Axiom Home Page Forums General Discussion Home Theater power conditioners

my friends, i get a hum from my ADCOM amp if i dont use a cheater plug. i was thinking about getting one of these, see link below.

http://catalog.belkin.com/PureAV_detail.process?Product_Id=178415

it sells for 350$ but i can get for 250$ from an authorized dealer. the specs seem better than the Monster units and it's 100$ less, what do yo think.

URL police Can't comment on the PureAV as I don't own one yet, but have been looking at them recently. There are many reviews on the net that say these things do exactly what they state, however, there are a few folks on this forum that will tell you it is all hype

http://catalog.belkin.com/PureAV_detail.process?Product_Id=178415

I have seen the PURE at BB but as stated above the reviews are a mixed bag. APC is coming out with 2 models for AV that I have been looking at including battery backup.

I would first try to find the source of the problem.Then if you still want a conditioner then I say go for it.

Hi 500,

You have a "ground loop", one of the most common ills affecting audio and A/V systems, and the power conditioner would be largely (or entirely) a waste of money and may not help. There is no need to "condition" the power for your Adcom amp. It already has a power supply with filters, transformers, etc. and no further filtering is normally required.

First, remove the cheater and use the regular Adcom plug. Now, look at all your connected components (preamp, turntable, video gear, CD player etc.). With the power OFF, reverse the AC plugs one by one of any other components that have a standard 2-prong plug that isn't polarized (one prong is wider than the other, so you can only insert it one way). Each time you reverse a plug, turn on the system with the attached component and your Adcom and see if the hum disappears. In most cases, reversing one or more plugs will eliminate the hum.

If you have a turntable with a separate ground wire, try removing the ground wire from the preamp (if you're using a separate ground). If not, connect the ground wire to the preamp or your Adcom and see if the hum disappears. Likewise, if you are using a powered subwoofer, try reversing the AC plug on the sub and see if the hum disappears on the Adcom. Anything connected to your system with an electrical link is suspect.

If you have any cable feed from a satellite or local cable system remove that, and see if the hum goes away. Often, it does. You may have to insert two cheap balun transformers end to end to "lift" the ground from the cable system, which may be faulty.

Try these fixes before you spend any money on a power conditioner. Keep at it, until you find the source of the hum.

Regards,

Wow! I didn't know why, but this solution fixed my hum as well. Turns out a have a video amplifier for my OTA HD and reversing the plug was the trick.

Alan. Thanks for the lesson.

That's why Alan gets paid the BIG bucks my friend. To help out guys like you and me.

Jay, a Alan pointed out in his excellent reply, the fact that the "cheater" plug worked shows that you have a ground loop. This is caused by there being more than one path to ground in your equipment rather than the desirable single point ground and has nothing to do with the "condition" of the power coming from the outlets. There are safer ways than using the cheater to stop the hum, but they don't require replacing a $1 item with a $250 one. Just to touch on perhaps the most likely cause, if you find that disconnecting a cable TV feed also stops the hum, you can use the item Alan mentioned, such as this one.

what do you mean by "reverse the AC plugs one by one" . do you mean change outlets. i currantly have all my gear plugged into a surge protector. also, the hum only appears once the ADCOM has been running for 20 min or so.

The AC plugs have a wide and a narrow blade. Most outlets will accept the plug with the wide blade on either side. Try unplugging, then rotating the plug 180 degrees, then plugging back in again.

Alternatively (if your outlets don't cooperate) disconnect the input signals (satellite, cable box etc..) one at a time to see when the hum goes away.

If you still get hum when only the amp and speakers are plugged in and hooked up that's probably something different, but usually grounding seems to be the issue.

Jay, there now appears to be two conflicting observations: the success of the cheater indicates a ground loop, with the cable TV connection being the most likely suspect; the fact that the hum only begins after the amp is on about 20 minutes would indicate that it's defective.

I'm not sure that it is defective, let me refrase my previous post. if i plug the amp into the outlet closest to my equipment the hum begins as soon as the amp is switched on. if the amp is plugged into another outlet on a differant wall the hum begins after the amp is running for 20-30 min's. i will try rotating the plugs a little later today. thanks for all the responses, i owe every one a beer.

Ok, so i just spent some time unplugging/plugging things in and out. NO LUCK. I can not rotate the plugs as the surge protector only accepts the plugs one way. i tried disconecting the main cable feed where it enters the house before the splitters, NO LUCK here either. i guess i could try the transformers from parts express and attempt to lift the ground. if that doesn't work i will buy the power conditioner because that worked for one of the reviewers over at hometheaterspot as his parasound amp's had a humming problem. wierd that I can't isolate the source of the hum... do you think i'm doing any damage to the ADCOM buy using the cheater plug? the surge protector it is plugged into has a 3 pronged ground plug. thanks again.

