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slam5 06-01-2011 03:32 AM

humming speakers on iMac
 
Hi all, i have a VERY annoying problem here. I have a 24" iMac9,1. The first one that uses ddr3 type memory. it works completely fine EXCEPT it generates a very consistent hum on my speakers. I am using a pair of Monsoon MM900 2.1 speakers. It is getting so bad that I have to power off the speakers except when I am listening to music(that drown out the hum). The speaker is not the problem as I plug it in my unibody Macbook and the problem gone away. Also, it didn't hum when I hooked it up with my Core 2 Quad desktop. All my equipment is protect with a UPS. I did some research and people was suggesting it is a ground problem. I bought an very expensive ebtech ground filter. Nothing helps so far. Has anybody got any ideas? tx

Housekat 06-01-2011 08:13 AM

Do you get the humming through your iMac speakers? Or just through the external speakers when you plug them in.

slam5 06-01-2011 08:40 AM

humming speakers
 
Quote:

Originally Posted by Housekat (Post 1245826)
Do you get the humming through your iMac speakers? Or just through the external speakers when you plug them in.

Just the external speakers. I hooked my macbook unibody and my thinkpad and the problem isn't there.

EvenStranger 06-01-2011 10:16 AM

You may want to try a ground noise filter. I've seen them run anywhere from $14-20 online, but I did find one on Ebay with a BuyItNow price of $5.

eBay (US) : 3.5mm Headphone Jack Ground Loop Isolator Noise Filter (item 280594919631 end time Jun-24-11 08:30:06 )

slam5 06-01-2011 11:32 AM

filter
 
Quote:

Originally Posted by EvenStranger (Post 1245883)
You may want to try a ground noise filter. I've seen them run anywhere from $14-20 online, but I did find one on Ebay with a BuyItNow price of $5.

eBay (US) : 3.5mm Headphone Jack Ground Loop Isolator Noise Filter (item 280594919631 end time Jun-24-11 08:30:06 )

I got one of these:

Ebtech HUM-X Exterminator Ground Loop AC Eliminator | eBay

and it didn't seem to help. I think I will try your suggestion. $ 7 is small change compared to my $ 68 that I spend already. tx

ps: will post the result once I try it

Housekat 06-02-2011 07:06 AM

Its definitely something with your audio jack, you could also try a different pair of speakers and see if its just a freak of nature with the ones you currently have.

slam5 06-02-2011 10:25 AM

Quote:

Originally Posted by Housekat (Post 1246431)
Its definitely something with your audio jack, you could also try a different pair of speakers and see if its just a freak of nature with the ones you currently have.

Yeah, but why would this problem not manifest in my macbook or thinkpad? I've another pair of speakers, i will try them today. tx

Housekat 06-02-2011 10:39 AM

Well, the audio output power could be different, just a thought and won't really hurt in testing

50voltphantom 06-02-2011 10:32 PM

Sounds silly, but make sure the speaker plug is seated in all the way. Some plugs seat harder than others.

pedropete 06-02-2011 11:37 PM

Quote:

Originally Posted by slam5 (Post 1245742)
Hi all, i have a VERY annoying problem here. I have a 24" iMac9,1. The first one that uses ddr3 type memory. it works completely fine EXCEPT it generates a very consistent hum on my speakers. I am using a pair of Monsoon MM900 2.1 speakers. It is getting so bad that I have to power off the speakers except when I am listening to music(that drown out the hum). The speaker is not the problem as I plug it in my unibody Macbook and the problem gone away. Also, it didn't hum when I hooked it up with my Core 2 Quad desktop. All my equipment is protect with a UPS. I did some research and people was suggesting it is a ground problem. I bought an very expensive ebtech ground filter. Nothing helps so far. Has anybody got any ideas? tx

I've never felt the need for ext. speakers on any of my Macs!!

The inbuilt ones sound great to me - and I do like good audio

slam5 06-09-2011 07:17 PM

well
 
Quote:

Originally Posted by pedropete (Post 1246845)
I've never felt the need for ext. speakers on any of my Macs!!

The inbuilt ones sound great to me - and I do like good audio


well, these are monsoon flatpanel speakers. very good quality even that it hasn't been made in 6 years.

John T 06-10-2011 07:20 PM

Your problem sounds like an obvious earthing problem. The problem is most likely in the earthing of your speakers. Using a mains filter will have no effect on mains hum. The reason why you are not getting any hum when the speakers are connected to your laptop is because it is battery powered (and therefore isolated from the mains) and your iMac is obviously connected to the mains. Connecting your speakers to the iMac is obviously creating an earth loop.

slam5 06-10-2011 07:51 PM

well, i think you probably are absolutely correct. what do you think is a good solution? I absolutely love these speakers.

slam5 06-10-2011 07:54 PM

Come to think of it, I never had this problem when I was connected to my pc. Does the PC have better grounding than the iMac.

BrianLachoreVPI 06-10-2011 08:16 PM

Quote:

Originally Posted by slam5 (Post 1250824)
Come to think of it, I never had this problem when I was connected to my pc. Does the PC have better grounding than the iMac.

It definitely sounds like a grounding issue - as has been pointed out. Have you tried a different outlet - for instance - the one that the PC was in that didn't exhibit the problem? Turn off lights - and any other appliance/electronics that may share that outlet's circuit.

It just wouldn't make any sense for the PC to have "better" grounding, not as a general statement, unless you happen to have a grounding issue with your particular iMac for some reason - or perhaps just your audio jack. Maybe your UPS is introducing the hum?? Try it without.


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