni. But thank you for the education about electret mics. The first really well-accepted "professional" electret mic was the Shure SM-81.
Rokket
Trailing Behind Again
Damn I love this forum! I hardly post in here at all, but I read everything you guys type. I am learning so much. My mic knowledge wouldn't fill a paragraph compared to the volumes you guys know.
My hat is off to you.
Now back to the posting...
My hat is off to you.
Now back to the posting...
PhilGood
Juice box hero
Harvey Gerst said:
Harvey, I hope you got my apology on the other thread.
I know panasonic makes electret capsules that are cardiod besides the usual omni. Transound also makes them.
H
Harvey Gerst
New member
So does Sony, Yausa, Primo, and even B&K, to name just a few.PhilGood said:
Similar threads
- astokesmusic
- Studio Building & Acoustic Treatment
