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Discussion Starter #1
I just installed a new Yamaha RX-673v receiver to replace a 22 year old Pioneer VSX-5500S. Today in my fairly small front room I noticed the familiar sound of a 60hz electrical hum. I turned off everything until I found it was coming from the new Yamaha receiver's case. I unplugged it and plugged the old Pioneer back in and heard the transformer humming in that one, too - except with more of an angry buzzing sound as well. Still, I had never really noticed the Pioneer's hum but the Yamaha seems to be catching my attention when the room is quiet.


Do all amps have this transformer hum or does this represent a serious flaw in the new receiver? I have to assume it's "normal" because the old Pioneer makes the same humming tone, but I wanted some other opinions since this is a brand new piece of equipment.
 

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Transformer hum can be exaggerated by neighboring resonating casings or furniture.

To some small extent transformer hum may always be present, but is usually inaudible. Sometimes a transformer winding may come lose and start vibrating.

I would talk to your dealer or a Yamaha service point if it is (or becomes) annoying.

Are you sure it comes from the casing and not from the speakers ?
 

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In my experience, transformer hum isn't good. I've had many power supplies begin to hum just before crapping out.
 

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Power transformer hum should not be audible..
Unless...

One has their ear right on top of the component..

It can be caused by a defective transformer and/or loose transformer mounting screws.


If audible within a couple of feet I would get it exchanged..

Why not go back to the store where it was purchased and listen to another unit..


Just my $0.02...
 

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Discussion Starter #5

Quote:
Originally Posted by M Code  /t/1435460/transformer-hum-from-receiver-normal#post_22522305


Power transformer hum should not be audible..
Unless...

One has their ear right on top of the component..

It can be caused by a defective transformer and/or loose transformer mounting screws.

If audible within a couple of feet I would get it exchanged..

Why not go back to the store where it was purchased and listen to another unit..

Just my $0.02...

Thanks for the replies all of you. It is DEFINITELY coming from the Yamaha's case and not the speakers. It starts immediately when the amp clicks on and disappears immediately when it clicks off. The speakers are wonderfully silent with no hiss or hum. It's coming from the mid-left area of the case. I can hear it from six feet away if t he room is otherwise quiet. I can't test out another because I purchased it through an online retailer. Returning it would be very expensive for me due to the shipping. I can hear the hum from a few feet away, but it is also in an old thick wood cabinet that I do think is acoustically amplifying it. I guess I'll write to Yamaha and ask their opinion. Having to pay to ship the thing off will negate any savings from the sale price - such is the gamble with internet purchasing.
 

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Discussion Starter #6
There is an authorized service center in town that does warranty work so I guess if there is a real problem I won't have to send it back to the online retailer who would not pay return shipping. I have written to Yamaha to inquire about it. I wish there was a showroom in town where I could check out some others to see if "they are all that way".
 

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Discussion Starter #7
Yamaha support emailed me back and said there should be no hum at all and the unit should be returned or serviced, but didn't say a word about how to go about any of that. My first and last attempt to try Yamaha. I only went with Yamaha this time around because of all the great reviews on quality and reliability.
 

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Yamaha without question produces the most reliable AVR...

If you can hear the transformer hum from 6' away then definitely you have bad unit...

I would push for a replacement unit, most authorized Yamaha sellers should exchange it..


Just my $0.02...
 

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Discussion Starter #9

Quote:
Originally Posted by M Code  /t/1435460/transformer-hum-from-receiver-normal#post_22524068


Yamaha without question produces the most reliable AVR...

If you can hear the transformer hum from 6' away then definitely you have bad unit...

I would push for a replacement unit, most authorized Yamaha sellers should exchange it..

Just my $0.02...

I took it out of my wood entertainment center and it was not audible from that distance anymore. The wood shelf/enclosure is definitely amplifying it. However, it is still audible and I can feel an electrical vibration when I touch the chassis.


After I get done paying all the shipping costs for an exchange I could have just got an v773 or something on the bottom of the Aventage line.
 

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If the hum is much lower now and not disturbing it is your choice returning it or not.

Transformers will usually be vacuum soaked in a sort of resin bath at end of production to eliminate any cavities between windings.

Sometimes some small air bubbles remain within the transformer allowing some windings to vibrate by the power line frequency depending on the transformer load.

This causes the mechanical hum heard by you.
 

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Discussion Starter #11
Today while at Fry's I saw they had a 673 hooked up so I attempted to listen to it to see if it had the same hum. Unfortunately their home theater section was on the other side of the aisle blasting Disney movies and there was absolutely no way to get enough quiet to hear it. One of the employees came over to inquire why i had it half off the shelf with my head pressed against the case. Haha.. I told him what i was doing and he said no way should any receiver have a hum. But I did indeed hear a transformer buzz coming from the unit, but there was just no way to hear if it had the 60hz low frequency hum in that environment unfortunately. I don't want to go through the significant expense of a return fi it's not going to solve anything. I guess if the retailer offers to pay return shipping due to defect then I'll give it a shot.
 

