Did I just cook my preamp?
I have a Simaudio Moon 110LP phone preamp amplifying a Dynavector 20X2L cartridge on a VPI Classic. It feeds in to an Outlaw Audio RR2160 amp which drives Magnepan LRS speakers.
I recently moved and two months in I realized my speaker placement wasn’t quite right, so today I reorganized my listening room. This involved unplugging some power cables but I kept most of the interconnects in place. I did have to disconnect the phone stage from the amplifier.
After getting things back into place, I listened to some music using coaxial input before reconnecting the interconnects of the phono stage. When I tried to, I actually got some electric current that burned my hand slightly. This came from the back of the amplifier. I made sure everything was unplugged and tried again - this time a spark and smoke from the interconnect making contact to the back of the amplifier.
I’m so confused why this would happen, but eventually I did get everything connected. Now the output from the phono stage is just a bump every 1 second. It doesn’t amplify the signal from the TT.
My amplifier has a built in phono stage and using this I was able to verify that the turntable is still producing a signal. The built in phono stage sounds terrible, however, as thin and flat as paper. It is music, however.
When I connect the phono stage to the power, the blue light on the front illuminates for a moment and then goes dark.
Incredibly, when I was unplugging the phono preamp, I actually got some current from simply touching the exterior of the box. Something is seriously wrong and dangerous with my setup, and this box was grounded to the turntable with a ground cable, which was connected to the outlet with a three prong cable with ground.
Has anyone experienced anything like this before? I will email Simaudio and see if they’ll repair it. I’m also taking recommendations for replacements. I liked the 110LP and maybe will just replace with the 110LPV2.
Hey OP, I just ran upstairs to answer you. I’m not usually an alarmist but it sounds like you have a potentially dangerous situation here. It seems like 2 things have occurred:
I strongly encourage you to take this seriously and resolve this. Potential side effects are electrocution or fire. What may have happened is that the power supply has become shorted to the chassis, hence the burn you received while attaching interconnects. That should _never_ happen. This happens when a short has developed and the normal path to ground (the ground AC pin) is not working correctly. In addition to potentially lethal shocks a fire can also happen as the current is flowing through your interconnects, which are absolutely not designed to do this. If you have previously removed a ground pin or used a cheater plug, immediately remove the cheater plug and/or get a properly functioning power cord with the ground pin working on both ends. Otherwise, find a qualified technician to examine your equipment and/or an electrician to inspect your outlets. You may also want to use a cheap AC outlet tester like this one. Be extremely cautious and use the breakers to disconnect power at the slightest hint of a shock. Also, of course, keep liquids and wet hands away from your equipment and wear insulated shoes while touching it while plugged in. |
Thanks for this advice. I agree with what you wrote. I bought the amplifier used and it came with a power cord without a ground. I’m going to immediately replace that power cord with a proper three prong power cord. I think that the preamp developed a short and current was definitely flowing through the interconnects into the amplifier. What a mess. How the preamp became so suddenly hazardous is beyond me. I can’t rule out the possibility that I connected it to the power when the other end of the TT interconnects wasn’t connected. It’s hard to remember assembly details like that one years later when you’re just moving some equipment around. Nevertheless, that should NEVER cause the dangerous situation that ensued. When I connected a ground wire from the TT to the amplifier after it had been roasted by the preamp, it SPARKED. Very upsetting. I don’t ignore the possibility that the ungrounded amplifier could be the source of the current, but the amplifier continues to function normally and doesn’t become charged unless connected to the preamp. |
