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.

obarrett
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it is actually the Southwire "10041N autoranging multimeter." I use it mostly for DC mA but occasionally I use it for checking continuity and less often for checking AC voltages.

It looks better. Also seems to have more user friendly features. Accuracy of AC voltage measurements??? It didn’t say it is a True RMS meter.

As for using the meter to check/set DC ma bias it is probably fine. Use the mA rotary switch setting. It should give a more accurate reading than using the 10 A setting.

Southwire 12 Function 0.1 Amp 600-Volt Digital Auto Ranging Multimeter (Battery Included)

I am about sure the manual says 270 to 300;

Manual says 275 to 300 ma. My understanding that is too high.

My Son bought a V12 a few years ago at, I believe an Estate sale. He said he was having problems setting the bias. He brought it over for me to look at. I tested the KT88 power tubes in the amp. On the "Life Test" all tested good except two tested good marginal.

What didn't test good was the 4 small signal tubes. He bought 2 new 6922 tubes (input / driver tubes) and 2 SV83/EL84 tubes (Current source tubes).

While he was waiting for the new tubes he searched Cary chat forums on the Net. He found a good site that said the Cary manual bias settings were too high. I can't remember where we set the DC ma bias at. What ever it was he hasn't had any problems with the Amp. That is when he uses it...

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@jeffbij Yes I’m sorry I misspoke. I was connecting to the RCA input of the amp, not the TT.

 

@jea48 yes wired coax to router, then Ethernet from router to bluesound node. Ethernet is not shielded. Both cables pass close to the interconnects going to/from the preamp through the back of my cabinet. I made a video: https://youtu.be/dPq8B54utCw?si=o6S-uJqUXYGxfJiT.

yes, I meant analog input of my RR2160. Apologies.

spark from outer shell of RCA cable. In video I show exactly where as it left a crater in the metal casing. NOT the center pin of the interconnect.

 

i ordered the Klein tools MM720 you recommend. It should arrive tomorrow. Please tell me what tests I should start with and how to execute them. I’m not going to get a separate outlet tester if it can be achieved using the multimeter. Thanks for all your help.

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