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dmloring
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Eliminate horrible hum/buzz sound from integrated amp/speaker

I recently got a used Exposure Super XV integrated amp. It would not turn on, so I had it repaired at a stereo repair shop. It turns on now and plays music, but immediately after powering on, even without music playing, it emits through the speakers a horribly loud, constant buzzing/humming sound. Loud enough that it actually hurts my ears (i.e. not a slight background noise). I tried moving around the cables some; making sure the power cord does not touch the speaker wires, but it had no effect.

Any thoughts? Perhaps the amp is still broken or they did not fix something?

David

mrlowry
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake


Quote:
Perhaps the amp is still broken or they did not fix something?

David

David-

That would be my first instinct. Take it back and ask them to hook it up and play it for you.

tom collins
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

if you don't take it back to the repair shop, see if you can hook it up at a friend's house. if it is gone, it may be your electric. if still there, probably the unit.
good luck.

Jan Vigne
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

It's possible a capacitor has failed after the repair was completed, or a solder joint has come loose. Take it back to the shop that did the original repair, they should work with you though don't expect them to pick up the entire cost of another repair.

SAS Audio
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake


Quote:
It's possible a capacitor has failed after the repair was completed, or a solder joint has come loose. Take it back to the shop that did the original repair, they should work with you though don't expect them to pick up the entire cost of another repair.

I concur with Jan. Since it would not turn on, it sounds like work was performed on the power supply, although an output stage could be drawing excessive current. Without actually seeing the problem first hand, does it sound like 60hz or 120hz hum? If 120hz, then probably either an open filter capacitor or a faulty solder connection connecting a filter capacitor in the power supply. I would contact the servicer and have them deal with it, explain the problem with them.

Hope this helps.

dmloring
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

Thanks for everyone's reply. I'll contact the repair shop. I'm not sure what the difference between a 60hz and 120hz hum/buzz would sound like? It's a steady loud buzz sound -- I cannot make out any pitch change in the hum/buzz noise.

I was doing some research last night, and it sounds like it could also be something called "ground loop" hum. There are apparently products out there like Ebtech Hum X Voltage Hum Filter that are "supposed" to eliminate this feedback noise, but I'm guessing it is somewhat of a gimmic and will not fix my problem.

I'll update when I learn more. Thanks again.

mrlowry
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

The way to see if it was a ground loop hum would be to hook the unit up to speakers (maybe even a pair you don't care about if you have some) with nothing else hooked to the Exposure then turn the unit on. Because a ground loop is the difference in grounding potential between TWO grounds and with only the Exposure hooked up you now only have ONE ground you would have eliminated a ground loop as a possibility. If you get the same hum with NO other components hooked up to the unit besides speaker the problem is in the Exposure.

Jan Vigne
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

Ground loops are typically not going to drive you out of the room. They are more likely to be low in level but persistent, not changing with position of cables or other equipment until the AC Voltage is removed from the offending component/cable.

The above suggestion will tell you whether the problem is external to the amplifier or is an issue within the amplifier itself. It's best to unplug all other sources and components from the AC outlet when doing this check, you don't want stray RF/EMI fields causing problems. Then slowly plug each component back into the amplifier if you suspect a ground loop. The offending component or cable will show up when you get to that source.

However, from your initial post, I would still expect you to require a technician's assistance with this problem.

dmloring
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

I will try your suggestion(s). Interestingly, I brought it back to the stereo repair store and the tech took a look at it. He hooked it up and no hum/buzz and he could find nothing wrong. He suggested that I go to home depot (or the like) and get a 3-prong to 2-prong adapter, essentially removing/lifting the grounding prong on my amp. He said that he imagines that will fix the problem. Thoughts? Dangers?

mrlowry
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

You don't have anything with a big power supply, like a big power amp sitting really close to the unit do you? It might work, but if it does it's a "band-aid" solution and shouldn't used long term. In domestic electrical service the neutral is tied to ground as well so it isn't dangerous under most circumstances.

What I'd recommend is while you are at the hardware store picking up the cheater plug (the three prong to two prong converter) also pick up a tester (probably less than $10) that will tell you if your outlet is wired correctly. It plugs in to a three prong out let and will tell you using a series of lights whether or not the outlet is properly grounded and if you have a reversal of the hot and neutral lines. If the outlet is mis-wired correcting it is fairly straight forward with a little research to correct the problem. Though if you aren't comfortable working with electricity or don't understand how to re-wire an outlet safely after doing your research please call an electrician. SERIOUSLY! A good electrician isn't nearly as expensive as one might think.

