It is a brilliant mic. But it is low output.
This post is about the GR1/L which has an even less voltage output. It can be made to sound loud, amazing, with the most extended, detailed and sensitive, loud response imaginable. with no s problems, amazing transient response. Silk smooth sound.
What is needed is an ultra low noise pre amplifier.
The Pleiades V6 battery powered electron tube preamplifier with deliberately underheated heaters as on the Neumann U47 internal VF14 preamplifier has been found to be ideal.The Pleiades V6 schematic is open source as everything Pleiades.
A preamplifier input transformer step up ratio of 1;30 works great as the impedance of this mic is 30 ohms.
If one wishes to further improve the overall signal to noise ratio (from singer's vocal chords to listener's brain) the singer has to be close to the mic.
The proximity effect would unacceptably increase bass from say 1KHz and downwards at 6 dB per octave. SO we need a complementary high pass filter of 6dB per octave rising up to say 1 KHz.
This can be done by a Pleiades filter ie a shunt inductor connected to the output of the mic. This is the same technique used on the great RCA ribbon mics, the great Electro-Voice RE-15 moving coil etc.
For real close singing to the mic an inductance as low as only 3mH seems suitable and gives amzing sound.
So the V6 preamplifier input transformer could be arranged to have a primary inducatnce of say 3mH. This means very few turns. only 10? for a Magnetec 070 core? The secondary turns would only be 300 making it a joy to wind.
Another option is to use a more ordinary 1:10 input transformer on the preamp.
ANd create the total of 1:30 by just adding an inbetween 1:3 impedance converter transformer. Again the primary inductance can be made low with a few turns to cut as much bass is needed for flat frequency response from singe's vocal chords to listener's brain.
The low inductance electromagnetically damps the ribbon (Lenz's law or conservation of energy law) so pops are almost off. But still we should not abuse such a great and sensitive microphone.
The above techniques may also be used for other ribbon microphones. Of course they are very suitable for world class moving coil microphones such as RE-15 for example making with them sound even more unbelievable. Same for pressure moving coil mics such as MD21, MD211, M55, F-96 etc.
The Grampian ribbon mic was also used to make amazing recordings of ensembles, or rockbands etc. It was used picking up all instruments. It sounds both great as a mono mic or a blumlein pair. The input transformer inductance has to be much greater as now the distance involved is much greater. An amazing signal path is:
Grampian GR1/L pair - Sowter 1:20 transformers - Ferrograph Series 6 electronic valve reel to reel recorder
At 7.5 ips it is hard to believe how well cymbals from the drums are reproduced. The electric bass sound in the room. The organ with SE PCL86 amplifier and Pleiades rotating speaker hung from the ceiling. The microphone captures the sound as our ear does, no need for any EQ. Broad band panel absorbers such as Pleiades absorbers would have improved the reverberation of LF frequencies while recording. More information on this amazing setup with just a couple of electron tubes from mic to tape can be found on another euroelectron post through google search. A great recording of flute and classical guitar was also done with the mics inside a church, Pavane -Gabriel Faure.
References:
Flat frequency response from singer's, actor's vocal chords to listener's brain, Sound Picture Recording and Reproducing Characteristics, Lowe, Morgan - Journal of the maotion picture sound engineers
Pleiades V6 schematic
Neumann U47 schematic
The Feynman Lectures on Physics
Coil Design and construction manual - Babani _ BP160
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