How to Sub 6U8a or 6GH8A for 7199?

[burnedfingers]

I finally got around to playing with an old broken down stereo 70 that has been sitting gathering dust for months. I modified the board which took less than 15 minutes and proceeded to put the dynaco back together. I must say that I thought the RCA brand 6GH8A's were just as quiet as the 7199's were. I noticed no difference in their sonic signature. The bass was just as tight. The midrange sounded just the same and so did the high frequency.

The amplifier's THD is the same now as with the 7199's with a number of tubes being tried. So the tube in my opinion provides the same performance with the availability being the only factor between it and the 7199.