Originally Posted by cporada
(Post 1071152)
Hi Glenn,
Thanks for your message. I am now almost certain the issue lies with the LP-2 based on the following diagnoses I have run through:
If I flip the input switch on the Decware Torii to the other inputs (to which nothing is connected), there is no hum, even if I turn the volume pot all the way up, so it seems to be somehow related to an interaction between the LP-2 and the Torii.
If I switch the preamp to the other set of inputs on the Torii, the hum follows the preamp - now the other input on the Torii (with nothing attached) is silent.
The hum persists irrespective of which set of inputs or outputs I use on the LP-2 (I only have one source – my Mojo Audio DAC).
I disconnected all power cords and interconnects and reattached them to see if there was a loose connection somewhere, but the hum persists.
If it helps at all, this hum started after I installed my new Sophia Princess 274b meshplate rectifier in the LP-2, but it only began after listening for about 2 hours.
Swapping out the 274b for the original 5Y3GT does not solve the problem. I have also tried swapping out all 3 6FM7 tubes to no avail.
The system is on a dedicated 20A circuit, and all gear is plugged into a Puritan PSM156 line conditioner that is grounded to a Puritan GroundMaster City. If it helps in diagnosis, the Puritan also filters any DC that might, for some reason, be on the line.
This is most frustrating, as it occurred with no warning, and I can’t figure out what is causing it or how to make it stop.
If I take the LP-2 out of the loop and just listen to my DAC directly into the Torii, the system is dead silent, so I have to conclude that the issue is with the LP-2.
Any thoughts/suggestions would be greatly appreciated.
Thanks again,
Chris
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