This GR1/L had many years ago been re ribboned with a random corrugation. It is now really a GR2/L as some pad must have been removed and it now is equally sensitive to both sides, ie figure of eight.
The book of Al Schmitt on microphone vocal and instrumental techniques came for Christmass.
Al Schmitt explains how important is that good quality mics are used so that the leakage sounds good and adds to the whole sound picture making a big sound.
The Pleiades 2N3053 amp was playing softly in a different room the Fame soundtrack CD, creating an ambience or leakage for the vocal mic to be tested in another room.
The Grampian sounded the best of all mics tested but there was some hiss as the Sony preamp had to be at max gain.
Signal path:
music ambience + male singing voice close to the mic - mic - Pleiades L filter if needed - Pleiades R,L filter if needed - low turn ratio step up transformer - phase inverter XLR barrel when needed - Sony TC-D5 Pro - Sennheiser HD580
A choice of 2 step up transformers was used according to which one sounded best with a mic. The Western Electric 1:2 primary inductance 1H and a BBC design 140mH to 2.1H.
The mic impressions:
MD21 HN
Impressive, the best s/n of all mics, too bright giving a character of its own but natural. Not as natural as the Grampian ribbon.
Ambience sounded good.
It had to be connected to a Pleiades filter of 82mH or more and then the WE transformer.
Or directly to the BBC transformer which has less inductance. Otherwise sound was not only treble but very much bass heavy.
RE-15
Impressive. Big sound too, less treble heaviness, natural.
Ambience sounded good.
Grampian GR1/L
Signal path:
Male singing voice at 10in - Pleiades 14mH low cut - Pleiades 8mH 1:3 transformer (low cut again) - WE or BBC transformer - Sony TC-D5 - Sennheiser HD580
Amazing sound with detail in treble and the whole frequency spectrum, smooth, big
Pity about the hiss, with a Pleiades V6 booster amp it is less (cathode under heating, very low voltage battery operated electron tubes with Pleiades pull up bias etc)
Ambience sounded amazing
Grampian DP6/L (omni)
Great sound possibly second best and MD21 or RE15 3rd best?
Nice ambience
No Pleiades filtered needed
Grampian DP4/L, 2 versions used, black at 25Ω and grey having out Z of 70Ω
More bass on the black model. In general similar sound to DP6/L. But the DP6/L more natural and without needing any Pleiades filter.
Shure 515SB Unidyne B made in USA
Used with a German 1:1 transformer so that the terminating inductance is about 470mH and then the Pleiades filter 130Ω,30mH.
Nice sound at 4-6in
Ambience not very good
Beyer M61
Too much proximity effect so Pleiades filters had to be used L and R,L
Ambience so and so.
Vocal sounded dynamic even at 8in.
Mic has just arrived so it is not known yet have to make it sound at its best for particular condition.
The Grampian ribbon sounded best of all and at 10-12in.
Without Pleiades filters the Grampian ribbon mic sounds bass heavy, so bass heavy that one might dismiss it as having no treble. The opposite is true. Once the excess bass heaviness is removed the treble detail shines. And detail shines throughout the frequency spectrum. A spacious big sound. a the mic sounded best at 8-10 in. The fighter of eight response made the room sound better.
Perhaps this is what textbooks mean when they mention that ribbon mics have the best transient response due to the low vibrating mass. It is a very natural sound with detail but no artificial detail. More, artificial detail may be good too at particular applications.
Moving coil mics sound great but have some coloration possibly due to the heavier diaphragm? They are robust and low noise.
The Pleiades V6 must be retried with the Grampian ribbon mic to increase s/n.
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