Monday, March 25, 2019

Vicky's Pleiades (R,L) filter settings for the AT802 microphone


(There is a systematic error as the mic was connected accidentally out of phase, but due to Vicky's great ability an adjustment for flat frequency response from producer's brain to listener's brain could be made).



It is also important to note that the output impedance of the AT802 omnidirectional moving coil in magnetic field mic is 500Ω.


Signal path:


Male voice singing The Power of Love - FGTH - AT802 - Pleiades (R,L) on Danbridge decade inductor, resistor boxes - Sony TC-D5 Pro - Sennheiser HD 580 - Vicky's ears, brain


Vicky after finding the voice bass, mid heavy from the straight microphone connection was asked to adjust the Pleiades filter R,L values for the most pleasing and natural voice sound.


One set of most preferred values is (200Ω,60mH). Resistance would be more than 200Ω due to the coil's wire resistance. Resistance measured across pins 2,3 with mic and preamp disconnected is 229Ω. Therefore the Pleiades filter vector is (229Ω,60mH). Ie a 229Ω resistor in series with an inductor of 60mH and the total connected across the AT802 microphone's pin 2,3 XLR output.


When Vicky was singing the same song, male listener found 40Ω,40mH a suitable set of values. Otherwise voice was bass heavy. R is more than 40Ω due to added coil resistance.







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