Ground loop

[Kingrex]

Why do I want one Al.

That amp is currently running. The ground loop issues appear to be resolved. It still has noise issues. It's not a very quiet amp. Lots of hum. I haven't measured it, but I would assume it's around 45 db about a foot from the cone when the gain is set it normal listening levels.

My Found Music Blade is a far better amplifier. The frequency extension alone blows the Audion out of the water. The Audion is a fun amp. It has a rich romantic sound. The bass is not bad. I may plug it in here and there. I can't see getting any money out of selling it. So why not sit on it for the next 20 years and play it once or twice.

 

[brad225]

Rex. I'm not saying this is an issue with your equipment, just sharing.

I was having a problem with the image staying centered and it the only logical piece was the preamp.
My EE friend put the power supply and control unit on the bench. The power supply tested fine but as expected it was the control unit.

There are regulated -12 supplies for both L & R channel. The right was only putting out -7.2 volts the left was fine at -12 volts. Hence the image moving left after warming up. The manufacturer suggested changing the volume control chips while he was working on it so he did.

After changing that, he checked other parts to be sure they are still within specs. While doing that he found 1 ground loop in each channel on the board of the control unit. He cut through both traces and soldered in a piece of OCC wire at those points to create only 1 ground circuit. That left the return ground trace on the board not connected.

When it was back in my system it was unlike when it left my room. The image was again centered but the ambient sound was quieter, wider, deeper with detail I had never heard.

He has worked on numerous pieces of equipment for me but this was the first time I called him and said.

You need to come over and hear the change in the sound.

He has removed ground loops in every piece of equipment of mine he worked on but this was the first time the additional work done would not have had this effect.

A week later I am still stunned at the improvement.

 

[Kingrex]

Rex. I'm not saying this is an issue with your equipment, just sharing.

I was having a problem with the image staying centered and it the only logical piece was the preamp.
My EE friend put the power supply and control unit on the bench. The power supply tested fine but as expected it was the control unit.

There are regulated -12 supplies for both L & R channel. The right was only putting out -7.2 volts the left was fine at -12 volts. Hence the image moving left after warming up. The manufacturer suggested changing the volume control chips while he was working on it so he did.

After changing that, he checked other parts to be sure they are still within specs. While doing that he found 1 ground loop in each channel on the board of the control unit. He cut through both traces and soldered in a piece of OCC wire at those points to create only 1 ground circuit. That left the return ground trace on the board not connected.

When it was back in my system it was unlike when it left my room. The image was again centered but the ambient sound was quieter, wider, deeper with detail I had never heard.

He has worked on numerous pieces of equipment for me but this was the first time I called him and said.

You need to come over and hear the change in the sound.

He has removed ground loops in every piece of equipment of mine he worked on but this was the first time the additional work done would not have had this effect.

A week later I am still stunned at the improvement.

Hey Brad. Were you in Issaquah area?

My amps were extensively reworked. They are supposed to be the Black Shadow II circuit. They only have an Electoprint output transformer. I'm not spending more on them. I have sank $19k or so into a $15k brand new amp. I'm done. They play. They don't have the odd issues they did in the past. They mechanically work. They are just noisy compared to all other amps I have had. And the frequency extension on the top is not there. But hey, I'm comparing my Electroprint output transformer to Monolith that reach up to 60,000 hertz.

I wish I had thrown them out and used the $ to purchase a Triode or other some such. I hear what SET is about. I like the lush warmth. Its seductive. There is a uniqueness to the tone of wood instruments. A better more quiet amp would expose the tone better.

 

[brad225]

My wife and I were there in 2021 on a motorhome trip out west. We went through Issaquah on our way north of Seattle and then to Olympic National Park.
We entered WA after being in Coeur d' Alene ID.

Wandered around through the north, Columbia River, Grand Coulee and more places than I can remember.
That was when wild fires closed down much of the Cascades we wanted to see.

Amazingly beautiful State.

 

[brad225]

Sorry to hear of the problem with your amps. What brand are they. I have never heard of the Black Shadow II circuit. But then I haven't heard of most of the equipment out there.

Brad

 

[Been There]

I was having the same problem with my Plinius Amplifier, believed was a 60hz hum.
Opened amp and saw one of the caps had expanded. Sent it in for repair. Thousands of dollars later, was returned, didnt even look like the same I sent in so beat up except the rear panel with the serial number, and - still had the same hum.
After it failed shortly after receiving it back from a complete, full service and upgrade returned it. Then gaslight from Plinius rep on all the problems, faults and damage stating were all caused by us.
When the amp returned again, it was in better condition, still not what was told was going to be done was done or as was when sent in, but miraculously, the hum was gone. We've been ghosted since on what the problems or causes were. Truly the worse experience ever and will never own another Plinius.
As for the hum you are experiencing, I would recommend you step through your system - Just amp alone with speakers see if you have the hum. If so, probably the amp. If not, add preamp with just connections to amp (On same receptacle / power conditioner), etc, etc until you identify where or what is introducing the hum.