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

@mark200mph

I could be wrong, ( the amp hasn’t been checked out yet) but I think the phono preamp is the problem.

I base that on this resent post from the OP.

But since all this I’ve listened to about 3 hours of music using the amp with no issues whatsoever (phono disconnected of course).

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He also posted the same thing earlier in the thread.

@jea48 RR2160 amp has built in DAC and has two coax inputs. One to CD player one to bluesound node. Since this episode I’ve been listening to music off the node without problems.

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Saturday, check for voltage from the outer shell of the output RCA jack of the phono preamp to the outer shell of the analog input RCA jack on the RR2160 amp.

Should of done that to begin with...

Both units powered on.

5.5Vac on V

0.02Vac on LoZ

When you get a chance check the wall outlets the equipment plugs into for proper Hot / Neutral polarity and for equipment ground. At least you will be able to check them off your list.

I sent a lot of messages last night so perhaps you missed:

I tested the outlets where things were plugged in. The hot/neutral is reversed. So the hot is the longer left slot, the neutral is the shorter slot on the right. The ground appears to be functioning.

Explicitly, this means when I’m on V or LoZ and I go into hot/neutral I get 120Vac. When I go neutral/ground I get close to zero, and when I go neutral/hot I get ~120Vac. However, hot/neutral is reversed.

i don’t think it matters but when I plug one lead of MM into ECG and the other isn’t connected to anything I get 5V on V but it disappears of course on LoZ.

Question... Is the SMPS 120Vac plug in blades the same width or is one wider than the other? Therein polarized. If both blades are the same reverse the SMPS 180 degrees in the receptacle and perform the test for high voltage again.

the blades are the same width. For the following test I plugged the SMPS into the wall in the same configuration as it was in when the incident occurred.

I don’t know what I was thinking yesterday... I should of had you do the tests with the phono preamp connected to the SMPS. Therein the connected load. Likely a defective connected load that might be overloading the SMPS. A real world test...

ok I did this test following your 7 instructions and got the following readings:

52.5Vac on V

0.16Vac on LoZ

i know you said LoZ not necessary but I did it and again the voltage disappeared.

0 on DC on V and LoZ (I looked into ghost voltage and it seems like a purely AC phenomenon).

i was watching the blue light on the 110lp as i was doing this test and it was blinking continually. I made a video: https://youtu.be/Dcaxu_ZM6VQ?si=sj70-NxTUOHN3noQ. The blinking did NOT fade away but kept going like this faintly.

I remember last weekend when I had the preamp connected to the amp’s analog 1 input and I listened, I heard a ‘bump’ paced exactly the same as this blue light’s blink. This was as a record was playing and the preamp was connected to the TT. I heard no music just this gentle regular bump.

 

I’m starting to think neither component (amp or preamp) is behaving evilly on its own (although the preamp seems clearly broken), but only together there is a toxic combination. Note, I used these components together fruitfully for the last 3 or 4 years. It was only when I moved them last weekend that disaster struck. It’s also conceivable to me that the preamp was dangerous but now some circuit is shot and it’s not dangerous anymore. I’d also like to test connecting something else to the RCA input on the amp but I’m not sure I have anything I can test. Maybe my TV. As mentioned I did connect the TT directly to the phono stage of the amp last weekend and it did function normally, just was unlistenable (because of how bad the integrated phono stage is).

 

I’m obviously leery of connecting them again but if there’s some way to do so safely I might be willing to try. Thanks for all your help.

 

and yes, I’ve been listening to music off the amp using the node (am doing so right now) and it sounds great. (Hariprasad Chaurasia today.)

 

one more remark: when I was trying to connect the IC from the preamp out to the amp analog 1 input last weekend, the whole general area of the rear of the amp felt dangerous. It wasn’t just the rca plug. It might have also included the speaker wire which is securely seated in the amp. On this point, you saw the crater on the IC exterior in my video but I’ve been unable to see any corresponding damage to the amp. I just looked closely. It almost seemed like the spark jumped from the air and landed on the IC. I don’t know if this is possible.

 

@mark200mph thank you. Fortunately I can still listen to music over digital and that is what’s keeping me sane.

@obarrett Said:

I will answer this first.

I’m obviously leery of connecting them again but if there’s some way to do so safely I might be willing to try. Thanks for all your help.

NO, I wouldn't if it was my equipment.

I haven't mentioned it yet. You may have damaged the analog L & R  input circuitry in the RR2160 amp. The pair of RCA jacks you plugged the ICs into from the phono preamp.

I haven't mentioned trying to connect a different source to any analog inputs on the amp as yet. You don't know yet what what is causing the problem.

I will go back to you previous post I was reading and respond to it.

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I haven’t mentioned it yet. You may have damaged the analog L & R input circuitry in the RR2160 amp. The pair of RCA jacks you plugged the ICs into from the phono preamp.

This wouldn’t be a big deal if the three other RCA inputs still worked. Last weekend I connected the preamp to analog input 4 on the amp and it made the same soft bump sound. I just remembered the blue sound node also has an integrated DAC and RCA out. So if I don’t mind risking frying it I could try connecting it. Ideally I should find something cheaper, maybe my TV (which is old and I don’t use). I’ll check if it has RCA out when I get home.