I agree with the above listing. A poor solder connection can cause hum, but generally only on the amp that has the poor connection. Hum is also caused by ground loops. Power down and run a temporary insulated copper wire connecting the chassis of the power amps to the preamp chassis (metal to metal). If the hum disappears, you probably have a ground loop problem or possibly a high resistive return path on an RCA plug for the connecting cables. If the hum is present in both channels, and since your amps are monoblocks, I would suspect ground loop problems. Ground loop problems can be usually solved by tying the chassis of the affected equipment together, thereby placing the components at the same ground potential.
Hum problem with Alpha Goertz Sapphire cable - RCA type
I use Alpha Core Goertz Sapphire between pre and power amp (mono blocks). Both amps are tube. Cables are a couple of months old. One day I noticed a stronbg background hum in both channels. Today I called the manufacturer to help me solve the hum issue.
Their Technical Guru said "Buy another cable, i.e. if you get hum you can't get rid of it".
You guys out there are a lot smarter than that. I know it. The preamp is in arack. The amps are on the floor. The distance from the RCA to RCA plug is probable .8 m. Cable length is 1 m. What do I do to avoid the hum. Tape the cable to the rack. Play with the power cables? Please help. There must be a solution.
Thanks.
Their Technical Guru said "Buy another cable, i.e. if you get hum you can't get rid of it".
You guys out there are a lot smarter than that. I know it. The preamp is in arack. The amps are on the floor. The distance from the RCA to RCA plug is probable .8 m. Cable length is 1 m. What do I do to avoid the hum. Tape the cable to the rack. Play with the power cables? Please help. There must be a solution.
Thanks.