JayGilb
Major Contributor
Thanks. That information was very helpful knowing that the company recently refurbished the unit and gave it a thumbs up.While not rare, the LS3B is unique. My wife gave it to me for my birthday back in the mid 1990’s, so it has a great deal of sentimental value and will always be part of my system. I have tried jiggling interconnects and, frankly, they are solidly connected and do not budge. There is also no difference in hum. In February, I sent the unit to the Audio Research factory just to make sure everything on the unit was ok. They replaced a couple of capacitors, due to their age, tested it thoroughly and said it works great. They also spent the past couple of weeks helping me troubleshoot remotely. Even their engineers are not able to find and fix my issue. It may be that this preamp becomes eye candy in the rack and gets replaced with something that was made in the 21st Century. But that would not be nearly as much fun. Ha! Again, I appreciate the help and suggestions.
I missed this comment and glad tonycollinet noticed it. Hopefully between several members, we can help figure out your problem.If I disconnect all of the single ended sources going into the preamp (LS3B), the hum goes away. Once any of my sources are reconnected, it returns. It has been most frustrating.
As he mentioned, either a connection diagram or a text description of the in/out connections to the preamp would be helpful.