If you want to be really tweaky while the electrician is there ask him about installing a 20 amp line which is dedicated solely to run the stereo system. It will help increase bass, dynamics, and reduce some background noise (though not to the level you problem is.) The price of a dedicated line varies depending on the difficulty of getting new wires from the outlet to the breaker box but it's usually a couple of hundred dollars or less. Many people report it's one of the single upgrades that they've ever done to their system.

dmloring
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

Thanks again for everyone's help. I think the problem is fixed. Knock on wood.

I disconnected all my components and connected each component one by one. No buzz/hum when all of the equipment was connected. However, the second I touched the cable line to my DVR (which, strangely, is not connected to my stereo, but is physically located right next to it and connected to the same outlet) the horrible buzz came back. So obviously the source of the problem is the cable line.

Don't ask me how, but I left my apartment to go and buy a transformer isolator -- apparently the device that connects to your cable line to eliminate the buzz. When I came back I noticed that the amp was on and the cable was connected, but there was no buzzing sound. I looked at my wife and she said she turned on the amp to watch a DVD (my DVD player is connected to the amp as well). She never heard a buzz sound, even though the cable line was connected. Go figure -- woman's touch? Or perhaps sending a signal through the DVD player to the amp fixed the problem? Whatever it is, the amp is perfect now. I went ahead and ordered a $10 transformer isolator in any event, in case the problem comes back.

As to the sound of the Exposure Super XV Integrated. Here are my first impressions after about 3 hours of listening:

As compared with my NAD 320BEE, the first thing I notice is the soundstage and detail in the sound. This is not a neutral or laid back (warm) amp like the NAD. The soundstage is wide and forward and it seems to really have great rhythm and timing.

Listening to a few of my favorite albums, Diana Krall's vocals on "Love Scenes" is just breathtaking. It is like she is singing 3 feet in front of me. You can hear the slight texture and graininess in her voice on "Peel Me a Grape." The Exposure reproduces the airiness of her vocals on "How Deep is the Ocean" to a degree that I've only heard on my father's system -- which uses far more expensive Musical Fidelity Amps and Preamps.

I moved onto one of my favorite jazz albums of all times, "Somethin' Else" with Cannonball Adderley, Miles Davis, Hank Jones, Sam Jones and, of course, Art Blakey. I love Cannonball, but the texture of which Davis' trumpet is reproduced on "Love for Sale" and the clarity and timing of the interplay between Cannonball and Davis on Somethin' Else with Blakey's delicate touch on the drums holding it all together is stunning. My NAD was unable to provide the separation between those sounds; it was unable to give the music the emotion and musicality that the Exposure can.

I did notice that with some piano music, like Oscar Peterson's Night Train, I missed the warmth of the NAD. I wouldn't say the Exposure is tiring on the ears, but perhaps at lower volumes when you want music just as a background, the Exposure is a little to bright and forward. However, I think that is a small sacrifice (as is the absence of a remote) to pay for all the improvements with the Exposure.

Enough rambling for me...

Regards,
David

SAS Audio
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

Glad things worked out ok David.

Enjoy.

RGibran
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

Dude, you are livin' the high life! Enjoy!

RG

mrlowry
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Re: Eliminate horrible hum/buzz sound from integrated amp/speake

If the problem returns here are some resources and thoughts on various parts.

http://www.xantech.com/Infrared/Infrared/IRAccessories/63400/
This one is only about $9 but it tends to knock out higher TV stations in digital cable systems and negatively affect pay-per-view and movie on demand capabilities. It's cheap enough to try and throw away if it doesn't work. But in my experience it usually causes some kind of problem. I only mention it to present all options.

http://www.klipsch.com/products/details/magic-box.aspx
It's about $100. Which is expensive by comparison but because of it's greater bandwidth tends not to knock out higher TV stations in digital cable systems. Nor does it usually cause problems with pay-per-view and on demand functions.

Tributaries used to make one but it doesn't look like it's available any more. It worked as well as the Mondial.

http://www.jensen-transformers.com/datashts
Jensen makes all kind of isolation transformers. This one looks good but, unlike the other ones I've never used it myself.

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