See the opinions most relevant to the LEM EMU 4535 which is exactly the same.
Electret microphone with high quality but quite old.
Cardioid fairly open, so with a relatively small feedback resistance.
LEM also sells Omni directional cells and cells previously sold hypercardioid.
Requires one AA battery 1.5 V inside. Long enough battery life even if we sometimes forget to turn off the microphone.
A 3-position switch toggles between the stop at the normal and the third position inserts a filter reducing the serious voice.
The pellet electret unscrews and it is then possible to turn a room with a small clip to reduce the sensitivity of 10 dB.
As my microphones were dying and very insensitive, I did not see the benefit of further reducing their sensitivity.
Micro comes in a plastic box not very strong, very serious with clamp, a windscreen formed of a wire mesh fine enough, and perhaps a cable 6m long.
-For all instruments with a wide bandwidth in the treble violin, cello, horns, etc.. Also suitable for the piano very well thanks to its extremely wide response.
Over Head-On to use the cymbals of a drum or a hi-hat.
Sound-global choir or orchestra, possibly in a stereo pair.
In the rigor-miking of voices in the studio with the filter limiting the serious and the windscreen.
The two mics I bought it used a decade ago have been gradually extinguished by the loss of electrostatic charge over the years.
I can not know if this extinction is normal like all electret microphone (about 15 years during the final extinction) or whether it comes from the poor quality of the sheet forming electret or moisture during storage before my purchase.
LEM can possibly provide replacement cells electrets. Quite expensive (40 € HT) but these pickups can be worth it. To date (16/07/2007) omni cells only in stock.
These pickups have a very good sound quality and workmanship, but a little dated.
I use electret microphones also more recent: Samson CO2 Behringer B-5.
I do not have the means to effectively compare these microphones.
The Behringer nine, when we spotted a model without noise, is better in terms of output level and perhaps bandwidth. Its cardioid and omni two cells give a greater flexibility of use.
The equivalent Nakamichi buying the two cells is significantly more expensive.
I would put a happy note for the build quality and sound obtained, but poor on the longevity of the cell and therefore the electret microphone, at least in my case.
Anyway, the other microphones that can not be réfrérence Veterans and should be in the same state, unless they have replaced the electret cell.