Digital "Grunge" and Component Power Supplies

We read all the time about dirty AC and digital components injecting noise onto the AC line. There are a lot of products that exist to deal with this issue.

My question is does anyone know of any published evidence showing that the filtering in a component's power supply is not adequate to handle the noise in a typical household AC supply or that injected by other devices within the household?
Which particular component's (brand and model) power supply would you suggest be measured in order to make this determination?

Power supply regulation/filtering in components varies greatly -- so measuring 100 different pieces of audio gear might yield 100 different sets of test results.

Why not do it the easy way and listen to an AC power regenerator in your own system? I'm betting that once you hear the benefits you won't be able to go without one. The benefits of having clean AC power are normally very easy to perceive, hence the multitude of products to address this problem.

The fact is that no residential AC users get clean power from their power companies and the electrical devices within their homes pollute the power even more. The stock power supplies in most components do not effectively filter out the EMI and RFI interference, nor do they protect against AC surges.
I agree with plato, every component could be different. My system has 3 dedicated 20 amp circuits suppling power. I thought my system (power distribution and components) were good.My system contains some good quality components (Mcintosh, Arcam, etc)which I would think have excellent internal filtering and voltage regulation. However, yesterday I installed a Panamax 5500 EX conditioner/AC regeneration unit. The change in my system was incredable! The HDTV was more vivid, detailed and with more clarity. My Mcintoch MX135 pre/pro showed a significant improvement in definition and imaging.This was no small improvement! The addition of an AC regeneration unit has made a major improvement in my system performance
This is a fertile field for the EMI/RFI witch doctors.
porziob --- I can understand your comment. I for one have a problem with things like $1,000 power cords, $25 fuses and questionable "tweaks". Hey,I'm open to just about anything until I try it myself. BUT If I did not see and hear (and my family - "Dad,, what happened to the TV and sound, It never looked and sounded so good"), I would have not passed on my observations. Everyones incoming power is different. What I thought was good clean power coming into my house was not! My results may be different from others. For me, It made a significant positive improvement. So I thought I would just share my observation with my fellow audiogon members to believe or not to believe.
I also think that the quality and resolution potential of the components in your system has an affect on whether power improvements will be noticed.
No particular component needs to be measured. I was curious about minimum requirements for some known levels of common AC noise.

The probable reason that so many products exist is because the market is easy prey.

The stock power supplies in most components do not effectively filter out the EMI and RFI interference, nor do they protect against AC surges.

How do you know this? That's the point of my question. We have been assuming it to be true, but where's teh evidence. Regarding surges, I agree that the component could not withstand a direct lightning strike, but they do handle, by design, a wide range of AC voltage fluctations. That's why there are regulators in the power supplies.

The reason that so many AC power filtering products exist is because there is a genuine need for them and their use results in easily perceivable performance improvements. Did you ever consider that possibility?

I used to have a friend who was a well known and respected audio designer. He built quite a few custom pieces of gear for me. I'd go to his shop and he'd put a piece of gear on his scope and you could see all the power line trash riding on the signal. He'd show me the signal before and after the power supply regulation within the component. That is how he judged the effectiveness of his regulator circuits. The junk on the AC line and the junk on the signal coming out of the component's power supply is indeed observable on the scope and measurable. In fact, if you saw what I saw riding on the AC line you would be shocked, appalled, and probably disgusted.

But as I said in my earlier post, these measurements and the amount of interference riding on the signal will vary according to the particular component and the particular quality of the AC power going into a particular home.

So what may be a true level of AC interference passed through a particular component at my home may be an entirely different level of AC interference when the measurements are made at your home (using the same component). The levels will also differ for different components with different levels of power supply filtering sophistication.

If my answer doesn't help you then why don't you just take a couple of your own components to a local technician and pay him to show you the trash riding on the incoming AC line on an ocilloscope and then show you the power signal coming off the component's power supply. That should clear it up nicely for you... Heck, just observing the amount of trash riding in on the incoming AC line should be an eye-opening experience.

No doubt I will have to acquire an oscilloscope to set my mind at ease.

If I was a manufacturer of power conditioning equipment that really worked, I'd have four images in my product literature: 1) a trace of the AC line at my office or wherever entering a power supply, 2) a trace exiting the power supply (full disclosure of power supply design with part numbers) and 3) & 4) repeat of 1) & 2) with my conditioner in place. I don't see that kind of advertising.
from what i have heard, aberdeencomponents/mauimods is one company that i know of , that uses a osilloscope for verification of their mod work as well as testing other companies components for the exact issues some have. you might want to look into it a little further since they might have answers to some of your questions. you might want to ask about the exactpower ep15a, and how it measures to other companies ac conditioners on a osilloscope.

Little evidence of this that I have seen published ....most of what I have seen is anecdotal. Of course noise is noise....if you don't have it then it is not a problem and you find it hard to understand those who suffer....if you suffer then it can be very annoying and hard to identify as to the root cause (and having paid very highly for the offending component there is a natural reluctance to swap it out even when you find the problem and even if this is the right thing to do)

No doubt that AC power is noisy for a variety of reasons considering all that is connected to it in a typical home. However, a well designed power supply should not pass this noise to the DC power of the audio circuits and the audio circuits are designed to operate robustly even in the face of some drift in the power supplied.

This is called "tolerance" in engineering design terms. Engineers design equipment to operate correctly in a window. Equipment with "close" tolerance will be affected more easily then better designs with liberal tolerances. Often the extra cost of high quality gear is that you gain in terms of the tolerances. Pro audio gear tends to have higher tolerances...for example they use balanced circuits and XLR cabling. They also use +4 dbu signals instead of -10 which helps too.

Obviously the best solution, if you are really worried about noise, would be to do what pros do.....go for pro grade gear only, all running at the much higher +4 signal levels and with balanced outputs and XLR interconnects...this is expensive.

Those who claim better soundstage or image from power conditioners are making miraculous claims...less noise perhaps or less distortion at the very limits of the equipments ability would be the most that a design engineer would expect in all but extreme cases of terrible AC power.
Shadorne, thanks for the rational response.

I've read references to the pro +4dbu versus consumer -10dbu level several times, but I've not read an explanation. Could you provide one?

This URL by Jim Price explains all the confusing terms very well, much better than I ever could;

Essentially, pro gear uses signal voltages at levels generally four times higher than consumer gear...this increases immunity to noise significantly.
Thanks for the link, Shadorne. Nice and concise.
if we are not using as you say PRO GEAR, would not the need for a ac noise conditioner be even more evident to use based on your assumption that there is more noise in lower voltage gear ???? your statement seems to justify the need for these devices. would not then the noise be reduced significantly as in pro gear but just achieved in a different way ???


I may be way off, but I think the higher signal level used in pro gear yields a higer signal to noise ratio. For a given environment, the noise will be the same regardless of the signal level.

-- Bob
Yes you can tell the difference when using some power conditioners. I never really believed all the ads I read. In the past I bought Monster power strips and a PS Audio and I did not hear much difference. I read a review from an actual owner of a Furman Elite 15 power conditioner and decided to buy one. Wow!!! Night and day better with video equipment. I pluged my ComCast box into the unit and even my wife was amazed! The Furman cost about $300. It was worth every cent I paid! I'm going to buy more in the near future...