Sounds like some sort of internal grounding issue in the amp. Since someone else built it debug could be more challenging. I assume you are connected via a three prong grounded outlet?
I’m back... My parts finally arrived today and I assembled the filter. The result... No Change!
Both of the Antek toroidals I bought are kind of misshapen lumps of copper compared to the Avels I have on my LM3875 chip amps. I think the Antek is just an electrically noisy transformer. Where do you guys buy your Plitons?
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The amplifier builder said
"it has do the Chassis grounding. you can open the top cover. at the Power supply board output "GND" has a wires conenct to the Chassis"
Therefore,too me It's seems that I'll need to do this,Chassis grounding, need to be well grounded in one location. is that correct?
Yeah certainly could be the transformer.
I went to a custom designed Avel Lindberg transformer.
The DC blocker is definitely an asset to have at your disposal, and I would box it up and implement it, so don't feel too disappointed it didn't give you the desired result.
Yes try to have ground terminated at one location = 'Star Grounding'
What is the mV AC on the speaker outputs? It also seems strange how the hum comes in when connected to a speaker load (you sure it's not the speaker wires passing near the power supply?
Real hard to troubleshoot with someone else's work. It could be anything.
Once all your ground connections have been checked, consider taking the boards out (or try 1 channel at a time taking 1 board out) and see how the hum is? In my VFET build this solved all my hum noise problem noted here (I didn't have the luxury of the F6 board having the input transformer at the far end on the board.
My Sony VFET CSX1 Adventures & Grief !
My firstwatt F6
An externally hosted image should be here but it was not working when we last tested it.
Sorry for the delay - Yes, I tried new Vishay bridges - no change.
I did have a bit of. breakthrough though. I hooked up another amp I haven’t used in a long time and discovered the same symptom - A very low hum/growl in the speakers when you put your ear right up to a cone. That amp is small, so I moved it around the house and found that noise on all the outlets I tried it on. I’m going to look further into the mains for a solution. It doesn’t seem like DC since Implementing that filter I built didn’t change the noise. I’ll try to eliminate as much stuff from the mains as I can to attempt to isolate the source.
I’m tempted to try an isolation transformer like this:
https://www.hammfg.com/electronics/transformers/line/171.pdf
I found this article here:
Isolation Transformer Use???
https://www.hammfg.com/electronics/transformers/line/171.pdf
I found this article here:
Isolation Transformer Use???
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If you're going to add the expense of a large isolation transformer then you may as well set it up for balanced AC.
Power Conditioning | Plitron Manufacturing
The transformer should be rated say around 50% higher than the mains specs to ensure it doesn't become a bottle neck.
For Australia I would want a 3.5kVA isolation transformer.
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How can you be sure? Did you test the noise level coming out of the speaker posts of the amps? I would not resort to looking at the house electrical without knowing the amps are really having issues. Furthermore, I would not look at the electrical wiring in the house when it could be other appliances connected to the house electrical that could be injecting noise in the lines. Inductive devices like electric motors found in fridges, air conditioning units, etc. But even still you should be able to measure that noise.
Are you certain it's not something simple like in wall rca cables and speaker wiring that may be close to electrical mains wiring?
I agree with that, an electrician will be far more experienced at helping the guy finding the source of the problem and determining the most appropriate solution though.
If it was me I would disconnect every single appliance in the home, refrigerator/freezer, tvs, computers everything, then see if the noise is still there.
If it goes away, then plug in one appliance at a time and determine which devices cause issues, there could be more than one.
You'll have more information to tell the electrician or just get rid of the offending equipment.
If it was me I would disconnect every single appliance in the home, refrigerator/freezer, tvs, computers everything, then see if the noise is still there.
If it goes away, then plug in one appliance at a time and determine which devices cause issues, there could be more than one.
You'll have more information to tell the electrician or just get rid of the offending equipment.
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No, I can’t be sure, and yes I have more work to do to investigate. Here’s an interesting article about isolating grounds loops...
Find and Eliminate Ground Loops | Circuit Cellar
Taking a next step toward testing my broadband/cable feed will need planning. My SLA with the family is five nines
