Tube Phonostage Causing Rumble and Noises

Hi Noromace, not in use means not playing and still connected to the select source.

my turntable is far away from a corner and the sub is at least 5 ft from the turntable.

At this point, I probably should try the rumble filter. I will give KAB a call tomorrow to get more info. Stereo5, did you mean RF-1 because I don’t see RF-5 on KAB website.

I appreciate everyone’s advices and help. Thank you all.

Do your tubes have tube dampers? It probably won't cure the problem you are having, but if the issue is microphonic tubes, damper rings may help.

Another thing to look at. A friend of mine had a terrible noise issue with his phono stage. It was later discovered to be a bad dimmer switch on the same AC circuit. You should try plugging the phono stage into different outlets to see if this is a noisy power issue.

Try changing out your interconnects. 

Hi dmguragno, thanks. I just moved the phono power cord to another receptacle.

I had an experience that a defective receptacle caused my power amp to overheat.

@agharion

If your rumble occurs with needle out of the groove, that is not turntable feedback! And it does indeed point to the Io Eclipse as a culprit for generating this unwanted LF noise. The needle has to be in groove to test for table feedback issues. I used the needle in groove, at rest, to test many many times in my "problematic" small room rig.

It’s a lot of money to have invested in that Io. I’d try to borrow another phono stage to really nail it down to the Io. Heck, maybe buy a Hagerman Trumpet MC - it sounds great for the money ($1289), might surprise you, works with almost any cartridge, won’t cause this horrible noise, and is handy to have around as a backup and sanity check.

But yes, the KAB rumble filter should "fix" this problem, but if it’s being generated by the Io I wouldn’t keep that phono stage in there regardless. My problem in my small room rig was feedback based, and the KAB did indeed resolve it (I went through 2 of these KAB’s actually; the 1st unit was defective) - though I don’t feel it’s quite 100% "sonically transparent" as claimed. However it is indeed good, and FAR better than dealing with the issue you describe. In the end my issue bugged me enough that I vowed to resolve the feedback issue itself, and eventually did. I now run happily without the KAB filter. I don’t think with all you’ve invested, you should tolerate a phono stage generating rumble. The fact that the company sent it back like this is a huge strike against.

And just philosophically, I don’t consider tubes capable of producing up to 80dB of phono gain without inviting massive noise issues. That’s why everyone else uses a JFET stage or SUT for MC gain. I’m sure it’s a nightmare selecting and re-selecting low noise tubes.