The R L (C?) filter of Sennheiser MD 214 N

Fortunately it had arrived as an eBay purchase and it was not working.


So it seems the voice coil is not connected.


This is a blessing in disguise as the shunt (in parallel) filter is only connected to the cable and can be measured.


It seems to be an R,L filter, R in series with L, see also Pleiades R,L gentle slope high pass or low cut filters.


On the Escort LCR meter:


R
114Ω


L
34mH


Sennheiser micro revue 70-71 says that this mic has the same capsule as mighty MD 211 N.


So how would an MD 211 N sound connected to the long cable of this MD 214 N which is terminated by the R,L goodies?


It may sound thin for speech.


But would the bass and treble heaviness for intimate singing be gone?


Answer:


No it sounded worse. Again bass and treble heavy. And without mid.mcould there be a capacitor too making and LCR filter? The meter shows 700nF. Needs investigation.


Then the following signal path was tried:


MD 211 N - Pleiades 130Ω,40mH - Sony TC-D5 Pro - Sennheiser HD580


A bit better.


Then a BBC LL/210A low ratio step up transformer was just connected.


A bit better but now treble heavy. Is the primary inducstnce too low? Yes it is. It is just 200mH. This experiment must be repeated with a Western Electric input transformer of 1H:4H ie a turns ratio of 1:2. (Later addition: yes with the WE it does sound great, see next posts).


The AKG MI 201-100 was connected directly to Sony and sounded very nice. Perhaps a bit lacking in treble but this may be perhaps because of the high treble that had just been heard.


D


D


D