Mazda 12au7 Gray Plates

(13 votes, average: 4.46 out of 5)

“… having a wonderful 3D sense of space and it does!! The stage seems larger than
life. The only flaw it might have would be on bright systems it tends
to have a happy high end, but I can live with it.” Read

“Beautiful punch/dynamics, with the leading edge of the Telefunken’s without the “etch”. The body of the harmonic is not quite as full as the long plate Mullard’s/Amperex’s but more body then the Telefunken’s. “ Read

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12au7 gray plates

(5 votes, average: 2.80 out of 5)

There is not much to say for the tubes. They all sound similar. All sound bad. Not worth the money that you would stand on them. When they were released, tube hardware was not considered high-end. Now, since the tubes are used in high-end by audiophiles having them is just not a good match for the amps. Sell, sell, sell.

I tried Sylvania, RCA (a bit better than the others), Baldwin, GE, Motorola all with the same results.

The only exception is RCA clear top – they don’t come with black plates and they sound quite good.

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Raytheon 12au7 black plates

(29 votes, average: 3.62 out of 5)

“Don’t miss trying the “organ stock” 12AU7 tubes that were sold to organ manufacturers. These sweet tubes were screened for audio use in organs, and have the organ brand on the label. Usually sold at bargain prices because of the re-branded label, the RCA cleartop and Raytheon blackplate versions are a great find!” Read

“…She told me that the yellow Raytheon 12au7 sounded WONDERFUL in the MG Head OTL, except that it was a little quieter. She reported that the sound quality was practically identical to the Raytheon 5751…” Read

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RCA 5963 Black Plates

(19 votes, average: 4.16 out of 5)

“A really fine blackplate from the 1950s, many audiophiles feel these outperform most of the other NOS 12AU7 tubes. Ranked on par with the European brands! “ Read

“Smooth and sweet, but bargain prices. Not side getter, but still has that great RCA sweet and smooth sound.” Read

“very smooth tube with no weaknesses. Very good top to bottom” Read

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