Manley Stingray Users

Hello,

I hope everyone had a great 4th.

Input tubes   Mullard CV 4024

Driver Tubes   RCA  BH 127A

Output   Mullard EL84's

I've been tube rolling the driver tubes and I like the RCA's but I need your help.

Other than the RCA's I've tried Tung Sol BH127A"s, GE 6414's and ATC 12AT7's from National Electronics.

As nice as the RCA's sound I'm getting a hum.  Also getting a hum from the Tung Sols and GE's but not as loud.

Install the 12AT7's and the hum is gone.

Tube issue or time to take the Stingray to the shop?

Thank You for your input!