Stepping up microphone impedance to 2000 ohms

This was tried today almost by chance or curiosity.


The Audio Technica AT802 microphone impedance was measured 500Ω.


Then it was connected to yesterday's setup which had the Western Electric 1:2 transformer in line between mic and the Sony TC-D5 preamplifier. It sounded great and bigger. And connecting the Pleiades filter at 2000Ω (ie after the 1:2 step up) created great edge and treble on singing voice.


So,it seems the input impedance of Sony TC-D5 Pro is at least higher than 2000Ω.


Signal path, setup:


Voulez-Vous ABBA CD playing in adjacent room on Pleiades 2N3053 amp, male singing voice 2in close to mic - (Pleiades 130Ω, 40mH) filter - (Western Electric 1:2 transformer) - (Pleiades 130Ω,40mH) - Sony TC-D5 Pro - Sennheiser HD 580


(If an element is in parenthesis it may or not be used, many possible permutations where tried)


Without a Pleiadss filter mic sounds loud but there is a lot of bass and mid heaviness even on the ambience music.


Connecting the gentle slope Pleiades filter after the mic immediatly clears up the sound making it full, big, in all parts of spectrum. Then connecting to Sony sounds nice and big.


But if connecting the 1:2 transformer before Sony the sound is much louder without noticiable change in frequency response.


If connecting the Pleiades (130Ω,40mH) filter after the WE transformer ie at 2000Ω, more edge of voice is revealed, reminding the vocals of the Power of Love - FGTH.