Channel Imbalance Mystery

I’ve been experiencing a channel imbalance for awhile now that I cannot seem to solve. I’m only running a turn table so I cannot troubleshoot with a digital source. I have ruled out the TT and cart as the problem because I had it tested in another system and it sounds great there. I’m running a Herron VTPH-2A phono pre into a Cronus Magnum II integrated amp with brand new KT120 power tubes. (The imbalance was present with older power tubes too). My channel imbalance is left leaning. When I swap the tt inputs into the Herron preamp the imbalance is fixed. Vocals are dead center but my stereo orientation is flipped. No problem, just swap my preamp outputs to get me back to the correct channel orientation but doing so shifts the center image back to the left a bit but soundstage is correct. It’s not nearly as bad as when my tt inputs were in the correct L/R positions. What the hell is causing this?! I’ve tried different interconnect cables with the same results so I don’t think it’s a cable issue. Could it be unmatched signal tubes in the Herron? Signal tubes in the integrated? Super frustrated. Thanks for any help. 
Swap the tubes and find out. I have all tube components. Whenever something odd like that happens it is a tube and swapping will quickly identify it as tubes are split along channels.

I also always have an extra set of tubes around as backup. They don’t fail or act strange often, but it is good to have if the do.
With tube equipment, it's almost always the tubes. Always the first thing to check.
@russ69 ok I changed the 12AU7 and 12AX7s in the integrated back to the JJ tubes that came stock with the amp from some Gold Lions and no change. I guess it must be the tubes in the Herron preamp then. I just replaced the 2 12AX7s in the Herron a few months ago so they should be good. I just ordered 2 new 12AT7 to replace in the Herron. Fingers crossed it’s the AT7 that need replacing! Do you know if there one type of signal tube that tends to go bad vs. another? Just wondering. Thanks 
My channel imbalance is left leaning. When I swap the tt inputs into the Herron preamp the imbalance is fixed.


This is the part I don't get, "It's fixed" by swapping left to right. Just the cables right? What do you mean fixed? Imbalanced, you mean one side is louder. Moving a cable is not going to make it right, unless the cable is broke or pulled to tight causing improper contact or pulled wires..

It's fixed means it's fixed.

101 cable.. move the cable and the signal changes something is lose or touching.. Do you have a broken center pin on a male RCA or a center pin broken off in the female RCA? Is it plugged in far enough or to far?

Get your phone and run test tones to check both speakers db level.
Go back from there. You have a test LP or a way to pipe your phone into an input. I use old S3 galaxy phone for head sets and all kinds of things.. Multi DB meters, Source, little mini network, the Wifi still works so does the camera, video, mic, a ton of things. I have a few old G? phones

Plug in to a head phone jack on your amp.

They work perfect for testing STUFF.

You can test right back to the wires for the phono cart if you want.. One cable one tube at a time.

I bet you could put a signal through that Herron via 1/4 stereo plug to L/R RCAs turn the phone down and check left and right signals..

"...Do you know if there one type of signal tube that tends to go bad vs. another?..."

Tubes can go bad at any time. What you do is swap all tubes left to right. If the problem changes sides, move the power tubes left to right and see if it changes. By process of elimination you can isolate the bad tube. 
Tubes, tubes, tubes!
Just today, I swapped out Chinese 12AT7s in my Atma MP-1 preamp. Channel balance was ok but the imaging was skewed of to the right. With the new NOS 12AT7s the image is now correct dead center.
@oldhvymec fixed is not the correct word. I would say the imbalance is better but not perfect when I swap the phono RCAs into the Herron then swap the RCA outputs. I called Keith Herron and he thought the same thing as you. Poor connection or bad cables. He also said it’s possibly the tubes so that’s where I’m at after swapping RCA cables and getting the same results. I agree, what’s happening is very odd. I do not get it. 
@mglik thats what I like to hear! I sure hope I get that same results when my replacement 12AT7s arrive. I purchased this preamp used a couple years ago and have only changed a couple of the 5 tubes so who knows how old those AT7 signal tubes are? Thanks for sharing your results after swapping your AT7s!. Appreciate it!
there is such a thing as a stereo triode…helps to know both the tube and the topology…


Keith will square you away.
@tomic601 my knowledge and understanding of this stuff is very limited. What is a stereo triode?! And yes, Keith has been very helpful and he seems like a great guy. 
dual Triode, 9 pin…mostly for the random tube swappers….

