Balance control?

Resurrection of an old thread, but I also run a Herron VTPH-2A phono stage. Keith was kind enough to include gain and trim pots for each channel to help with tube imbalance if this is indeed the case. There can be many causes, as per the posts above, but if you trace it back to the phono stage don't be afraid to try a little trim. 

@bimmerman2 wow really?! That’s very cool. Yeah Keith is a very helpful and pleasant guy to chat with. What are trim pots? Are they different from the loading plugs?

They are different from the loading plugs, which I don’t use with my Aphelion cartridge as per Keith’s suggestion. The pots are inside next to the tubes and are labeled, you just have to remove the top cover. You can turn them with a small screwdriver. On mine I ended up having to lower the louder channel a bit and increase the quieter one as the adjustment range isn’t huge. I’ll post a picture in my virtual systems section under "Final Set" so you can see them. They are the little blue pots. There are 3 per channel, gain, trim and bias. Don't mess with the bias pots. 

@bimmerman2 

Awesome Keith did that! That's a great mod. I wish more preamps with analog volume controls would provide a few high quality (high quality resistors) discrete steps of ~ 1/3rd dB in each direction L/R. That should provide enough flexibility for most use cases (more than 1 - 1.5 dB cumulative imbalance and something is wrong) without a significant SQ penalty. 

It’s pretty slick he has that inside there, the range of adjustment isn’t huge by any means, but it was enough to balance out the very slight imbalance I was getting. Took forever to track down what it was, did all the steps above, cart good, cables good, speakers/room placement symmetrical to the 1/16th of an inch. That simple little tweak of the pots brought it into perfect focus.