Humming...

Home Theatre Systems

unleash_me

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My apologies if this question is a repeat or a noobe one! I get a constant ??humm?? from my speakers when ever I connect any analogue inputs in my receiver (Denon 4306). How can I fix this?!

I see that on backside there is ??Signal Ground or Grounding/Polarization? near the Antenna section as well as around the center of the reciever, is it something I can fix this with?

Should I get the receiver serviced or is this something I should be fixing it from my end?

Thanks in advance!

http://usa.denon.com/avr4306_back_rdax_1200x462.jpg

Note: I asked this question elsewhere also, so common members please excuse:rolleyes:
 

suniil

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is it common for all analogue devices connected?

I'm sure you know all these, but just cross-checking

as a starting point, i would disconnect everything from the circuit except the AVR & one device connected to analogue inputs of AVR. If the hum still exists disconnect earthing from the circuit and test again. Please disconnect any arials / cable tv connection etc too before testing

when ever I connect any analogue inputs in my receiver (Denon 4306). How can I fix this?!
 
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dinyaar

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Hi Unleash,
Ya disconnect all and reconnect and see. Am not familiar with most AVR s but the signal ground should be only for a turn table. Are u using some extension box/power strip with an inbuilt fuse? My Nakamichi tapedeck had a hum when connected to a powerstrip but the hum vanished when directly plugged into the wall outlets. A tuner is also notorious for all kinds of induced noise. Are u using shielded ICs? Else move them a bit and see.
Actually i too am having some electrical interference in my set up and am considering an Isolation Transformer of 2KVA.
Regards
 

awedeophile

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Hi, I have had this problem in the past and could possibly help. Some questions:

1. How loud is the hum?
2. What equipment is connected to the receiver?
3. Is the hum constant regardless of the volume level?
4. Is any of the equipment connected to electrical earth via the mains plug?
5. What is the equipment that gives a hum when connected?
6. Is there hum even if the RCA's are connected to the receiver and not connected on the other end?
 

unleash_me

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Thank you all for helping me out here.

Sunil,

The ??humm? is common across all the analogue inputs. Don??t know how to disconnect the earthing as I haven??t done any earthing as such myself. And yes, I have not connected any aerials or cable tv connections, except for the FM receptor.

Dinyaar,

I??m not sure if the humming was always there, but yes I??m using an surge protector/extension-strip at the moment. When I noticed the buzz, I tried with at least 4 different extension-strips lately. Nothing seems to fix this. Infact, like you mentioned if an Isolation Transformer is the way to go, might as well try that. Btw, I have connected the extn strip to a 1kv servo stabilizer; don??t know if this helps.

Awedeophile,

Here are your answers buddy.

1. How loud is the hum?
Well it becomes noticeable from around -20db and becomes quite high when I go to the ??00?? level. Not to mention the upper limits.

2. What equipment is connected to the receiver?
TV audio-out, RCA to 3.5mm and a CDP at the moment with the respective analogue i/p in the reciever.

3. Is the hum constant regardless of the volume level?
No it is not. It increases with the volume level.

4. Is any of the equipment connected to electrical earth via the mains plug?
I??m completely unaware of this and frankly I don??t know how to do/undo this. I stay in an apartment complex, so don??t have any clue about the earthing circuitry-if I have understood you correctly.

5. What is the equipment that gives a hum when connected?
Interestingly, any equipment regardless of the respective input mentioned in the AVR, generates a humm. CDP give out more, in my opinion. I have mixed and matched all the sources in question and selected the respective mode in the reciever, the humm seems to be constant across the analogue inputs.

6. Is there hum even if the RCA's are connected to the receiver and not connected on the other end?
This is something I??ve not tried. Will do it tonight and let you know.

The fact is the "humm" is irritating the hell outta me, its like a bee buzzing around your head. Either I'm too sensitive regarding sound or my wife needs to consult an ENT, cuz she seems to be the least bothered with all this!:eek:

Again, thank you guys for chipping in. Really appreciate it. Awaiting for your response.:)
 

dinyaar

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Hi again,
If the hum can be heard its a problem that should be solved!!! U are using a 1KVA stabilizer for all the AV? Is that sufficient? Not that i feel thats the culprit. Try an Isolation transformer from some Bglore Co, as if it does not solve the problem u need not buy it.
Actually Awedeophile is a guru for all this. He suggested a UIT to me.
In my opinion ur problem could be related to the earthing.
Regards
 

awedeophile

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With everything else in place, remove the Cable TV wire from your TV and tell me if the hum goes or stays.

If any of your components has a 3 pin plug, you're probably connected to earth. In a 3 pin plug the top (thicker) one is the earth. Are any like this?
 

unleash_me

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With everything else in place, remove the Cable TV wire from your TV and tell me if the hum goes or stays.

If any of your components has a 3 pin plug, you're probably connected to earth. In a 3 pin plug the top (thicker) one is the earth. Are any like this?

I'll check the cable tv wire in the evening itself and yes, many of the components have 3pin plugs, so i guess the systems are earthed afterall.

thanks!
 

saikat

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I am also having a similar problem when i connect the headphone out of the laptop (hp pavilion dv5120us) to the aux-in of my amplifier. However connecting my dell latitude 420 has no issues.

Amp: NADC352
Cables: Monster RCA
Converter: RCA - EP

Common grounding between the amp and laptop.

Does impedance mismatches lead to hums?

Thanks,
Saikat.
 

unleash_me

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Well Saikat, since the dell is working fine, the problem seems to be with the headphone out of the HP. However, the only way to find out is to be just patient and try out every component in the system and nail the one that creates the humm.

In my case - with the help of sunill, dinyaar, awedeophile and mukund - I just kept checking every single component connected to my receiver. At the end, all I had to do was to just change the power strip I was using at that time!

All the best.
 

saikat

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Thanks unleash_me. I just figured out the problem. There is a micro-switch inside the earphone plug of the hp. Trying to be extra careful, I had just assumed that the jack was in all the way while it was merely stopping at the switch.

Shall remember to push it in a bit more the next time..[no puns intended..:D

-Saikat
 

dinyaar

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Hi Saikat/Unleash,
Glad that ur problems are solved saikat. Actually these locally made power strips which claim to have a surge protect/built in fuse etc etc are notorious for inducing hum and hence if u must use a power strip get one made. As i mentioned earlier somewhere my tapedeck always had a hum when used through a power strip which vanished when connected directly to the wall outlets. Finally i made a power strip with anchor switches/anchor plastic box/finolex 2.5 sq.mm wire for looping/ finolex 4 sq.mm 3 core cable. Worked well till i got my wiring re done.
Regards
 

venkatcr

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Dinyaar:

For a long time I have also been using power strips that were made by my electrician under my watchful eyes. I have used Finolex cables as well as Anchor sockets. These have worked well with Indian plugs. I have had issues with imported plugs such as those on mobile chargers, 2-in-1s etc, that do not sit properly. Though I have used the best adapters from Mx. I have burnt a items.

I recently came across a well made power strip by some company called Oxygen. These loog good and have 4 three pins sockets and 2 two ping sockets. They accept Indian, UK, US and other plugs. Best is all plugs are tight and site well removing my phobia with sparks. I have started slowing using these for all my electronic equipment. These strips come with a fuse and a surge protector.

Here is a photo for those who want to use them. They don't have any company or address, and you have to look for the product with the way the name 'Oxygen' is written.




Cheers
 
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