Funny as its seems, the iPad has a very generous low cut for bass boost proximity compensating .
Many great and legendary microphones were auditioned. Path was microphone - Pleiades JFET pre preamplifier, or Pleiades V - iPad (GarageBand). It's is very convenient that iPad supplies voltage to drive the JFET directly in its drain. So this makes a fair comparison for dynamic mics as they can fairly easily be made connected active too like electret and condensers. The JFET had a 56nF coupling capacitor from mic transformer secondary to gate, a 680ohm source resistor in parallel to 47uF Elna red capacitor, drain to iPad.
In many cases Pleiades low cut filters need not be used as the iPad low cut is already too deep.
The Grampian ribbon mic sounded great, this needing Pleiades filer. So a Pleiades transformer with about 3mH primary inductance was used driving the JFET K117. Treble was great, bass smooth and presence and naturalness as you would expect from a nice ribbon.
The Electrovoice RE16 sounded very natural too, but it has to be connected to a higher inductance transformer, (Canford impedance converter, 400mH primary inductance). Plan is to make a Pleiades transformer with 0.05mm thin wire in the Magnetec 073 core and hiding everything in a Neutrik cylindrical module, including the JFET.
The vintage Sennheiser MD421 HL sounded much more bright but this may be useful.
The Shure Unidyne iii sounded great with Canford in parallel with a Pleiades 100Hz (333mH), overall 212mH.
But then the Unidyne was used with its internal high impedance transformer winding with amazing sound at 2in. So the obvious thing is to make a Pleiades JFET K117 pre preamp inside the Amphenol 4 pin mic connector and connect directly to iPad.
Mr Nikos Efthimiadis at Shure Hellas, his son and his team were very kind to locate their last vintage new old stock 4 pin connector. It was a great opportunity to meet a gentleman.
Hopefully this set up will make a nice field recording combination for near anechoic free field
music recording.
Retried the experiment with lesser results, the shunt cable of 180in was not there anymore as the new connector was connected on its own. It seems shunt capacitance (across secondary of mic transformer this time) plays a major role in compensating high frequency increase at small distance (obstacle effect). The obvious thing is to add a capacitor in parallel.
Many great and legendary microphones were auditioned. Path was microphone - Pleiades JFET pre preamplifier, or Pleiades V - iPad (GarageBand). It's is very convenient that iPad supplies voltage to drive the JFET directly in its drain. So this makes a fair comparison for dynamic mics as they can fairly easily be made connected active too like electret and condensers. The JFET had a 56nF coupling capacitor from mic transformer secondary to gate, a 680ohm source resistor in parallel to 47uF Elna red capacitor, drain to iPad.
In many cases Pleiades low cut filters need not be used as the iPad low cut is already too deep.
The Grampian ribbon mic sounded great, this needing Pleiades filer. So a Pleiades transformer with about 3mH primary inductance was used driving the JFET K117. Treble was great, bass smooth and presence and naturalness as you would expect from a nice ribbon.
The Electrovoice RE16 sounded very natural too, but it has to be connected to a higher inductance transformer, (Canford impedance converter, 400mH primary inductance). Plan is to make a Pleiades transformer with 0.05mm thin wire in the Magnetec 073 core and hiding everything in a Neutrik cylindrical module, including the JFET.
The vintage Sennheiser MD421 HL sounded much more bright but this may be useful.
The Shure Unidyne iii sounded great with Canford in parallel with a Pleiades 100Hz (333mH), overall 212mH.
But then the Unidyne was used with its internal high impedance transformer winding with amazing sound at 2in. So the obvious thing is to make a Pleiades JFET K117 pre preamp inside the Amphenol 4 pin mic connector and connect directly to iPad.
Mr Nikos Efthimiadis at Shure Hellas, his son and his team were very kind to locate their last vintage new old stock 4 pin connector. It was a great opportunity to meet a gentleman.
Hopefully this set up will make a nice field recording combination for near anechoic free field
music recording.
Retried the experiment with lesser results, the shunt cable of 180in was not there anymore as the new connector was connected on its own. It seems shunt capacitance (across secondary of mic transformer this time) plays a major role in compensating high frequency increase at small distance (obstacle effect). The obvious thing is to add a capacitor in parallel.
