Inductor in series with resistor then connected to Shure Unidyne III, AKG D1000E

The D1000E has a very nice 2 position low cut high pass filter.
On this test its low cut filter was off.


An L=53.5mH inductor was connected in series to a 300Ω log potentiometer.


The combination was connected to a female XLR at pins 2,3 so that any mic can be connected.


The potentiometer was connected only on 2 of its pins and so wired that counterclockwise gave most bass.


This Pleiades filter was also connected to the Shure Unidyne III, (vintage SM57).


The 53 5 mH inductance was chosen by chance. It gives a high turnover frequency 600Hz? assuming a mic of 200Ω and the variable R should adjust the slope.


They worked fine.


A typical value of resistance for neither bass heavy nor bass thin voice for the Uni III at 2-3in male voice is 77Ω.


But it also has to be taken into account that there is another high pass from the 140mH input inductance of the mic input transformer on the Pleiades V6. And a low cut of around 100Hz taking place due to the output transformer primary inductance. So other more bass heavy setups may need different values of L, R or mic distance.


Then the omnidirectional Grapian DP4/L 25Ω was connected which is currently the reference. It still sounds much more natural and this without the need of any filter or EQ connected to it except the 149mH input transformer inductance. This is an amazing mic. It is also a mic that is not affected by any buzz radiatiting interference from other sources. And it is currently connected with an unbalanced output jack. is this because the diaphragm is aluminum and there is no stepup transformer inside it and the voice coil is 25Ω? It can faithfully pick up even the fairest sounds from far away. (This is not to compare the D1000 of Uni III in this respect as they are connected with clips on the LR filter. The Grampian D.P.4/L. has never caused a buzz problem no matter what compared to any mic on any Pleiades exoeriment. Since there is no low cut needed to compensate for the proximity effect the background soundscape sounds natural and not bass thin or HF exagerated.


Signal path, setup:


Make singing voice at 2-5in - (LR Pleiades filter but not for the DP4/L) - Pleiades V6 - Sony TC-D5 pro - Sennheuser HD580