Jay, the 20 minute delay on another outlet is totally puzzling, so no further comment. If you disconnected the cable feed and still got the hum, it's been found not guilty and there'd be no purpose in getting the cable isolation transformer. Since you mention splitters, apparently it's connected to several TVs; if any of them are grounded(3-prong plug in separate outlet) and are also connected to the other components with an interconnecting cable(wire, of course, an optical connect won't form a ground loop), this can form a ground loop. If you didn't already do so, disconnect their power cords(even if they're turned off) to check for hum. Yes, it'd sometimes hard to trace the loop, but disconnect everything until you get to the point where it's gone.

No, using the cheater can't possibly damage the equipment, but it could possibly damage you. If the amp isn't grounded through its power cord then it's grounded through any interconnect which runs to a component which is grounded. This may or may not be an adequate ground, although you read of some who use the cheater plug except on one 3-prong grounded component, and rely on that for the entire ground.

500: try disconnecting your tv cable at your HT location. Sounds like you have several tv's hooked up and you want to minimize the possibilities.

Good Luck!

i've unplugged washers, dryers, heaters, cable boxes, tv's, subwoofers etc.... pretty much eveything i own and no luck. i orderd the isolation transfer because it was only 10 bucks and figured what the hell. i was going to place it between the the splitt cable wire and my cable box unless you think i should place it on the main wire before the splitters. if that doesn't work i'll get the power conditioner and hope the filters in that unit work.

Hey Rat, if I recall you have a Tripplite Isobar HTPowerbar10 surge/conditioner, how do you like it, I'm thinking about getting one?

Sir: you have an excellent memory! I have 2 of them. One is in my HT room with all the cables/ power running through it and the other is in the wife's study where she has her computer and TV.

They seem to work just fine!!!!

I would recommend them to anyone.

"Sir: you have an excellent memory!" thanks for the vote of confidence , actually I used the search tool to see if anybody has discussed this model in the past. It seems to have some faithful followers over on AVSforum. I would be using to protect my HT equipment.

Randy

Axiom 60's 150 350 4-Qs8's
Denon 2805
Sanyo Z2 Projector
Panasonic S97S DVD
Samsung HD Tuner

Jay, if you disconnect enough(of the AV equipment), of course connecting cables as well as power cords, the ground loop has to eventually be broken. I assume that you don't mean that there was still a hum if nothing was connected except the plugged-in Adcom to the speakers with wire.

If you get the cable isolation transformer it should be placed on the main cable feed before any splitters, etc. The idea is to isolate the ground on the cable line(but, as already mentioned, if there's a hum with the cable completely disconnected, that can't be it). Unless the amp has a defective power supply section(apparently not, if a cheater plug stops the hum), it's definitely a connection problem that has nothing to do with filtering of the power supply.

Buy.com used to have a good price on them. You might want to check there and also pricegrabber.com.

As I recall, there was also free shipping from buy.com. That can save you a few more $$$$ considering the price of fuel.

I have no idea why it worked but i inserted the isolation transformer between the split cable wire and my HDcable box and the hum is GONE!!!!!! so long, bye bye... i didn't think it would work since i unhooked the cable and the ADCOM still had a hum, but it did so i'm happy. no more cheater plug for me.

Thanks Rat, I just ordered one online for $90 from http://www.acetechnologysolutions.com it was cheapest I could find online.

I have long been a fan of Tripp Lite products. I have the Isobar HTPOWERBAR10 in my main HT system and the Isobar HT10DBS on my PC based system. Great products!!!!!

Good news, Jay, and for an "upgrade" from about $1 to $10. Maybe the exact path of the groundloop will forever remain a mystery, but if I followed what you did, it's still not the cable TV feed itself, since disconnecting it didn't help, but whatever(presumably another TV)is grounded on the part of the split where you don't have the isolation transformer.

Speaking of power conditioners...which I know *can* be a very touchy subject, I use a MonsterPower HTS 2600 not to produce some sort of magical video and audio into my system but for me it covers the surge protection that keeps my mind in a state of peace *and* I really do like the organized manner in which I can plug all of my devices and keep 'em looking nice and neat. I also like the way it looks externally, matches my system well.

Ditto, Bob!