Like i mentioned, Keith a superb engineer has you covered…
Get a GOD**** Tube Tester! 

I cannot imagine loving tube sound and denying myself the ability to have confidence or find problems in active and replacement tubes.

Test the tubes, short? good or bad? go from there. Have the tester for the rest of your life! Get or download the manual. It's not rocket science. I test new matched tubes when I receive them.

this little tester has given me confidence and found problems for over 40 years. I have a big fancy one, they always agree, I don't bother with the big one anymore, I'm gonna give it away or sell it someday when I get around to it.

I would take it apart, hose it's guts with contact cleaner/lube, twirl the controls this way and that, blow it dry, wait overnight for further drying, and get right to it.

Paul, it is probably an illusion created by room acoustics and imbalances canceling each other. 

My system has always run 3 dB hotter on the Lt in my current room. There is an alcove on the left side wall. In preparation for a new turntable I finally completed the built in cabinet for that alcove. My left channel now runs 1 dB hotter. Now if my right channel electronics had 0.5 dB more gain switching channels like you did would cancel out the imbalance. This is what a balance control is for. Unfortunately, that imbalance is hardly ever equal across the audio spectrum so your frequency response curve is being shifted. This is where room control is very effective. For reference a 0.5 dB imbalance is just noticeable. A 1 dB imbalance is obvious. 
This will solve things until you ascertain what is going on. Gives you remote balance as well as remote volume.

Then, after you 'fix' whatever is going on, you have it, it is noise free 120db s/n and neither I or my friends can hear whether it is in or out of my systems.

I love having remote balance from my listening position for the few tracks that need a balance tweak. A small adjustment can make a large difference, so much ’opens up’ when the balance is spot on.

It also has automatic ’Loudness’, progressively engaged ONLY for low volume listening, the primary benefit is retaining bass presence, a big part of maintaining involvement at low level listening for me.

@mijostyn it’s not room acoustics. There was a time when I had beautiful channel balance in this same room with the same system. It’s gotta be the tubes or something else. 
May be tube related or not. It may also be a recording issue, I hear many early stereo and some mono recordings have left of center bias. Sometimes this is intended bias created by engineers/producers, other times poor remastering and or duplication.
What about your ears, ear wax can cause this, or maybe some other reason for loss of hearing.
I find a little logic and a very few minutes of swapping tubes sufficient to identify tube issues. For instance I had a channel a bit weak not that long ago (new equipment). I reseated the tubes and it went away… 15 seconds of work.

Also, I noticed the Tung-sol site basically says the best way to test a tube is in the equipment. There are all sorts of testers and none really guarantee performance in the equipment.

Although I am attracted to instruments (I have 4 pollution sensors). I admit I am lazy and don’t want more junk around the house when it comes to audio.

"With tube equipment, it's almost always the tubes. Always the first thing to check."

I don't know about that. . Tubes are easy to check as the first thing, that's about it. Reseating sometimes works wonders.

Talk to some old timers who work with tubes, they're the LAST thing as suspect. Tubes powered WWII. They generally are fool proof. 

"...There are all sorts of testers and none really guarantee performance in the equipment..."

If a tube sounds good, it is most cases.  
Before we go any further is the (balance) knob at the 12:00 position?
You stated that when you swapped the cables it was “fixed”. It is kind of confusing. The only other thing I can think is when you swapped the tubes you did not redo the bias of each tube. Rogue has been known to have a bias setting for each individual tube. Please do this first. They even give you the little inset screw driver so you don’t arc anything. Once you bias each tube to factor specs redo your test. Positive to positive and negative to negative.  If it is still unbalanced try the opposite. I have a feeling in swapping things around certain things were not done. These reasons may be why it worked on another system but not the Rogue. I hope one of these works so you can get back to listening.