Topic: Electret vs Back Electret?

[Roving Sign]

Is there any difference...? Seems like the older mics all call it a "Back Electret"

I've read somewhere that the "back" variety are more prone to loss of charge...? Any truth?

Wiki also mentions a "Front electret" - assuming this is the same as just saying "electret"

[illconditioned]

Is there any difference...? Seems like the older mics all call it a "Back Electret"

I've read somewhere that the "back" variety are more prone to loss of charge...? Any truth?

Wiki also mentions a "Front electret" - assuming this is the same as just saying "electret"

The first electrets had the charge on the diaphragm.  But this limited materials and lost charge.  Any modern electret is a "back electret", so people take out the word "back" now.

One thing I worry about is mics losing charge over time.  I'm thinking of the really old electrets, like AKG Ck1x and some of the older omni mics.  I don't know if this happens or not, though.

  Richard

[John Willett]

The original electrets were "front" electrets, with the electret material on the diaphragm.  The diaphragm was a bit stiff and unresponsive, but they were cheap to make.  The only front electrets nowadays (as far as I know) are in telephones and dictaphones.

The back-electret moves the electret material to the back-plate, making the diaphragm the same as a true condenser and a lot mote responsive.  Originally invented by Sennheiser, the patents expired ages ago (so I understand) and any good electret nowadays will be a back-electret (often called a pre-polarized condenser).

[John Willett]

.....  I'm thinking of the really old electrets, like AKG Ck1x and some of the older omni mics. 

The old AKG CK1 was *not* an electret - it was a standard AF condenser.

The new C414 *is* an electret, though.

[DSatz]

John, I think you probably mean that AKG's C 451 B "reissue" is an electret, while the original C 451s and 452s were not. The C 414-series microphones are still polarized in the traditional manner with externally applied DC; their pattern-switching arrangement depends on that.

Do you have any evidence for the claim that Sennheiser invented the back electret? I'd like to check that out, since I remember differently.

--best regards

[bugg100]

JLI Electroncs sells the TranSound line of electrets, some with good looking specs with a range of both back electrets and electrets.  Some models availabe with a choice between the two types.  Why would they offer the choice or even offer front electrets if it was as simple as " newer tech " elimanating front electrets as quality capsules?


Unfortunately, I think JLI changed web site design, losing some spec. l istings in the process.

I'm glad this question got asked, really curious about this......

Joe

[guysonic]

You can usually tell the 'back' electrets from the 'front' capsules from the extended >20K Hz high frequency response of the 'back' types.  Front types usually top out at <16K Hz

[John Willett]

John, I think you probably mean that AKG's C 451 B "reissue" is an electret, while the original C 451s and 452s were not. The C 414-series microphones are still polarized in the traditional manner with externally applied DC; their pattern-switching arrangement depends on that.

Yes, you are correct - I was writing quickly and put 414 instead of 451.

Do you have any evidence for the claim that Sennheiser invented the back electret? I'd like to check that out, since I remember differently.

Only this is what someone high up at Sennheiser told me many years ago.

[TNJazz]

.....  I'm thinking of the really old electrets, like AKG Ck1x and some of the older omni mics. 

The old AKG CK1 was *not* an electret - it was a standard AF condenser.

The new C414 *is* an electret, though.

Richard is referring to the active capsules AKG made for use with the mk46 cables, CK1X, CK2X, CK3X.  These *are* electrets, although the standard CK capsules are not.