good discussion on power cords

Or perhaps someone heard about using silver grease on a circuit breaker and decided they would "slather" some on the connection point point to the buss-bar, not knowing that the technique is used to grease the contacts of large breakers, not the connection points of residential breakers .... likely the result also of not knowing the contact resistance of that connection to the buss-bar.

I suppose that the parts of a circuit breaker one would slather with a silver grease, might be those that grip the box’s buss bar and Romex, could escape some.

I am impressed. Usually those things are riveted together or sonic welded such that you can't access the contacts to grease them.

I just popped in a new 20 amp Square D slathered with silver grease.

But if someone else put them in your system, would they sound like they remembered, or if they didn't tell you, would you notice at all?

I am not surprised we don't have public measurements. I wouldn't be surprised by a small reduction in noise floor (which would likely only matter if you already have a really low noise floor source), perhaps even a small reduction in IM/THD with the right set of equipment ... but the question is, when do the diminishing returns reach 0 (at what price point), and are there less expensive ways to accomplish the same thing?

That does not make what the late Charles Hanson said an accurate analogy, but I think we can state pretty unequivocally that the goal of the power supply is to isolate the output (audio) from the input as best as possible. One thing you don't want to do it "modulate" the AC into the audio. Technically the diodes in the power supply perform a modulation function on the incoming AC which is why you get DC.

You can disagree but I get the impression you are not technically qualified to do any more than "disagree".  No they are not "all related". A primary purpose of the power supply in an amplifier is to isolated completely the AC from its impact on the audio signal.


Rectification is the electrical function, modulation is the signal processing operation that occurs. The rectification is a signal processing multiplication function, or modulation. Ideally you would only modulate the 60Hz AC with only 60Hz to yield 0Hz = DC, but the modulation function ends up being something more akin to a pulse (rectangular waveform) multiplied by a sine wave, hence you end up with all kinds of harmonics of 120Hz that you need the capacitors to filter out. Ideally you design your power supply with inductive filters to extend that "pulse" and reduce those high frequency harmonics to there is less ripple for the capacitors to filter.

andy21,171 posts07-05-2020 10:28pm

but I think we can state pretty unequivocally that the goal of the power supply is to isolate the output (audio) from the input as best as possible.

I would disagree with that statement. There is really no "isolation". They are all related.

Technically the diodes in the power supply perform a modulation function on the incoming AC which is why you get DC.

I think that is called "rectificatioin", not "modulation".  

The minimum gauge will be 18. It absolutely will not be 20 or 22. For the JA800 based on current draw, it will be 16 or 14 minimum. Most companies will at least meet the basic electrical code requirements even if they don't get proper safety certification.

Why would I not agree with him if he makes a poor analogy? I don't idolize people who made interesting products but didn't contribute to moving the science or art forward.


You laughing at my description of modulation shows you had no clue what I was talking about. No worries people who understand this stuff will know exactly what I mean or will at least know enough to ask the right questions. The joke is on you. Understand frequency domain analysis makes designing power supply filters much easier and the results more successful. That's the difference between tinkering and engineering I guess.

You could just admit you don't have any real engineering knowledge ...

andy21,176 posts07-06-2020 12:46am^^^ OK, whatever, so you're a pretty good at copy and paste.  

It's almost like he is saying the goal of a power supply is to I-S-O-L-A-T-E the AC from the audio ....   His analogy is a bit better when it is all there huh ....  Of course if you don't understand what he means, you could come to the conclusion that matches what you want it to say.

When you understand how an amplifier works—that you're making a copy of the signal by modulating the power supply—then you see that the power supply directly drives the speaker. Anything that's not right about the power supply is going straight into the speakers. That's why we use such a huge power supply—take off the lid and you'll see that about 90% of the innards are the power supply. We have a giant transformer, stacks of chokes, and all those filter capacitors to regulate the front-end. Compared to the audio circuitry, whether you're looking at board-space or cost, that stuff represents 80-90% of the design.