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I turned on my system and flipped my Pass X1 input over to phono to listen to some vinyl. I was surprised to discover hum coming from my speakers. My TT setup is: Benz SL -> Linn Akito 2B -> AR ES-1 -> Cardas Clear -> Plinius Jarrah -> Cardas Clear -> Pass X1. The table is plugged into a VPI PLC. The only time before this I ever had hum was when an errant light dimmer control in my home (there are several of these) was accidentally left on. When they are all off there has never been any other hum issue. The Cardas DIN cable is grounded to the Plinius. Hum varies with volume.
I tried ungrounding the DIN cable. The hum went away, but as soon as I flipped on the VPI PLC that caused a different hum that I would get from the VPI PLC, which caused me to ground the DIN cable in the first place. With the DIN cable grounded this hum goes away. Let me repeat I have never had a hum issue with this configuration.
I tried one thing, disconnecting the phono cable in its entirety - signal plugs and ground - from the phono stage. That worked; with the inputs to the phono stage floating open there was no hum. What could have possibly happened to make hum appear when it was not there just last week? Could some sort of damage to the cart cause this? The hum is coming from both channels. Normal line level inputs (when selected) to not exhibit any hum.
Follow Ups:
The main regulator input caps in my Plinius Jarrah had finally given up the ghost. One was leaking and the other was bulging. Since I could not find the exact replacement I had to try some of the newer well regarded PSU caps. Bought various Nichicon, Rubycon, and Panasonic caps. Pulled the old ones and tried the Nichicons to start. Hum is now really gone.
Considering the phono pre had been on 24/7 for at least 7 years I guess this was bound to happen.
But it really is a weird kick in the pants. Just to be clear, I have the ground from my DIN cable grounded to the Plinius phono preamp. The Plinius has its own power supply which terminates in a three prong plug. The VPI PLC has a captive power cord that terminates in a three prong plug. They are both plugged into my Haley power conditioner. Up until this started happening everything was working like a Swiss watch.
I started troubleshooting. The first thing I did was remove the cart. Much as I hated to do that it seemed like a smart first step; it gave me a chance to carefully examine the wires inside the cart and take another, better look at the whole thing under the Dino-Lite. That all looked good. With the cart removed I turned on the system and was still getting hum (I made sure the cartridge clips were not touching). Long story short - I had to unground the DIN cable from the Plinius and run the DIN cable ground directly to the VPI PLC! I never in a million years ever did that before. For some reason now that's the only way to make the hum go away.
Okay experts - what in the world does this suddenly suggest?
"I tried ungrounding the DIN cable. The hum went away, but as soon as I flipped on the VPI PLC that caused a different hum that I would get from the VPI PLC, which caused me to ground the DIN cable in the first place. With the DIN cable grounded this hum goes away. Let me repeat I have never had a hum issue with this configuration."
This is a little confusing, what DIN cable, a 5 pin din at the base of a tonearm or a balanced interconnect? Seems like the PLC is the likely suspect unless you hooked up an additional ground and caused a ground loop? The 5 pin DIN cable comes with a ground wire so how could the PLC cause you to ground the DIN cable?
BIRD LIVES
You might try removing the VPI PLC altogether. This is a very old unit (I had one in the 80s, I believe) and prone to problems, unlike the later SDS. If memory serves, I ditched mine for this very reason.
Hmm, that's an interesting thought. On the one hand I've never had a problem before, but on the other hand we have been having severe thunderstorms lately. I normally unplug my equipment in advance of storms, but the last one came on us unexpectedly in the middle of the night. We didn't lose power but I wonder now if there could have been some damage. The power switch to the PLC was off, though.
It is worth checking out. We had a power conditioner at our church go bad. It had gone through several storms over the last decade. Of course it was no longer under warranty, but it was cheaper to replace than all the equipment downstream. :)
I don't think that's the problem, but FWIW a power surge caused by a lightning strike can go right through a switch, even in the "off" position. My only other thought is to check to be sure that something "else" in your house is now turned on that usually is turned off.
The suggestion below by risabet is a good one. If you haven't already done so, make sure you use Caig DeoxIT Gold on all connections. From your description, it seems like the hum is coming from your turntable, tonearm, or cartridge since you say it goes away when you unplug everything from your phono stage. Did you move anything electrical close to your turntable such as a lamp or another component? Something definitely changed after the last time you played you system when it was hum free.
Good luck,
John Elison
John, see my response to risabet. I have not added anything new around my equipment and I haven't changed the way any of the cables are dressed. It was just last Friday that I played a bunch of vinyl and it sounded fine.
Could you conceive that some sort of cart damage could cause this? I had another thread last week where I posted that on one of my 7" 45s the cart accidentally dropped on to the mat instead of the lead in groove. But when I played disks after that it sounded fine. I'm really not looking forward to having to send this off to Pete for inspection and possible repair.
I don't know what your problem is either. Your guess is as good as mine.
Sorry,
John Elison
nt
By denying scientific principles, one may maintain any paradox.
Galileo Galilei
I did this a few months ago. They went on nice and snug, but I'll check them again. What concerns me is that if it were something with the clips, it would most likely be one clip. The hum I'm getting is out of both channels at the same volume.
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