I think I've got transformer hum

[darien87]

I did a search and found a few threads about amplifiers that hum. My Acurus 200x3 has a noticeable hum that I believe is NOT a ground loop. I disconnected it and plugged it into an outlet that is on a separate circuit from the rest of my system, and the hum is still there.

The hum seems to be coming from a large round "wiry" object in the center of the unit. I assume this is the transformer. The amp functions fine and the hum does not come through the speakers. It's just kinda bugging me. From what I have read, all amps hum to a certain degree, and a noisy transformer is not an easy fix. Is this true? There's really nothing I can do about it?

 

[PENG]

I visited enough high end stores to know that all amps hum. However, if you can hear it clearly from say 6 ft away, I would say it is on the loud side. As you know, the main source of hum is the power supply transformer. Toroidal transformers may be quieter in general but not always. I am not sure about the newer Adcom models, but the Adcom GFA555 must be one of the quietest amplifier ever made. There are no shortage of amplifiers (2Ch ones) in the >$3,000 price range that hum much louder than the old Adcom. My point is, don't assume (not that you would but just in case) expensive amps are quieter amps.

 

[Ohmen]

I have the same problem with my Infinity subwoofer. It sucks, I am ready to shitcan it because of the noise.

 

[EJD]

Take the cover off and see if the bolt or nut that holds the transformer to the chassis is loose and can be tightened a bit. I have heard that can happen and cause it to vibrate slightly.

 

[avaserfi]

I have the same problem with my Infinity subwoofer. It sucks, I am ready to shitcan it because of the noise.

Hey, I would check it article out if I were you. It probably isn't the sub.

http://www.audioholics.com/tweaks/connecting-your-system/ground-loops-eliminating-system-hum-and-buzz/

 

[mtrycrafts]

I have the same problem with my Infinity subwoofer. It sucks, I am ready to shitcan it because of the noise.

You have an transformer hum? Or the sub driver is humming?

 

[mtrycrafts]

I did a search and found a few threads about amplifiers that hum. My Acurus 200x3 has a noticeable hum that I believe is NOT a ground loop. I disconnected it and plugged it into an outlet that is on a separate circuit from the rest of my system, and the hum is still there.

The hum seems to be coming from a large round "wiry" object in the center of the unit. I assume this is the transformer. The amp functions fine and the hum does not come through the speakers. It's just kinda bugging me. From what I have read, all amps hum to a certain degree, and a noisy transformer is not an easy fix. Is this true? There's really nothing I can do about it?

Before you pull the cover as EJD suggested, be sure you know safety what to not touch in there. The admin folks don't like to read such recommendations, I know, I gave a couple before finding it out
If you feel comfortable doing it, press on the transformer and see if that hum is lessened or not. That would be a clue.

 

[darien87]

Before you pull the cover as EJD suggested, be sure you know safety what to not touch in there. The admin folks don't like to read such recommendations, I know, I gave a couple before finding it out
If you feel comfortable doing it, press on the transformer and see if that hum is lessened or not. That would be a clue.

I might give that a shot. I guess it couldn't hurt. But I am a little leery of messing with the internals of my amp. The hum is only noticeable if you're within a couple feet of the amp, and with my cabinet door closed, you really don't hear it at all. It's just my own perfectionist nature getting the best of me. I know it's there, so it's bugging me.

Thanks for the help guys.

 

[EJD]

The admin folks don't like to read such recommendations, I know, I gave a couple before finding it out

Doh...Thanks for the tip

 

[jcPanny]

Amp Hum

Darian,
Before cracking the case, I would verify that your wall AC outlets are connect appropriately (correct hot and common polarity and ground connection) and check if there are any dimmers on the same circuit. Cheap dimmers can generate a lot of electrical noise.

 

[darien87]

Darian,
Before cracking the case, I would verify that your wall AC outlets are connect appropriately (correct hot and common polarity and ground connection) and check if there are any dimmers on the same circuit. Cheap dimmers can generate a lot of electrical noise.

Well my Belkin says that the wiring and ground of the outlet the amp was originally plugged into is ok. I'm not sure how reliable of a check that is though. I don't believe there are any dimmers on the same circuit. Although there is a light switch that is connected to another switch upstairs, so that you can turn the stairs light on or off from upstairs or downstairs. I'm not sure if that is on the same circuit or not.

 

[avaserfi]

I know when I first plugged my belkin in I wanted to see how its check showed up and it said evrything was fine even though the outlet had a horrible ground. Just a heads up I don't think those internal checks are that great.

edit: These things seem to look for any sort of ground. It was even happy with my 3 to 2 prong adapter when I tested it. (Don't worry I replaced it right away, I just had to play first)

 

[PENG]

I would to make two points:

1) If you are sure the hum is from the transformer itself, that is, it hums even without any speakers connected then it is most likely not a ground loop related problem.

2) As I mentioned before, if the hum is only noticeable when you are within 2 ft from the amplifier, it is nothing unusual. Go to a high end store and check out their amps on display, stick your ears to the chassis and you will know what I mean.

You can buy a device on line that claim to be effective in lowering transformer hums due to dirty power line, specifically d.c. components in the incoming a.c. source. Of course such d.c. killer will, in theory, only work if the transformer hum is worsen by the presence of d.c. components in your a.c. line. Other than that, just don't listen to music closer than 3 ft from the amp and you will be fine.

 

[mtrycrafts]

I might give that a shot. I guess it couldn't hurt. But I am a little leery of messing with the internals of my amp. The hum is only noticeable if you're within a couple feet of the amp, and with my cabinet door closed, you really don't hear it at all. It's just my own perfectionist nature getting the best of me. I know it's there, so it's bugging me.

Thanks for the help guys.

Did you by chance try to press on the case itself, all around the sides, back, front, top, bottom to see if that made it go away? Perhaps that transformer hum induced into a panel that is just a bit loose and rattles/hums in sync?

 

[Ampdog]

Firstly I accept that the safety warning by Mtrycrafts is heeded.

I have more than once found that transformer bolts (clamping the laminations) can be loose - this will of course depend on the transformer type. If shrouded, the shells can merrily vibrate - they are usuallty steel. I have had success in taking the transformer out, applying mains without load and listening carefully or even feeling the core with a finger (Again, feel the core, not any high voltage wires! Take care.) Applying some laquer/sealant could also help. As said, mere replacement is no guarantee of success, sadly.

Bottom line: The problem can quite often be cured by mechanical investigation and measures - also not neglecting the presence of other magnetic substances in the vicinity.