|Here's the system I am working with: |
VPI Aries Table with XLR junction box. Aluminum platter, rim drive and outer ring. Two 10.5i arms with Kleos cartridges on each. 1M XLR run of Cardas Golden Reference to a Jeff Rowland Cadence phono stage with a separate power supply. 4M XLR run of Cardas Golden Reference to a Criterion Preamp. 1.5m XLR of Cardas Golden Reference Speaker Cables to the Classe 600 Monoblocks. Dedicated power lines and very stable and clean power.
Hum has kicked in since I switched to the Kleos and the Criterion. Before that, no hum.
The hum is in one channel primarily (but not entirely), and gets louder with a volume increase. Once the volume is turned above 70 db on the Criterion it becomes audible from the listening chair which is about 8 feet from the speakers. It's not audible while music is playing.
All cables are on elevators and separated from power cords. The Criterion just came back from Jeff Rowland with a clean bill of health.
In trying to isolate the hum, I have checked the tonearm connectors for both cartridges. All appear secure. Switched between the two arms and Kleos cartridges. No difference to the quality, placement or volume of the hum. I have actually switched out another Cadence phono stage and power supply. No difference to the quality, placement or volume of the hum. I also have switched out Cardas cables from the turntable to the phono stage and the cable run from the phono stage to the preamp. No difference.
However, when I reverse the Cardas cables running from the turntable junction box to the Cadence, the hum does change channels. It also changes channels when I reverse the Cardas Cables that run from the Cadence phono stage to the Criterion preamp. There is no change in the channel for the hum when I reverse the speaker cables.
The long run between the phono stage and the preamp jumps out as a possible issue, but then why the switch in channels when I reverse the cables from the turntable to the phono stage. Also, I haven't had the issue before the two Kleos and Criterion additions. I was running a Grado Reference Reference moving magnet though.
Any thoughts from the group?