Power conditioners and amps (1 Viewer)

[Dan Sloane]

Thanks for the explanation Chu. I may have to put a whole house line conditioner in due to X10 lighting control and just wondered if it would effect my amps or other HT equipment.

 

[Chu Gai]

Nope, it won't have any effect whatsoever. Get a few quotes from electricians and/or talk to some legitimate electrical supply houses in your area. Tons of companies make these things because they're easy to make. For most everybody, a 1000 joule or thereabout unit will be perfect. Now that's a real 1000 joules across H-N, H-G, G-N, and it'll stop the real nasty stuff from getting into your home. Since it's a quick job and electricians are going to have a minimum charge to cover their Krispy Kreme tab, you might also want to consider having a separate outlet or two run to your HT area. Few dollars more.

 

[mark-h]

All I can say is one of the best, most informative threads I've read in quite a while.

I for one am going the whole house route.

Thanks for all the good information and the education.

Mark

 

[Mike_Skeway]

For surge suppression, the whole house method is a good way to go. Gets everything protected. They are not a hard install for the most part, most people can do it, but if you are uncomfortable with doing it, get and electrician to do it for you. Additional circuits are a good idea too. I have added several circuits myself to my house for the HT and the many computers I have.

 

[Pete Saunders]

The only power conditioners I use in my house are Richard Grays, and I don't even plug my amp into that. The amp still gets some benefit from Richard Gray's parallel setup.

I believe all line filters limit current in some way through the use of an extra power cord (extra resistance) all the equipment is plugged into, the line filter's own fuse and the use of isolation transformers in some which really limit total current. Series line conditioners are a big no no!

I try to reduce as much EMI/RF as I can by using upgraded power cords (no, they don't clean up current just block EMI/RFI coming from your own electronic products, cell phones, power switching supplies, etc), by removing any affending items such as wall wart plugs, rheostats, etc, and by using ERS sheets.

ERS sheets are made of impregnated carbon fiber (developed by the air force) which blocks or absorbs EMI/RF in the air.

 

[Chu Gai]

If you're into the whole ERS sheet thing (I think there's metal in there too), you can run a Google search on EMI cloth and find a variety of manufacturers who just might send you an evaluation sample.

 

[Pete Saunders]

I tried just one ERS sheet positioned on top of my HD RPTV at a certain angle and a very specific place, and it made all the difference in the world! Sharper focus and deeper colors, it took what digital grunge I had left out of my system, tightened up focus and firmed up the bass. All this for under $30.00!

ERS is by far the cheapest and best tweak I have ever done!http://www.cryotweaks.com/Ers.shmtl

 

[Matt_Doug]

I agree Chu If you've identified your AC as the cause of noise in your system then your suggestion about the sub panel and isolation transformer is good solution. In fact its the cheapest (isolation transformers are a penny per watt rating on the used market) and most effective solution I know of and it worked for me. I do disagree that if you do identify your ac as the problem its because your gear is defective. Michael Price a few posts back very effectively rebutted that conclusion in his response to Brad Harper's statement "If you can hear a difference between day and nighttime voltage then your amp has lousy filtering built into its power supply. This is easily fixed with a soldering iron and some cheap capacitors". For us non electrical engineers, consumers of mid fi gear, who are not handy with a soldering iorn or familliar with a PCB, and for whom HT is just a hobby, so called "lousy power supplies" (ever heard of wall warts, I have 4 components that use them) are a the norm. I don't believe you share Brad's views Chu as you're not one for waxing omnisciently.

 

[Chu Gai]

Well I'm not sure it's a rebuttal as I'd interpret that as either a defective or poorly made device. Seems like something that would occur with greater frequency though with some inexpensive if that's the right word tube based devices or a lot of the DIY things that people make. OTOH one can look at psychological reasons as to a person's mental state at the end of the day. Crudely put, I'll say the system sounds a hell of a lot better after doing the horizontal mambo and sounds worse when I see my kid's report card. There are crappy wall warts and then there are better ones when it comes to noise. Manufacturers will tend to use them because it simplifies regulatory compliance and saves money.

 

[Michael R Price]

I think power line conditions can make a difference because most power amplifiers use a few very large electrolytic capacitors forming a single pole lowpass filter on the power rails. These capacitors, especially lower cost and older ones, have a significant series resistance and inductance which limits their ability to filter high frequencies. Looking at the datasheet for CDE's new computer grade capacitors there is an impedance approaching 1 ohm at 1 MHz. That would mean noise products at high frequencies (passed with little reduction by toroidal transformers) would be filtered as little as 20-30db. And since power supply rejection decreases significantly with frequency, those high frequency noises could cause distortions in the audio signal. Then you also have to deal with noise radiated from pretty much everywhere.

 

[Chu Gai]

What makes you think manufacturers don't add emi/rfi circuitry early on in the signal and elsewhere trace with strategically placed surface mount devices? And besides, a $30, give or take, 'surge protector' is going to have maybe 40 dB of filtration and that's with probably with pretty trivial amounts of RFI to begin with. Further, depending upon where those electrolytics are in the signal path, if they degrade signficantly you're now going to have other problems like loss of LF information. That's broke in my book. Of course, most people don't realize this since if it happens, it happens over time. And then they audition a new receiver at home and say, damn if that new receiver doesn't have some LF punch. What the hell kind of stupid stuff was Chu saying about amps sounding the same? What a putz! Of course they sound different.
If it's a classic, sell it on audiogon. People buy the funniest stuff over there like technologically obsolete CD players.
BTW, if you're down 30 dB as in your example, you've reduced RFI by 99.9% and if the intensity of RFI was 30 dB down from the signal, then...Now stop scaring people already! It's not Halloween!

