12AU7 and 12AX7 long black plates vs short black plates. Any difference ?

@slaw I'm not claiming to know a great deal about them either but I have been enjoying them for about the last 25 years or so. I would guess that the non gold pin Sylvanias would not sound as good as the 3 mica Gold Pins as they were their "top of the line" and have commanded pretty high prices over the last 20 plus years. I used to buy them for $15 to $30 apiece back when I started buying them. I bought NOS and lightly used ones at those prices. You'll be hard pressed to find any Sylvania Gold Pins for less than $80 to $150 now, with 3 micas bringing the highest prices. Must be something to it. I never had any Sylvania 5751's that were not gold pins. I do have others, like 5814A's in steel pins and they are fine but I imagine if you found the same in a gold pin, it would be even better. I don't think it's so much the pins themselves that make them better (although it can't hurt) but what went into the rest of the tube as well that made them a premium tube. My 2c.

@billpete If I am reading it correctly, according to Joes Tube Lore the Gold Brand 5751 3 mica black plates are identical to the gold pin 3 mica black plate tubes other than the color of the pins.

Per google: " Gold is used on tubes for its inert properties, specifically to prevent oxidation and corrosion on the pins over time. It is not for significantly better conductivity compared to nickel or copper, but rather to ensure a reliable, quiet connection."

@jetter You may be right. I lost my link to Joe's a long time ago but have notes that I wrote down and I haven't looked at them in years. I still give gold pins a slight advantage as it stays nice and clean and does conduct better than steel. Does it make a difference? I can't really say as I've not had the same tubes in both steel and gold pin to compare. It might be a fun thing to check.

As to @slaw finding them bright in his preamp, it might be just the difference between the EAR preamp and the Cary PH301 that I used. This is why we have to make our own comparisons as every piece of gear will have it's differences. I always try to find someone who has the same piece of equipment that I have and see what they liked for tubes in theirs. Finding two exact same systems would be about impossible and why we see so many varied opinions on just what worked for each of us. Total agreement on anything is virtually impossible for many reasons.

Best of the best 12au7's CBs Hytrons of the 1950's or the square getter rca JHY12au7, I will lookup the other super 12au7 tube in my stash later this evening. You need to locate yourself and buy a  NYAL George Kaye Small Signal Tube Tester if you are serious.

Best of the best 12au7's CBs Hytrons of the 1950's or the square getter rca JHY12au7, I will lookup the other super 12au7 tube in my stash later this evening. You need to locate yourself and buy a  NYAL George Kaye Small Signal Tube Tester if you are serious.