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Quote:
Originally Posted by virsat  /t/1435460/transformer-hum-from-receiver-normal#post_22528128


Today while at Fry's I saw they had a 673 hooked up so I attempted to listen to it to see if it had the same hum. Unfortunately their home theater section was on the other side of the aisle blasting Disney movies and there was absolutely no way to get enough quiet to hear it. One of the employees came over to inquire why i had it half off the shelf with my head pressed against the case. Haha.. I told him what i was doing and he said no way should any receiver have a hum. But I did indeed hear a transformer buzz coming from the unit, but there was just no way to hear if it had the 60hz low frequency hum in that environment unfortunately. I don't want to go through the significant expense of a return fi it's not going to solve anything. I guess if the retailer offers to pay return shipping due to defect then I'll give it a shot.

There are (2) types of hum...

The 1st is electrical and is leaked through the audio circuit.

The 2nd is mechanical which may be caused by a couple of issuses.
a. Defective workmanship for the internal power transformer assembly
b. Poor quality of transformer components and/or laminations
c. Loose physical mounting of the transformer



Note that power transformer is the highest cost component within an AVR's bill of materials. So here frequently the transformer source will attempt to shave costs....


Another short cut is to use a higher guage(thinner) copper winding to save costs, this type of transformer may deliver the target specification voltage but is more likely to saturate sooner...



Just my $0.02...
 

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Discussion Starter #14

Quote:
Originally Posted by M Code  /t/1435460/transformer-hum-from-receiver-normal#post_22529836


Just my $0.02...

In this case it doesn't come over the speakers at all, it resonates from the chassis. As I mentioned before, my 22-year old Pioneer has almost the exact same hum/buzz on its transformer, but the new Yamaha sounds deeper or more resonant.


At Fry's I could hear a bee-like buzz coming from their 673 transformer but it was too loud there to hear the gentle low 60hz hum.


I posted a request for people to listen to their 673's in the 673 thread but nobody appears to be willing to put their ear near it so far.


I just don't want to go through all the hassle and expense of an exchange through an internet company to end up with the same thing again. If it's present on my old receiver, and this new one, and there was the buzz but could not verify the hum due to noise level of the same model in a store, what are the chances that I would get one that was quieter?
 

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I am curious if there was ever a resolution to this problem. I am having the same problem with my Anthem Avm 50. The transformer buzzes in outlets throughout my house, however when I brought it to the technician - it was dead silent. Leads me to believe than he problem lies within the wiring in my house or to the pole outside. I checked the cable line for ground loop and disconnected all the other equipment. I am reall at a loss on this one. Any advice would be greatly appreciated.
 

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In my experience, transformer hum isn't good. I've had many power supplies begin to hum just before crapping out.


My Bryston 4b over 20 years old has started to hum louder as impulses when I turn it on for about 20-30 seconds when I turn it on. It goes like this humm__________hummm_______hum 3 or 4 times just till it warms up a little.



I posted up on a Bryston forum and no one was too concerned about it. I may send it in to get re-capped at some point but for now it still sounds great.
 

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One leading cause of transformer "hum" is the presence of DC (direct current) on your incoming AC line. This is caused by excessive 2nd harmonic distortion on the AC line which can be the result of loads such as motors from your neighbors or some industrial site.



Your receiver's transformer might not be defective at all. There are inexpensive filters which you can buy which are specifically designed to eliminate DC on power lines. These place capacitors in series with the line which block the DC.



Emotiva makes one. I would try this route before assuming your receiver is defective.
 

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...and 6 years later to your post, still many Yamaha Receivers have the same symptoms... Got 2 Rx-A3070 units that shown the same symptom... Had a talk with Yamaha USA and Yamaha Canada and they all says that they are NOT AWARE of this problem! Yeah right... ...and I am Peter Pan! :mad:

A transformer in an AVR should not physically hum period.... There is tremendous cost pressure on AVR's, and transformers are relatively expensive. Always buy an AVR from a source that accepts returns. Just move on to another product if you get an AVR with a humming transformer. Certainly move on if you get two in a row. Even the least expensive AVR isn't cheap, moving up to more expensive models in a product line means the equipment should just work; no problems.
 

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Dirty power can make a transformer hum. And by "dirty" I mean non-pure sinusoidal. Most of us don't have "pure", more like adequately clean-ish. Since you've noticed this for other A/V gear: is some device in your house making the power messy? Fridge, A/C etc., something that comes on regularly and automatically. UPS power can do it too, if not a great UPS, or if somewhat overloaded. Even a neighbor's crap can do it; my next-door neighbor had a wonky hot tub heater and it caused lots of probs for me (I assume through our shared local distribution transformer, across the street) until the heater "blew up" (wasn't me :)).
 

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One leading cause of transformer "hum" is the presence of DC (direct current) on your incoming AC line. This is caused by excessive 2nd harmonic distortion on the AC line which can be the result of loads such as motors from your neighbors or some industrial site.

Your receiver's transformer might not be defective at all. There are inexpensive filters which you can buy which are specifically designed to eliminate DC on power lines. These place capacitors in series with the line which block the DC.

Emotiva makes one. I would try this route before assuming your receiver is defective.
Ohhh. Thanks for this answer. I'll look at this more closely. So you are talking about something like this? https://www.pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html

I'll post a reply later with more info. Thanks!

***OH, and you are not talking about EMI/RFI Noise right?
 
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