 

[Matt_Doug]

crudely put indeed, I’m not an EE. except for the few wall warts I tore into. my only exposure to this stuff is theoretical and anecdotal. my.$.02 But Chu i believe You're not completely correct about the use of wallwarts. The reasons you give might be valid but overly simplify. Manufacturers have other more important considerations such as noise and ergonomics. You might have noticed that virtually all wallwarts contain transformers of the EI type as opposed to toroid (donut shaped) transformers which anchor the vast majority of integrated component power supplies. EI’s have more restrictive bandwidth and hence more inherent noise rejection capabilities than Toroids. Also they're cores don't saturate as readily as toroids so they’re less susceptible to DC offset. The reason being, there is much more distance between primary and secondary windings, and laminations within EI type transformers than there is with toroids. That increased distance may be good for limiting noise rejection and core saturation but is poor for efficiency (EI type transformers are much less efficient than toroids) and for for ergonomics (EI with an equal ratings as a toroid are much larger). Another reason that toroids are so efficient is that the magnetic field they generate is mostly focussed on the center of the torroid donut, as opposed to EI's which have multiple points of focus. as such it is very easy to isolate the magnetic field of a toroid from surrounding sensitive circuitry in the cramped space of a component chassis, than it is to do the same for an EI of equal rating. toroids lend themselves well the ergonomics of cramped chassis' but there are drawbacks that most manufactures don’t go out of their way to compensate. Consider that many of the components that utilize wallwarts don't draw much power and are very sensitive. As you have stated yourself Chu, wallwarts are not the best at rejecting noise on the AC, but toroids are worse.

BTW, DC offset is a condition where differences between phases in a multiphase circuit sum on the neutral as dc current. Phases become asymmetrical when the load on one leg is greater than the other, which happens very often during peak draw during the day. Less so at night. Toroids react very badly to DC on the ac as their cores saturate very quickly. The result being increased noise let through , increased electromechanical noise and decreased efficiency.

 

[Chu Gai]

Some people think that transformers hum because they don't know the words

Sure I oversimplified when it came to walwarts. Another consideration is that it greatly facilitates UL approval. 'Course that doesn't sound like a reason you'd want to tell consumers. I think the DC offset/toroid thing would need to be looked at on a case by case basis. Some manufacturers employ self-balancing servo logic to deal with offsets. If it's a concern for people then hunt down amps that don't use torroids. Again, when problematic, this seems to more likely to occur in some tube setups and people doing DIY. In any event, what would you recommend that a consumer do if this is a concern?

 

[Matt_Doug]

An Isolation transformer worked for me Chu. Self balancing servo??, not in my mid fi amp, how exactly does that circuit look? I must be getting too geeky as I actually found your hum joke hillarious

best regards.

 

[Michael R Price]

Of course any good circuit includes decoupling. But it's impossible to get rid of all the noise. I was thinking from a voltage standpoint where -30db means 3 percent. I personally have no idea what level of noise is "acceptable" or doesn't make any difference, but it seems like that level is below what regular equipment acheives. Otherwise there would be no point in designing good low noise power supplies. I know of some fancy regulator circuits delivering noise in the nanovolts range, I hope to try one soon and see how it compares to a standard chip in my CD player. (Now if it's still behaving differently at night after that, I'll really be confused.)

It is true I've heard that toroids are much more susceptible to DC offsets and certain types of toroids behave better than others. I do not know how DC on the primary would affect an amp's sound quality though.

 

[Matt_Doug]

Michael by noise I didn't mean dc. I know there is no possibility of DC on the output of a transformer. If you apply DC to the primary of a transformer, what happens is that it wastes capacity of the transformer as it only serves to heat up the primary winding. You can see if the power transfer is not optimal then a component will not perform at its best.

 

[Chu Gai]

BAT did or does use that approach with their amps Matt. Another thought on possible electrical issues that you may or not may have that might've been correctable by examining and possibly improving the outside ground where you live. Not knowing the nature of the soil, moisture, rod, wiring, it's purely speculation upon my part. I tried a little levity as I didn't want the rest of this to get too ponderous. I wouldn't mind hearing more about your particular travails though Matt. PM me if you want. Always curious about problems that occur and what attempts were made to finally arrive at a satisfactory solution.
I'd calculated the conversion based on power, as a voltage it is ~3%. I don't have any broad figures with confidence levels for RFI and grunge on AC lines. I'd suspect that for most it's not all that bad.
My general point in all of this is that people take a more prudent and cautious approach to slaying dragons.

 

[charlie o]

So where do i pick up a whole house protector? Electical supply house?

 

[Chu Gai]

I'd call a couple in your area to see what they have. You're looking for something that you can run all your lines through:AC, cable, phone. If they have models post back and let's try and make some sense out of it. Sound reaonsable? Otherwise, give someone like Intermatic a call. They've got a toll free # and you can speak to an engineer who can probably put you in touch with a local distributer for their recommendation.

 

[Mike_Skeway]

They can also be found at most home improvement stores as well.