Wednesday, February 17, 2016

Pleiades filters and matching transformers, K117 JFET pre preamplifier inside Neutrik Modules

It would be great to use beautiful Neutrik modules as follows:


Neutrik NM3FXI (XLR female) to NM3MXI (XLR male) with a Magnetec 073 nanoperm core wound and connected in parallel with pins 2 and 3 to create a very effective Pleiades low cut and pop filter. This combination not only looks very dishy it is also shorter than a standard XLR male to female adaptor.


Also, the same Neutrik XLR modules as above but the Magnetec 073 core wound as transformer or auto transformer.


Using the above one could have various combinations for different low cut frequency according to how close the microphone would be to source. In fact it is analogous to using different macro lenses to focus on a close object or having various magnification lenses as an astronomer has in front of the telescope ready to be exchanged according to circumstance.


Pleiades microphone low cut filters can be connected in cascade for cutoff frequency additive results (change of optimum mic to source distance). For example if a Pleiades 200Hz filter is connected to a Pleiades 400Hz the resultant 2 XLR Neutrik modules will be a Pleiades filter of  600Hz, just about right for very close SM58 use with pristine quality.


So far we have passive filtering or amplification. If one wishes to connect to an iPad mic input it may be done as follows. A Neutrik cable outlet CM module can be used connected to NM3FXI (XLR female module). A Pleiades K117 pre preamplifier can be built inside using only a low noise JFET such as K177 and a resistor from JFET's source to ground for bias. Also since a K117 JFET and a small resistor do not take much space they can be built inside a standard Neutrik female cable connector.


Or one could use the above Neutrik XLR combination to include a Magnetec 073. Therefore it can be a Pleiades mic input step up transformer with proximity compensation, driving the K117 Pleiades
front end. The output cable can be connected directly to iPads mic input which will also power the low noise K117 stage.


When connected to a world class mic like Shure Unidyne III, Electro Voice RE16, or Seenheiser MD421 one could record to GarageBand with great resolution and low noise, and everything being lightweight and portable. Just the mic, the Pleiades pre preamplifier inside the Neutrik module connected to mic and iPad.


Example setup:


Electro Voice RE16 - Pleiades proximity compensating step up transformer - Pleiades K117 pre preamplifier - iPad

(Pleiades input transformer with Magnetec toroidal core and K117 with resistor inside Neutrik Modules)






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