What a microphone.
It had been bought together with its twin brother in England from a ham or vintage wireless society fest.
They had been destroyed by measuring DC resistance but they were very carefully re ribboned using a few microns thick aluminium foil from an Endinbourgh gold beaters company was James Laird if memory is correct. Random corrugation was used by hand folding the foil sandwiched in a zig zag accordion manner. The brass ribbon mounting, fastening support had been pristinely mirror polished so that the ribbon would make a very low resistance contact.
They still sound amazing.
If connected to a Sony TC-D5 Pro almost no sound results as it is a 20Ω output impedance mic.
Various step up transformers were tried today in order to step up 20Ω to anything close to 800Ω.
Perhaps the most suceesful of all is a 1:6 transformer wound on a very small Magnetec core. If memory is correct it is an autotransformer. At the moment there is some buzz possibly due to improper grounding. Primary impedance is 3.8mH, secondary impedance 119mH.
A food wrap transparent foil was used as pop, saliva filter. It worked with no degradation of sound.
Still ther is hiss on the Sony TC-D5 Pro. These mics were the primary reason why Pleiades electron tube preamplifiers were made. This had led to the very low noise battery powered Pleiades V6. The heaters are deliberately at lower temperature as it's done on Neumann U47. Pleiades bias from a resistor from anode to grid is used. So the electron tube can operated at just 3.6V with very low noise performance. Perhaps it's time to revisit this amplifier.
Still with buzz and noise (see above problem) the GR1/L sound superb with great naturalness and transient response and not like spitting as is the case with many condenser mics. The primary inductance used as stated above is very low so bass is cut and treble is revealed.
Then the Shure SM59 one of the best moving coil microphones with or without a Pleiades (130Ω,40mH) filter was compared. It is an amazing microphone. It does sound like a ribbon microphone with its transient detail and subtle, smooth and detailed sound. But there was some slight sense of plastic, slight veil to the sound that does not exist on the GR1/L.
Perhaps there is nothing microphonewise on our planet than a good ribbon microphone.
How would the GR1/L sound with a Pleiadss (R,L) filter feeding the Pleiades V6 battery powered electron tube front end?
How would it sound directly connected to UHER 4200 report through a handmade 1:5 toroidal transformer, or through a Beyerdynamic 1:5 transormer?
Next day addition:
Vicky listened too. She like the naturalness and detail without harshness or sibilant artifacts of the mic.
She preferred a 1:4 autotransformer to a 1:6.
Then she listened to a higher primary inductance and high turn ratio German inline transformer (470mH:60H) and preferred this as more full body sound. Preferred on this listening tests distance about 9in.
How would the Grampian GR1/L sound for singing voice with Pleiades V5 battery electron tube front end pre amplifier?
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