The bread Board amp (Be Bamp) built some time back had swapable driver stages: 6N1P in a timber box and 6SN7 on cast Al base. Both had the same inter-stage caps (Russian military PIO) and both were driven from a common PS. I was asked which driver stage I prefered but had never taken the time to compare. But now I have.
The test arrangement was a laptop playing 24Bit 88.2khz Flac files through a high rez D2A, BoZSE into each driver stage (6N1P and 6SN7) then powered by the Be Bamp (KT120 tubes), Speakers were KEF IQ30. A rock track, single piano and orchestral track were played over and again through the two different driver stages. I could not really pick the difference until I played the single piano tracks.
The pick has to be the 6N1P in the Twinnings Tea box. This driver stage brought the piano forward and focused it well between the speakers. It WAS an single paino and apart from open and deep reverb into the recording hall nothing alse. The 6SN7 wanted to place the piano more balanced into the hall and make the reverb sound like a second or third instrument producing a very smooth mix of solo instrument and reverb/hall. With the 6N1P there was no mistaken the fact that you were listening to just one piano, reverb and hall decay were a result of the instrument and not a part of it.
The 6N1P had been picked by a freind when I demonstrated the Be Bamp at his place. His discription was "more open". The 6N1P is a punchy tight little tube. I have used it in other amps which have been pruchased on a single audition. Well the Russians got something right.
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